Charly De Marez
email: charlydemarez@univ-brest.fr

Pierre L'hégaret

Mathieu Morvan

Xavier Carton

On the 3D structure of eddies in the Arabian Sea

Keywords: Mesoscale, Eddies, Oceanic Vortices, Arabian Sea, Argo, Sea of Oman

In the Arabian Sea, mesoscale eddies are prominent features of the circulation. They influence biological activities, tracer transport, and physical and chemical properties of the seawater. In particular, the pathways of salty water masses outflowing from the marginal seas are strongly impacted by the mesoscale eddies that evolve in the western part of the basin.

The impact of mesoscale eddies on the different salty water masses has been investigated in previous studies with altimetric data and in situ data for short durations. In this study, we extend this analysis to most of the mesoscale eddies detected from altimetry data for the period 2000-2015. We use Argo floats colocalized with eddies to describe the 3D impact of mesoscale eddies on the dynamical and thermohaline properties of water masses in the Arabian Sea. The ∼30,000 Argo stations used show a well characterized distribution of water masses in the different sub-basins of the Arabian Sea, with the Persian Gulf Water (PGW) flowing from the north and the Red Sea Outflow Water (RSOW) from the northwest.

In addition, colocalizing Argo profiles in or out of these eddies allows for the extraction of temperature and salinity anomalies related to mesoscale eddies. Then, we present the vertical structure of density associated with these eddies. These results allow us to divide the Arabian Sea into areas depending on their hydrological and dynamical properties. In the Gulf of Oman and the Gulf of Aden, the water in the core of eddies is fresher than at their edge. Thus, most of eddies residing in these gulfs were generated in the Arabian Sea. In these eddies, the salinity anomalies corresponding to PGW and RSOW are on average stronger at their edge than in their core; this indicates that eddies in these gulfs impact outflow waters via advecting processes on their rim. Finally, we select the northern part of the Arabian Sea (including the Gulf of Oman), where most Argo profiles were collected. We calculate

Introduction

Mesoscale eddies have a strong influence on the circulation in the Arabian Sea [START_REF] Fischer | Mesoscale eddies, coastal upwelling, and the upperocean heat budget in the Arabian Sea[END_REF]. This basin, located in the Northern Indian Ocean between the African and Asian landmasses, is a region dominated by the monsoon wind regime. This forcing generates reversing alongshore currents and upwellings, which are an essential part of the regional circulation [START_REF] Lee | The upper-ocean response to monsoonal forcing in the Arabian Sea: seasonal and spatial variability[END_REF]. The monsoon cycle is associated with strong and steady southwesterly winds across the basin in summer and with weaker northeasterly winds in winter [START_REF] Findlater | A major low-level air current near the Indian Ocean during the northern summer[END_REF]. This cycle leads to currents reversing in direction depending on the season, see Fig. 1 in L' Hégaret et al. (2018) which presents the mean surface circulation. In this region, quantities related to the spatial structure and to the magnitude of mesoscale activity, such as eddy kinetic energy [START_REF] Scharffenberg | Seasonal variations of the large-scale geostrophic flow field and eddy kinetic energy inferred from the TOPEX/Poseidon and Jason-1 tandem mission data[END_REF] or eddy available potential Energy [START_REF] Roullet | Global interior eddy available potential energy diagnosed from Argo floats[END_REF], have values comparable with those of other eddy rich regions (e.g the Antarctic Circumpolar Current or the Agulhas Current). Indeed, the alongshore currents destabilize and form meanders with 100-200 km wavelengths; they produce eddies with similar diameters [START_REF] Schott | The monsoon circulation of the Indian Ocean[END_REF]. Wind stress forcing, and baroclinic Rossby waves generated at the eastern boundary of the Arabian Sea, can strengthen such eddies or contribute to their propagation [START_REF] Saafani | Westward movement of eddies into the Gulf of Aden from the Arabian Sea[END_REF]. The specific places mentioned in the article are indicated in Fig. 1. Also, we refer the reader to Fig. 2 in [START_REF] Vic | Mesoscale dynamics in the Arabian Sea and a focus on the Great Whirl life cycle: A numerical investigation using ROMS[END_REF] for a description of the mean stationary eddies such as the Great Whirl and the dipole of Ras Al Hadd.

In the global ocean, mesoscale eddies influence biological activities [START_REF] Chelton | The Influence of Nonlinear Mesoscale Eddies on Near-Surface Oceanic Chlorophyll[END_REF], tracer transport [START_REF] Zhang | Oceanic mass transport by mesoscale eddies[END_REF], and physical and chemical properties of the water column [START_REF] Dong | Global heat and salt transports by eddy movement[END_REF]. In the Arabian Sea, understanding the evolution of eddies is of primary importance: they carry and upwell/downwell (depending on the eddy polarity) oxygen and nutrients [START_REF] Queste | Physical Controls on Oxygen Distribution and Denitrification Potential in the North West Arabian Sea[END_REF], and modulate plankton blooms [START_REF] Tollefson | Ocean scientists work to forecast huge plankton blooms in Arabian Sea[END_REF] and green algae generation [START_REF] Do Rosario Gomes | Massive outbreaks of Noctiluca scintillans blooms in the Arabian Sea due to spread of hypoxia[END_REF], which impact the fishing economy, sustaining 120 million people living on the rim of the Arabian Sea. Moreover, the eddy-driven circulation of the Arabian Sea strongly impacts the spreading of the dense salty water masses outflowing from the adjacent marginal seas [START_REF] Bower | Mesoscale eddies in the Gulf of Aden and their impact on the spreading of Red Sea Outflow Water[END_REF][START_REF] Carton | Mesoscale variability of water masses in the Arabian Sea as revealed by Argo floats[END_REF]. [START_REF] Smith | Global Sea Floor Topography from Satellite Altimetry and Ship Depth Soundings[END_REF].

In the Persian Gulf, a shallow (<100 m depth) semi-enclosed basin, warm and salty water is formed via evaporation near the western boundary [START_REF] Pous | A model of the general circulation in the Persian Gulf and in the Strait of Hormuz: Intraseasonal to interannual variability[END_REF]. This water mass is called the Persian Gulf Water (PGW). After flowing through the Strait of Hormuz, the PGW stabilizes between 200 and 300 m depth and spreads into the Gulf of Oman and into the Arabian Sea [START_REF] Bower | Character and dynamics of the Red Sea and Persian Gulf outflows[END_REF]. Similarly, the Gulf of Aden receives dense and saline water, the Red Sea Outflow Water (RSOW), which is formed in the Red Sea and outflows in the Arabian Sea through the shallow Strait of Bab al Mandeb (∼150 m) before swiftly descending between 500 and 1000 m depth [START_REF] Bower | Character and dynamics of the Red Sea and Persian Gulf outflows[END_REF].

The common point between these two outflows is that the spreading of the saltier waters into the Arabian Sea strongly depends on the mesoscale structures lying in the gulfs [START_REF] Bower | Gulf of Aden eddies and their impact on Red Sea Water[END_REF][START_REF] Bower | Mesoscale eddies in the Gulf of Aden and their impact on the spreading of Red Sea Outflow Water[END_REF][START_REF] Ilicak | How does the Red Sea outflow water interact with Gulf of Aden Eddies?[END_REF][START_REF] Vic | Mesoscale dynamics in the Arabian Sea and a focus on the Great Whirl life cycle: A numerical investigation using ROMS[END_REF]. For instance, in the Gulf of Oman, during the spring intermonsoon, a recurrent cyclone near Ras al Hamra advects the outflowing water away from the coast of Oman, sending northward pulses of PGW from the Omani coast to the Iranian coast [START_REF] L'hégaret | Mesoscale variability in the Arabian Sea from HYCOM model results and observations: impact on the Persian Gulf Water path[END_REF]. Similar advective processes take place in the Gulf of Aden, where the outflow is stirred by gulf-size eddies [START_REF] Bower | Gulf of Aden eddies and their impact on Red Sea Water[END_REF][START_REF] Ilicak | How does the Red Sea outflow water interact with Gulf of Aden Eddies?[END_REF]. When the RSOW and the PGW reach the Arabian Sea, they can be detected far from the gulfs, as far south as 25 • S for the RSOW and 5-10 • N for the PGW [START_REF] Quadfasel | Water-Mass Distributions at Intermediate Layers off the Somali Coast during the Onset of the Southwest Monsoon[END_REF]. In particular, these water masses have been observed in the core of mesoscale eddies, indicating that they may be trapped by such eddies, and that they can travel southward in them [START_REF] L'hégaret | Mesoscale variability in the Arabian Sea from HYCOM model results and observations: impact on the Persian Gulf Water path[END_REF]. Moreover, it has been shown that the salinity anomalies associated with waters flowing out of the Persian Gulf and of the Red Sea into the Arabian Sea have increased during the past fifty years. This increase is concordant with the broad-scale surface warming and with the intensification of the global hydrological cycle [START_REF] Durack | Fifty-Year Trends in Global Ocean Salinities and Their Relationship to Broad-Scale Warming[END_REF]. It is thus essential and timely to determine what is, on average, the 3D structure of eddies in the Arabian Sea to further discuss the physical processes involved in the mesoscale eddy/outflow interactions.

Previous observational studies provided a few snapshots of eddy vertical structure in the Arabian Sea [START_REF] Carton | Mesoscale variability of water masses in the Arabian Sea as revealed by Argo floats[END_REF][START_REF] L'hégaret | Mesoscale eddies and submesoscale structures of Persian Gulf Water off the Omani coast in spring 2011[END_REF], or showed the surface properties of such eddies [START_REF] Trott | Eddy Tracking in the Northwestern Indian Ocean During Southwest Monsoon Regimes[END_REF]. However, the systematic study of the 3D structure of eddies from in situ data in the Arabian Sea is lacking. To obtain the 3D structure of eddies in a specific area, several observational methods can be used. Either a given eddy can be sampled by many vertical profiles [START_REF] Zhang | Observed 3D Structure, Generation, and Dissipation of Oceanic Mesoscale Eddies in the South China Sea[END_REF][START_REF] Souza | Estimation of the Agulhas ring impacts on meridional heat fluxes and transport using Argo floats and satellite data[END_REF]; or, the 3D structure of a 'composite' eddy can be obtained via the analysis of Argo float data in the core of different eddies [START_REF] Chaigneau | Vertical structure of mesoscale eddies in the eastern South Pacific Ocean: A composite analy-sis from altimetry and Argo profiling floats[END_REF][START_REF] Yang | Mesoscale eddies in the northwestern subtropical Pacific Ocean: Statistical characteristics and three-dimensional structures[END_REF][START_REF] Pegliasco | Main eddy vertical structures observed in the four major Eastern Boundary Upwelling Systems[END_REF][START_REF] Keppler | Observed Characteristics and Vertical Structure of Mesoscale Eddies in the Southwest Tropical Pacific[END_REF]. It is now possible to consider the latter method to study eddies in the Arabian Sea. New altimetric products with 1/8 • resolution combining different missions are now available. They resolve more accurately eddies with radii twice or thrice the first baroclinic Rossby radius of deformation (wich is between 50 and 100 km in the Arabian Sea).

