Evaluation of European Land Data Assimilation System (ELDAS) products using in situ observations

Three land-surface models with land-data assimilation scheme (DA) were evaluated for one growing season using in situ observations obtained across Europe. To avoid drifts in the land-surface state in the models, soil moisture corrections are derived from errors in screen-level atmospheric quantities.With the in situ data it is assessed whether these land-surface schemes produce adequate results regarding the annual range of the soil water content, the monthly mean soil moisture content in the root zone and evaporative fraction (the ratio of evapotranspiration to energy available at the surface). DA considerably reduced bias in net precipitation, while slightly reducing RMSE as well. Evaporative fraction was improved in dry conditions but was hardly affected in moist conditions. The amplitude of soil moisture variations tended to be underestimated. The impact of improved land-surface properties like Leaf Area Index, water holding capacity and rooting depth may be as large as corrections of the DA systems. Because soil moisture memorizes errors in the hydrological cycle of the models, DA will remain necessary in forecast mode. Model improvements should be balanced against improvements of DA per se. Model bias appearing from persistent analysis increments arising from DA systems should be addressed by model improvements.

[1]  G. Balsamo,et al.  A simplified variational analysis scheme for soil moisture: Developments at Meteo-France and MSC , 2005 .

[2]  Limin Yang,et al.  Development of a global land cover characteristics database and IGBP DISCover from 1 km AVHRR data , 2000 .

[3]  Jared Entin,et al.  Evaluation of the AMIP soil moisture simulations , 1998 .

[4]  A. Holtslag,et al.  Influence of Soil Moisture on Boundary Layer Cloud Development , 2004 .

[5]  Ü. Rannik,et al.  Respiration as the main determinant of carbon balance in European forests , 2000, Nature.

[6]  Matthias Drusch,et al.  Initializing numerical weather prediction models with satellite‐derived surface soil moisture: Data assimilation experiments with ECMWF's Integrated Forecast System and the TMI soil moisture data set , 2007 .

[7]  W. J. Shuttleworth,et al.  Integration of soil moisture remote sensing and hydrologic modeling using data assimilation , 1998 .

[8]  R. Hess,et al.  Assimilation of screen-level observations by variational soil moisture analysis , 2001 .

[9]  Thomas Foken,et al.  The energy balance experiment EBEX-2000 , 2002 .

[10]  Jean-François Mahfouf,et al.  Evaluation of the Optimum Interpolation and Nudging Techniques for Soil Moisture Analysis Using FIFE Data , 2000 .

[11]  Pedro Viterbo,et al.  An Improved Land Surface Parameterization Scheme in the ECMWF Model and Its Validation. , 1995 .

[12]  Ü. Rannik,et al.  Estimates of the annual net carbon and water exchange of forests: the EUROFLUX methodology , 2000 .

[13]  Jean-François Mahfouf,et al.  Analysis of Soil Moisture from Near-Surface Parameters: A Feasibility Study , 1991 .

[14]  W. Oechel,et al.  FLUXNET: A New Tool to Study the Temporal and Spatial Variability of Ecosystem-Scale Carbon Dioxide, Water Vapor, and Energy Flux Densities , 2001 .

[15]  A. E. Green,et al.  Determination of Area-Averaged Water Vapour Fluxes with Large Aperture and Radio Wave Scintillometers over a Heterogeneous Surface – Flevoland Field Experiment , 2002 .

[16]  K. G. McNaughton,et al.  Stomatal Control of Transpiration: Scaling Up from Leaf to Region , 1986 .

[17]  Thomas Foken,et al.  The energy balance experiment EBEX-2000. Part II: Intercomparison of eddy-covariance sensors and post-field data processing methods , 2007 .

[18]  F. Kucharski,et al.  Variational analysis of effective soil moisture from screen‐level atmospheric parameters: Application to a short‐range weather forecast model , 1999 .

[19]  Wim G.M. Bastiaanssen,et al.  A New Methodology for Assimilation of Initial Soil Moisture Fields in Weather Prediction Models Using Meteosat and NOAA Data. , 1997 .

[20]  R. Uijlenhoet,et al.  Impact of plant water uptake strategy on soil moisture and evapotranspiration dynamics during drydown , 2006 .

[21]  R. Lacaze,et al.  A Global Database of Land Surface Parameters at 1-km Resolution in Meteorological and Climate Models , 2003 .

[22]  Janneke Ettema,et al.  Analysis of Soil Moisture Changes in Europe during a Single Growing Season in a New ECMWF Soil Moisture Assimilation System , 2008 .

[23]  C. Jacobs,et al.  The Sensitivity of Regional Transpiration to Land-Surface Characteristics: Significance of Feedback , 1992 .

[24]  Pedro Viterbo,et al.  The European Summer of 2003: Sensitivity to Soil Water Initial Conditions , 2006 .

[25]  Matthias Drusch,et al.  Optimized Surface Radiation Fields Derived from Meteosat Imagery and a Regional Atmospheric Model , 2004 .

[26]  Reinhold Hess,et al.  Evaluation of the variational soil moisture assimilation scheme at Deutscher Wetterdienst , 2008 .

[27]  Matthias Drusch,et al.  The Usage of Screen-Level Parameters and Microwave Brightness Temperature for Soil Moisture Analysis , 2004 .

[28]  A. Holtslag,et al.  Towards Closing the Surface Energy Budget of a Mid-latitude Grassland , 2007 .

[29]  C. Priestley,et al.  On the Assessment of Surface Heat Flux and Evaporation Using Large-Scale Parameters , 1972 .

[30]  R. H. Shaw,et al.  Availability of Soil Water to Plants as Affected by Soil Moisture Content and Meteorological Conditions1 , 1962 .

[31]  J. Noilhan,et al.  A simplified bi‐dimensional variational analysis of soil moisture from screen‐level observations in a mesoscale numerical weather‐prediction model , 2004 .

[32]  W. Bastiaanssen.  Regionalization of surface flux densities and moisture indicators in composite terrain. A remote sensing approach under clear skies in Mediterranean climates. , 1995 .

[33]  J. Mahfouf,et al.  The ISBA land surface parameterisation scheme , 1996 .

[34]  M. Baldwin,et al.  THE WGNE ASSESSMENT OF SHORT-TERM QUANTITATIVE PRECIPITATION FORECASTS , 2003 .

[35]  A. Sterl,et al.  The ERA‐40 re‐analysis , 2005 .

[36]  The use of soil moisture in hydrological forecasting , 2005 .

[37]  C. Bernhofer,et al.  The Energy Balance Experiment EBEX-2000. Part I: overview and energy balance , 2007 .

[38]  M. Friedl,et al.  An Empirical Investigation of Convective Planetary Boundary Layer Evolution and Its Relationship with the Land Surface , 2005 .

[39]  P. Jarvis.  The Interpretation of the Variations in Leaf Water Potential and Stomatal Conductance Found in Canopies in the Field , 1976 .

[40]  Pedro Viterbo,et al.  Land-surface, boundary layer, and cloud-field coupling over the southwestern Amazon in ERA-40 , 2005 .

[41]  A. Smedman,et al.  The Baltic Sea Experiment (BALTEX): A European Contribution to the Investigation of the Energy and Water Cycle over a Large Drainage Basin , 2001 .