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|Effect of litter depths on general and dustbathing behaviour in laying hens : Litter behaviour laying hens
Emous, R.A. van; Ogink, ; Gunnink, H. - \ 2017
Laying hens, litter depth, behaviour, dustbathing.
Due to the European Union (EU)-wide ban on conventional cages for laying hens, the use of alternative housing systems (i.e., floor systems and aviary systems) has increased in many European countries. The litter in these alternative systems is usually composed of the birds’ droppings (manure and uric acid), feathers, and bedding material spread onto the floor (Cambra-López et al., 2011). These materials deteriorate into tiny particles and become airborne (fine dust = PM10) through drying and the mechanical agitation by bird activity, such as scratching, dust bathing, wing-flapping and so on (Calvet et al., 2009).
Strategies for greenhouse gas emissions mitigation in Mediterranean agriculture: A review
Sanz-Cobena, A. ; Lassaletta, L. ; Aguilera, E. ; Prado, A. Del; Garnier, J. ; Billen, G. ; Iglesias, A. ; Sánchez, B. ; Guardia, G. ; Abalos Rodriguez, Diego ; Plaza-Bonilla, D. ; Puigdueta-bartolomé, I. ; Moral, R. ; Galán, E. ; Arriaga, H. ; Merino, P. ; Infante-Amate, J. ; Meijide, A. ; Pardo, G. ; Álvaro-Fuentes, J. ; Gilsanz, C. ; Báez, D. ; Doltra, J. ; González-Ubierna, S. ; Cayuela, M.L. ; Menéndez, S. ; Díaz-Pinés, E. ; Le-Noë, J. ; Quemada, M. ; Estellés, F. ; Calvet, S. ; Grinsven, H.J.M. Van; Westhoek, H. ; Sanz, M.J. ; Gimeno, B.S. ; Vallejo, A. ; Smith, P. - \ 2017
Agriculture, Ecosystems and Environment 238 (2017). - ISSN 0167-8809 - p. 5 - 24.
An integrated assessment of the potential of different management practices for mitigating specific components of the total GHG budget (N2O and CH4 emissions and C sequestration) of Mediterranean agrosystems was performed in this study. Their suitability regarding both yield and environmental (e.g. nitrate leaching and ammonia volatilization) sustainability, and regional barriers and opportunities for their implementation were also considered. Based on its results best strategies to abate GHG emissions in Mediterranean agro-systems were proposed. Adjusting N fertilization to crop needs in both irrigated and rain-fed systems could reduce N2O emissions up to 50% compared with a non-adjusted practice. Substitution of N synthetic fertilizers by solid manure can be also implemented in those systems, and may abate N2O emissions by about 20% under Mediterranean conditions, with additional indirect benefits associated to energy savings and positive effects in crop yields. The use of urease and nitrification inhibitors enhances N use efficiency of the cropping systems and may mitigate N2O emissions up to 80% and 50%, respectively. The type of irrigation may also have a great mitigation potential in the Mediterranean region. Drip-irrigated systems have on average 80% lower N2O emissions than sprinkler systems and drip-irrigation combined with optimized fertilization showed a reduction in direct N2O emissions up to 50%. Methane fluxes have a relatively small contribution to the total GHG budget of Mediterranean crops, which can mostly be controlled by careful management of the water table and organic inputs in paddies. Reduced soil tillage, improved management of crop residues and agro-industry by-products, and cover cropping in orchards, are the most suitable interventions to enhance organic C stocks in Mediterranean agricultural soils. The adoption of the proposed agricultural practices will require farmers training. The global analysis of life cycle emissions associated to irrigation type (drip, sprinkle and furrow) and N fertilization rate (100 and 300 kg N ha−1 yr−1) revealed that these factors may outweigh the reduction in GHG emissions beyond the plot scale. The analysis of the impact of some structural changes on top-down mitigation of GHG emissions revealed that 3–15% of N2O emissions could be suppressed by avoiding food waste at the end-consumer level. A 40% reduction in meat and dairy consumption could reduce GHG emissions by 20–30%. Reintroducing the Mediterranean diet (i.e. ∼35% intake of animal protein) would therefore result in a significant decrease of GHG emissions from agricultural production systems under Mediterranean conditions.
