Ceschia E

Publications (10)9.01 Total impact

• Source

  Available from: Werner Leo Kutsch

  Article: The net biome production of full crop rotations in Europe

  Kutsch WL, Aubinet M, Buchmann N, Smith P, Osborne B, Eugster W, Wattenbach M, Schulze ED, Tormellieri E, Ceschia E, [......], Di Tommasi P, Grünwald T, Jones M, Magliulo V, Marloie O, Olioso A, Sanz MJ, Saunders M, Søgaard H, Ziegler W
  Agriculture Ecosystems & Environment 01/2010; 139:336-345. · 3.00 Impact Factor
• Article: Management effects on net ecosystem carbon and GHG budgets at European crop sites

  Ceschia E, Béziat P, Dejoux JF, Aubinet M, Bernhofer Ch, Bodson B, Buchmann N, Carrara A, Cellier P, Di Tomasi P, [......], Marloie O, Moors EJ, Moureaux C, Olioso A, Osborne B, Sanz MJ, Saunders M, Smith P, Søgaard H, Wattenbach M
  Agriculture Ecosystems & Environment 01/2010; · 3.00 Impact Factor
• Article: Management Effects on European Cropland Respiration

  Eugster W, Moffat A, Ceschia E, Aubinet M, Ammann C, Davis PA, Osborne B, Smith P, Jacobs C, Moors E, [......], Olioso A, Bernhofer C, Cellier P, Larmanou E, Loubet B, Wattenbach M, Marloie O, Sanz MJ, Søgaard H, Buchmann N
  Agriculture Ecosystems & Environment 01/2010; · 3.00 Impact Factor
• Article: Modelling LAI at a regional scale with ISBA-A-gs: comparison with satellite-derived LAI over southwestern France

  Brut A, Rüdiger C, Lafont S, Roujean J.-L, Calvet J.-C, Jarlan L, Gibelin A.-L, Albergel C, P. Le Moigne, Soussana J.-F, Klumpp K, Guyon D, Wigneron J.-P, Ceschia E
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  ABSTRACT: A CO2-responsive land surface model (the ISBA-A-gs model of Météo-France) is used to simulate photosynthesis and Leaf Area Index (LAI) in southwestern France for a 3-year period (2001–2003). A domain of about 170 000 km2 is covered at a spatial resolution of 8 km. The capability of ISBA-A-gs to reproduce the seasonal and the interannual variability of LAI at a regional scale, is assessed with satellite-derived LAI products. One originates from the CYCLOPES programme using SPOT/VEGETATION data, and two products are based on MODIS data. The comparison reveals discrepancies between the satellite LAI estimates and between satellite and simulated LAI values, both in their intensity and in the timing of the leaf onset. The model simulates higher LAI values for the C3 crops than the satellite observations, which may be due to a saturation effect within the satellite signal or to uncertainties in model parameters. The simulated leaf onset presents a significant delay for C3 crops and mountainous grasslands. In-situ observations at a mid-altitude grassland site show that the generic temperature response of photosynthesis used in the model is not appropriate for plants adapted to the cold climatic conditions of the mountainous areas. This study demonstrates the potential of LAI remote sensing products for identifying and locating models' shortcomings at a regional scale.
  Biogeosciences. 01/2009;
• Source

  Available from: Jean-Philippe Gastellu-Etchegorry

  Article: Uncertainty analysis of computational methods for deriving sensible heat flux values from scintillometer measurements

  P. A. Solignac, Brut A, Selves J.-L, Béteille J.-P, Gastellu-Etchegorry J.-P, Keravec P, Béziat P, Ceschia E
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  ABSTRACT: The use of scintillometers to determine sensible heat fluxes is now common in studies of land-atmosphere interactions. The main interest in these instruments is due to their ability to quantify energy distributions at the landscape scale, as they can calculate sensible heat flux values over long distances, in contrast to Eddy Correlation systems. However, scintillometer data do not provide a direct measure of sensible heat flux, but require additional data, such as the Bowen ratio (β), to provide flux values. The Bowen ratio can either be measured using Eddy Correlation systems or derived from the energy balance closure. In this work, specific requirements for estimating energy fluxes using a scintillometer were analyzed, as well as the accuracy of two flux calculation methods. We first focused on the classical method (used in standard software). We analysed the impact of the Bowen ratio according to both time averaging and ratio values; for instance, an averaged Bowen ratio (β) of less than 1 proved to be a significant source of measurement uncertainty. An alternative method, called the "β-closure method", for which the Bowen ratio measurement is not necessary, was also tested. In this case, it was observed that even for low β values, flux uncertainties were reduced and scintillometer data were well correlated with the Eddy Correlation results.
  Atmospheric Measurement Techniques Discussions. 01/2009;
• Article: Mesoscale modelling of the CO₂ interactions between the surface and the atmosphere applied to the April 2007 CERES field experiment