Furthermore, with the increase in Argo Float deployments, the water column properties are more densely sampled in the Arabian Sea. Thus, the vertical properties of eddies in this area can be studied more precisely.

In this paper, we study the 3D properties of eddies in the Arabian Sea. Unlike previous studies, we study the average structure of eddies using a composite approach. We address the following questions: (1) Do eddies in the Arabian Sea exhibit different vertical patterns depending on their geographic area ? (2) What is the average 3D shape of mesoscale eddies in the Arabian Sea ? (3) Which water masses of the Arabian Sea can be detected inside eddies ?

In section 2, we present the dataset and the methods. Then, we use Argo floats to study the dynamical and hydrological properties of eddies in the different sub-basins of the Arabian Sea, and to compute a composite 3D structure of eddies in the northern Arabian Sea.

Methods and materials

Argo floats

Profiles collected by Argo floats in the period 2000-2015 in the region of interest (30 • E to 80 • E and 5 • N to 30 • N) are used to determine the vertical structure of the water column inside and outside mesoscale eddies. Only profiles containing both temperature (T) and salinity (S) data flagged as 'good' were downloaded from the Coriolis website (www.coriolis.eu.org).

This dataset consists of 45,978 profiles (i.e T, S and pressure (P) data at a given time) non-uniformly distributed in the region (Fig. 2(a)). The number of profiles increases with time such that about half of the available profiles (21,113), were collected between 2012 and 2015. Contrary to this interannual trend, there is no seasonal bias in sampling: profiles are uniformly distributed in time for each year, with a median of 4,162 profiles per month for the 2000-2015 period.

Once the data were downloaded from the Argo repository we did additional processing, as follows. Firstly, any profile containing fewer than five measurment or sampling less than 10% of the water column was discarded. These two conditions discarded profiles concentrated near the surface and thus diminish biases in statistics. Secondly, profiles with suspicious variations of salinity and temperature at the bottom were removed. 29,516 profiles representing 64% of the initial dataset remained after these quality controls. Then, the depth (z), the density (ρ), the conservative temperature (CT) and the absolute salinity (SA) at each station were computed from the T, S and P profiles using the Gibbs SeaWater (GSW) Oceanographic Toolbox [START_REF] Mcdougall | Getting started with TEOS-10 and the Gibbs Seawater (GSW)[END_REF] which uses the TEOS-10 equation of state for seawater (http://www.teos-10.org). The profiles were then linearly interpolated on 500 regularly spaced vertical levels in the range 0 to 2200 m, similar to the method used in Chaigneau et al. (2011). This interpolation retains small scale variations on the vertical, without creating artificial water masses where data are missing. In this study, data will be averaged over numerous profiles to extract mean T, S and ρ profiles inside and outside eddies.

Surface drifters

To obtain an in situ estimate of surface velocities in eddies, we use the position and horizontal velocity data from 15-m drogued drifters of the Global Drifter Program (GDP).

The dataset consists in 39,247 values of velocities distributed over the regions of interest for the 2000-2015 period. For further information on these data see [START_REF] Lumpkin | Lagrangian Analysis and Prediction of Coastal and Ocean Dynamics[END_REF] and [START_REF] Laurindo | An improved near-surface velocity climatology for the global ocean from drifter observations[END_REF]. The density of drifters is directly related to the surface flow convergence and divergence, with a maximum number of drifters located where velocities are weak and the convergence is large [START_REF] L'hégaret | Shallow CrossEquatorial Gyres of the Indian Ocean Driven by Seasonally Reversing Monsoon Winds[END_REF]. In our case, most drifters were located on the Eastern boundary of the Arabian basin and at latitudes lower than 20 • N (Fig. 2(b)).

Eddy detection from altimetry

A regional 1/8 • resolution altimetric product is used to detect mesoscale structures in the Arabian Sea for the 2000-2015 period. This specific altimetric series was processed by Collecte Localisation Satellites (CLS) and features interpolated absolute dynamical topography (ADT) and surface geostrophic velocities on a daily Mercator grid. It combines up-to-date datasets from different available missions (Topex/Poseidon, ERS-2, GFOO, Jason-1, Envisat, Jason-2, Cryosat-2, Altika and HY2A). A snapshot of ADT and surface velocity from this product in the region of interest is presented in Fig. 2(d). As discussed in previous studies [START_REF] Le Traon | An Improved Mapping Method of Multisatellite Altimeter Data[END_REF][START_REF] Vu | Angular Momentum Eddy Detection and Tracking Algorithm (AMEDA) and Its Application to Coastal Eddy Formation[END_REF], nonphysical fluctuations or distortions in this 1/8 • gridded product could be induced by the spatiotemporal heterogeneity of the satellites' tracks. This leads to errors of O( 1 We used the Angular Momentum Eddy Detection and tracking Algorithm (AMEDA), recently developed and optimized by [START_REF] Vu | Angular Momentum Eddy Detection and Tracking Algorithm (AMEDA) and Its Application to Coastal Eddy Formation[END_REF] to detect mesoscale eddies in this area. One of the benefits of AMEDA is that it does not depend on arbitrary thresholding, which would require a fine-tuning of geometrical parameters. Also, the algorithm is robust with respect to the grid resolution and can thus be applied to a wide variety of velocity fields (experimental, numerical, altimetry...). This algorithm works as follows: (a) from the velocity fields, it computes the local normalized angular momentum (LNAM), as defined in [START_REF] Mkhinini | Long-lived mesoscale eddies in the eastern Mediterranean Sea: Analysis of 20 years of AVISO geostrophic velocities[END_REF] and the local Okubo-Weiss parameter (LOW) at each point; (b) then, it seeks LNAM local maxima where LOW<0; (c) if these maxima are surrounded by a closed streamline, they are flagged as eddy centers. A full description of the algorithm is presented in Fig. 1 of Le [START_REF] Vu | Angular Momentum Eddy Detection and Tracking Algorithm (AMEDA) and Its Application to Coastal Eddy Formation[END_REF].

For a detected eddy, the algorithm gives, among other information, the position of the eddy center, its shape, defined as the largest closed streamline, its polarity, and the day of detection. As shown in Le [START_REF] Vu | Angular Momentum Eddy Detection and Tracking Algorithm (AMEDA) and Its Application to Coastal Eddy Formation[END_REF] the altimetric product detailed above allows the accurate detection of mesoscale eddies when their characteristic radius is larger than the local Deformation Radius R D [START_REF] Chelton | Geographical Variability of the First Baroclinic Rossby Radius of Deformation[END_REF], which is about 50 km in the northern Arabian Sea (∼ 25 • N) and 100 km in the southern part of our domain (∼ 5 • N).

Applied to altimetric data, AMEDA detected 489,562 eddy occurrences for the whole period. Eddy occurrences are not indicative of unique eddies. The AMEDA algorithm would identify an eddy occurring in the same location on two subsequent time steps as two eddy occurrences, although this would (most likely) be the same eddy. An example of such detection is shown in Fig. 2(d) at a given time (2013-12-26). As in [START_REF] Trott | Eddy Tracking in the Northwestern Indian Ocean During Southwest Monsoon Regimes[END_REF] the number of eddies in the Arabian Sea is roughly constant throughout the years, with a median of 30,450 eddies detected per year. The radius of detected eddies also increases as latitude decreases, with a standard deviation of the eddy radii of 172 km at 5 • N, and 58 km at 25 • N.

The northern part of the basin, north of 17 • N, is the region where AMEDA detected the most eddies (Fig. 2(c)); most likely because of the decrease of the eddy radius from the equator northward.

Methodology of colocalization

To characterize the 3D structure of eddies we implemented an algorithm of colocalization allowing to determine if either an Argo float or a surface drifter lies inside or outside an eddy detected by the AMEDA algorithm. The method is here illustrated with Argo profiles, but the algorithm works the same on surface drifters dataset. Every day, we seek all Argo profiles collected. Then, for each eddy detected on this day, we check if an Argo float has surfaced inside the streamline defining the eddy contour. To do so, the eddy contour is decomposed into a 20-vertex polygon. A 'point-in-polygon' algorithm is then used to determine if the float is inside the eddy. If this condition is met, the Argo profile is flagged as 'colocalized'. An example of such colocalization is presented in Fig. 3. We also collect the surface geostrophic velocity at the position of the Argo float from the altimetric dataset. All Argo profiles which have not been colocalized are flagged as 'out of eddies'; they will allow us to compute thermohaline climatologies out of eddies. This method could lead to errors due to the misevaluation of the eddy position at the moment of Argo float sampling, due to the time interpolation of the altimetric product. Thus, we seek Argo floats surfacing within ±12hours around the time of eddy detection by altimetry. The tolerance is set knowing that the typical time for an Argo float to achieve a profile is about 5 hours (2000 m of ascent at ∼ 10 cm s -1 for APEX and SOLO floats) and the transmission time varies between an hour and a dozen of hours (depending on the transmission system). As discussed in [START_REF] Chaigneau | Vertical structure of mesoscale eddies in the eastern South Pacific Ocean: A composite analy-sis from altimetry and Argo profiling floats[END_REF] or [START_REF] Keppler | Observed Characteristics and Vertical Structure of Mesoscale Eddies in the Southwest Tropical Pacific[END_REF], this error may lead to a misevaluation of the distance between the center of the eddy and the profiles of O(1 -5) km. In the case of an Argo float lying close to the contour of an eddy, this error could cause a false classification of the profile inside or outside this eddy.