Measuring gas emissions from livestock buildings: A review on uncertainty analysis and error sources
Calvet, S. ; Gates, R.S. ; Zhang, G. ; Estelles, F. ; Ogink, N.W.M. ; Pedersen, S. ; Berckmans, D. - \ 2013
Biosystems Engineering 116 (2013)3. - ISSN 1537-5110 - p. 221 - 231.
measuring ammonia emissions - fattening pig house - ventilation rate - carbon-dioxide - broiler houses - air-flow - rates - poultry - manure - performance
Measuring gaseous and particulate emissions from livestock houses has been the subject of intensive research over the past two decades. Currently, there is general agreement regarding appropriate methods to measure emissions from mechanically ventilated buildings. However, measuring emissions from naturally ventilated buildings remains an elusive target primarily because there is no reference method for measuring building ventilation rate. Ventilation rates and thus building emissions estimates for naturally ventilated buildings are likely to contain greater errors compared with those from mechanically ventilated buildings. This work reviews the origin and magnitude of errors associated with emissions from naturally ventilated buildings as compared to those typically found in mechanical ventilation. Firstly, some general concepts of error analysis are detailed. Then, typical errors found in the literature for each measurement technique are reviewed, and potential sources of relevant systematic and random errors are identified. The emission standard uncertainty in mechanical ventilation is at best 10% or more of the measured value, whereas in natural ventilation it may be considerably higher and there may also be significant unquantifiable biases. A reference method is necessary to obtain accurate emissions estimates, and for naturally ventilated structures this suggests the need for a new means of ventilation measurement. The results obtained from the analysis of information in this review will be helpful to establish research priorities, and to optimize research efforts in terms of quality of emission measurements.
Methods for measuring gas emissions from naturally ventilated livestock buildings: Developments over the last decade and perspectives for improvement
Ogink, N.W.M. ; Mosquera Losada, J. ; Calvet, S. ; Zhang, G. - \ 2013
Biosystems Engineering 116 (2013). - ISSN 1537-5110 - p. 297 - 308.
dairy-cattle buildings - milk urea concentration - ammonia emission - carbon-dioxide - manure stores - gaseous emissions - animal houses - co2 balance - wind-tunnel - tracer gas
The objectives of this paper are: 1) to give an overview of the development of methods for measuring emission rates from naturally ventilated livestock buildings over the last decade, 2) to identify and evaluate strengths and weaknesses, 3) to summarise and conclude the current state-of-art of available measurement concepts and their perspectives for improvement. The methods reviewed include determination of concentration and air exchange rate separately, tracer gas ratio, passive flux samplers, flux chambers, and combined downwind measurement and dispersion modelling. It is concluded that passive flux samplers, flux chambers and combined measurement and dispersion modelling are useful, but for limited fields of application only and require further development and validation against reference methods. The most robust method to investigate emission rates available at this stage is the tracer gas ratio method, but improvements are required. They include more detailed estimates of CO2 release rates (when using CO2 as a tracer) and research into optimising dosing performance of tracer gas release systems. The reliability of tracer gas ratio methods applied in buildings with large ventilation openings needs to be improved by a more profound understanding of tracer-pollutant ratios and their spatial variability, and the development of improved sampling methods for concentration ratios. There is a need for a field reference method against which other methods can be evaluated. None of the discussed measurement methods can be marked as a solid reference for all conditions; tracer gas ratio methods are the most likely candidate but need further improvement.
