The 
Case and Validation Studies
Last update: 24 January 2002
General
ELDAS is organised around a number of case/validation studies (see the project structure). These serve to guide the system design and to generate demonstration databases. The validation studies are meant to assess the quality of the soil moisture fields using independent data. The case studies are demonstration studies in semi-operational settings.
A set of central databases will be constructed, one covering Europe for the year 2000, and the other for 2003. Some of the case- and validation studies described here use this central data base.
Validation Studies
Four workpackages are devoted to validation of the products.
GSWP validation
Coordinator: Eddy Moors. The emphasis in this workpackage will be on validation of the 2000-dataset using methodologies developed in the context of the Global Soil Wetness Project. Validation data will be gathered from river discharge records, flux tower and scintillometer stations scattered across the domain, in situ soil moisture records and synoptic observations.
SSM/I or AMSR validation
Coordinator: Matthias Drusch. Using radiative transfer models, the top of atmosphere microwave radiation will be generated from the surface state in the data assimilation modules. These will be compared to the record of SSM/I measurements for the 2000 data base, and possibly with AMSR data for the 2003 database. SSM/I is not an optimal sensor for soil moisture detection, but careful site selection and signal filtering has given rise to valuable comparison material from recent studies.
GLDAS
Coordinator: Bart van den Hurk. In this workpackage, results from the N/GLDAS system will be compared to the outcome from the ELDAS system. N/GLDAS forcings will be fed to the ELDAS data assimilation system, and the resulting hydrological budgets from a number of major American river basins will be evaluated.
French river basins
Coordinator: Joel Noilhan. Starting from the Rhone basin (as evaluated in the so-called RhoneAGG experiment), CNRM/Meteo France has operationalized the production of surface forcings for a dense 8km grid over France. River discharge observations from major river basins are available for evaluation of the hydrological balance calculated by the surface schemes part of the ELDAS system. A control simulation of the surface hydrology by the surface schemes without data assimilation allows to evaluate the added value of the data assimilation component of the land surface simulations.
Case Studies
In a number of case studies, semi-operational practice cases are used to evaluate how ELDAS will possible improve routine results.
UK Floodings
Coordinator: Eleanor Blyth. The flooding events in the autumn of 2000 in the UK were partially affected by a combination of high initial soil water content and excessive precipitation. The workpackage will focus on how ELDAS may enable a proper estimate of the initial soil moisture content prior to the precipitation events, aiming at an improved timing of the actual floodings.
Rhine floodings
Coordinator: Erik van Meijgaard. In this workpackage two parallel NWP cycles will be operated, one with and one without soil moisture adjustments. Again the skill of the runoff generated by the NWP cycles will be compared to the rover discharge of the Rhine river for a number of events that still have to be selected.
European NWP cycles
Coordinator: Ernesto Rodriguez Camino. Similarly, a number of parallel NWP cycles will be carried out overlying the entire European continent, and covering the full 15-month period in 1999-2000. The focus of this experiment will be the skill of ELDAS to produce an adequate seasonal cycle in the land surface moisture conditions, aiming at better predictions or diagnosis of period with relative drought. ELDAS will be compared to current practice of soil moisture assimilation based on synoptic data solely.