The dimensionless position with respect to the center of the eddy is computed for each colocalized Argo position (Fig. 3). The Euclidean distance between the center of the eddy and the Argo position defines a distance dR. We then compute a local radius of the eddy R by finding the intersection between the eddy contour and a straight line which passes through the center of the eddy and the Argo position. The dimensionless position is defined as r = dR/R. If r = 0, the profile is collected at the center of the eddy; if r = 1 the profile is collected on the edge of the eddy. This calculation allows us to calculate average density profiles in each radial section in a given eddy, without taking into account its actual shape (i.e this means that we reshape each eddy to a circular form).

To summarize, for all eddies where Argo floats were colocalized, we have:

• The position of the center of the eddy;

• The horizontal shape of the eddy;

• Profiles of T, S, ρ and P(z) collected by Argo floats within the eddy;

• Surface geostrophic velocities at the position of the floats;

• Dimensionless position of the profiles with respect to the center of the eddy r.

Composite eddy calculation

To determine the 3D structure of eddies, we need a vertical representation of the thermohaline and dynamic properties in the range r ∈ [0, 1]. To do so we use a composite approach by considering numerous eddies in a given area, assuming that they have similar characteristics, as for instance in [START_REF] Chaigneau | Vertical structure of mesoscale eddies in the eastern South Pacific Ocean: A composite analy-sis from altimetry and Argo profiling floats[END_REF]. This method is then applied to eddies lying in the northern Arabian Sea.

All the eddies considered are assumed axisymmetric. All profiles with the same r are localized on the same circle around the center of a 'normalized eddy'. If we assume that the properties of eddies do not depend on the angular position within the eddy, the circle of constant r collapses into a radial point. Therefore, we compute mean profiles of T, S and ρ for all r comprised in bins of dimensionless width 0.05. Note that the number of profiles per bin is higher towards the edge than at the center (Fig. 4(top panel)), giving a better confidence in the averages for 0.5 < r < 1. For T, S and ρ we may thus compute 2D fields T (r, z), S(r, z) and ρ(r, z) representing the variations of thermohaline properties in the core of the chosen eddies.

We assume that the stratification out of the composite eddy is well represented by the average of density profiles outside eddies in the area encompassing the composite. We use this mean profile for ρ(r, z) where r > 1. Values for r < 0 are mirrored from values at r > 0. This method is used to smooth the density field at the center of the eddy (where r = 0) and at its edge, without discarding values at these locations during the smoothing (Fig. 4(bottom panel)). The density ρ(r, z) is horizontally smoothed using a Gaussian kernel of width σ = 0.3, removing all density variations over distances smaller than 4 measurement points, using altimetric data with 1/8 • resolution. In the area considered, the mean radius of eddies is about 120 km. The smoothing thus operates over scales smaller than 40 km. This smoothing removes sharp density gradients over small distances, which may have altered the geostrophic velocities calculation. We thus obtain a smooth density field ρ s (r, z) without assuming any analytic shape of eddies (contrary to [START_REF] Keppler | Observed Characteristics and Vertical Structure of Mesoscale Eddies in the Southwest Tropical Pacific[END_REF]).

We use the thermal wind equations to compute the eddy-induced angular velocity. By considering geostrophic equilibrium and hydrostatics, the geostrophic velocities can be calculated in polar coordinates as:

f ∂ z u θ = -1 ρ 0 g ∂ r ρ s (r, z), (1)
where (r, θ) are respectively the radial and angular directions [START_REF] Gill | Atmosphere Ocean dynamics[END_REF]. The average Rossby number of the eddies in this study being weak, R o ∼ 0.05, no cyclogeostrophic correction is applied [START_REF] Ioannou | Dynamical Evolution of Intense Ierapetra Eddies on a 22 Year Long Period[END_REF]. R o is calculated using the velocity of the altimetric dataset at the location of the Argo profiles we considered to compute the composite. We also assume that density varies only radially, so that u r = 0. In the obtained sections, the density anomaly vanishes below the positive (resp. negative) anomalies for cyclones (resp.

anticyclones). This results from density averaging at depth. We assumed a level of no motion at 1500 m depth (u θ (-1500 m) = 0). This is the maximum common dive depth for the Argo floats considered in the northern Arabian Sea. This assumption, used in previous studies [START_REF] Chaigneau | Vertical structure of mesoscale eddies in the eastern South Pacific Ocean: A composite analy-sis from altimetry and Argo profiling floats[END_REF][START_REF] Keppler | Observed Characteristics and Vertical Structure of Mesoscale Eddies in the Southwest Tropical Pacific[END_REF], may underestimate the velocity since deep motion is assumed nil. Finally, we obtain the azimuthal velocity with:

u θ (r, z) = -f ρ 0 g z -1500 m ∂ r ρ s (r, z) dz. (2)
The error in density composite structure with respect to the density values of the Argo profiles is estimated. It is the relative Root Mean Square Error between the value of density of the composite ρ s (x, y, z) and the actual Argo-collected value at the same location ρ A (x, y, z), such as:

Relative error = ρ A (x, y, z) 2 -ρ s (x, y, z) 2 ρ A (x, y, z) .
The horizontal extension of the composite structure is re-dimensionalized by the mean radius of eddies used for its creation, and is projected on the (x, y) coordinate following the usual polar to Cartesian coordinate transformation. Notice that in this calculation, the Argo profile locations with respect to the center of the eddy are expressed in Cartesian coordinates (x, y), to take into account the actual distribution of floats in space. Here we study the density computed from the conductivity and the temperature collected by a SeaSoar.

Results

We present here the results of our study. First, we show that the Arabian Sea can be divided into different areas, based on their thermohaline properties and the values of the First Baroclinic Rossby Radius of Deformation R D . We then focus on the dynamical properties of eddies in the different areas and we isolate the surface cyclonic eddies (CE) and subsurface anticyclonic eddies (AE) with radii R D < R < 3 R D in the northern Arabian Sea. We finally present the composite eddies computed for these two classes of eddies.

Distribution of water masses

The Arabian Sea is decomposed into 6 areas: 2 areas which directly cover the outflows from the Persian Gulf and the Red Sea: the Gulf of Oman and the Gulf of Aden; and 4 areas which have distinct water mass signatures, see Fig. 5(a). The number of Argo profiles collected in each area, depending on their position inside or outside eddies is presented in Table 1. Though most Argo profiles were collected in the northern Arabian Sea, and at the southeastern boundary (area C), the number of profiles collected in each area is sufficient The TS-diagrams we present correspond to the usual description of the water masses presented in Fig. 1 of [START_REF] Quadfasel | Water-Mass Distributions at Intermediate Layers off the Somali Coast during the Onset of the Southwest Monsoon[END_REF].

First of all, we isolate the two Gulfs at the western and the northern boundary of the basin: the Gulf of Aden (GA) and the Gulf of Oman (GO). These two areas are known as areas were RSOW and PGW flow out from the Red Sea and the Persian Gulf [START_REF] Bower | Character and dynamics of the Red Sea and Persian Gulf outflows[END_REF][START_REF] Carton | Mesoscale variability of water masses in the Arabian Sea as revealed by Argo floats[END_REF]. In the GA, TS-profiles exhibit a clear peak centered on the 27 kg m -3 σ 0 -level. This signature is typical of the Red Sea outflow which stabilizes between 600 and 1000 m depth in the GA [START_REF] Bower | Mesoscale eddies in the Gulf of Aden and their impact on the spreading of Red Sea Outflow Water[END_REF]. Similarly, the TS-diagram of the GO area reveals the PGW signature, with an anomaly centered at 300 m depth between the 26 and the 27 kg m -3 σ 0 -levels.

We compare the mean TS-profiles collected inside and outside eddies in these two areas (Fig. 6). We averaged profiles depending on their position in the eddy where they lay.

Note that the number of profiles collected near the center of eddies, for r < 0.25 is much smaller than at their edges; also, more profiles were collected in the GO than in the GA, giving a better confidence in the results concerning the GO. The peaks on the TS-profiles corresponding to the RSOW and the PGW decrease radially inward in the eddies. Such eddies are often generated at the mouth of the gulfs, where the outflow salinity is weaker than west of the gulfs. Since these eddies propagate westward in the gulfs, they encounter saltier outflow waters (Al [START_REF] Saafani | Westward movement of eddies into the Gulf of Aden from the Arabian Sea[END_REF] in the GA) and thus the radial salinity difference increases. Nevertheless, due to their non uniform rotation, these eddies stir the external waters (the outflow waters) at their edge. PGW or RSOW are clearly present at the eddy rim (for 0.5 < r < 1); a large number of profiles gives a fairly good confidence into these results (296 in the GA and 845 in the GO). Thus, the outflows are also steered by these eddies, as demonstrated in the GA by [START_REF] Bower | Gulf of Aden eddies and their impact on Red Sea Water[END_REF] or [START_REF] Ilicak | How does the Red Sea outflow water interact with Gulf of Aden Eddies?[END_REF] and in the GO by [START_REF] Vic | Eddytopography interactions and the fate of the Persian Gulf Outflow[END_REF]. Our results substantiate the idea that eddies influence the spreading of PGW and RSOW in the GO and the GA via advective processes. Between the two Gulfs, along the southern coast of the Arabian Peninsula, we define area A, where outflows from the Red Sea and the Persian Gulf meet (see for instance Fig. 20 in [START_REF] Carton | Mesoscale variability of water masses in the Arabian Sea as revealed by Argo floats[END_REF], which shows an Argo float, sampling both PGW and RSOW, near 55 • E, 15 • N). We confirm this by detecting weak peaks in the TS-diagram of this area at the σ 0 -levels of PGW and RSOW.

