Lars Gidhagen
email: lars.gidhagen@smhi.se

Cecilia Bennet
email: cecilia.bennet@smhi.se

David Segersson
email: david.segersson@smhi.se

Gunnar Omstedt
email: gunnar.omstedt@smhi.se

Exposure Modeling of Traffic and Wood Combustion Emissions in Northern Sweden Application of the Airviro Air Quality Management System

Keywords: Airviro, dispersion modelling, residential wood combustion, PM2.5, health adfa, p. 1, 2011

Traffic and residential wood combustion (rwc) constitute the two dominating local sources to fine particulate matter PM2.5 concentration levels in Sweden. In order to meet the authorities' requirements of air quality assessments, a national modelling system SIMAIR has been developed. The system is based on the commercial Airviro air quality management software, a three tier client/server/web system which includes modules for measurement data collection, emission databases and dispersion models with very high performance in terms of data access and model execution. The technical characteristics of Airviro databases and models have facilitated web based national air quality systems, of which some examples are given. The present Airviro/SIMAIR application had the objective to assess the impact of rwc in three urbanized areas in northern Sweden. The Airviro Scenario module was used to determine exposure and health impact of the rwc contribution. The estimated mortality due to PM2.5 concentrations from residential wood combustion is about 4 persons/year, which corresponds to approximately 0.4% of the total number of deaths (excluding accidents). Cities which have well established district heating facilities have a lower rwc use and a very different exposure to locally generated PM2.5. Umeå, one of the three areas in the study, is such a city. A similar assessment with impact only from traffic emissions shows an increase of 4.4 deaths for the Umeå population, while the impact of wood combustion in the city contributes with 2.5 deaths per year. The advantages of using the Airviro software in combination with annually updated databases for input data on the national scale, are summarized. The approach facilitates for municipal end users and non-meteorological professionals like epidemiologists to perform by themselves advanced dispersion simulations and health impact assessments.

Introduction

Fine particles with diameter <2.5µm (PM2.5) suspended in ambient air constitute a leading risk factor contributing to premature death [START_REF] Lim | A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010[END_REF][START_REF]Ambient air pollution among top global health risks in 2010[END_REF]. In Sweden the most important local source is road traffic emitting particles generated both by combustion and by road wear and brake abrasion. Another important source is residential wood combustion (rwc) and people living in smaller cities with rwc are exposed to elevated PM2.5 levels. According to a recent health review [START_REF] Who | Review of evidence on health aspects of air pollution -REVIHAAP Project[END_REF] these rwc particles may have a similar effect on health as traffic combustion particles. Strong impact of wood combustion is common not only in northern Sweden but also considered to be a large and well spread source of PM2.5 in Europe [START_REF] Genberg | Light-absorbing carbon in Europe -measurement and modelling, with a focus on residential wood combustion emissions[END_REF].

To facilitate the supervision of local air pollution hot spots and allow urban planning where air pollution levels can be held below European and Swedish standards, the Swedish EPA, the Swedish National Road Administration and the Swedish Energy Agency jointly commissioned the development of the web tool SIMAIR [START_REF] Gidhagen | SIMAIR -Evaluation tool for meeting the EU directive on air pollution limits[END_REF][START_REF] Omstedt | New model tools for meeting the targets of the EU Air Quality Directive: description, validation and evaluation of local air quality improvement due to reduction of studded tyre use on Swedish roads[END_REF]. SIMAIR is a coupled model system covering all Swedish regions and urbanized areas, where local authorities can assess the current status of air quality. The SIMAIR system is based on a commercial air quality management software used in many locations around the world, the Airviro system [7]. SIMAIR has most of the environmental and activity data required in dispersion modeling preloaded, e.g. the entire Swedish road network. For Sweden this gives possibilities of annual overviews of spatial and temporal variations in PM10, PM2.5, NO2, CO and benzene levels. The system has previously been used to simulate national exposure of particulate matter for a specific year (2004) [START_REF] Gidhagen | High resolution modeling of residential outdoor particulate levels in Sweden[END_REF]. The exposure was then related to self-reported health problems [START_REF] Willers | Fine and coarse particulate air pollution in relation to respiratory health in Sweden[END_REF]. The Airviro software has also been used as a platform for an integrated climate change enabled Environmental Decision Support System (EDSS) [START_REF] Denzer | How to Build Integrated Climate Change Enabled EDSS[END_REF]. Recent development of the Airviro system includes a module, Airviro Scenario, where the exposure on the entire population can be assessed with respect to health outcomes and economical costs for different air quality scenarios. In much this module bears a strong resemblance with U.S. EPAs BenMap system [START_REF] Epa | Environmental Benefits Mapping and Analysis Program (BenMAP)[END_REF]. The present study describes how the Airviro software, including Airviro Scenario, has been used together with SIMAIR input data to assess the health impact of air pollution from residential wood burning and road traffic. We also discuss potential users to this health impact assessment tool.

Software

The Airviro system has been developed during more than 30 years, originally for powerful (at the time) work stations and then migrated to Linux servers, i.e. it did not raise from personal computer platforms. Its highly optimized databases assure a rapid access of time series, both point and field data, which has made it ideal for large regional and national systems. The principal and fully integrated functionalities of the Airviro system are

• data collection, storage, validation and presentation

• emission database for point, area, line and grid sources • dispersion models Through requirements from users in Europe, Asia and Latin America there is now a great flexibility for users to select among e.g. some 20 data collection protocols and an extensive list of dispersion models including Airviro models for different scales and purposes as well as open-source models like AERMOD, CALPUFF and AUSTAL2000.

A strength of the Airviro system is the capacity to process very large emission inventories with a mix of individual sources and gridded emissions. Also, the integration with the time-series database allows the use of live data, such as continuous stack measurements, traffic flow measurements or ship movements to be described in near real-time. A specialized type emission source has been developed to represent ship emission sources, in which the movements of the ships are described based on the positions of the individual ships found in AIS (Automatic Identification System) data for the sea area of interest. By adding information on ship engine data from available sources, Airviro allows the emissions from ships to be described with high temporal and spatial resolution. The emission database for residential wood combustion presented in this paper is another example of an advanced emission model for a very large number of individual sources.

Current versions Airviro 3.2x is a three tier client / server / web system. It runs on Linux platforms but Red Hat, Fedora and CentOS Linux are the preferred operating systems. The clients normally run on PCs using Java JRE (run time plugin) compatible web browsers such as Internet Explorer and Firefox. The web server side is using lean CGI scripts and heavy programs written primarily in C. The pages at the client side use html and java script and are built on the server. Some small applets written in Java are also used on the client side primarily for caching, maps and user interfaces that are too complex to be written using html and JavaScript. All models are written using FORTRAN.

The Airviro databases are based on the FairCom CTREE™ server version 4.3 or on proprietary solutions. Communication of data into and out of the Airviro databases is performed through ASCII or EXCEL interfaces, or through Web services using HTTP or HTTPS protocols. An OGC compliant service layer to access, interrogate, execute models and upload/download gridded time series in Airviro was developed as part of the EU FP7 project SUDPLAN [START_REF] Denzer | How to Build Integrated Climate Change Enabled EDSS[END_REF].

The great flexibility of the Airviro system gives advantages to large applications. National monitoring databases in Singapore, UK, Estonia and Chile are operated by Airviro. In a current upgrade of the Singapore system data collection is extended to high resolution precipitation sensors and other climate instruments. Other countries like Estonia, Chile and Sweden also uses the data collection together with emission inventories and dispersion models on a national scale. Airviro has recently been implemented in Turkey to collect and quantify emissions from ship traffic in the Bosphorus straight and adjacent seas. Smaller systems are serving local authorities and industries in some 20 countries.

The flexibility and generality of the system has the drawback that it makes it complex to configure and new users often require support for setting up the system and fill it with useful information serving the purpose of air quality management (which is not only doing diagnostic work of how things are today, but also to be able to identify air pollution control actions and project their effects on future air quality as part of a planning procedure). While this is manageable for large and specialized institutions, it is for users in individual cities or industries a threshold that is sometimes difficult to overcome. This is why the SIMAIR system, to be described in the next section, has been developed. SIMAIR is basically a simplified Airviro interface where less experienced users can access the preloaded information required to execute dispersion models for whatever location within Sweden.