Natural land carbon dioxide exchanges in the ECMWF integrated forecasting system: Implementation and offline validation
Boussetta, S. ; Balsamo, G. ; Beljaars, A.C.M. ; Panareda, A.A. ; Calvet, J.C. ; Jacobs, C.M.J. ; Hurk, B.J.J.M. van den; Viterbo, P. ; Lafont, S. ; Dutra, E. - \ 2013
Journal of Geophysical Research: Atmospheres 118 (2013)12. - ISSN 2169-897X - p. 5923 - 5946.
global vegetation model - data assimilation system - net ecosystem exchange - era-interim reanalysis - isba-a-gs - interannual variability - co2 exchange - stomatal conductance - southwestern france - soil respiration
The European Centre for Medium-Range Weather Forecasts land surface model has been extended to include a carbon dioxide module. This relates photosynthesis to radiation, atmospheric carbon dioxide (CO2) concentration, soil moisture, and temperature. Furthermore, it has the option of deriving a canopy resistance from photosynthesis and providing it as a stomatal control to the transpiration formulation. Ecosystem respiration is based on empirical relations dependent on temperature, soil moisture, snow depth, and land use. The CO2 model is designed for the numerical weather prediction (NWP) environment where it benefits from good quality meteorological input (i.e., radiation, temperature, and soil moisture). This paper describes the CO2 model formulation and the way it is optimized making use of off-line simulations for a full year of tower observations at 34 sites. The model is then evaluated against the same observations for a different year. A correlation coefficient of 0.65 is obtained between model simulations and observations based on 10 day averaged CO2 fluxes. For sensible and latent heat fluxes there is a correlation coefficient of 0.80. To study the impact on atmospheric CO2, coupled integrations are performed for the 2003 to 2008 period. The global atmospheric growth is well reproduced. The simulated interannual variability is shown to reproduce the observationally based estimates with a correlation coefficient of 0.70. The main conclusions are (i) the simple carbon dioxide model is highly suitable for the numerical weather prediction environment where environmental factors are controlled by data assimilation, (ii) the use of a carbon dioxide model for stomatal control has a positive impact on evapotranspiration, and (iii) even using a climatological leaf area index, the interannual variability of the global atmospheric CO2 budget is well reproduced due to the interannual variability in the meteorological forcing (i.e., radiation, precipitation, temperature, humidity, and soil moisture) despite the simplified or missing processes. This highlights the importance of meteorological forcing but also cautions the use of such a simple model for process attribution.
Uncertainty modelling to evaluate nitrogen balances as a tool to determine N2 and N2O formation in ammonia bioscrubbers
Estelles, F. ; Calvet, S. ; Melse, R.W. ; Ogink, N.W.M. - \ 2012
Environmental Engineering Science 29 (2012)6. - ISSN 1092-8758 - p. 520 - 525.
sensitivity-analysis - biotrickling filter - ventilation rates - waste gases - air - removal - emissions - netherlands - buildings - europe
Biological scrubbers aim at reducing gaseous ammonia emissions by transferring it to a water phase followed by conversion to nitrite and nitrate. A small part of the removed nitrogen may be emitted as N2 and N2O produced as a result of denitrification processes. Due to the large greenhouse warming potential of N2O, even a small emission could be a point of concern. Determining these N losses in form of N2 and N2O via nitrogen balance is an alternative, but little is known about the uncertainty associated to this method. The main aim of this work was to develop an uncertainty model that evaluated N-balances in biological scrubbers in terms of result uncertainty. Secondary objectives were to provide a methodology to determine individual uncertainties involved, and to conduct a sensitivity analysis to identify the main contributors to the final uncertainty. For a defined scenario (biotrickling scrubber, 70% NH3 removal; 5% of inlet N-NH3 lost as N2 and N2O), the standard uncertainty expressed in relative terms of the average was 132% (released N in form of N2 and N2O). Main contributors to the final uncertainty were airflow rate and water volume in the scrubber basin. Uncertainty of the measurements of gaseous NH3 concentrations and N compounds in water had a reduced effect on the final uncertainty. Based on these results, N balances are not recommended to evaluate N2 and N2O formation in biological scrubbers, at least for the conditions considered in this work.