Then, we isolate the Somali Basin (area B), where in summer, the Great Whirl (GW), a large quasi-stationary eddy develops at the northern part of the Somali Current (see L'Hégaret et al. ( 2018) for a discussion on the circulation in this region, and [START_REF] Vic | Mesoscale dynamics in the Arabian Sea and a focus on the Great Whirl life cycle: A numerical investigation using ROMS[END_REF] for a description of the GW). Many water masses are present in this region; their distribution also depends on the season because of the monsoon regimes. However it has been shown that RSOW can clearly be identified there [START_REF] Warren | Water masses and patterns of flow in the Somali Basin during the southwest monsoon of 1964[END_REF][START_REF] Quadfasel | Water-Mass Distributions at Intermediate Layers off the Somali Coast during the Onset of the Southwest Monsoon[END_REF]. We observe RSOW in the TS-diagram of area B, with a peak at the 27 kg m -3 σ 0 -level; this peak is weaker than in the GA, showing that RSOW has been mixed with surrounding waters through its journey out of the GA.

Area C corresponds to the southeastern part of the Arabian Sea, where Bay of Bengal Water (BBW) flows into the Arabian Sea during the northern monsoon (winter), via the Northeast Monsoon Current [START_REF] Kumar | Salinity distribution in the Arabian Sea[END_REF][START_REF] L'hégaret | Shallow CrossEquatorial Gyres of the Indian Ocean Driven by Seasonally Reversing Monsoon Winds[END_REF]. In the TSdiagram of this area, lighter and fresher water is detected at the surface. Its T/S properties show evidence of BBW in area C. Denser, saltier water, called Arabian Sea High-Salinity Water (ASHSW) is also found; it is formed in the north of the basin (near 20 • N) in winter, and it spreads southward below the surface, on the 24 kg m -3 σ 0 -level [START_REF] Kumar | Formation and spreading of Arabian Sea highsalinity water mass[END_REF]. A weak peak of PGW is also detected; therefore, water from the Persian Gulf may spread this far south.

Finally, we isolate the northern part of the Arabian Sea, called area D. As mentioned above, this place is the site of formation of ASHSW in winter, and we observe the presence of this water mass in the TS-diagram, with denser saltier water located in subsurface. As shown in [START_REF] Carton | Mesoscale variability of water masses in the Arabian Sea as revealed by Argo floats[END_REF] (their appendix A), the salinity and the temperature at 300 m depth is larger north of 16 • N, with a fairly constant zonal distribution. This pattern is mostly due to the spreading of PGW in this part of the basin. We confirm this by detecting a large peak of salinity at the σ 0 -level corresponding to the depth of stabilization of PGW in this area.

In the Arabian Sea, R D varies meridionally and zonally. The mean values of R D are thus different in areas A, B, C and D [START_REF] Chelton | Geographical Variability of the First Baroclinic Rossby Radius of Deformation[END_REF]. Therefore, the horizontal structure of eddies will be different depending on the area they lie into. In particular, areas B and C

respectively have mean values of R D of 141 and 131 km while areas A and D, have mean values of R D of 66 and 51 km. This is due to the increase of R D as latitude decreases.

Similarly, the mean values of R D are larger at the western boundary (area B compared to area C for instance). The Arabian Sea decomposition into specific areas we made thus takes into account these meridional and zonal gradients.

To further discuss the dynamical properties of eddies, we choose to merge the GO area and the area D, and we define a largest area representing the northern Arabian Sea (NAS area hereafter, see 5(a)). This area merging provides more Argo profiles to compute 3D composite structures of eddies. It is justified by the following observations. ( 1) As we can notice in Fig. 5(b), the TS-profiles of area D and GO are similar, even though the peak of PGW is weaker in area D because of its distance from the the Persian Gulf. ( 2) In these two areas, R D is roughly constant, with an average of about 48 km, and a standard deviation of 8 km, meaning that the horizontal properties of isolated eddies may be fairly homogeneous.

(3) As mentioned above, and as shown in Fig. 6, eddies lying in the GO are most likely generated outside of the gulf. The merging of the two areas thus allows us to span the entire lifetime of eddies generated at the eastern part of the basin, and traveling westward into the GO.

Mean dynamical properties of eddies as revealed by Argo floats

An outside-eddy density climatology is constructed by averaging all outside-eddy density profiles in a specific area. For each profile localized inside eddies, we compute density anomaly profiles with respect to this climatology, and we differentiate profiles collected inside a CE or AE.

As presented in ASSASSI (see their Fig. 2), four classes of eddy may be observed: surfaceintensified CE, surface-intensified AE, subsurface-intensified CE, and subsurface-intensified AE. Surface-intensified eddies are characterized by a maximum of density anomaly at the surface; positive for the CE, and negative for the AE. Subsurface-intensified eddies have a maximum density anomaly at depth. We filtered the profiles collected inside eddies depending on the depth of their maximum density anomaly. All profiles localized inside CE (resp.

AE) with a maximum (resp. minimum) of density anomaly above 50 m depth are flagged as 'surface-intensified', while the profiles with a maximum (resp. minimum) between 600 m and 50 m depth are flagged as 'subsurface-intensified'. We then average anomalies depending on the distance r between the profile location and the center of the eddy (Fig. 7). We indicate in Fig. 7 the number of profiles used for each average, and the standard deviation associated with it. Notice that for some areas (e.g in the GA and surface-intensified eddies in area A, B and C), the number of profiles is weak with large standard deviations, giving a poor confidence in their density anomaly profiles. For instance in the GA the small number of profiles may lead to a bias due to the sampling of only a few eddies by Argo floats.

The density anomaly profiles obtained are in agreement with the standard structures of 20 CE and AE in stratified and rotating flows [START_REF] Vallis | Atmospheric and oceanic fluid dynamics[END_REF]. Indeed, CE have a positive density anomaly while AE have a negative one, consistent with thermal wind balance (a surfaceintensified cyclonic flow forces isopycnals to rise while an anticyclonic flow makes isopycnals dive creating respectively positive and negative density anomalies). Moreover, for each area where enough profiles were collected at the center of eddies, we clearly notice that the norm of the anomaly intensity decreases as r increases. It results from the fact that the density at the edge of eddies tends toward the climatology out of eddies.

The maximum density anomalies are observed for subsurface-intensified AE in area B,

where the GW develops in summer. As shown in [START_REF] Trott | Eddy Tracking in the Northwestern Indian Ocean During Southwest Monsoon Regimes[END_REF], the GW has a radius and an intensity larger than those of most eddies in the Northwestern Indian Ocean. Its velocity maximum, up to 1 m s -1 , lies between 100 and 200 m depth [START_REF] Beal | The Great Whirl: Observations of its seasonal development and interannual variability[END_REF][START_REF] Vic | Mesoscale dynamics in the Arabian Sea and a focus on the Great Whirl life cycle: A numerical investigation using ROMS[END_REF]; at this depth, also lies the maximum of density anomaly of AE that we observe in area B.

To compute a 3D composite structure of eddies, we focus on the two categories of eddies with the highest sampling rate: surface-intensified CE and subsurface-intensified AE in the NAS. The maximum density anomaly of subsurface AE is relatively spread out there with a peak near 200 m depth, while surface-intensified CE have a well-marked peak near 30 m depth.

Isolating specific classes of eddies

We notice different spatial and seasonal patterns of eddies in the different regions (Fig. 8). In the GA, most eddies have radii between 100 and 150 km. Such eddies fill the whole Gulf of Aden, where they often form a row of alternate polarities [START_REF] Bower | Mesoscale eddies in the Gulf of Aden and their impact on the spreading of Red Sea Outflow Water[END_REF].

The size of eddies in this area is thus directly related to the size of the Gulf. Areas B and C being closer to the equator, R D is large and so are the detected eddies in these regions (as shown for instance in Smith ( 2007)). In area B, we again notice the influence of the Great Whirl, with more floats colocalized during the summer and fall, in large AE (see purple line in the panel corresponding to AE with radii R D < R < 3 R D in Fig. 8).

Nevertheless, most colocalized floats were found in eddies of radii

R D < R < 3 R D ,
regardless of the region. Indeed, AMEDA more accurately detects eddies larger than R D The black contoured yellow lines correspond to the floats we consider to compute the composite structures.

Notice that the y-scales are not the same depending on the radius classes.

(Le [START_REF] Vu | Angular Momentum Eddy Detection and Tracking Algorithm (AMEDA) and Its Application to Coastal Eddy Formation[END_REF]. The upper boundary (3 R D ) for single eddy detection is associated with eddy interactions, such as eddy merger or splitting into smaller ones, or dissipation by interaction with topography. Splitting and topographic bottom friction reduce the lifetime of eddies with large radii while merging extends it.

Hereafter, we focus on the region with the highest sampling rate by Argo floats: the northern Arabian Sea (NAS). We exclude eddies with radii smaller than R D because these small eddies may result from detection errors, and may have dynamics more transient than that of larger mesoscale eddies. Eddies larger than 3 R D are also excluded to avoid the inclusion of contours surrounding multiple close eddies. In the NAS we can also construct a generic 3D eddy shape during the whole year, since the number of floats colocalized is large throughout the year (> 100 per month). We search for a possible generic 3D structure of surface-intensified CE and subsurfaceintensified AE with R D < R < 3 R D in the NAS area, by using the colocalized Argo profiles in such eddies. This represents 531 profiles for CE and 1130 profiles for AE.

The final composite 3D dynamical structures of typical CE and AE in the NAS are presented in Fig. 9(top row). CE have a maximal velocity localized at the surface, with a peak value of azimuthal velocity reaching 0.3 m s -1 near r ∼ 0.5. AE are weaker, with a peak value of azimuthal velocity of about 0.2 m s -1 near 50 m depth and r ∼ 0.9. Note that these structures do not correspond to all eddies in this area, but to an average shape of eddies.

We finally notice that both CE and AE have a deep-reaching dynamical influence, with a velocity signature down to a thousand meters.