Method

Figure 1 gives an overview of the Air Quality Management system and the work flow required for an health impact assessment based on a given emission scenario. Starting point is the formulation of an emission scenario. Health effects can be based on absolute emissions, but it is also common to quantify the health benefits by comparing a scenario with reduced emissions to a reference (business-as-usual) scenario, i.e. health benefits achieved by a certain change in emissions. The results to be presented below will separately quantify the different health effects of the two largest local PM2.5 sources in Swedish cities (Figure 2). The next step is to feed the system with meteorological information, which can be taken -if available -directly from meteorological towers, from meteorological model output or from a combination (analyzed gridded data based on surface data, meteorological models, satellite and radar data routinely produced all over Sweden). With this it is possible to execute an appropriate dispersion model among those Gaussian and Eularian models available in Airviro. Population exposure calculations for entire cities are applications with tough requirements on performance, this since the rapid decrease in pollutant concentrations close to roads makes it necessary to describe the dispersion of pollutants with high spatial resolution. To facilitate these calculations, Airviro simulations can be made on a locally refined computational grid (Fig. 3). Fig. 3. Example of refined computational grid -named quad grid -along a main highway. The original grid of 800x800 m is refined to 50x50 m along all roads where traffic emission intensity is above a specified threshold. For this example the number of grid cells are only 4.13% of that of a regular grid with 50x50 m resolution. Since all models produce hourly time series of pollution concentrations, it is possible to evaluate model output through a comparison with monitor data. Such quality assurance comparisons should always be performed when measured concentrations are at hand. It is common to find rather severe errors in the emission description, calling for a new round in the emission-dispersion-monitoring cycle of Fig. 1.

When confidence in simulated concentrations has been achieved, the Airviro Scenario module can be used to combine the dispersion model results with demographic data to assess the health effect on the population. For Sweden this means the use of high resolution population data with 100x100m grid, separated into age intervals of 5 years. The Scenario module can handle health outcomes of long-term exposure, either mortality or the incidence of different diagnosis like cardiovascular or respiratory diseases. Concentration-response relationships should be taken from epidemiological studies published internationally. The present study has assessed the relative risk of mortality (the risk of dying in exposed population compared to the risk of dying in non-exposed population) due to PM2.5 particles and the concentration-response relationship was set to 1.17 per 10 µg/m3 [START_REF] Jerrett | Spatial Analysis of Air Pollution and Mortality in Los Angeles[END_REF].

The calculations were performed for three different locations in northern Sweden close to the city Umeå (63.8N, 20.3E): the villages Vännäs (population 6062), Sävar (population 2976) and the city Umeå (population 90230). Air quality parameters of particles -PM2.5 and sot, polyaromatic hydrocarbons, elementary carbon and black carbon -were measured in four different places and used for validation.

The emissions were estimated from chimney sweeps registers, including detailed data for about 3700 wood boilers and about 16900 stoves. Heating habits and wood consumption were estimated from interviews in 176 houses using a standardized form.

Results and Discussion

Figure 4 shows measured and modelled local daily mean concentrations of PM2.5 (µg/m 3 ) from residential wood combustion in Sävar. The local contribution of the measurement is estimated as the difference between the measured local concentrations and the background concentration. In average the local contribution in Sävar is small, about 2 µg/m 3 . The daily variations are large, some days the local contribution can be higher than 10 µg/m 3 . These variations are typical for residential wood combustion in Sweden. As shown in the figure the model can reproduce these variations and the long term average rather well. The results of the health impact assessment are summarised in Table 1. The calculated maximum concentrations due to wood combustion vary between 2 and 4 µg/m3 while the traffic in the regional capital Umeå contributes up to 6 µg/m3.

The calculated population averaged concentrations due to wood combustion vary between 0.2-0.9 µg/m3 and are higher in the villages Vännäs and Sävar than in the city Umeå. This is due to the fact that extensive district heating system is used in Umeå but not in the two villages. The fraction of households using wood for residential heating is therefore much lower in Umeå where most wood stoves are used primarily for comfort and well-being and not as the main source of heating the house. This is also seen in the exposure histogram Figure 5. The estimated mortality due to PM2.5 concentrations from residential wood combustion for the summed population in the three locations of about 100 000 people is about 4 persons/year, which corresponds to approximately 0.4% of the total number of deaths (excluding accidents). Scaling up this estimate to the whole population of Sweden, the estimated mortality due to PM2.5 from wood combustion is about 374 persons per year. This number can be compared with earlier estimates of about 100-340 persons per year by Forsberg et al. [START_REF] Forsberg | Comparative health assessment of local and regional particulate air pollutants in Scandinavia[END_REF] and about 216-282 persons per year by Brandt et al. [START_REF] Brandt | Contribution from ten major emission sectors in Europe and Denmark to the health-cost externalities of air pollution using the EVA model system -an integrated modelling approach[END_REF] for Denmark. Scaling up the Danish estimate to the Swedish population, by the ratio between the Swedish and the Danish population i.e. 9.6/5.6, it means that the estimated mortality is about 370-483 persons per year. The estimated mortality due to PM2.5 from local wood combustion in this project is thus close to earlier estimates in Sweden and Denmark.

Location

For the Umeå population the traffic impact is higher (4.4 deaths per year) than the impact of wood combustion (2.5 deaths per year). Traffic impact was not assessed in the smaller cities, but it is obvious from Table 1 and Fig. 5 that wood combustion is there the dominating source contributing to PM2.5 exposure. The Airviro application presented, in which the impact of the two largest contributors to PM2.5 -traffic and residential wood combustion -have been assessed in urbanized areas with different characteristics, can easily be repeated for whatever city in Sweden. This because input data and model tools are available and updated each year, in order to allow the municipal authorities assess compliance to EU directive and Swedish environmental objectives. The concept behind the national modelling system SIMAIR can be summarized as making available on the web the Airviro software plus all input data: As for health impact studies this can also be done by external users, however experiences show that a health impact assessment require some training and understanding of epidemiological concentration-response relationships. Potential users of the health impact module are found at the regional health authorities rather than at individual municipalities.

Conclusions

The Airviro modeling system with the health impact calculation Scenario module has been used to assess the number of premature deaths from residential wood burning in the northern part of Sweden. In a summed population of 100 000 inhabitants, local wood combustion is estimated to cause about 4 premature deaths per year, which is about 0.4% if the total number of deaths in this area. The fraction of the population exposed to large pollution contributions due to residential wood combustion is smaller in the city of Umeå compared to the neighboring villages, this since district heating is available to almost all residences in Umeå, but not in the same degree in the other two villages. However, for the Umeå population the traffic impact is higher with 4.4 deaths per year, as compared to wood combustion which there contributes with 2.5 deaths per year. The advantages of using the web based Airviro software in combination with annually up-dated databases for input data on the national scale have been described. The approach facilitates for municipal end users and non-meteorological professionals like epidemiologists to perform by themselves advanced dispersion simulations and health impact assessments.

Fig. 1 .

 1 Fig. 1. Overview of data flows in the Airviro Air Quality Management System which involve four major modules: Emission Database, Dispersion models, Time series database/presentation/analyzing tool and the Scenario module with exposure assessments.

Fig. 2 .

 2 Fig. 2. The two major sources to PM2.5 pollution in Sweden and how the GUIs of the Airviro Emission Database can be used by local end-users to modify/update information of mobile sources (left) and residential wood combustion sources (right).

Fig. 4 .

 4 Fig. 4. Comparison of measured (blue cross) and modelled (red line) local daily mean PM2.5 concentrations (µg/m 3 ) at Sävar. r is the correlation coefficient and F2 denotes fraction of calculated concentrations that are within a factor of two of the measured concentrations.

Fig. 5 .

 5 Fig. 5. Calculated number of persons (%) that are exposed to locally generated PM2.5 from residential wood combustion in different concentrations intervals.

source type PM2.5(µg/m 3 )year ly mean

					Health Impact
					Assessment
			Max	Population	Population	Mortality
				average	(number of	(number of
					people	people/year)
	Umeå	local wood comb.	2.38	0.165	90230	2.50
	Umeå	local traffic	6.20	0.295	90230	4.40
	Vännäs	local wood comb.	2.47	0.913	6062	0.93
	Vännäsby	local wood comb.	3.85	0.887	2976	0.44

Table 1 .