Evaluation of the NH3 removal efficiency of an acid packed bed scrubber using two methods: a case study in a pig facillity
Estellés, F. ; Melse, R.W. ; Ogink, N.W.M. ; Calvet, S. - \ 2011
Transactions of the ASABE / American Society of Agricultural and Biological Engineers 54 (2011)5. - ISSN 2151-0032 - p. 1905 - 1912.
livestock buildings - northern europe - ammonia - emissions - operations - rates
The use of air cleaning systems to reduce ammonia emissions from animal houses is increasing. These systems are normally used in order to comply with local or national regulations of ammonia emission. Therefore, accurate determination of the proportion of ammonia being removed by these systems is crucial. There are two main methods available to measure ammonia removal efficiency of scrubbers: air balance (based on the measurement of ammonia concentrations in air) and combined water-air balance (in which it is also necessary to determine the amount of nitrogen recovered in the liquid phase). The first method is simpler to establish, while the second method might provide deeper information about the processes occurring. The main aim of this work was to assess, in terms of the variability of the results, the use of these two methods to evaluate the efficiency of an acid packed bed scrubber on a pig farm. An acid packed bed scrubber (70% NH3 removal) was monitored during ten complete 24 h cycles for ammonia concentrations, airflow rates, and nitrogen accumulation in the acid solution basin. The average efficiency calculated using the air balance method was 71% (Â±4%), close to the design value of 70%, while the average efficiency when using the combined water-air balance method was 255% (Â±53%). The accumulation and precipitation of ammonium salts in the packing material seem to be the main cause of the high variability and inaccuracy of the combined water-air balance method observed for this type of scrubber. According to these results, it is recommended to use the air balance method when determining the ammonia removal efficiency for acid packed bed scrubbers similar to the one studied here. According to the variability of the results observed in this work, at least 24 measurement days are needed in order to keep the relative error below 5% when using the air balance method to determine the ammonia removal efficiency of an acid packed bed scrubber
Effects of diurnal emission patterns and sampling frequency on precision of measurement methods for daily ammonia emissions from animal houses
Estelles, F. ; Calvet, S. ; Ogink, N.W.M. - \ 2010
Biosystems Engineering 107 (2010)1. - ISSN 1537-5110 - p. 16 - 24.
livestock buildings - poultry houses - rates - facilities
Ammonia concentrations and airflow rates are the main parameters needed to determine ammonia emissions from animal houses. It is possible to classify their measurement methods into two main groups according to the sampling frequency: semi-continuous and daily average measurements. In the first method, ammonia concentrations and airflow rates are monitored during a certain period and instant emission rates are calculated. When using daily average methods, 24-h average ammonia concentrations and airflow rates are used to determine the average daily emission rate. As less information is used in the second method, an error may be expected. The aim of this work was to determine the nature and magnitude of this error. Three databases containing data from semi-continuous ammonia emissions measurements from different animal houses (pigs, poultry and rabbits) in three European countries (Denmark, The Netherlands and Spain) were used to characterise this error. An average systematic deviation between methods of 1.5% was found. The magnitude of this bias was directly related to the daily variation of ammonia concentration and airflow rate. The magnitude of this bias, and also the random component of the error, were modelled. The developed model adequately described variation in bias in the studied dataset (R2 = 0.85) and can be used as a tool to decide which type of measurement methods can be used.
