Public Release of 30-year (1979-2008) NLDAS High-resolution Products - Analysis and Validation for Soil Moisture and Temperature

The NCEP Environmental Modeling Center (EMC) collaborated with its CPPA (Climate Prediction Program of the Americas) partners to develop a North American Land Data Assimilation System (NLDAS, http://www.emc.ncep.noaa.gov/mmb/nldas). The NLDAS includes multi-model analysis/monitoring products to focus on drought and flooding monitoring. NLDAS products consist of 30-year (1979-2008) retrospective and 0.5-year near realtime (2009-current time, with a 4-day lag) water (i.e., evapotranspiration, runoff, canopy evaporation, sublimation) and energy (sensible heat flux, latent heat flux, ground heat flux, net radiation) fluxes, and state (i.e., soil moisture with different layers, soil temperatures, snow water equivalent, snow depth, snow cover) variables with an hourly temporal resolution and a 1/8th degree spatial resolution for four land surface models (NCEP/Noah, NASA/Mosaic, OHD/SAC, and Princeton/VIC). This study used common hourly land surface forcing derived from NCEP's retrospective and realtime North American Regional Reanalysis System (NARR) except for precipitation. The precipitation forcing is anchored to a daily gauge-only precipitation analysis over CONUS that applies the Parameter-elevation Regressions on Independent Slopes Model (PRISM) correction. This daily precipitation analysis is then temporally disaggregated to hourly precipitation amounts using stage II radar and satellite retrieved precipitation products. The NARR-based surface downward solar radiation is bias-corrected using seven years (1997-2004) of GOES satellite-derived solar radiation retrievals. This presentation summarizes the NLDAS concept, configuration, forcing data, the four land surface models and their output. All 30-year hourly forcing and hourly outputs from four land surface models are stored on a NCEP public server, which can be download by public users. In this presentation, we analyze soil moisture and temperature for four models and validate them using the Illinois soil moisture data bank. We also show water and energy flux comparisons for the four land surface models and validate sensible and latent fluxes using observations at several sites over CONUS.