 1 Summary of results from the calculations of annual mean concentrations, exposure and health impact.

  Use of Airviro software with all input provided for a first preliminary assessment in whatever Swedish location, i.e. long range transported contributions, urban contributions, local emissions and local meteorological information, all pre-stored as hourly data in a national database inside Airviro.• The municipal user just has to execute the local model to get a first preliminary result of total pollution concentrations, separated in different contributions. By reviewing and adjusting the local data that he or she are best suited to deliver, i.e. local traffic intensities, share of heavy duty vehicles etc., improved impact assessments are made for traffic environments. Similar improvements in wood combustion areas can be made with access to local chimney-sweeper data and interviews/questionnaires on wood consumption.

	•
		80
				Exposure of PM2 . 5 from wood smoke year 2013
		60		Umeå Sävar
	Population (%)	40		Vännäs -Vännäsby
		20
		0
		0	0 . 2	0 . 4 PM2 . 5 (µg/ m 3 ) contribution from wood -combustion 0 . 6 0 . 8 1 1 . 2 1 . 4 1 . 6 1 . 8	2	2 . 2


Sergey Medvedev

Alex Topaj
email: alex.topaj@gmail.com

Vladimir Badenko
email: vbadenko@gmail.com

Vitalij Terleev
email: vitaly_terleev@mail.ru

Medium-Term Analysis of Agroecosystem Sustainability under Different Land Use Practices by Means of Dynamic Crop Simulation

Keywords: crop rotation, sustainable agriculture, generic crop simulator, computer experiment, multivariate analysis, simulation software adfa, p. 1, 2011

The role of dynamic crop models as an intellectual core of computer decision support systems in agricultural management increases significantly in recent time. However, the scope of model applications is often limited by short time scale i.e. crop simulation/forecasting is performed within a particular vegetation season. The use of dynamic models in long-term planning is still much less developed. This contribution presents the author's efforts in development and improvement of the integrated system of crop simulation «APEX-AGROTOOL» for its use as a tool of model-oriented analysis of land use environmental sustainability. Attention is paid to the modification of the existing software in order to provide an ability to simulate agro-landscape dynamics taking into account crop rotation effects.

Introduction

Maintaining or even increasing the fertility of agricultural landscapes during their active agricultural use is one of the most important scientific problems in theoretical agricultural science. The importance of this issue has recently increased due to significant changes in land use. For example, the new energy-oriented agriculture needs scientific support in many aspects: choice of the proper cultures, choice of crop rotation scheme, choice of crop allocation in different spatial scales etc. The main problem is to bridge the gap between economic requests and scientific methodological support of sustainable land use. In recent years agricultural science reinforced the efforts to achieve agrolandscape environmental sustainability instead of maximum productivity [START_REF] Costanzo | Functional agrobiodiversity and agroecosystem services in sustainable wheat production. A review[END_REF]. The paper presents efforts for development and improvement of the integrated system of crop simulation «APEX-AGROTOOL» for analysis and investigation of alternative medium-term planning strategies in land use, taking into account the crop rotation influence on environmental sustainability and saving resources.

Material and Methods

The use of dynamic imitation models is well-known and wide-distributed modern tool in agroecology and crop production for analyzing, forecasting and decision support. Numerous benefits of this approach in comparison with statistical and regression models are:

• improved accuracy and approximation of the calculations by taking more factors into account; • obtaining multiple results based on the wider range of variations of input data;

• results produced as distributions of indicators on probability samples of external conditions can be readily used in risk analysis; • almost unlimited number of monitored indicators of the agroecosystem model (productivity, environment, fertility, etc.); • reduced uncertainty of model calculations, etc.

All these advantages of dynamic models are the basis of their wide application to real-time forecasting and crop management in the short time scale (within a particular growing season) [START_REF] Tonitto | Application of the DNDC model to the Rodale Institute Farming Systems Trial: Challenges for the validation of drainage and nitrate leaching in agroecosystem models[END_REF]. However, their use for long-term planning is still much less developed. Until recently, it was mainly caused by technical limitations such as computational efficiency or memory size. At present, however, due to the progress in hardware engineering as well as in information technologies, the most significant restrictions have been overcome. Thus the subject-oriented requirements have become the principal feature for the applicability of imitation models in mid-term forecasting in agriculture [START_REF] Belcher | Agroecosystem sustainability: A system simulation model approach[END_REF].

An appropriate solution requires adaptation of both the models and the computer simulation environment for fulfilling the relevant task requirements. First of all, it refers to the need for a full description of the changes during the long-term crop rotation [START_REF] Dury | Models to support cropping plan and crop rotation decisions. A review[END_REF]. The latter involves the following specific requirements to imitation model:

• Universal character of the simulation algorithm. It includes structural identity of the models for different cultures/cultivars, soil-climate conditions and technologies.

• Comprehensive sequence analysis. The model should fully take into account the influence of culture predecessors in all significant aspects such as decomposition of crop residues and changes in the agrochemical and the physical properties of the soil, symbiotic nitrogen fixation legumes, etc. [START_REF] Alva | A crop simulation model for predicting yield and fate of nitrogen in irrigated potato rotation cropping system[END_REF][START_REF] Davari | Effect of cropping systems and crop residue incorporation on production and properties of soil in an organic agroecosystem[END_REF]. • «Wintering» imitation. The model should be able to simulate abiotic processes in the agroecosystem (soil frost penetration and thawing, snowfall and snow melting etc.) during off-seasons period. • Environmental orientation. The model should be able to estimate yield as well as the dynamics of various parameters of the sustainability, such as soil fertility indexes (humus content, carbon sequestration), energy-matter balance of the agrolandscape (emission of greenhouse gases, biogen transfer to water body), etc.

In addition, special software for planning and performing the computer experiments with the model must be developed to provide the following:

• Multivariate analysis of the studied crop model. It means multiple running of the model with different input data sets defined during preprocessing. Moreover, crop rotation research needs strong sequence of scenario execution. • GIS interface or integration with GIS software for visualization of simulated results (economical as well as ecological variables) on a farm scale. • Built-in tools of model information support for model-based forecasting (weather and field test databases, stochastic weather generator, etc.)

Only the existence of a comprehensive ecologically oriented crop model and a special software providing cyclical scheme of model computation (taking into account crop rotation) will solve the problem of analyzing long-term trends of indicators of soil fertility and other parameters of the environmental sustainability of agricultural landscapes. The above mentioned requirements to a «model-centric» computer system of analysis and decision making support in sustainable agriculture seem to be rigorous. Nevertheless, the prototypes of such a system have been developed. For example, DSSAT (leading solution for crop modeling in the USA) includes special application for crop rotation analysis that assess economic risks and environmental impacts taking into account irrigation, fertilizer management, climate variability and changes, soil carbon sequestration, and precision management [START_REF] Jones | The DSSAT cropping system model[END_REF].

Examples of successful DSSAT applications for crop rotation analysis and optimization of combination of crop residue and N application rate for sustainable production are also known [START_REF] Sarkar | Sequence Analysis of DSSAT to Select Optimum Strategy of Crop Residue and Nitrogen for Sustainable Rice-Wheat Rotation[END_REF][START_REF] Salmerón | DSSAT nitrogen cycle simulation of cover crop-maize rotations under irrigated mediterranean conditions[END_REF]. One of the most known European solutions for modelbased analysis incorporating mid-term planning in farm scale is LandСаrе-DSS developed in the Leibniz Center of Agrolandscape Research [START_REF] Wenkel | LandCaRe DSS -An interactive decision support system for climate change impact assessment and the analysis of potential agricultural land use adaptation strategies[END_REF]. LandСаrе-DSS features includes an original cartographical interface, close connection with a built-in module of economic analysis and the usage of different type of crop simulators depending on the spatial resolution of the investigated problem: from simplified regression model YieldStat at regional level to dynamic crop model МОNIСА at farm or field level.

Integrated simulation environment «APEX-AGROTOOL» is, probably, the most advanced Russian product providing information support, planning and running of multivariate computer experiments in crop modeling. The system was developed in Agrophysical Research Institute (Saint-Petersburg) and consists of two main parts: dynamic crop model AGROTOOL [START_REF] Poluektov | Agrotool -a system for crop simulation[END_REF] and the system of model multivariate analysis APEX [START_REF] Medvedev | Crop simulation model registrator and polyvariant analysis[END_REF]. The principal modifications which have been made in software for «APEX-AGROTOOL» system to satisfy the above mentioned requirements of long term environmental analysis of agroecosystem dynamics are presented further.