PGW and ASHSW are observed in the core of AE and CE. The mean salinity sections in CE and AE are computed within eddies: S(r, z) (as explained in 2.5). Removing the average vertical distribution of salinity in the area gives salinity anomalies (Fig. 9). In both CE and AE, salinity anomalies and their associate standard deviations indicate the presence of ASHSW and PGW between the surface and 500 m depth (see TS-diagrams inserts in Fig. 9). In CE, the ASHSW is found very close to the surface, above 50 m depth, and the PGW between 100 and 300 m depth. On the other hand, the water masses detected in AE are deeper than in CE because of the diving of isopycnals, with a PGW signature near 400 m depth. The signature of ASHSW is stronger while the signature of PGW is weaker than inside CE. Indeed, more CE were found near the Strait of Hormuz (39 % of them in the Gulf of Oman), where the PGW is diluted, whereas only 12% of AE were found there (Fig. 10). Because we selected a large area to compute the composite structures, these 3D profiles present a large standard deviation, as shown in Fig. 9. This is due to the large number of eddies generated (and detected, see Fig. 10) along the eastern boundary of the Arabian Sea and propagating into the Gulf of Oman. Surface velocities obtained from altimetry and surface drifters show accordingly good agreement with the surface angular velocity of the composite 3D structures of eddies, see for the density profiles. The relative error (see Fig. 12) shows that our calculation provides a fair estimate of the velocities in the ocean interior as well as at the surface. In particular, the agreement with the data is very good at the vortex edge (r > 0.5) with an error < 25%, where structures are best sampled. At the eddy center the error is related as much to the inaccuracy in positioning the center as to the small number of Argo profiles.

3.4.2. A particular cyclone in the Gulf of Oman We compute a vertical section from a 3D density field reconstructed with the composite shapes of AE and CE (see Appendix C). It shows good agreement with the section collected during the Phys-Indien experiment in 2011 by the SeaSoar, see Fig. 14(c). The bending of isopycnals associated with the CE is similar in the two cases, showing that our representation of CE in the area is consistent with observations. For the AE, though the bending of isopycnals at the bottom seems to match between the generic profile and the observed one, the vertical spacing between isopycnals near 100 m depth is not similar. Indeed, in the in situ measurement, the AE exhibits a positive anomaly of density at this depth resulting in a bending of isopycnals opposite to the composite AE. These differences are likely due to the fact that the AE observed in 2011 was deeper and more intense than the composite one, with an ADT anomaly about 4 times larger than the mean ADT of eddies we used to compute the composite AE. The method we used to compute the composite eddies did not take into account the reversal of the isopycnal bending, because we only consider profiles with a density anomaly minimum localized at depth. To fit with the AE sampled in 2011, another criterion should be set to isolate eddies with large positive density anomaly at the surface, but this would discard a lot of profiles.

Discussion

We analyzed the thermohaline properties of the Arabian Sea eddies using about 30,000 We added to the previous studies mentioned above the automatic identification of profiles in or out of eddies. It allowed us to discuss the average thermohaline properties inside eddies in comparison to those outside. The salinity anomaly corresponding to the signature of RSOW (resp. PGW) is on average larger out of the eddies than in their core when considering only the GA (resp. GO). Mesoscale eddies in the gulfs have thermohaline properties of the water masses out of the gulfs, consistent with a generation in the Arabian Sea.

Then, we focused on a larger area, from the GO to the Indian coast, where most Argo profiles were found. In this area, as previously shown in [START_REF] Carton | Mesoscale variability of water masses in the Arabian Sea as revealed by Argo floats[END_REF], we observe intense PGW at depth. We investigated the mean thermohaline and dynamical properties of mesoscale surface-intensified CE and subsurface-intensified AE by computing the 3D composite profiles of eddies. We showed that eddies carry in their core a significant amount of PGW between 200 m and 400 m depth. This contrasts with the previous finding that in the GO, the PGW is preferentially found at the edge of eddies. This difference is due to the inhomogeneous sampling by Argo floats of the NAS and the eddies in this region. Indeed, 52% (resp. 30%) of the profiles used for the composite salinity calculation with r < 0.25 (resp. 0.5 < r < 1) were collected in the GO, in particular close to the Straits of Hormuz (see Table 1). Thus, the core of the composite eddy mostly represents the northwestern GO eddies, while its edge mostly represents the southwestern eddies of the NAS (in area D).

Because we compute salinity anomalies with respect to the background climatology of the whole NAS, the composites exhibit intense salinity anomalies at their center. They are on average 0.4 psu in the CE core, with a standard deviation of about 0.3 psu. For the AE, the average salinity anomaly is much weaker, about 0.2 psu, but with a standard deviation up to 0.35 psu in the whole core of the eddy. Moreover, PGW is on average found preferentially in the core of CE than in AE. This is most likely due to the fact that ( 1 Though the area we considered is large, we could extract a composite 3D dynamical structure of eddies in the NAS that is fairly consistent with geostrophic velocities computed via the altimetry, the currents speed measured by surface drifters, and with in situ sampling of mesoscale eddies. These composites provide an estimate of the velocity field induced by eddies in the water column, from 1500 m up to the surface. Our results suggest that, on average, CE have a larger angular velocity than AE with a maximum of about 0.3 m s -1

for CE and of about 0.2 m s -1 for AE. The profiles of density anomalies in AE show that, on average, they are subsurface-intensified, with an angular velocity increasing from the surface to 50 m depth and vanishing at depth. Since we used a 3D method, our estimation of the typical maximal velocity of AE in this region is thus more accurate than if we only considered a surface-only product (e.g an altimetric dataset). CE are surface-intensified, and their maximum velocity is at the surface. Nevertheless, the estimated error of these composites is important, respectively 31% and 56% for the CE and the AE. It indicates that these composites do not represent all eddies in the area, and that mesoscale eddies in the NAS can have significantly different properties than the composites we present here.

Conclusion and future work

To summarize and to answer the questions we initially asked: this study aimed at extracting and characterizing the 3D structure of eddies in the Arabian Sea with a combined approach using altimetric data and Argo floats. Eddies were detected in the whole Arabian Sea and in adjacent gulfs using AMEDA, but the distributions of Argo floats and surface drifters were heterogeneous. With this dataset, we confirmed previous studies concerning the distribution of the important water masses in the different sub-basins of the region, and discussed the mean stratification one may find in eddies depending on the area (our first question). We then used a composite approach to find the mean 3D structure of mesoscale eddies of the NAS (our second question). We focus only on surface-intensified CE and subsurfaceintensified AE, with a radius R D < R < 3 R D , as these two categories had the greatest sampling/least error. This allowed us to extract composite 3D dynamical and thermohaline structures which are representative of these two types of eddies in the NAS. However, the composite CE can be more trusted than the composite AE, since its relative error is smaller.

We show that the PGW is found at the edges of eddies in the GO, indicating a spreading of this water mass by stirring process, and in the core of eddies averaged in the whole NAS, indicating a possible trapping of this water mass out of the GO (our third question).

Our 3D computation will be improved in the future when more Argo floats are deployed in the Northern Indian Ocean. With more floats (combined with available altimetric products), the computation of statistically-robust composite structures will be possible in other parts of the Arabian Sea such as the Gulf of Aden. In addition, with the recent initiation of the Biogeochemical Argo program (http://biogeochemical-Argo.org/), biological parameters will be available [START_REF] Gruber | Adding Oxygen to Argo: Developing a Global In Situ Observatory for Ocean Deoxygenation and Biogeochemistry[END_REF]. Equivalent 3D composite structures such as the one discussed in this paper may thus be computed (using the same method of colocalization)

for oxygen or chlorophyll and may determine the potential impact of eddies on biological activity.

A possible use of 3D structures as the one we extracted may be the reconstruction of an eddy-induced 3D density field in an area where the circulation is mainly driven by the mesoscale activity (e.g the Gulf of Aden or Oman). Such reconstruction may be done systematically by identifying each surface-detected eddy with a 3D structure computed from eddies of the same polarity, radius, location and depth of intensification, and use a similar reconstruction procedure as the one discussed in Appendix C. The applications of such a reconstruction are numerous and of possible great interest. As an example, this may allow us to use Lagrangian advection procedure on the resulting 3D velocity field to quantitatively estimate the contribution of eddies in the transport of tracers. Another example may be to isolate fine structures in transects (e.g submesoscale fronts or vortices, internal waves...) by removing the contribution of mesoscale eddies.

The reconstruction of such 3D field requires an intensive sampling on the vertical to compute enough 3D composite structures which are representative of all eddies in an area.

In the future, enough floats will allow us to measure in real time the structure of all eddies detected by satellite and to reconstruct their real time vertical structure.

Figure 1 :

 1 Figure 1: Bathymetry in the Arabian Sea and adjacent gulfs from ETOPO2 (Smith & Sandwell, 1997).

Figure 2 :

 2 Figure 2: Distribution of (a) Argo floats, (b) Surface drifters and (c) Detected eddies from the altimetry, for the period 2000-2015 in the Arabian Sea. (d) Snapshot of ADT from the altimetric product used for the detection of eddies. The contour of eddies from the AMEDA eddy detection (red and blue dashed lines), the positions of Argo profiles and Surface Drifters on the same date are superposed.

  ) cm, where the amplitude of the sea surface height is O(50) cm. An estimation of the typical error induced by this heterogeneity in the Arabian Sea is shown in Fig. A.15.

Figure 3 :

 3 Figure 3: Example of colocalization. Blue lines indicate the 20-vertex polygon into which the 'point-inpolygon' algorithm is processed. The gray-shaded arrows show the surface geostrophic velocity from altimetric data. The red arrow is the surface velocity collected at the location of the Argo float.

Figure 4 :

 4 Figure 4: Smoothing procedure of the density for cyclonic eddies in the northern Arabian Sea. (top) Number of Argo in each bin. (bottom) Smoothing of the density at a given level. The dashed line fits the mean value of density at each depth used for the smoothing. Error bars indicate the standard deviation in each bin. The red thick line is the result of the smoothing used to compute the density anomaly and the geostrophic velocity.

2. 6 .

 6 The 2011 Phys-Indien Experiment We compare the 3D composite structures of eddies from this study with a cyclone and an anticyclone sampled during the Phys-Indien experiment in 2011 along the Omani coast. This experiment measured the circulation and water masses in the sub-basins around the Arabian Peninsula from February to April 2011. This cruise used two CTD probes on a SeaSoar, and a VM-ADCP. More details about the campaign are discussed in L'Hégaret et al. (2016).

