North America Land Data Assimilation System Phase 1 (NLDAS-1) hourly forcing data are available now from the Hydrology Data and Information Services Center (HDISC) at the Goddard Earth Sciences Data and Information Services Center (GES DISC). NLDAS-1 forcing data contain fifteen fields of land surface meteorology and hydrology data over the continuous United States and parts of Canada and Mexico, in 1/8th-degree grid spacing and for the time range of August 1, 1996 to December 31, 2007. The NLDAS-1 model data will be available in the near future.
The most significant difference between NLDAS-1 and NLDAS-2 is the timeframe of each dataset. NLDAS-1 is available from mid-1996 to the end of December 2007, while NLDAS-2 is available from January 1979 to present. Another major difference between the two phases of NLDAS are the actual sources of model data and observations used to create the respective forcing datasets. NLDAS-1 uses the 40-km spatial resolution National Centers for Environmental Prediction (NCEP) Eta model-based Data Assimilation System (EDAS) for surface meteorology; in contrast, NLDAS-2 uses the 32-km spatial resolution North American Regional Reanalysis (NARR) system. For downward shortwave radiation at the surface, NLDAS-1 uses geostationary operational environmental satellite (GOES)-based satellite retrievals, with EDAS data used when/ where GOES data are not available; NLDAS-2 uses GOES data to bias-correct the NARR shortwave radiation. For more information about the differences between NLDAS-2 and NLDAS-2, please visit the LDAS FAQ at http://ldas.gsfc.nasa.gov/faq/#NLDAS_1vs2.
Users can access the data by searching and downloading via anonymous ftp or Mirador. Mirador, the GES DISC's innovative data search engine, uses keywords to find data quickly in a Google-like interface. NLDAS-1 data are also provided via a GrADS Data Server (GDS). GDS users can access the data and perform subsetting and analysis operations online. More advanced tools will be provided in later releases, such as spatial and parameter subsetting and data format transformation. The data will also be made available in the GES DISC online visualization and analysis system Giovanni.
Data access link: http://disc.sci.gsfc.nasa.gov/hydrology/data-holdings