Changes in the AGROTOOL Software

The simulation algorithm of AGROTOOL can be written in the form of recurrent discrete expression:

x(k+1) = f(x(k), a, w(k), u(k)), x(0) = x 0 , k = 0,1...T (1)
where x -vector of dynamic state variables; a -vector of constant parameters; uvector controlled external impacts (agricultural technician); w -vector uncontrollable external impacts; k -the time step for the model (time step is equal to one day), f -the evolution operator (a logical essence of the simulation algorithm). Thus, AGROTOOL model recursively computes the vector of values of the modelling characteristics of the agroecosystem in the next step of the calculation on the base of the vector from the previous step. The main technical feature of the current version of AGROTOOL software is that all the data necessary for the calculation are stored in the model operational database, which is a multi-sheet Microsoft Excel document. Moreover, the same Microsoft Excel document also stores a detailed simulation results in the form of the state vector model at each step for calculating y(k)=y(x(k)). Another important feature of AGROTOOL is the universal character of the simulation algorithm, i.e. it is so-called generic crop simulator.

A special modification has been developed for sequential modeling of crop rotation using AGROTOOL. Now it uses data from the operational database, stored there during the previous stage of calculation (for the predecessor crop) to be used as initial state for the calculation of the next crop. A formal procedure to perform recalculation is following: x 0 i+1 =g(y i (T)). In turn, the results of this calculation can be used to generate the initial state of the calculation of the crop of the successor of the second order, and thus closes the next "round" of crop rotation.

To carry out model calculations within the crop rotation in the current version of AGROTOOL software, it is necessary to know the dry biomass residue (separately for aboveground and root parts), nodule nitrogen (if the predecessor culture is legume), the total mineral nitrogen content and the humus in the soil. These values are fixed at the end of the season for the predecessor crop and "frozen", i.e. do not change until the time of sowing of the next succeeding crops. In the future, it is planned to develop an algorithm to study the behavior of these characteristics for non-vegetation period (wintering), including a simplified description of the transformations of these variables.

4

Changes in the APEX Software

The APEX software can be considered as a versatile repository of external crop model descriptors. Its interface permits users to register its own crop model or model version. Also APEX provides a universal environment for the polyvariant model analysis. It means designing and preparation of a multivariate computer case study, performing the model runs in batch mode and applying advanced procedures of statistical treatments for results obtained. Each set of input data forms a single scenario calculation. The scenario is a cortege of references to specific gradation of selected factors (information domain) specific to the subject area. These factors are following "soil", "culture", "area", "initial state", "technology" and "weather." During the registration of the model the software allows the user to specify the structure of variables and parameters for the specific model and to generate a list of tables and their fields, as well as an array of metadata. A more detailed description of the structure and principles of operation of the APEX software can be found in [START_REF] Medvedev | Crop simulation model registrator and polyvariant analysis[END_REF]. Rigid specification of the predefined factors enabled to perform "semantically rich" analysis of the results obtained using specialized software tools for preparation of input data (e.g. weather generator), although these features limit flexibility of the system. In particular, it allows implementation of the calculation of the crop rotations within the APEX software.

For automated calculation of crop rotations in APEX it is necessary to develop the following additional functionality:

• To implement a mechanism for the explicit specification of the sequence for the execution of scenarios in a framework of the project of computer experiment and to specify "boundary" scenarios, defining the beginning of the crop rotation block for a particular agricultural field. • To create a flexible interface for specification the method for the "continuity" of the results of the previous scenario during the formation of the initial state for the next scenario (taking into account the "predecessor crop") in the procedure of the metadata specification describing the connected model.

The fundamental idea underlying the formation of an ordered list of scenarios in a structured polyvariant project calculation of crop rotation can be demonstrated by analogy with SQL-queries in a relational database (Fig. 1). A simple project, realized by all possible combinations of all gradations of predefined factors (a full factorial experiment) in the framework of this analogy, can be represented by a QUERY1 (Fig. 1 -red), where the WHERE clause explicitly chooses the set of gradations for each of the predefined factors. The result of such query will be the Cartesian product of "all vs. all", generating N * M * K * P * Q * R scenarios in a project. Obviously, not all combinations of the factor gradations are meaningful. So it is clear that in a given year on the specific field only one crop involved in the crop rotation can grow. Thus, it is necessary to restrict the number of possible combinations and to form an incomplete factorial experiment scheme -QUERY2 (Fig. 1 -green).

Here, the second block of the AND clause is a set of additional links between the factor gradations. They are defined by the user in the specific APEX interface designed for the so-called "factor coupling".

A significant feature of the crop rotation project is the clear sequence of the execution of scenarios as results of the previous calculation can be used to generate the initial state at the next startup model in strict accordance with the scheme of crop changing. This is achieved by including a mechanism of the explicit specification of the order within factor gradations and between factors. The latter can be demonstrated by the introduction of sorting like QUERY3 (Fig. 1 The sequence of these factors in the SORT BY clause completely defines the scenario ordering within the project. The wizard dialog for creation of a new project for a simple "three-field -three-year" crop rotation scheme is shown in Fig. 2. Fig. 2. The first step of the New Project Wizard Fig. 2 shows which factor used as a "separator" in the determination of the crop rotation (in this case, this factor is "soil"). As a result, a user can transparently specify the correct scenario order and define the boundaries of the "result continuity" blocks within simulated crop rotation. APEX performs the transfer of the results from the previously calculated variant to initial state of next variant inside every block following by the separating scenario. Thus, a set of scenarios, which make up the project, and a series-parallel scheme of their execution are fully defined. A typical interface with the project created in APEX is shown on Fig. The method for transferring the results of the previous calculations into the certain fields of the gradation of the INITIAL_STATE factor for the next variant is described via a special APEX interface that is part of the input metadata about the connected models. Currently APEX supports two following modes: a) the selected INITIAL_STATE field can be directly equated to the value of selected calculation result and b) it can be declaratively assigned to a constant value. The latter method is used in conjunction as "environment APEX + model AGROTOOL».

Results

The degree of conformity of the achieved functionality of APEX and AGROTOOL with the above mentioned requirements of mid-term planning in land use is briefly summarized in Table 1. The abilities of the developed integrated environment cover the needs completely and thus, the «APEX-AGROTOOL» system can be used as a tool of model-oriented analysis of land use environmental sustainability [START_REF] Badenko | ARGOTOOL software as an intellectual core of decision support systems in computer aided agriculture[END_REF].

Table 1. Correspondence between mid-term planning requirements and abilities of «APEX+AGROTOOL» integrated software

Fig. 1 .

 1 Fig. 1. Demonstration of the fundamental idea approach (syntax does not coincide with the standard SQL)

Fig. 3 .

 3 Fig.2shows which factor used as a "separator" in the determination of the crop rotation (in this case, this factor is "soil"). As a result, a user can transparently specify the correct scenario order and define the boundaries of the "result continuity" blocks within simulated crop rotation. APEX performs the transfer of the results from the previously calculated variant to initial state of next variant inside every block following by the separating scenario. Thus, a set of scenarios, which make up the project, and a series-parallel scheme of their execution are fully defined. A typical interface with the project created in APEX is shown on Fig.3.

  -blue).

	SELECT CULTURE.*, LOCATION.*, SOIL.*, WEATHER.*,
	TECHNOLOGY.*,INITIAL_STATE*
	FROM CULTURE, LOCATION, SOIL, WEATHER,
	TECHNOLOGY, INITIAL_STATE
	WHERE
	CULTURE IN (CULT 1 , CULT 2 , CULT 3 …CULT N )	AND	QUERY1
	LOCATION IN (LOC 1 , LOC 2 , LOC 3 …LOC M )	AND
	SOIL IN (SOIL 1 , SOIL 2 , SOIL 3 …SOIL K )	AND
	WEATHER IN (WEA 1 , WEA 2 , WEA 3 …WEA P )	AND	QUERY2
	TECHNOLOGY IN (TECH 1 , TECH 2 , TECH 3 …TECH Q ) AND
	INITIAL_STATE IN (INST 1 , INST 2 , INST 3 …INST R )
	AND
	CULTURE CORRESPONDS SOIL		QUERY3
	AND
	WEATHER CORRESPONDS SOIL
	AND
	TECHNOLOGY CORRESPONDS WEATHER	AND
	…
	SORT BY
	LOCATION,
	SOIL,
	WEATHER,
	CULTURE,
	TECHNOLOGY,
	INITIAL_CONDITION

Requirement

Current state Crop model: AGROTOOL:

Generic simulator

Versatile algorithm for all maintained cultures. Calibrated models for cereals (summer and winter wheat, winter rye, barley, oats), maize, potato, root vegetables, annual and perennial forages, legumes.