  Sarrat C, Noilhan J, Lacarrère P, Ceschia E, Ciais P, A.J. Dolman, J.A. Elbers, Gerbig C, Gioli B, Lauvaux T, Miglietta F, Neininger B, Ramonet M, Vellinga O, J. M. Bonnefond
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  ABSTRACT: This paper describes a numerical interpretation of the April 2007, CarboEurope Regional Experiment Strategy (CERES) campaign, devoted to the study of the CO₂ cycle at the regional scale. Four consecutive clear sky days with intensive observations of CO₂ concentration, fluxes at the surface and in the boundary layer have been simulated with the Meso-NH mesoscale model, coupled to ISBA-A-gs land surface model. The main result of this paper is to show how aircraft observations of CO₂ concentration have been used to identify surface model errors and to calibrate the CO₂ driving component of the surface model. In fact, the comparisons between modelled and observed CO₂ concentrations within the Atmospheric Boundary Layer (ABL) allow to calibrate and correct not only the parameterization of respired CO₂ fluxes by the ecosystem but also the Leaf Area Index (LAI) of the dominating land cover. After this calibration, the paper describes systematic comparisons of the model outputs with numerous data collected during the CERES campaign, in April 2007. For instance, the originality of this paper is the spatial integration of the comparisons. In fact, the aircraft observations of CO₂ concentration and fluxes and energy fluxes are used for the model validation from the local to the regional scale. As a conclusion, the CO₂ budgeting approach from the mesoscale model shows that the winter croplands are assimilating more CO₂ than the pine forest, at this stage of the year and this case study.
  Biogeosciences. 01/2009;
• Source

  Available from: Jan Elbers

  Article: Mesoscale modeling of the CO₂ interactions between the surface and the atmosphere applied to the April 2007 CERES field experiment

  Sarrat C, Noilhan J, Lacarrère P, A.J. Dolman, Gerbig C, J.A. Elbers, O.S. Vellinga, Gioli B, Miglietta F, Neininger B, Lauvaux T, Ciais P, Ramonet M, Ceschia E, J. M. Bonnefond
  [show abstract] [hide abstract]
  ABSTRACT: The paper describes a numerical interpretation of the April 2007 CarboEurope Regional Experiment Strategy (CERES) campaign, devotedto the study of CO₂ cycle at the regional scale. The four consecutive clear sky days with intensive observations of CO₂ concentration, fluxes at the the surface and in the boundary layer have been simulated with the Meso-NH mesoscale model. Aircraft observations of CO₂ have been used to identify surface modelling errors and to calibrate the CO₂ components of the surface model. After this calibration, the paper describes a systematic comparison of the model outputs with all the data collected during CERES, in April 2007. As a conclusion, an example of CO₂ budgeting from the mesoscale model is given.
  Biogeosciences Discussions. 01/2009;
• Source