Figure 5 :

 5 Figure 5: (a) The different areas defined in our study, black (resp. red) dots shows the location of Argo profiles outside (resp. inside) mesoscale eddies. The black thick line indicates the northern Arabian Sea (NAS), where we compute the composite eddies. GA (resp. GO) is the abbreviation of Gulf of Aden (resp. Gulf of Oman).(b) TS-diagram of the different areas, dashed lines are averages for each area. Bold dashed lines are iso-density lines (i.e σ 0 -level). The number of Argo profiles used to compute these diagrams is

  to describe the different water masses locally. Diagram of CT versus SA (TS-diagram hereafter) are shown for each area in Fig. 5(b).

Figure 6 :

 6 Figure 6: Averaged TS-diagrams in (left) the Gulf of Aden and (right) the Gulf of Oman. Black dashed lines indicate the mean TS-profiles outside eddies, and colored solid lines indicate the mean TS-profiles inside eddies. The color indicates the position of the Argo float with respect to the center of the eddy it was localized in. Numbers at the top of each panel indicate the number of profiles used to compute the averages. Black (resp. red) errorbars are the standard deviation of CT and SA associated with the mean profiles outside (resp. inside, r < 0.25) eddies.

Figure 7 :

 7 Figure 7: Average density anomalies profiles inside (a) surface-intensified, and (b) subsurface-intensified AE (blue) and CE (red) in each area. Solid, dashed and point lines (resp. errorbars) present the averages (resp.standard deviation) for profiles colocalized at a distance r < 0.25, 0.25 < r < 0.5 and 0.5 < r < 1 from the center of the eddy it was colocalized in. Columns of numbers indicate the number of profiles used to compute the average profiles (top: r < 0.25, middle: 0.25 < r < 0.5 and bottom: 0.5 < r < 1). Notice that the x-scale of plots is not the same depending on the area.

Figure 8 :

 8 Figure 8: Number of colocalized Argo stations, depending on the period of the year, the area and the radius of the eddy in which the float is colocalized, for CE (top row) and AE (bottom row). Each column corresponds to a different range of eddy radius. Colors indicate the area in which the eddy is located.

Figure 9 :

 9 Figure 9: 3D composite structure of eddies in the NAS area computed using 531 Argo profiles for the CE and 1130 ones for the AE. (top row) Anomaly of density (black contours indicate isopycnals separated of 0.5 kg m -3 ) and angular velocities for CE and AE. (bottom row) Sections of salinity anomalies (with contours of salinity superposed) and standard deviation of salinity. Inserts are TS-diagram for the profiles of the composite structures. Dashed areas indicates areas with a salinity greater than 0.15 psu, also indicated with the red dots in the TS-diagrams.

Figure 10 :

 10 Figure 10: Distribution of the position of eddies considered to compute the 3D composite (a) surfaceintensified CE, and (b) subsurface-intensified AE, in the NAS. The black polygon indicates the area in which 39% of CE and 12% of AE were found.

Figure 11 :

 11 Figure 11: Estimation of the error on the density anomaly between the composite CE (top) and AE (bottom), and the Argo profiles used for the creation of the composites. (a) (resp. (d)) Values of the density anomaly where it is maximal, at 20 m depth (resp 200 m) from the Argo profiles used to compute the composite CE (resp. AE). The perimeters of half the eddies considered for the creation of the composite are presented in thin dashed gray lines. (b,e) Same values of density anomalies as in (a,d), superposed over the density anomaly field of the composite at the same depth. Notice that the color-scale is different between CE and AE. The horizontal extension of the composites have been re-dimensionalized by the mean radius of eddies used for the creation of the composite, which is about 120 km for both CE and AE. (c,f) relative Root Mean Square Error between the value of density of the Argo profile, and of the composite at the same location.

Figure 12 :

 12 Figure 12: Comparison between the surface velocity of the composite eddies and altimetric and drifter data. (top) Percentage of error between the composite eddy and data. (bottom) Angular velocity for each dataset. Errorbars are standard deviations in each bin. The velocity estimation from the altimetric (resp. surface drifters) data is computed using 531 (resp. 834) values for CE and 1130 (resp. 889) for AE. The maximum of error between the composite AE and the drifter data reaches 500% at the center of the eddy.

Fig. 12 .

 12 Fig. 12. The surface geostrophic velocities collected during the colocalization of surface drifters with altimetry (see 2.4) are projected into an angular and a radial component with respect to each eddy. The angular component is then averaged in bins of width dr = 0.05 as

Figure 13 :

 13 Figure 13: Study of a particular CE in the Gulf of Oman. (a) Position of the eddy. (b) Evolution of the shape of the eddy, and position of the colocalized Argo float. (c) TS-diagram from profiles collected by the Argo float. The colorbar indicating the lifetime of the eddy when profiles are collected is used for (a), (b) and (c). (d) Profiles of salinity collected by the float superposed on the composite structure of salinity. Variations around these radial positions are the differences between the raw profiles (black line in insert) and a smoothed profiles (red line in insert). (e) Angular velocity of the Argo float with respect to the center of the eddy, compared with the composite structure of CE in the area. Each value of angular velocity is averaged in a bin of size dr = 0.05, the number of values used for the average is indicated by the size of the square and the standard deviation associated with the values is indicated by the color of the arrows. Note that the maximum depths of (d) and (e) are different.

  Argo profiles during the 2000-2015 period, and we confirmed observations made in previous studies (e.g[START_REF] Warren | Water masses and patterns of flow in the Somali Basin during the southwest monsoon of 1964[END_REF],[START_REF] Quadfasel | Water-Mass Distributions at Intermediate Layers off the Somali Coast during the Onset of the Southwest Monsoon[END_REF],[START_REF] Bower | Character and dynamics of the Red Sea and Persian Gulf outflows[END_REF],[START_REF] Bower | Mesoscale eddies in the Gulf of Aden and their impact on the spreading of Red Sea Outflow Water[END_REF] [START_REF] Carton | Mesoscale variability of water masses in the Arabian Sea as revealed by Argo floats[END_REF][START_REF] L'hégaret | Mesoscale eddies and submesoscale structures of Persian Gulf Water off the Omani coast in spring 2011[END_REF]). The ASHSW is observed near its generation site (20 • N), spreading towards the southeastern part of the Basin. In this latter region, the BBW coming from the Bay of Bengal is also observed. The RSOW is observed in the GA and in the southwestern part of the Arabian Sea: the Somali Basin and the southeastern coast of the Arabian Peninsula. Similarly, we observe the spreading of PGW in the GO and in the northern part of the basin (north of 16 • N), with a high salinity (up to 39 psu) between the 26 and the 27 kg m -3 σ 0 -levels. A weak signature of PGW is also spotted in the southeast, suggesting that this water mass can spread out far from the Strait of Hormuz.

  ) at the Strait of Hormuz where PGW is concentrated, more CE are found (e.g the cyclone discussed in section 3.4, and as shown in Fig. 10); and (2) the cyclone of the Ras Al Hadd's dipole is long lasting and can trap more concentrated PGW than its paired anticyclone (L'Hégaret et al., 2015), because it is closer to the Strait of Hormuz. This situation with a CE near the Strait of Hormuz and a dipole near Ras Al Hadd's can be seen in Fig. 2(d).

Fig. 14

 14 Fig. 14(a) and (b)). This gives a 3D field of density anomaly with a horizontal distribution comparable with the Phys-Indien sampled eddies. (4) We finally add the density climatology of the NAS to represent the mean stratification.

Table 1 :

 1 presented in Table1. Water masses are abbreviated as follows: Red Sea Outlflow Water (RSOW), Persian Gulf Water (PGW), Bay of Bengal Water (BBW) and Arabian Sea High Salinity Water (ASHSW). Number of Argo profiles collected, depending on the area it was found in and its position inside or outside an eddy. Percentages indicate the fraction of profiles in a given area.

	Number of profiles
	Inside eddies

Acknowledgments

This work was funded by the Direction Générale de l'Armement (DGA) via a full grant for Charly de Marez's PhD. We gratefully acknowledge B. Le Vu and A. Stegner's help, who provided the eddy detection algorithm AMEDA and its output on the Arabian Sea.

AMEDA has been developed under the funding of the ANR-Astrid Project DYNED-Atlas (ANR 15 ASMA 0003 01). The altimeter products were produced by SSALTO/DUACS and distributed by AVISO, with support from CNES. This work is also a contribution to PRC 1069 'Meso and submesoscale vortices in the Atlantic and Indian Ocean', funded by CNRS and RFBR. The authors thank the five anonymous reviewers whose remarks widely improved the contents of this paper. In order to encourage readers to bring the 3D generic structure of eddies to life, the 3D field of the different quantities we computed are available with this paper (de Marez et al., 2019).

We compare the composite structure with a particular eddy detected in the Gulf of Oman. This eddy carried PGW in its core, and had a deep dynamical influence. It was detected via altimetry near the Strait of Hormuz (see Fig. 13(a)) nearly continuously for about a year. Its shape did not vary much during that time (see Fig. 13(b)), and an Argo float was trapped in it for about 40 cycles (i.e 40 consecutive data transmissions).

Argo profiles in the eddy indicate that PGW is trapped in the core of the eddy. Indeed, the TS-diagram (Fig. 13(c)) peaks near 26.5 kg m -3 indicating a salty water with the same characteristics as those discussed in Fig. 5(b) for the GO. This water mass is located around 200 m depth (see the salinity profiles in Fig. 13(d)), as predicted by the 3D composite structure of salinity (Fig. 9 or Fig. 13(d)) and as discussed in [START_REF] Bower | Character and dynamics of the Red Sea and Persian Gulf outflows[END_REF]. The salinity signature of PGW can thus be well described by the 3D composite structure. Nevertheless, the salinity anomaly is greater than the salinity anomaly of the composite eddy. Indeed, the mean salinity near the Strait of Hormuz is larger than its climatological value in the NAS area. The occurrence of layering in salinity profiles in the eddy is likely due to stirring of the eddy water with ambient water (see for instance L' Hégaret et al. (2016) and Fig. 13(d)).