«Wintering» Continuous calculation. Modified descriptions of snow melting and soil thermal regime.

Predecessor influence

Separated calculation of litter and root residues in the module of carbon-nitrogen transfer and transformation in soil. Sub-model of symbiotic nitrogen fixation and nodule nitrogen dynamics. Simulation infrastructure: APEX:

Multiple running

Validated and implemented integrated environment for multivariate analysis and automation of computer experiments with crop models.

Crop rotation support

Special plug-in for planning not full factorial experiments and performing complex serial-parallel schemes of scenario computation.

Forecasting

Built-in stochastic generator of daily weather variables taking into account possible climate changes.


Jana Soukopová
email: soukopova@econ.muni.cz

Jiří Hřebíček
email: hrebicek@iba.muni.cz

Jiří Valta
email: jiri.valta@cenia.cz

National Environmental Data Facilities and Services of the Czech Republic and their Use in Environmental Economics

Keywords: environmental data, information system, environmental services, eGovernment, open government data, environmental economics

National environmental data facilities and services are part of the environmental information systems of the Ministry of the Environment of the Czech Republic that have been under development since 1990. In 2010 the development of the National Information System for Collecting and Evaluating Information on Environmental Pollution project started, co-financed by the European Regional Development Fund. This project consists of an integrated system of reporting (ISPOP), an environmental help desk (EnviHELP), and the national INSPIRE geoportal, which were developed between 2010 and 2013 and were discussed at ISESS 2013. This paper introduces the current development of several national environmental and financial data facilities and services based on eGovernment implementation in the Czech Republic and the open environmental and financial data approach of the Czech Ministry of the Environment and the Czech Ministry of Finance. It also introduces the web information system that enabled us to find the relationship between environmental economics and municipal waste management in the Czech Republic.

Introduction

The development of eGovernment is part of the current strategy for the modernisation of public administration in the Czech Republic which was approved in July 2007: "Efficient Public Administration and Friendly Public Services -Strategy on Realisation of Smart Administration in the Period 2007-2015" (further "Smart Administration Strategy"). The overall purpose of this policy instrument is for the Public Administration (PA) to achieve effectiveness comparable to that of the European Union (EU) and its Member States. The "Strategic Framework of the Development of eGovernment 2014+" further develops the Smart Administration Strategy and outlines steps and measures to be taken to enhance electronic governance, to improve and upgrade its architecture, to secure its financing, and to transform it into a standard information and communication technology (ICT) tool used by all PAs in their everyday communication with their clients -the public, representatives of the business sector, and other subjects [1]. The construction of environmental data facilities and infrastructure focuses primarily on the transparent disclosure of data created during these processes. In 2013, the Ministry of the Interior (MoI) of the Czech Republic adopted the "Strategic Framework for the Development of eGovernment 2014+", which regards eGovernment as an interactive process involving PA authorities, i.e., national, regional, and municipal governments, as well as citizens, entrepreneurs, and other stakeholders. The activities of the MoI in eGovernment are connected with the information agendas of the Ministry of the Environment (MoE) and their registration in the Register of Rights and Obligations of the Basic Public Administration Registers of eGovernment [START_REF]Základní registry veřejné správy (Basic public administration registers)[END_REF] which have been in place since 1 July 2012. These agendas are a cornerstone of the eGovernment of the Czech Republic. Their basic objective is to help citizens, companies, and other entities that come into contact with PA by minimizing the number of their personal visits to government offices through the use of ICT tools with on-line access from anywhere, at any time. At the same time, the agendas require that the PA must perform a safe, efficient, and transparent exchange of accurate and up-to-date environmental data [START_REF] Hřebíček | Environmental information systems (in Czech). Akademické nakladatelství CERM[END_REF].

The strategic approach to the development of national environmental data facilities and services focuses on a high level of eEnvironment services [START_REF] Hřebíček | eEnvironment: Reality and Challenges for eEnvironment Implementation in Europe[END_REF] and on building support for MoE information services. The approach enables a broader effectiveness of MoE policy instruments for environmental protection. The basis for such changes is the management of the organizational framework and strategy of ICT resources, support, and services. The Environmental Information Systems (EISs) of the MoE manage the processing, retrieval, and presentation of environmental data and information, in support of the Aarhus Convention [START_REF]Århus Convention[END_REF], [7].

In the Czech Republic there are currently about 40 different EISs in operation, including a geographic information system in compliance with INSPIRE standards [START_REF]INSPIRE standards[END_REF] and several thousand environmental databases [START_REF] Hřebíček | Environmental information systems (in Czech). Akademické nakladatelství CERM[END_REF]. Most of these information resources are directly available to the general public, regardless of the applicability of their content.

The notification of the scope to national environmental data and services (agendas) in eGovernment of the Czech Republic has now finished [START_REF]Základní registry veřejné správy (Basic public administration registers)[END_REF]. This notification ensured the legitimacy of access to environmental data through the information system of the Basic Public Administration Registers of eGovernment. The information flow within the EISs of the MoE has been formalized with the necessary degree of ICT infrastructure. These EISs are reflected in the new concept of the Information Strategy of MoE [7], whose attestation took place in November 2012 [START_REF] Prášek | National INSPIRE Geoportal of the Czech Republic[END_REF].The PA currently publishes environmental and related data mostly through prepared EIS applications.

However, these applications only suit a certain type of user. Users wishing to use the environmental data in a different manner than that intended by the PA are excluded. Data that users might want that is not published by the PA include: tenders and budgets; payments made by individual towns, cities, regions, and national institutions; and the composition of municipal representation and the individual votes of its members [START_REF] Soukopová | Decision Support of Waste Management Expenditures Efficiency Assessment[END_REF].

Various third-party developers can create many applications that display, analyse, and link the data in ways that may be interesting to the public. For example, applications can be created that show: trends in the numbers and amounts of tenders in individual regions; trends in municipal budgets in individual regions; tenderwinning companies that are led by municipal representatives; and the ten biggest suppliers for each regional city.

Most of the necessary data for environmental economic modelling is produced from taxpayers' money [START_REF] Soukopová | Decision Support of Waste Management Expenditures Efficiency Assessment[END_REF] and collected by the PA information systems. The related data is even often available on the PA websites, such as those of the MoI, MoE, the Ministry of Finance (MoF), the Ministry of Regional Development (MoRD), and the Czech Statistical Office (CZSO). However, due to the way this data is published, the creation of smart custom applications is challenging for the future development of eGovernment in the Czech Republic, both financially and in terms of time [1].

In section 2 of the paper, we present our experience with the standard means of collecting environmental data through the Integrated System of Reporting (ISPOP) [START_REF]ISPOP -Integrated System of Reporting[END_REF], which enables open public access to nationwide data for several EISs. It provides environmental data in a form that allows access to anyone at any time and freely allows the data to be combined. In section 3 of the paper we discuss our experience with the open data infrastructure of the MoF, which enables public access to financial data through its MONITOR web information system [START_REF] Monitor | [END_REF] and with the ROZPOČETOBCE [START_REF] Řezáč | Web portal for the evaluation of public municipal budgets[END_REF][START_REF]Rozpočet obce[END_REF] system, which enables the comparison of financial data for every municipality in the Czech Republic in a time series. Further discussion in section 3 is devoted to our experience in creating software applications [START_REF] Kuttner | Web portal for the evaluation of the cost of waste management for municipalities, districts and regions[END_REF] for the environmental economic modelling that the public really needs.

National Environmental Data Facilities and Services of Public Administration

Collection of Environmental and Financial Data

Environmental legislation of the Czech Republic is in compliance with the European Union (EU) and requires organizations, companies, enterprises, etc. (i.e. environmental reporters) to provide the PA with information on the environmental impact of their activities. Their environmental reports and the duty of notification are defined by the relevant Czech environmental legislation, which obliges environmental reporters to keep prescribed records and report them to the PA of environmental protection.

