NCA-LDAS: Providing Data Products for Evaluating Hydrologic Trends across the Continental United States during the Satellite Era (1979–Present)

Hydrologic climate trend indicators across the continental U.S. are presented that can be used for scientific analysis and decision support. Indicators are derived from the National Climate Assessment - Land Data Assimilation System (NCA-LDAS) data products. NCA-LDAS is a terrestrial hydrology satellite data assimilation system developed within the NASA Land Information System (LIS) modeling framework. NCA-LDAS integrates input data from multiple sources including a near 39-year record (1979-present) of satellite Earth observations employing multi-sensor, multivariate data assimilation of Earth observations of soil moisture, snow depth and cover, and irrigation intensity using the Noah 3.3 land surface model at 1/8th degree resolution. Climate change indicators of the principal land surface hydrology components are presented including annual mean precipitation, heavy precipitation days, temperature, net radiation, runoff, evapotranspiration, soil moisture, snow cover days and snow water equivalent (SWE). Trends in snow cover, evapotranspiration, and runoff are evaluated against independent data for the different NCA regions. The NCA-LDAS trends exhibit an overall improvement when compared to non-data assimilation results, and compare favorably to similar published indicators based mainly on in situ data. Links are provided to access the 42 daily NCA-LDAS land surface data products at the NASA GES-DISC archive.