We computed the difference between these salinity profiles and the profiles smoothed with a Gaussian kernel (the smoothing length is about 50 m) to highlight the spatial variations of salinity, see Fig. 13(d). Salinity steps at about 50 m depth exhibit jumps up to 1 psu. Such layering has already been observed in the same region; it may be due to different processes: double diffusion [START_REF] Ghazi | Physical Properties of Persian Gulf Outflow Thermohaline Intrusion in the Oman Sea[END_REF][START_REF] Azizpour | Seasonal variation of the double diffusion processes at the Strait of Hormuz[END_REF], salt fingering, convective diffusion [START_REF] Schmitt | Double Diffusion in Oceanography[END_REF], stirring by the eddy flow or breaking of internal waves generated on the shelf. Salt mixing in and near the eddies is thus responsible in part for the salinity distribution in the composite eddy.

The deep motion of the colocalized Argo float is consistent with a deep velocity of the CE, see Fig. 13(e). Since the float is parked at 1000 m depth during its drift, we can estimate the velocity at this depth. We compute the angular velocity of the float in the frame of reference of the eddy (see Appendix B). The float angular velocity is positive. Thus, it appears to be advected by the eddy even if lying at 1000 m depth. The magnitude of this velocity is in good agreement with the values predicted at this depth by the 3D composite structure of CE (though the standard deviation of this velocity is large and the velocity is x , u f y ), with u f x (resp. u f y ) the zonal (resp. meridional) component.

Note that this assumption could lead to an under-estimation of the float velocity since its actual trajectory may be bent. Because distances between positions were computed in the frame of the eddy, u f is the relative velocity of the float with respect to the eddy.

The velocity of the float u f is then projected on an azimuthal and a radial component We remain cautious on the accuracy of this procedure. Firstly, the velocity of the float may be over-estimated because while transmitting its data, it drifts at the surface, advected by surface currents and/or wind. The value of the velocity may also be impacted by the errors in positioning the center of the eddy. Finally, as discussed in [START_REF] Ollitrault | ANDRO: An Argo-Based Deep Displacement Dataset[END_REF] the depth of Argo floats may be inaccurate, and it may vary substantially. Here we only know that the 1000 m parking depth (as indicated on the Coriolis website, bit.ly/2DtItM4) is consistent with the bathymetry of about 1200 m depth; thus we set the depth of drift to 1000 m.

Appendix C. Reconstruction of an instantaneous 3D density field

We present here the 3D density field reconstruction from the composite structure we computed in the NAS. This reconstruction was done to match a large anticyclone centered


Marie-Alexandra Solari

Dochead dossier

Keywords: aromathérapie, huile essentielle, insomnie, trouble du sommeil

T2 Les huiles essentielles disponibles

TEG1 Une seule HE ou un mélange d'HE peuvent être proposés. Une association Lavande vraie, agrume et conifère est très agréable au niveau olfactif tout en étant efficace. Lorsqu'une sédation majeure est nécessaire, une petite quantité de Camomille noble peut être ajoutée dans la formule. Enfin, quand l'insomnie se double de manifestations telles douleurs abdominales, tachycardie, dyspnée, il faut penser à la Marjolaine à coquille ou à l'Ylang-ylang.

TEG1 Pour une question de simplicité mais aussi de prudence, il est préférable de proposer une seule HE, en tout cas de ne pas dépasser trois ou quatre HE par formule. TEG1 Les résultats peuvent parfois n'apparaître qu'au bout d'une semaine, le patient doit être prévenu. Quand l'utilisation dépasse deux semaines, une fenêtre thérapeutique doit être respectée, par exemple un jour de pause tous les quatre ou cinq jours.

T1 Voies d'administration

Certaines voies d'administration paraissent particulièrement adaptées aux patients souffrant d'insomnie 1 .

T2 Diffusion

La diffusion d'une HE ou d'un mélange d'HE peut être conseillée dans la chambre avant le coucher [2]. L'Orange douce, riche en coumarines, molécules hypnotiques, et la Lavande vraie, contenant de l'acétate de linalyle, un ester à propriétés sédatives, se prêtent bien à cette utilisation. La diffusion doit être réalisée 15 minutes avant d'aller dormir, jamais en continu ni pendant le sommeil. Elle est déconseillée en présence de personnes asthmatiques, de femmes enceintes et de jeunes enfants.

TEG1 Insomnie légère :

• 40 % Petit grain bigaradier + 30 % Lavande vraie + 20 % Mandarine ;

• si le fabricant du diffuseur conseille d'utiliser dix gouttes d'HE au total, quatre gouttes de Petit grain bigaradier + trois gouttes de Lavande vraie + deux gouttes de Mandarine ;

• si la quantité nécessaire est de 1 mL, cela correspond à 0,4 mL (environ 12 gouttes en considérant qu'il y a 30 gouttes d'HE par mL) de Petit grain bigaradier + 0,3 mL (environ neuf gouttes) de Lavande vraie + 0,2 mL (environ 6 gouttes) de Mandarine.

TEG1 Insomnie avec fond de stress ou de rumination : 60 % Orange douce ou Mandarine + 30 % Petit grain bigaradier + 10 % Camomille noble. La Camomille noble, qui renferme 80 % d'esters, est très sédative, contient une petite quantité de cétones et s'avère vite entêtante, ce pourquoi elle ne sera utilisée qu'en petite quantité. TEG1 Insomnie avec stress et "besoin de respirer" : 40 % Sapin de Sibérie (très apaisant, avec une bonne odeur de forêt) + 30 % de Pamplemousse + 20 % de Lavande vraie. L'efficacité de la diffusion avant le coucher est renforcée par une diffusion équivalente en fin d'après-midi.

Encadré

Pour une diffusion adaptée aux enfants TEG1 Moins de 3 ans : poser une goutte d'huile essentielle (HE) de Lavande vraie ou de Petit grain bigaradier sur le coin inférieur du matelas.

TEG1 Plus de 3 ans : diffuser les HE de Lavande vraie ou Petit grain bigaradier pendant 10 minutes, puis attendre une heure après la fin de la diffusion avant de coucher l'enfant.

Sur 1 colonne T2 Voie cutanée

La voie cutanée est également très adaptée à la gestion de l'insomnie. Un rituel de massage très localisé pourra être effectué chaque soir au moment du coucher.

Dans ce contexte, c'est un mélange qui est le plus souvent utilisé, composé de 20 % d'HE dans 80 % d'huile végétale (HV). Ainsi, pour constituer un flacon de 10 mL, le patient versera 2 mL, soit environ 60 gouttes d'une HE ou d'un mélange, et complétera avec l'HV. Cette préparation peut également se réaliser dans un roll-on.

Une demi-heure avant le coucher, il convient de prélever cinq à dix gouttes du mélange et de l'appliquer sur le plexus solaire ou de part et d'autre de la colonne vertébrale, par exemple. Il est important de se laver soigneusement les mains ensuite. L'utilisation du roll-on permet d'appliquer la préparation sans la toucher, ce qui est intéressant en cas de réveil nocturne ou précoce.

Avant la première utilisation cutanée, il faut réaliser un test d'allergie en plaçant deux gouttes de la préparation au pli du coude. La solution peut être utilisée si aucune réaction n'apparaît après 15 minutes. TEG1 Difficultés d'endormissement : dans un flacon de 10 mL, mettre 1,2 mL (36 gouttes) de Lavande vraie + 0,6 mL (18 gouttes) de Petit grain bigaradier + 0,2 mL (six gouttes) de Camomille noble, puis compléter avec de l'HV de noyaux d'abricot, de noisette, de pépins de raisin ou de jojoba, par exemple. Cinq à dix gouttes du mélange peuvent être appliquées sur le plexus solaire.

TEG1 Réveil nocturne avec rumination ou angoisse : dans un roll-on de 10 mL, verser 1 mL (30 gouttes) de Lavande vraie + 0,8 mL (24 gouttes) de Petit grain bigaradier + 0,2 mL (six gouttes) de Marjolaine des jardins, avant de compléter avec une HV. Ce mélange doit être appliqué au coucher et en cas de réveil nocturne. La Marjolaine des jardins permet d'atténuer les manifestations du stress comme les spasmes abdominaux, la tachycardie et la dyspnée. Elle peut être remplacée par l'Ylang-ylang qui possède des propriétés calmantes et sympatholytiques (baisse de la pression artérielle, ralentissement du rythme cardiaque, relaxation générale), limitant ainsi les réveils intempestifs.

TEG1 Réveil précoce : dans un roll-on de 10 mL, mélanger 1 mL (30 gouttes) de Mandarine, 0,5 mL (15 gouttes) de Lavande vraie et 0,5 mL (15 gouttes) de Verveine citronnée, puis compléter avec une HV. Ce mélange peut être utilisé le soir au coucher et en cas de réveil trop précoce ; il convient de respirer calmement et profondément le roll-on trois fois de suite.

Encadré

Pour une utilisation cutanée adaptée aux enfants TEG1 Moins de 3 ans : une goutte d'huile essentielle (HE) de Lavande vraie ou de Petit grain bigaradier dans 10 à 20 gouttes d'huile végétale (HV) ; masser la voûte plantaire ou l'abdomen.

TEG1 Plus de 3 ans : deux gouttes d'HE de Lavande vraie ou de Petit grain bigaradier dans 10 à 20 gouttes d'HV ; masser la voûte plantaire (risque de glissade), le plexus solaire ou le bas du dos.

Sur 1 colonne T2 Bain

Un bain dans lequel auront été versées des HE peut être pris le soir, à une température inférieure à 38 °C. Pour bénéficier au mieux des vertus calmantes des HE, il convient de sortir de l'eau sans se rincer. Par ailleurs, il ne faut jamais y verser d'HE pure.

TEG1 Bain détente : 10 à 15 gouttes de Lavande vraie ou de Petit grain bigaradier dans un dispersant (base pour le bain, savon liquide neutre, HV) ou cinq gouttes de Lavande vraie + cinq gouttes de Mandarine + deux gouttes d'Ylang-ylang.

TEG1 Bain pour enfant : une goutte de Lavande vraie ou de Petit grain bigaradier par année d'âge (par exemple, quatre gouttes pour un enfant de 4 ans) dans un dispersant.

Parmi les conseils à la disposition de l'équipe officinale, l'aromathérapie présente des atouts non négligeables. Toutefois, il importe de bien connaître les avantages et les inconvénients de l'utilisation des HE, notamment leurs effets indésirables et les précautions à prendre.

