Hydrologic Trends and Indicators using the National Climate Assessment – Land Data Assimilation System (NCA-LDAS)

A recently-released daily gridded data product of surface hydrologic states and fluxes is available for public download and assessment of terrestrial water trends over the continental United States during the satellite era. The data product was created using the National Climate Assessment - Land Data Assimilation System, or NCA-LDAS, a terrestrial water analysis system developed as an end-to-end enabling tool for sustained assessment and dissemination of hydrologic indicators in support of the National Climate Assessment. The NCA-LDAS uses NASA’s Land Information System (LIS) software framework to assimilate remotely-sensed hydrologic states into a land-surface model, driven by a high-quality surface meteorological dataset. The forcing dataset includes a CPC daily gridded precipitation analysis with an orographic correction, hourly Doppler Stage II radar-estimated precipitation data, North American Regional Reanalysis (NARR) surface meteorology, and bias-corrected shortwave radiation using GOES. Remote sensing observations used by NCA-LDAS for data assimilation include surface soil moisture estimates from a number of microwave instruments (SMMR, SSM/I, AMSR-E, and SMOS), surface snow-covered area from optical instruments (MODIS, IMS), snow depth from passive microwave instruments (SMMR, SSM/I, AMSR-E, and AMSR2), and irrigation intensity estimates from MODIS. The NCA-LDAS Version 001 product is a 1/8th-degree gridded daily-averaged dataset from Jan 1979 to Dec 2015, centered over the continental U.S. from 25 to 53 degrees North, of over forty hydrologic variables including principal terrestrial water and energy balance stores, states, and fluxes. Variables that are available include precipitation, soil moisture, fluxes, snow, runoff, and streamflow, among others. The NCA-LDAS data products are archived at and distributed by the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC). The data products can be accessed via HTTP, OPeNDAP, Mirador search/download, Giovanni, and NASA Earthdata Search. This presentation will include an overview of NCA-LDAS, including details of how it was constructed as well as evaluations of the output using several in situ and gridded reference datasets. Sample water availability trends and indicators from using the NCA-LDAS product will also be presented. These results will be compared against results from the 3rd National Climate Assessment report as well as other reference products. NCA-LDAS data products are publicly provided to enable research and improved assessment of hydrologic indicators across the U.S. Specific links to access these data products will be provided.