  Available from: Lutz Merbold

  Article: Precipitation as driver of carbon fluxes in 11 African ecosystems

  Merbold L, Ardö J, Arneth A, R. J. Scholes, Nouvellon Y, A. de Grandcourt, Archibald S, J. M. Bonnefond, Boulain N, Brueggemann N, [......], Kergoat L, V. Le Dantec, Mougin E, Muchinda M, M. M. Mukelabai, Ramier D, Roupsard O, Timouk F, E.M. Veenendaal, W. L. Kutsch
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  ABSTRACT: This study reports carbon and water fluxes between the land surface and atmosphere in eleven different ecosystems types in Sub-Saharan Africa, as measured using eddy covariance (EC) technology in the first two years of the CarboAfrica network operation. The ecosystems for which data were available ranged in mean annual rainfall from 320 mm (Sudan) to 1150 mm (Republic of Congo) and include a spectrum of vegetation types (or land cover) (open savannas, woodlands, croplands and grasslands). Given the shortness of the record, the EC data were analysed across the network rather than longitudinally at sites, in order to understand the driving factors for ecosystem respiration and carbon assimilation, and to reveal the different water use strategies in these highly seasonal environments. Values for maximum net carbon assimilation rates (photosynthesis) ranged from −12.5 μmol CO2 m−2 s−1 in a dry, open Millet cropland (C4-plants) up to −48 μmol CO2 m−2 s−1 for a tropical moist grassland. Maximum carbon assimilation rates were highly correlated with mean annual rainfall (r2=0.74). Maximum photosynthetic uptake rates (Fpmax) were positively related to satellite-derived fAPAR. Ecosystem respiration was dependent on temperature at all sites, and was additionally dependent on soil water content at sites receiving less than 1000 mm of rain per year. All included ecosystems dominated by C3-plants, showed a strong decrease in 30-min assimilation rates with increasing water vapour pressure deficit above 2.0 kPa.
  Biogeosciences. 01/2009;
• Article: Precipitation as driver of carbon fluxes in 11 African ecosystems

  Merbold L, Ardö J, Arneth A, R. J. Scholes, Nouvellon Y, A. de Grandcourt, Archibald S, J. M. Bonnefond, Boulain N, Bruemmer C, [......], Kergoat L, V. Le Dantec, Mougin E, Muchinda M, M. M. Mukelabai, Ramier D, Roupsard O, Timouk F, E.M. Veenendaal, W. L. Kutsch
  [show abstract] [hide abstract]
  ABSTRACT: This study reports carbon and water fluxes between the land surface and atmosphere in eleven different ecosystems types in Sub-Saharan Africa, as measured using eddy covariance (EC) technology in the first two years of the CarboAfrica network operation. The ecosystems for which data were available ranged in mean annual rainfall from 320 mm (Sudan) to 1150 mm (The Republic of Congo) and include a spectrum of vegetation types (or land cover) (open savannas, woodlands, croplands and grasslands). Given the shortness of the record, the EC data were analysed across the network rather than longitudinally at sites, in order to understand the driving factors for ecosystem respiration and carbon assimilation, and to reveal the different water use strategies in these highly seasonal environments. Values for maximum net carbon assimilation rates (photosynthesis) ranged from 12 μmol CO2 m−2 s−1 in a dry, open Acacia savanna (C3-plants) up to 40 μmol CO2 m−2 s−1 for a tropical moist grassland. Maximum carbon assimilation rates were highly correlated with mean annual rainfall (R2=0.89). Maximum photosynthetic uptake rates were positively related to satellite-derived fAPAR. Ecosystem respiration was dependent on temperature at all sites, and was additionally dependent on soil water content at sites receiving less than 1000 mm of rain per year. All included ecosystems, except the Congolese grassland, showed a strong decrease in 30-min assimilation rates with increasing water vapour pressure deficit above 2.0 kPa.
  Biogeosciences Discussions. 01/2008;
• Source

  Available from: Jan Elbers

  Article: CO₂ budgeting at the regional scale using a Lagrangian experimental strategy and meso-scale modeling

  Sarrat C, Noilhan J, Lacarrère P, Masson V, Ceschia E, Ciais P, Dolman A, Elbers J, Gerbig C, Jarosz N
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  ABSTRACT: An atmospheric Lagrangian experiment for regional CO₂ budgeting with aircraft measurements took place during the CarboEurope Regional Experiment campaign (CERES) in south-western France, in June, 2005. The atmospheric CO₂ aircraft measurements taken upstream and downstream of an active and homogeneous pine forest revealed a CO₂ depletion in the same air mass. This field experiment is analyzed with a meteorological meso-scale model interactively coupled with a surface scheme, allowing plant assimilation, ecosystem respiration, CO₂ anthropogenic emissions and sea fluxes. First, the model is carefully validated against observations close to the surface and in the atmospheric boundary layer. Then, the carbon budget is evaluated using the numerous CERES observations and as well as the modeling results in order to estimate the relative contribution of each physical process. A good agreement is shown in terms of the estimation of the regional CO₂ surface flux by the Eulerian meso-scale model budget and by the observations at the surface flux sites. A Lagrangian estimation of regional CO₂ surface flux from aircraft observations is more difficult due to several sources of uncertainty. In our case, probable errors are due to the determination of CO₂ vertical profile measurements and owing to the difficulties in monitoring the meteorological condition evolution during several hours.
  Biogeosciences Discussions. 01/2008;