SEtHyS_Savannah: A multiple source land surface model applied to Sahelian landscapes

The existing SEtHyS SVAT model was developed further to model heat and water fluxes over savannah landscapes with the final objective to use remote sensing for regionalization and monitoring at larger scale. This new development incorporates two vegetation layers (low and high covers) above the soil. The transfer of soil water was revised in order to improve the simulated hydrology over Sahelian and semi-arid regions, by incorporating a mulch representation in a three-layer soil scheme. The two versions of the model, original and modified, have been compared at local scale over two instrumented local sites of the AMMA-Niger supersite: a fallow and a millet field equipped with surface flux, soil moisture and vegetation measurements. After calibration of the model parameters using the Multiobjective Calibration Iterative Process (MCIP) methodology on the 2005 dataset, the simulations of the two versions of SEtHyS were compared to observations over 2006. Significant differences were found between the simulations, and a better agreement with in situ measurements was observed for the new model. These differences are discussed in relation to the parameterizations of the hydrological and vegetation processes.

[1]  G. Collatz,et al.  Coupled Photosynthesis-Stomatal Conductance Model for Leaves of C4 Plants , 1992 .

[2]  Luca Ridolfi,et al.  Plants in water-controlled ecosystems: active role in hydrologic processes and response to water stress: III. Vegetation water stress , 2001 .

[3]  D. Lawrence,et al.  Regions of Strong Coupling Between Soil Moisture and Precipitation , 2004, Science.

[4]  J. V. Soares,et al.  Estimation of bare soil evaporation from airborne measurements , 1988 .

[5]  C. Ottlé,et al.  The AMMA-CATCH experiment in the cultivated Sahelian area of south-west Niger – Investigating water cycle response to a fluctuating climate and changing environment , 2009 .

[6]  David C. Goodrich,et al.  Preface paper to the Semi-Arid Land-Surface-Atmosphere (SALSA) Program special issue , 2000 .

[7]  Sylvie Galle,et al.  Runoff generation processes: results and analysis of field data collected at the East Central Supersite of the HAPEX-Sahel experiment , 1997 .

[8]  Luis A. Bastidas,et al.  Constraining a physically based Soil‐Vegetation‐Atmosphere Transfer model with surface water content and thermal infrared brightness temperature measurements using a multiobjective approach , 2005 .

[9]  A. Verhoef,et al.  The role of the Sahelian biosphere on the water and the CO2 cycle during the HAPEX-Sahel Experiment , 1997 .

[10]  A. Verhoef,et al.  A SVAT scheme describing energy and CO2 fluxes for multi-component vegetation: calibration and test for a Sahelian savannah. , 2000 .

[11]  A. Verhoef,et al.  A comparison of surface fluxes at the HAPEX-Sahel fallow bush sites , 1997 .

[12]  Yann Kerr,et al.  An overview of HAPEX-Sahel: a study in climate and desertification. , 1997 .

[13]  O. Zurfluh,et al.  Flux heterogeneity and evapotranspiration partitioning in a sparse canopy: the fallow savanna , 1997 .

[14]  C. Field,et al.  A reanalysis using improved leaf models and a new canopy integration scheme , 1992 .

[15]  Hassane Bil-Assanou Issoufou,et al.  Towards an understanding of coupled physical and biological processes in the cultivated Sahel - 2. Vegetation and carbon dynamics , 2009 .

[16]  W. J. Shuttleworth,et al.  Parameter estimation of a land surface scheme using multicriteria methods , 1999 .

[17]  S. Jalota.  Evaporation through a Soil Mulch in Relation to Mulch characteristics and Evaporativity , 1993 .

[18]  Catherine Ottlé,et al.  Contribution of Thermal Infrared Remote Sensing Data in Multiobjective Calibration of a Dual-Source SVAT Model , 2006 .

[19]  C. Thorncroft,et al.  African Monsoon Multidisciplinary Analysis: An International Research Project and Field Campaign , 2006 .

[20]  Christian Valentin,et al.  A runoff capability classification system based on surface features criteria in semi-arid areas of West Africa , 1992 .

[21]  Niall P. Hanan,et al.  AMMA-CATCH studies in the Sahelian region of West-Africa: an overview , 2009 .

[22]  J. T. Ball,et al.  AN ANALYSIS OF STOMATAL CONDUCTANCE , 1988 .

[23]  Soroosh Sorooshian,et al.  A brief history and mission of SAHRA: a National Science Foundation Science and Technology Center on ‘sustainability of semi‐arid hydrology and riparian areas’ , 2002 .

[24]  Bertrand Decharme,et al.  Introduction of a sub-grid hydrology in the ISBA land surface model , 2006 .

[25]  C. Ottlé,et al.  Water and energy budgets simulation over the AMMA-Niger super-site spatially constrained with remote sensing data , 2009 .

[26]  J. Harte,et al.  Energy and water. , 1978, Science.

[27]  J. Deardorff.  Efficient prediction of ground surface temperature and moisture, with inclusion of a layer of vegetation , 1978 .

[28]  Xavier Briottet,et al.  Monitoring land surface processes with thermal infrared data : Calibration of SVAT parameters based on the optimisation of diurnal surface temperature cycling features , 2008 .

[29]  A. Huete,et al.  Deconvolution of remotely sensed spectral mixtures for retrieval of LAI, fAPAR and soil brightness , 1997 .

[30]  G. Collatz,et al.  Physiological and environmental regulation of stomatal conductance, photosynthesis and transpiration: a model that includes a laminar boundary layer , 1991 .

[31]  Catherine Ottlé,et al.  An improved SVAT model calibration strategy based on the optimisation of surface temperature temporal dynamics , 2007 .

[32]  Bernard Cappelaere,et al.  Towards an understanding of coupled physical and biological processes in the cultivated Sahel - 1. Energy and water , 2009 .

[33]  C. Taylor,et al.  Observational Evidence of Persistent Convective-Scale Rainfall Patterns , 1998 .

[34]  M. Vauclin,et al.  Unidimensional modelling of a fallow savannah during the HAPEX-Sahel experiment using the SiSPAT model , 1997 .

[35]  Soroosh Sorooshian,et al.  Sensitivity analysis of a land surface scheme using multicriteria methods , 1999 .