Evaluation of Multi-Model Simulated NLDAS-2 Soil Moisture Using the North American Soil Moisture Database (NASMD)

The North American Land Data Assimilation System phase 2 (NLDAS-2, http://www.emc.ncep.noaa.gov/mmb/nldas/) jointly developed by NOAA/NCEP, NASA/GSFC, NWS/OHD, and several universities (e.g. Princeton University, University of Washington), has generated 34-years (1979-20012) of hydrometeorological products from four state-of-the-art land surface models (Noah, Mosaic, SAC, VIC). The soil moisture data from these models have been used for national operational drought monitoring activities (http://www.emc.ncep.noaa.gov/mmb/nldas/drought/), water resources management and planning, initialization of regional weather and climate models, and other meteorological and hydrological research purposes, but so far have not yet been comprehensively evaluated due to the lack of comprehensive soil moisture observations, although NLDAS-2 was evaluated using limited soil moisture observations (e.g., Oklahoma Mesonet, Illinois, Soil Climate Analysis Network). In this study, we used the observations over 1200 sites in the North America collected from 27 observational networks in the North American Soil Moisture Database (NASMD, http://soilmoisture.tamu.edu/) developed by Texas A&M University to evaluate the model-simulated soil moisture for different time scales varying from daily to annual, different vegetation cover varying from grassland to forest, and different soil texture varying from sand to clay. At the same time, three sensitivity tests were performed using the Noah model to examine the effect of soil texture and vegetation type mismatch on NLDAS-2 soil moisture simulation when site observed soil texture and vegetation type are used. This presentation reports some preliminary results from this evaluation.