The duty of environmental reporters is to deliver relevant environmental data, information, and messages to the PA authorities and institutions concerned. Legal provisions exist to control the reporting obligation. Environmental reports include primary environmental data such as air, water, and soil pollution, the generation and treatment of waste, electrical and electronic waste, etc. Most of these reports are processed by the Czech Environmental Information Agency (CENIA) [START_REF] Prášek | National INSPIRE Geoportal of the Czech Republic[END_REF] through the Integrated System of Reporting (ISPOP) [START_REF]ISPOP -Integrated System of Reporting[END_REF] of the MoE, which was developed in collaboration with IBM between 2008 and 2013. ISPOP was constructed to ensure flexibility in terms of its expansion to other environmental reporting agendas and to ensure compliance with updated environmental legislative obligations [START_REF] Prášek | National INSPIRE Geoportal of the Czech Republic[END_REF] The basic idea of ISPOP is a form solution in the information technology of Adobe LiveCycle ES. Electronic smart forms are available in PDF format and are part of the XML layer for computer processing [13]. The forms also include a PDF layer for an electronic signature, by means of which it is possible to authorize a document. Filling in the forms and browsing through them is possible with Adobe Reader.

Standardized PDF forms enable: obtaining and storing structured content (XML according to the valid XSD template); editing forms in Adobe Reader; online checking and sending reports to ISPOP; online submission to ISPOP Data Storage; content encoding forms into 2D bar codes.

The main technical requirement for using ISPOP is the ability to connect to the Internet, at least for the amount of time necessary for receiving/being assigned to the environmental report. A user needs an internet browser with the additional free software of Adobe Reader to work with ISPOP web applications.

ISPOP built the universal input data gateway of several EISs, providing incoming data files in a specified standardized format and the control and distribution of target processing systems. ISPOP enables the management of reports submitted using the environmental record form and the archiving and evaluation of their content (in cooperation with other related systems of eGovernment).

The Central System of State Accounting Information (CSÚIS) [28] of the MoF is designed to gather the accounting records of selected entities (accounting units, e.g. all municipalities in the Czech Republic) for the operational management of the MoF. It collects only the prescribed obligatory forms with financial data, which responsible persons submit in the automatically encrypted XML files using the Simple Object Access Protocol (SOAP) interface (the preferred option) or manually using the CSÚIS web application or the application of the batch statements. It is a similar collection method to that of the collection of environmental data through ISPOP.

Public Access to Environmental and Financial Data

The web information system EnviHELP [START_REF]EnviHELP -Environmental help desk[END_REF] provides support for a particular operating state of ISPOP, e.g. administration for incumbents fulfilling reporting obligations under Act No. 25/2008 Coll., as well as business communities and the general public in providing environmental information in relation to Act No. 123/1998 Coll., on public access to environmental information and the Aarhus convention.

Many EISs have been developed in the Czech Republic in the past decade, but only some collect environmental data through ISPOP with standardized interactive PDF forms.

Data standards [13] for reporting through ISPOP are published every year by the MoE, where for any legislative obligation there is a data standard (in XSD format) and a detailed description (in PDF format). These data standards describe the data structures, the data formats and the automated checks of the content of the submitted information. Forms are available in the accounts of registered environmental reporters after login into the ISPOP system. Here is a brief description of two EISs using prescribed data standards:

• Integrated Pollution Register (IRZ), [START_REF]Integrated register pollution[END_REF], in compliance with the Pollutant Release and Transfer Register (PRTR), is an environmental database or inventory of potentially hazardous chemical substances and/or pollutants released to the air, water, or soil and transferred off-site for treatment or disposal according to the OECD Council Recommendation [START_REF]Recommendation of the Council on Implementing Pollutant Release and Transfer Registers (PRTRs)[END_REF]. IRZ is a publicly accessible database of plants for which the amount of pollution produced beyond the legal limits has been reported. The system records 93 different pollutants of every plant monitored in all types of releases and transfers, according to the established threshold, which is reported as the amount of a substance in kilograms per calendar year.

• Information system of waste management (ISOH) [18] is a publicly accessible

database containing data on the waste generation and treatment by generators and data on facilities for treatment, recovery, and disposal of waste. The system records annual reports of more than 70,000 different generators in all 6,500 municipalities and more 3,000 facilities. The annual ISOH database contains more than 50,000 records of municipal waste generation and 10,000 records about their treatment. The nationwide database VISOH [START_REF]VISOH -Public Waste Management Information System of the Ministry of the Environment[END_REF], which contains the aggregated data of ISOH, is accessible to the general public. The nationwide database ALLISOH [20], which contains all of the data of ISOH, is accessible for the staff of the State administration in environment protection.

MONITOR [START_REF] Monitor | [END_REF] is a specialized web information portal of the MoF that allows open public access to budget and accounting information from all levels of the PA. MONITOR also provides the financial statements of all PA units. The presented information comes from the Integrated Information System of the Treasury (IISSP) [START_REF] Monitor | [END_REF] of the MoF and CSUIS, and they are updated quarterly.

The primary version of MONITOR was released in May 2013. It replaced the previous MoF web information portals ARIS [START_REF]ARIS-Automatized budget information system[END_REF] (database of municipalities' accounting from 2000 to 2009) and ÚFIS [24] (database of municipalities' accounting from 2010 to 2012). In December 2013 the analytical part of portal was made available, which allows dynamic data analysis using advanced tools for financial reporting.

Unfortunately, other transparently published data by the PA in the eGovernment services are not in a proprietary format (only scanned to PDF or manually created tables). They are not published with standardized open formats that would allow the general public to: share the data freely and combine the data freely.

Case Study: Environmental Economic Model and Information System of Municipal Waste Management

We developed environmental economic models and information systems [START_REF] Soukopová | Model of cost and price relationships for municipal waste management of the Czech Republic[END_REF][START_REF] Hřebíček | Integrated economic model of waste management: Case study for South Moravia region[END_REF] for all types of waste treatment facilities: mechanical biological treatment plants, incineration plants with energy recovery and landfills, composting and biogas plants, and sorting plants. We wanted to use a time series to investigate municipal waste management and financial data. We used municipal waste management data from ISOH with the collaboration of the CENIA agency and the MoE for the time series 2008-2013. We also needed a time series of municipal financial data. We tried to use the publicly accessible data from the web portals ARIS, ÚFIS, and MONITOR of the MoF. However, they do not provide simple tools for downloading publicly accessible data like the systems VISOH for the public or ALLISOH for the PA. It is very difficult to find an appropriate time series of financial data of a given municipality. Therefore, we analysed the database structures of ARIS and UFIS. One student developed the web information system ROZPOČETOBCE [START_REF] Řezáč | Web portal for the evaluation of public municipal budgets[END_REF][START_REF]Rozpočet obce[END_REF] in 2012 and updated it in 2013. ROZPOČETOBCE enables the presentation of publicly accessible financial data (public income and expenditure) of every municipality in the Czech Republic in the period from 2000 to 2013 from many different viewpoints. Every citizen and user of this smart web system can analyse complete public incomes and expenditures of a municipality in the Czech Republic. We chose the city of Brno as an example; see Figs. 2 and3 where per capita expenditures in municipal waste management are presented. The expenditure of municipal waste management in the municipalities covers the costs associated with the collection, pick-up, transportation, use, disposal, other treatment, and prevention of municipal waste (Fig. 2). In environmental economic models and information systems [START_REF] Soukopová | Model of cost and price relationships for municipal waste management of the Czech Republic[END_REF][START_REF] Hřebíček | Integrated economic model of waste management: Case study for South Moravia region[END_REF], we also used publicly accessible data from the Information System on Public Procurement and RISY [START_REF]RIS -Regional Information Service[END_REF] of the MoRD, where we had to develop a special parser to download the required municipal data.

We continued, on the basis of the ROZPOČETOBCE system, to create a new information system [START_REF] Kuttner | Web portal for the evaluation of the cost of waste management for municipalities, districts and regions[END_REF] for the automatic visualization of public incomes and expenditures in waste management of all municipalities, districts, and regions with the use of a time series of publicly accessible data from the VISOH and ALLISOH of the MoE, ARIS, ÚFIS and MONITOR of the MoF, and RISY of the MoRD web information systems. The new complete database system has more than 15 million records.

One of the outputs of the new system [START_REF] Kuttner | Web portal for the evaluation of the cost of waste management for municipalities, districts and regions[END_REF] covers the expenditure and revenue of municipalities on waste management, the generation of waste in municipalities, and the cost of landfill waste, including their aggregation with respect to the number of municipal inhabitants. For data analysis in the system [START_REF] Kuttner | Web portal for the evaluation of the cost of waste management for municipalities, districts and regions[END_REF], we used a mathematicalstatistical theory of sets and a cluster analysis of each municipality. We sorted municipalities into groups (sets) according to population. For the nine resulting groups of municipalities we compared the data on the average per capita expenditure, the maximum and minimum value of per capita expenditure, and the standard deviation of expenditure and per capita data for the entire file with the set of all municipalities in the Czech Republic; see Table 1. The information from Table 1 would be appropriate to add to the analytical tools of the MONITOR system so that a municipality could compare its own expenses with that of other municipalities (e.g., according to their position in the district or region, by size category, etc.) and thus uncover potential methods for reducing costs and increasing efficiency in waste management.