Airborne pariculate matter from livestock production systems: A review of an air pollution problem
Cambra-Lopez, M. ; Aarnink, A.J.A. ; Zhao, Y. ; Calvet, S. ; Torres, A.G. - \ 2010
Environmental Pollution 158 (2010)1. - ISSN 0269-7491 - p. 1 - 17.
swine confinement buildings - space-charge system - dust concentration distribution - dose-response relationships - particle-size distribution - volatile organic-compounds - ventilated broiler houses - lung-function - respiratory symptoms - source apportionment
Livestock housing is an important source of emissions of particulate matter (PM). High concentrations of PM can threaten the environment, as well as the health and welfare of humans and animals. Particulate matter in livestock houses is mainly coarse, primary in origin, and organic; it can adsorb and contain gases, odorous compounds, and micro-organisms, which can enhance its biological effect. Levels of PM in livestock houses are high, influenced by kind of housing and feeding, animal type, and environmental factors. Improved knowledge on particle morphology, primarily size, composition, levels, and the factors influencing these can be useful to identify and quantify sources of PM more accurately, to evaluate their effects, and to propose adequate abatement strategies in livestock houses. This paper reviews the state-of-the-art of PM in and from livestock production systems. Future research to characterize and control PM in livestock houses is discussed. Control of particulate matter emissions, a major challenge to modern livestock production.
Effect of land use on carbon dioxide, water vapour and energy exchange over terrestrial ecosystems in Southwestern France during the CERES campaign
Jarosz, N. ; Beziat, P. ; Bonnefond, J.M. ; Brunet, Y. ; Calvet, J.C. ; Ceschia, E. ; Elbers, J.A. ; Hutjes, R.W.A. ; Traulle, O. - \ 2009
Biogeosciences Discussions 6 (2009). - ISSN 1810-6277 - p. 2755 - 2784.
Eddy fluxes were measured over different ecosystems, winter and summer crops, a maritime pine forest at different stages of development and grassland, from 17 May to 26 June 2005 in the southwestern region of France. During the experiment, summer crops started growing whereas winter crops and grassland achieved their senescence. Comparatively, the other ecosystems had a much slower growth emphasized by soil water deficit at forest sites. The ten ecosystems showed different partitioning of available energy. Net radiation was the highest above the maritime pine forest, followed, in decreasing order, by the crops, the vineyard and the grassland. Over the whole campaign period, the Bowen ratio (ß=H/LE) was larger above the forest sites than for the other sites. The various vegetation types also showed contrasting net ecosystem exchange (NEE) dynamics following their growth status and respective behaviour in response to drought. Both the clearcut and summer crops before irrigation and plant growth behaved as sources of CO2, whereas the vineyard, the mature forest and winter crops acted as sinks. However the maize crops became substantial sinks of CO2 after the start of irrigation and canopy growth, with fluxes twice as large as for the mature pine forest. Finally, throughout the experiment, forest, grassland and crops sequestrated from about 50 gC m-2 to 230 gC m-2, while the cleacut and the beans crop rejected about 30 gC m-2. These results support the idea that converting a mature forest to a clearcut or bare soil available to agricultural use enhances the sensible heat flux and shifts the ecosystem from a sink to a source of carbon
|Ability of EO products to validate and constrain a terrestrial biosphere model
Demarty, J. ; Friend, A. ; Chevallier, F. ; Viovy, N. ; Bacour, C. ; Ciais, P. ; Calvet, J.C. ; Beljaars, A. ; Hurk, B. van den; Moors, E.J. - \ 2006
In: The Second International Symposium on Recent Advances in Quantitative Remote Sensing, Torrent, Spain, 25 - 29 September, 2006. - Valencia, Spain : Universitat de Valencia - ISBN 9788437065335 - p. 503 - 508.
|Towards near-operational global and regional monitoring of natural carbon fluxes over land using EO data
Calvet, J.C. ; Munoz-Sabater, J. ; Rudiger, C. ; Brut, A. ; Roujean, J.L. ; Beljaars, A. ; Lafont, S. ; Jarlan, L. ; Friend, A. ; Demarty, J. ; Hurk, B. van den; Voogt, M. ; Moors, E.J. ; Jacobs, C.M.J. - \ 2006
In: The Second International Symposium on Recent Advances in Quantitative Remote Sensing, Torrent, Spain, 25 - 29 September, 2006. - Valencia, Spain : Universitat de Valencia - ISBN 9788437065335 - p. 497 - 502.
