The Southern Great Plains 1997 (SGP97) Hydrology Experiment originated from an interdisciplinary investigation, "Soil Moisture Mapping at Satellite Temporal and Spatial Scales" (PI: Thomas J. Jackson, USDA Agricultural Research Service, Beltsville, MD) selected under the NASA Research Announcement 95-MTPE-03. The Global Energy and Water Cycle Experiment (GEWEX) Continental-scale International Project (GCIP) Enhanced Observing Period (EOP) takes place in the Mississippi River basin, which provides a number of watershed areas that are potentially useful for hydrologic focused studies. The temporal coverage for this dataset is as follows: Begin datetime: 1996-07-09 00:00:00, End datetime: 2001-12-31 23:59:59. This dataset contains the National Centers for Environmental Prediction (NCEP) Environmental Modeling Center (EMC) 4 KM GRIB multi-sensor analysis ("MUL") data. A prototype, real-time, hourly, multi-sensor National Preciptation Analysis (NPA) has been developed at NCEP in cooperation with the Office of Hydrology (OH). This analysis merges two data sources that are currently being collected in real-time by OH and NCEP. Hourly digital precipitation (HDP) radar estimates are created by the WSR-88D Radar Product Generator on a 131 X 131 4-km grid centered over each radar site. Data analysis routines, including a bias correction of the radar estimates using rain gage data, have been adapted by NCEP on a national 4-km grid from algorithms developed by OH and executed regionally at NWS River Forecast Centers (RFC). This dataset only contains the NCEP 4 KM GRIB Data multi-sensor hourly, 6-hourly, and daily analysis (gage and unbiased radar). 6-hourly data are generally available at 00Z, 06Z, 12Z, and 18Z. Daily data are generally available at 12Z. Depending on the time period selected, all three datasets may or may not be available. Other NCEP 4 KM GRIB Data including gage-only analysis, radar estimate, radar estimate after bias removal, and gage-only analysis using 24h accumulated ("RFC") data are available as independent datasets. Depending on the time period selected, all five types may or may not be available. Please see GCIP/EOP: Surface NCEP Ancillary Catalogue of Available GCIP Precipitation Data (NCEP/EMC). The format of the files is GRIB. The files are compressed using the UNIX "compress" command and "uncompress" must be used before decoding.