Conclusion

All of the PA information systems in the Czech Republic that are accessible through the web interface have similar shortcomings. Legislation in the Czech Republic has presented no centralized way to constitute and fully fulfil public data access following Directive 2003/98/EC, known as the "PSI Directive", as announced in the Smart Administration Strategy. Each Ministry created its own information system or database system, which have been in closed forms. The exception is the MoE strategy [7], which had its own format and application of EIS dependent on standardized data.

The applicability of other PA information systems is difficult. For the user, this means prevented or restricted work with the data of the PA. Current social, technological, and economic changes create challenges and new expectations for national environmental data facilities and services based on ISPOP. Given that these challenges are largely intertwined, any vision for the future of public data services needs to take a multi-disciplinary approach.

Fig. 1 .

 1 Fig. 1. Public expenditure on waste management per capita in Czech crowns [Kč] in the city of Brno in 2012.

Fig. 2 .

 2 Fig. 2. Graph of per capita public expenditure on waste management in Czech crowns [Kč] in the city of Brno 2000-2013.

  . The hardware architecture of ISPOP consists of the IBM server eCenter BladeCenter, HS 22, and IBM disc array storage System Storage DS3400. Communication infrastructure is based on Cisco network elements. The software architecture consists of several modules: VMware virtualization; Novell SUSE Linux operating system; Jboss and Tomcat application servers; Oracle 11g database and ISPOP application layer (own J2EE application); CMS Magnolia (presentation); Adobe LiveCycle ES2 (operation with PDF form); Novell eDirectory (identification); and Novell Access Gateway (SSO).

Table 1 .

 1 Total per capita expenditure on waste management for municipalities in the Czech Republic in 2012

				Expenditure per capita in
	Population	Number of municipalities	Total of inhabitants	Czech crowns [Kč] Average Standard
					deviation
	≤ 500	3,464	835,971	862.81	487.13
	501 -1,000	1,352	953,662	830.16	465.81
	1,001 -4,000	1,047	1,917,991	962.38	807.25
	4,001 -10,000	198	1,210,408	968.83	493.9
	10,001 -20,000	62	871,834	964.31	419.7
	20,001 -50,000	41	1,167,522	987.91	423.16
	50,001 -100,000	16	1,137,171	854.52	173.68
	100,001 -1,000,000	4	947,894	693.50	209.61
	> 1,000,000	1	1,241,664	1,097.70	0

  One solution may be embracing open government data, based on the principles of collaboration, transparency, and participation within an appropriate governance framework. Such an open government model of national data facilities and services builds on open data, open services and open decisions.

Acknowledgement

This research was supported by the Czech Science Foundation (GACR) under the project "Unfair competition and other economic factors influencing the efficiency of the provision of public services".


Guillaume Binet
email: guillaume.binet@3-5lab.fr

Jean Decobert

Nadine Lagay

Nicolas Chimot

Christophe Kazmierski

Investigation of 1.3 µm AlGaInAs Multi Quantum Wells for Electro-Absorption Modulated Laser

Keywords: III-V semiconductors, AlGaInAs, multiquantum well, electro-absorption modulator, quantum confined Stark effect

and research institutions in France or abroad, or from public or private research centers.

Investigation of 1.3 µm AlGaInAs multi-quantum wells

for electro-absorption modulated laser

Introduction

With the development of the internet, smart phone applications and cloud computing, the demand for data rate for local area network (LAN) is exploding. Electro-Absorption Modulators (EAM) integrated with a laser or Directly Modulated Lasers (DML) are already used for 10 Gbit and 40 Gbit transmission applications due to their small size and low electrical consumption [1,[START_REF] Klein | Proceedings of ECOC 2013[END_REF]. To address the specifications for 100Gbit and 400Gbit Ethernet, the number of components on chip has to be increased but at the expense of larger footprint, as well as extra cost and electrical consumption. Monolithic integration on InP is a way to facilitate the fabrication of complex Photonic Integrated Circuits (PIC) provided with multiple functions. We have sucessfully shown that InP actually provides the lowest-size full-monolithic transmitters (TX) for complex modulation formats (m-PSK, QAM etc) using a novel prefixed optical phase switching by low drive using EAM [START_REF] Dupuis | [END_REF]4,[START_REF] Mardoyan | Proceedings of OFC, Th5C.2 ([END_REF]. While keeping simple the transmitter and its driving electronics, it has the advantage over the more standard Pulse Amplitude Modulation (PAM) format to suppress the optical carrier and to provide better energy efficiency [START_REF] Kazmierski | [END_REF]. However, up to now, this technique was mostly used to fabricate monolithic transmitters in 1.55 μm band as clear applications for 100 Gb/s long-haul transmissions [START_REF] Valicourt | Proceedings of OFC, Th5C.3 ([END_REF]. However, the small size and low consumption monolithic transmitters appear as an attractive solution for emerging terabit short reach connections and probably for the next speed rise in access network also being very sensitive to costs of terminals. These applications make use of 1.3μm bands for low dispersion of fibre.

With this aim, we are studying basic quantum well design for a laser and an electro-absorption modulator switch to be integrated into Photonic Integrated Circuits (PIC) using our Selective Area Growth (SAG) platform. Optimum design for 1.3 μm imposes new more stringent requirements.

In the first part of this paper, we present our SAG integration platform. Then, we present the trade-off on bandgap and well thickness on the excitonic properties in EAM. We show the MQW design of efficient modulator using AlGaInAs MQWs in the 1.3 µm band. It has been reported that compared to conventional InGaAsP, the quaternary AlGaInAs allows enhanced excitonic effects, a higher bandwidth and high temperature operation [START_REF] Sweeney | [END_REF]9]. We also report on experimental results from several structures and evaluate exciton strength and shift under electric field. Finally we present measurements about basic material lasing performances of the different structures.

Photonic integration technology

The EAM integrated with a DFB laser (EML) is a photonic integrated circuit with 3 types of functions which are separated into component sections: continuous wave laser, EAM and passive waveguides for section separation and optical power. Because EAM is really sensitive to the detuning between the laser emitting wavelength and the modulator absorption edge, optimal bandgap engineering of the optical functions is mandatory.

An integration scheme easily suitable for this purpose is SAG by metal organic vapour phase epitaxy (MOVPE). It is a powerful technique for monolithic integration, where different bandgap materials are defined simultaneously in a single epitaxial growth. It is performed on dielectric patterned substrates. Because the dielectric is amorphous, the active precursors do not nucleate on it, so they diffuse and induce growth variation in the vicinity of the masked zone. Then for any alloy composed of more than twp elements, not only an enhancement of the thickness happens but also a compositional shift due to different decomposition rates of group III element precursors in the vapour phase.

Thus modeling is necessary to design the mask stripes. For quaternary alloys AlyGaxIn1-x-yAs, it is more difficult because three elements III are mixed in the vapor phase. A simple approach to model SAG is to consider only vapor phase diffusion (VPD) as the source material of supply. If no interaction is assumed between group III elements, each binary element can be considered to have an independent growth enhancement ratio that leads to identification of the composition and the growth enhancement ratio of the alloy in the vicinity of the mask [START_REF] Dupuis | [END_REF].

Material design

Optimal bandgap engineering is essential to optimize relevant EAM features such as optical saturation intensity, extinction ratio (ER) and modulation efficiency expressed in dB/V. Power saturation phenomena in the EAM is known to be due to a slow carrier sweep-out from the active region resulting in photogenerated low-mobility hole accumulation (pile-up) in the valence band wells [10]. The presence of carriers has different consequences such as field screening and decreased Quantum Confined Stark Effect (QCSE) leading to low ER, large capacitance and so limited bandwidth. The optical saturation intensity is given by [11] 𝐼 𝑆 = ℏ𝜔𝑁 𝑆 𝛼 (𝐿 𝑤 + 𝐿 𝑏 ) 𝑚 𝑒 + 𝑚 ℎ 𝑚 𝑒 𝜏 ℎ + 𝑚 ℎ 𝜏 𝑒 (1) with ℏω the photon energy, 𝑁 𝑆 the carrier population at saturation, 𝛼 the absorption coefficient, 𝐿 𝑤 (𝐿 𝑏 ) the well (barrier) thickness, 𝑚 𝑒 (𝑚 ℎ ) the electron (hole) effective mass and 𝜏 𝑒 (𝜏 ℎ ) the electron (hole) lifetime.