Points à retenir

• L'équipe officinale est régulièrement sollicitée pour apporter une solution à la gestion des insomnies.

• Pour limiter l'utilisation de benzodiazépines, des alternatives non médicamenteuses peuvent être proposées.

• L'aromathérapie constitue une approche permettant d'améliorer la qualité du sommeil.

• Le conseil en aromathérapie relève de professionnels de santé bien formés pour une utilisation sécuritaire des huiles essentielles.

• Les voies d'administration les plus adaptées à la prise en charge de l'insomnie sont la diffusion, la voie cutanée et le bain.

  voies d'utilisation peuvent être pertinentes et cumulables entre elles. Il importe toutefois de tenir compte des contre-indications et précautions d'emploi de chacune d'entre elles, des HE en fonction du profil du patient et de la dose totale. Par exemple, la prudence commande d'éviter la diffusion chez un sujet asthmatique, la voie cutanée étant plus appropriée. Le stick olfactif est souvent choisi pour sa simplicité d'utilisation en combinaison avec la voie cutanée et la diffusion. Quant au bain, il peut être proposé une à deux fois par semaine en complément. TEG1 Comme il est interdit de réaliser des préparations personnalisées sans prescription médicale, l'équipe officinale doit prendre soin de bien expliquer au patient comment constituer lui-même son flacon en vue d'une application cutanée ou d'une diffusion. Un outil expérimental d'aide à la dispensation a été réalisé afin de sécuriser ce conseil [1].

  et mélanges proposés dans cet article le sont à titre d'exemples. Références [1] Andersen L. Rôle du pharmacien d'officine dans la prévention et la gestion des événements indésirables impliquant les huiles essentielles. [Thèse de doctorat en pharmacie]. Dijon: Faculté de pharmacie; 2018. [2] Buiron T. Intérêt de l'aromathérapie par voie inhalée dans le traitement de l'insomnie : une revue de la littérature. [Thèse de doctorat en pharmacie]. Dijon: Faculté de pharmacie; 2018. Pour en savoir plus • Chien W, Cheng SL, Liu CF. The effect of lavender aromatherapy on autonomic nervous system in midlife women with insomnia. Evid Based Complement Alternat Med. 2012(1741-427X):740813. • Hajibagheri A, Babaii A, Adib-Hajbaghery M. Effect of Rosa damascene aromatherapy on sleep quality in cardiac patients: a randomized controlled trial. Complement Ther Clin Pract. 2014;20(3):159-63. • Moeini M, Khadibi M, Bekhradi R et al. Effect of aromatherapy on the quality of sleep in ischemic heart disease patients hospitalized in intensive care units of heart hospitals of the Isfahan University of Medical Sciences. Iran J Nurs Midwifery Res. 2010;15(4):234-9. Déclaration de liens d'intérêts L'auteur déclare ne pas avoir de liens d'intérêts.


Jacques Buxeraud
email: jacques.buxeraud@unilim.fr

Sébastien Faure

Dochead outils à l'officine Sous-dochead information professionnelle Documentation à l'usage de l'équipe officinale (1)

De nombreux documents permettent de s'informer à l'officine sur les médicaments, la thérapeutique, les conseils à donner aux patients… La Haute Autorité de santé diffuse des synthèses d'avis et des fiches sur le bon usage des médicaments. Quant aux outils proposés par le Comité d'éducation sanitaire et sociale de la pharmacie française, ils sont particulièrement utiles pour se former et communiquer.

T1 Les documents de la HAS

La Haute Autorité de santé (HAS) met à la disposition des professionnels de santé des documents indispensables comme les synthèses d'avis et les fiches bon usage sur les médicaments [START_REF]Synthèses d'avis et fiches bon usage sur les médicaments[END_REF]. En diffusant ces données sur son site internet, elle a pour ambition de fournir des informations objectives, concises et appropriées à leur pratique.

T2 Les fiches "bon usage"

TEG1 Les synthèses d'avis ne remplacent pas les fiches "Bon usage du médicament", qui concernent une dizaine de spécialités par an au maximum et visent à apporter des informations essentielles, notamment pour la délivrance au comptoir de la pharmacie [START_REF]Synthèses d'avis et fiches bon usage sur les médicaments[END_REF].

TEG1 Ces fiches traitent en général de médicaments dont la population cible est importante ou qui présentent un risque de mésusage, leur but étant de faire connaître les résultats de l'évaluation d'un médicament ou d'une classe thérapeutique par la Commission de la transparence. Les données portant sur le niveau d'efficacité du médicament, ainsi que le progrès qu'il est susceptible d'apporter pour les patients ou certains groupes de patients permettent de préciser sa place dans la stratégie thérapeutique, par rapport aux moyens déjà disponibles.

Encadré 1. Qu'est-ce que la Commission de la transparence ?

La Commission de la transparence est une instance scientifique composée de médecins, pharmaciens, spécialistes en méthodologie et épidémiologie [2]. Elle évalue les médicaments ayant obtenu leur autorisation de mise sur le marché (AMM), lorsque le laboratoire qui les commercialise souhaite obtenir leur inscription sur la liste des médicaments remboursables [START_REF]Code de la sécurité sociale[END_REF]4].

Sur une colonne près de son appel T1 Les documents du Cespharm

TEG1 Le Comité d'éducation sanitaire et sociale de la pharmacie française (Cespharm) a pour vocation d'aider l'équipe officinale à s'impliquer dans la prévention, l'éducation pour la santé et l'éducation thérapeutique du patient. Il est rattaché à la direction générale de l'Ordre national des pharmaciens. Ses travaux s'appuient sur une commission plénière qui définit les grandes orientations et sélectionne les thématiques portées par les groupes de travail.

TEG1 Les principales missions du Comité sont :

• contribuer à l'information et à la formation dans le domaine de la santé publique ;

• fournir des outils d'information et d'éducation du public ;

• relayer les campagnes nationales et mondiales de santé publique ;

• aider à concevoir et à réaliser des actions de santé publique ;

• faciliter la collaboration avec les différents acteurs de la prévention et de l'éducation sanitaire [START_REF]Comité d'éducation sanitaire et sociale de la pharmacie française (Cespharm)[END_REF]. Ces documents, pratiques, à caractère éducatif et conformes aux recommandations en vigueur, sont destinés à l'amélioration et l'actualisation des connaissances de l'équipe officinale et peuvent même être portés à la connaissance du public (encadré 2) [START_REF]Comité d'éducation sanitaire et sociale de la pharmacie française (Cespharm)[END_REF][START_REF]Comité d'éducation sanitaire et sociale de la pharmacie française (Cespharm). Les outils[END_REF].

TEG1 Le Cespharm développe ainsi diverses activités pour aider les pharmaciens à s'impliquer dans la prévention et l'éducation

Encadré 2. Comment se procurer la documentation du Cespharm ?

Les affiches, brochures, vidéos, outils éducatifs ou d'information professionnelle proposés par le Comité d'éducation sanitaire et sociale de la pharmacie française (Cespharm) sont librement téléchargeables pour la plupart et disponibles à la commande pour les pharmaciens inscrits à l'Ordre national des pharmaciens.

Sur une colonne près de son appel

TEG1 Les vidéos proposées peuvent être :

• visionnées par l'équipe officinale comme support d'information professionnelle ;

• visionnées avec le patient (sur une tablette ou un écran d'ordinateur) comme un support éducatif, par exemple dans le cadre d'un entretien pharmaceutique ;

• téléchargées et diffusées sur les écrans des espaces d'attente (officines, laboratoires de biologie médicale, hôpitaux) afin de sensibiliser le public et l'inviter à ouvrir le dialogue avec l'équipe officinale.

TEG1 Les affiches destinées à l'information de la clientèle sont apposées dans la vitrine et l'espace public de l'officine. Elles mettent en avant l'implication de la pharmacie sur un thème de santé particulier, souvent en rapport avec l'actualité ou la saison. Elles ont pour vocation de sensibiliser le public et de l'inciter à engager le dialogue avec l'équipe officinale.

T2

  Les synthèses d'avis TEG1 Les synthèses d'avis de la Commission de la transparence (encadré 1) sont précieuses pour l'activité officinale. Elles concernent entre autres les nouveaux médicaments proposés au remboursement par les laboratoires et, pour les spécialités déjà remboursées, leurs nouvelles indications. TEG1 Le but est d'informer les prescripteurs sur l'intérêt d'un médicament ou d'une classe de médicaments dans la prise en charge d'une affection, notamment au regard des alternatives thérapeutiques disponibles. TEG1 Ces synthèses sont brèves et les messages essentiels sont résumés en début de document. Les rubriques proposées sont très utiles pour le comptoir : stratégie thérapeutique, données cliniques, conditions particulières de prescription, intérêt du médicament (service médical rendu [SMR], amélioration du service médical rendu [ASMR], remboursement).

  sanitaire : élaboration et diffusion de documents, relais des campagnes de santé publique, conception et mise en oeuvre d'actions de santé publique, participation à des groupes de travail, mise en place d'études de d'enquêtes, participation à l'élaboration de programmes de formation. TEG1 Les pharmaciens peuvent disposer gratuitement d'une sélection de supports d'information et d'outils éducatifs sur 40 thèmes de santé auprès de cet organisme. Les "Repères pour votre pratique" (maladie de Lyme, vaccinations…) et les fiches professionnelles (Accompagner la dispensation d'un autotest VIH, Compléments alimentaires et dopage…) en font partie.

TEG1

  Les brochures sont des supports d'information et de sensibilisation destinés au public. Elles sont de préférence remises individuellement par l'équipe officinale aux patients concernés par leur thématique ou laissées à disposition sur un comptoir ou un présentoir. Ces documents sont très appréciés des patients. TEG1 Les outils éducatifs, pratiques et didactiques, sont destinés à aider l'équipe officinale dans sa démarche d'accompagnement et d'éducation du patient.

Figure Bux_fig1 Figure 1 .

 Bux_fig11 Figure Bux_fig1Figure 1. Exemple de renseignements fournis par les synthèses d'avis de la Haute Autorité de santé pour l'antiviral Maviret®. © HAS Sur 1 colonne + marge près de son appel