Robustness of modelled carbon-water relations in C-TESSEL
Jacobs, C.M.J. ; Voogt, M.H. ; Moors, E.J. ; Kruijt, B. ; Hurk, B.J.J.M. van den; Beljaars, A.C.M. ; Calvet, J.C. - \ 2006
In: European Geophysical Union; general assembly 2006. - [S.l.] : EGU/Copernicus - p. 06850 - 06850.
The carbon observatory of Geoland: results and prospects
Calvet, J.C. ; Beljaars, A. ; Friend, A. ; Hurk, B. van den; Moors, E.J. ; Jarlan, L. ; Lafont, S. ; Demarty, J. ; Voogt, M. ; Jacobs, C.M.J. - \ 2006
In: European Geophysical Union; general assembly 2006. - [S.l.] : EGU/Copernicus - p. 03024 - 03024.
Modelling of the carbon cycle in the Geoland project
Calvet, J.C. ; Viterbo, P. ; Hurk, B. van den; Friend, A. ; Moors, E.J. ; Jarlan, L. ; Gibelin, A.L. ; Lafont, S. ; Voogt, M. ; Demarty, J. ; Jacobs, C.M.J. ; Chevallier, F. ; Muñoz-Sabater, J. ; Viovy, N. - \ 2005
In: Global earth-system monitoring. - Reading (UK) : ECMWF - p. 155 - 163.
|Assimilation of remote sensing data to monitor the terrestrial carbon cycle: the carbon obsrvatory of geoland
Calvet, J.C. ; Viterbo, P. ; Ciais, P. ; Hurk, B. van den; Moors, E.J. ; Kaptein, A. ; Leroy, M. - \ 2005
In: Proceedings of the ECMWF/ELDAS workshop on land surface assimilation. - Reading (UK) : ECMWF - p. 197 - 202.
Assimilation of remote sensing data to monitor the terrestrial carbon cycle: the carbon observatory of Geoland
Calvet, J.C. ; Viterbo, P. ; Friend, A. ; Hurk, B. van den; Jacobs, C.M.J. ; Kaptein, A. ; Leroy, M. - \ 2004
In: EGU 1st general assembly. - [S.l.] : EGU/Copernicus - p. 01755 - 01755.
SVAT modeling over the Alpilles-ReSeDA experiment: comparing SVAT models over wheat fields
Olioso, A. ; Braud, I. ; Chanzy, A. ; Courault, D. ; Demarty, J. ; Kergoat, L. ; Lewan, E. ; Ottle, C. ; Prevot, L. ; Zhao, W.G.G. ; Calvet, J.C. ; Cayrol, P. ; Jongschaap, R.E.E. ; Moulin, S. ; Noilhan, J. ; Wigneron, J.P. - \ 2002
Agronomie 22 (2002)6. - ISSN 0249-5627 - p. 651 - 668.