According to (1), the optical saturation intensity is enhanced by reducing the well thickness and the carriers lifetime. However, only the hole lifetime can be taken into consideration because of the difference in effective mass with electrons which are swept out much faster than holes. The latter is given by [11] 𝜏 ℎ -1 ≈ 𝜏 𝑅 -1 + 𝐴 ℎ exp (-∆𝐸 𝑣,𝑒𝑓𝑓 𝑘 𝐵 𝑇 ) + 𝐵 ℎ exp (-2𝐿 𝑏√ 2𝑚 ℎ ∆𝐸 𝑣,𝑒𝑓𝑓 /ℏ) [START_REF] Klein | Proceedings of ECOC 2013[END_REF] with ΔE v,eff the effective valence band offset (ΔE v -E 1 ) as shown on Figure 1. In (2), the first term is the carrier recombination, the second term the thermionic emission and the third the tunnelling emission [11,12]. It shows that the hole lifetime is reduced with ΔEv,eff.

Furthermore, ER and modulation efficiency are governed by the excitonic absorption. It is therefore important to enlarge the exciton strength and exciton shift ΔE under electric field F so as to benefit from large ER and large modulation efficiency. Firstly, according to [13], ΔE is proportional to the fourth power of the well width (3)

∆𝐸 ∝ 𝐹 2 𝐿 𝑤 4 (3)
Increasing ΔE is therefore inconsistent with the optimization of the optical saturation intensity according to (1). It is also inconsistent with the exciton strength enlargement with L w lowering [14]. However, the exciton strength can be improved by enhancing exciton binding energy by improving carrier confinement through the barrier bandgap increase. Nevertheless it also turns out to be opposite to the optical saturation intensity improvement. These different trade-offs emphasize the relevance of the bandgap engineering.

Moreover, it was demonstrated that highly strained barriers reduce the carrier escape time [15]. Figure 2 shows simulated effective band offset for both electrons and holes from AlGaInAs MQW structures. The barriers are 6nm thick with different bandgaps and strain and identical 5nm thick wells are used for all the structures. When the tensile barrier strain is fixed at -0.6%, it can be noticed that when the barrier bandgap is reduced, a low ΔE v,eff is achieved so as to reduce the hole carrier pile-up and optical saturation. However, the effective conduction band offset is also reduced which can be too detrimental for laser thermal properties. This effect can be addressed by increasing the tensile barrier strain for a 1.12eV barrier bandgap with -1% tensile strain.

Characterization results

Sample structure and fabrication

The crystal growths were carried out by MOVPE. The MQW active layers are undoped and made of compressively strained wells between tensile strained barriers. Seven structures were grown with the same undoped active layer thickness to keep a constant applied electric field and a constant confinement parameter (see Table 1). All the structures are 1% compressively strained well. The structures A and B consist respectively of 8 and 6 nm thick well with ΔE v,eff . The structure C was grown to evaluate the barrier strain influence as described on Figure 2. An example of stack is described in Table 2.

QSCE measurements

Photocurrent spectra were recorded to access QCSE shift and excitonic absorption strength. The spectra for the structure A1 is shown in Figure 3 as an example. The excitonic peak can be identified around 1265 nm at 0V. The shift and the decrease of the excitonic peak are also clearly visible when the electric field is increased. We reported the relative amplitude and the wavelength shift for all the structures respectively in Figures 4 and5. In Figure 4, the relative exciton peak height represents the photocurrent of the exciton peak normalized by its value at 0 V. From Figures 4 and5, it can be noticed by comparing structures A and B that the first order effect on the exciton strength and shift is the well thickness. Then, the exciton strength and shift trade-off with the well thickness is clearly visible and confirms the expectations described previously. Besides, for a given well thickness, the larger the ΔEv,eff, the higher the exciton strength,and the lower the exciton shifts. This can be explained by a reduction of the barrier bandgap which induces a decrease of the exciton binding energy. The structure B3 (6 nm-thick well and ΔEv,eff of 70 meV) presents a lower excitonic strength while having a higher exciton shift and differs clearly from structures B1 and B2 with higher ΔEv,eff.

0 V -0,5 V -1 V -1,5 V -2 V -3 V -4 V
In the case of structure B3, only one heavy hole level is confined in the valence band. The field screening is thereby reduced but the excitonic strength is also reduced due to a decreased exciton binding energy.The specific 5 nm-thick well structure C was grown with 1 % tensile strain barrier and presents a ΔEv,eff of 45 meV. The objective was to reduce the offset to increase the exciton shift and keep a large effective conduction band offset. Thus, from 0 to 2V under inverted bias, the shift is comparable to the 6 nm well structures with an ΔEv,eff of 98 meV and 128 meV. This demonstrates the relevance of strain engineering to reach low ΔEv,eff with narrow wells while keeping a large effective conduction band offset and opens the path to refine band structure design.

Broad area laser characteristics

Figure 6 Summary of the threshold current density J inf /well (green), the characteristics temperature T 0 (blue) and the internal quantum efficiency (red) for the different structures To verify the quality of the material in terms of lasing performance, broad area (BA) lasers are generally fabricated. They are used to evaluate the threshold current density for an infinite ridge J inf /well, the internal quantum efficiency η and the characteristic temperature T 0 and this has been done for the seven structures.

Thus, for J inf /well, the average behaviour of the different structures is comparable, except that for a given well thickness the threshold decreases with the barrier height. Then, the internal quantum efficiency of the different structures are alike and characteristic temperature is better for thinner wells.

In consequence by using SAG, it is possible to tune the laser bandgap to use the optimal detuning.

Summary and conclusion

Discrete or small scale PIC transmitting components, especially those based on indium phosphide technology, have become an integral part of the optical fiber communication industry. In this context, InP-based quantum well electro-absorption modulators (EAMs) emerge as ones of the smallest (<100µm waveguide length) and most energy-efficient electro-optic converters.

In this paper, we presented the influence of well thickness and barrier bandgap on AlGaInAs-based MQW EAM performances and BA laser performances. This work gives paramount information on EAM design and compares the influence of some material parameters in terms of absorption. It also shows the possibility of integrating the EAM with a laser by SAG, as the BA performances are sufficient. Structures for efficient modulators show best trade-offs with a 6 nm well thickness structure with the lower barrier.

Figure 1

 1 Figure 1 Schematic diagrams of AlGaInAs MQW band diagram with 1% well strain and -0.6 % barrier strain

Figure 2

 2 Figure 2 Simulation of ΔE v,eff and ΔE c,eff for AlGaInAs MQW of 5 nm well thickness and 6 nm barrier thickness

Figure 3

 3 Figure 3 Measured photocurrent spectra for the structure A1

Figure 4 Figure 5

 45 Figure 4 Measured QSCE absorption spectra

Table 1

 1 Summary chart of the seven structures

	Structure	Well thickness	Barrier thickness	ΔEv,eff	Barrier strain
	A1 A2 A3	10 x 8 nm	11 x 10 nm	126 meV 107 meV 91 meV	-0.6 %
	B1 B2 B3	13 x 6 nm	14 x 7.5 nm	126 meV 98 meV 70 meV	-0.6 %
	C	16 x 5 nm	17 x 6 nm	45 meV	-1 %

Table 2

 2 Schematic of AlGaInAs compressive strained MQW of structure A1

	Layer	Composition	Thickness (nm)	doping
	p contact	InGaAs	300	p=3x10 19 (Zn)
	spacer	InP	2500	p=1.4x10 18 (Zn)
	SCH	Al39Ga08In53As	20	undoped
	Barrier	Al0.375Ga0.185In0.440As	10	undoped
	Well	Al0.166Ga0.174In0.660As	8 (x 10)	undoped
	Barrier	Al0.375Ga0.185In0.440As	10 (x 10)	undoped
	SCH	Al39Ga08In53As	60	undoped
	buffer	InP	2000	n=1x10 18 (Si)
	substrate	InP

Acknowledgements

Part of this work was supported by the Ministry of Industry STEAM project and the Nano2017 program.