soil-water - surface-temperature - land - evaporation - vegetation - parameterization - prediction - moisture - equation - zone
Remote sensing is an interesting tool for monitoring crop production, energy exchanges and mass exchanges between the soil, the biosphere and the atmosphere. The aim of the Alpilles-ReSeDA program was the development of such techniques combining remote sensing data, and soil and vegetation process models. This article focuses on SVAT models (Soil-Vegetation-Atmosphere Transfer models) which may be used for monitoring energy and mass exchanges by using assimilation of remote sensing data procedures. As a first step, we decided to implement a model comparison experiment with the aim of analyzing the relationships between the models' complexity, validity and potential for assimilating remote sensing data. This experiment involved the definition of three comparison scenarios with different objectives: (i) test the models' capacity to accurately describe processes using input parameters as measured in the field; (ii) test the portability of the models by using a priori information on input parameters (such as pedotransfer functions), and (iii) test the robustness of the models by a calibration/validation procedure. These 3 scenarios took advantage of the experimental network that was implemented during the Alpilles experiment and which combined measurements on different fields that may be used for calibration of models and their validations on independent data sets. The results showed that the models' performances were close whatever their complexity. The simpler models were less sensitive to the specification of input parameters. Significant improvements in the models' results were achieved when calibrating the models in comparison with the first scenario
Monitoring energy and mass transfers during the Alpilles-ReSEDA experiment
Olioso, A. ; Braud, I. ; Chanzy, A. ; Autret, H. ; Bethenot, O. ; Bonnefonds, J.M. ; Calvet, J.C. ; Courault, D. ; Demarty, J. ; Ducros, Y. ; Gaudu, J.C. ; Gonzales-Sosa, E. ; Gouget, R. ; Jongschaap, R.E.E. ; Kerr, Y.H. ; Lagouarde, J.P. ; Laurent, J.P. ; Lewan, E. ; Marloie, O. ; Mc Anneney, J. ; Moulin, S. ; Ottlé, C. ; Prévot, L. ; Thony, J.L. ; Wigneron, J.P. ; Zhao, W. - \ 2002
Agronomie 22 (2002)6. - ISSN 0249-5627 - p. 597 - 611.
soil hydraulic-properties - insitu measurement - moisture - evapotranspiration - assimilation - parameters - region - probe - model
The Alpilles-ReSeDA program was initiated to develop and test methods for interpreting remote sensing data that could lead to a better evaluation of soil and vegetation processes. This article presents the experiment that was setup in order to acquire the necessary data to achieve this goal. Intensive measurements were performed for almost one year over a small agricultural region in the South of France (20 kilometers square). To capture the main processes controlling land-atmosphere exchanges, the local climate was fully characterized, and surface energy fluxes, vegetation biomass, vegetation structure, soil moisture profiles, surface soil moisture, surface temperature and soil temperature were monitored. Additional plant physiological measurements and a full characterization of physical soil parameters were also carried out. After presenting the different types of measurements, examples are given in order to illustrate the variability of soils and plant processes in the area in response to the experienced climate
|Meso-scale effects of tropical deforestation in Amazonia: preparatory LBA modelling studies :Dolman.
Dolman, A.J. ; Calvet, J.C. ; Ashby, M. ; Tahara, A.S. ; Delire, C. ; Kabat, P. ; Fisch, G.A. ; Nobre, C.A. - \ 1999
Annales geophysicae 17 (1999)8. - ISSN 0755-0685 - p. 1095 - 1110.
As part of the preparation for the Large-Scale Biosphere Atmosphere Experiment in Amazonia, a meso-scale modelling study was executed to highlight deficiencies in the current understanding of land surface atmosphere interaction at local to sub-continental scales in the dry season. Meso-scale models were run in 1-D and 3-D mode for the area of Rondonia State, Brazil. The important conclusions are that without calibration it is difficult to model the energy partitioning of pasture; modelling that of forest is easier due to the absence of a strong moisture deficit signal. The simulation of the boundary layer above forest is good, above deforested areas (pasture) poor. The models' underestimate of the temperature of the boundary layer is likely to be caused by the neglect of the radiative effects of aerosols caused by biomass burning, but other factors such as lack of sufficient entrainment in the model at the mixed layer top may also contribute. The Andes generate patterns of subsidence and gravity waves, the effects of which are felt far into the Rondonian area. The results show that the picture presented by GCM modelling studies may need to be balanced by an increased understanding of what happens at the meso-scale. The results are used to identifykey measurements for the LBA atmospheric meso-scale campaign needed to improve the model simulations. Similar modelling studies are proposed for the wet season in Rondonia, when convection plays a major role.