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GLDAS Noah Land Surface Model L4 monthly 0.25 x 0.25 degree V2.1 (GLDAS_NOAH025_M) at GES DISC

This data product is a replacement for GLDAS-1 0.25 degree monthly data product. Global Land Data Assimilation System Version 2 (hereafter, GLDAS-2) has two components: one forced entirely with the Princeton meteorological forcing data (hereafter, GLDAS-2.0), and the other forced with a combination of model and observation based forcing data sets (hereafter, GLDAS-2.1). This data set, GLDAS-2.1 Noah 0.25 degree monthly, was generated through temporal averaging of GLDAS-2.1 Noah 3-hourly data simulated with the Noah Model 3.3 in Land Information System (LIS) Version 7. The data set contains 36 land surface fields from January 2000 to present. GLDAS-2.1 simulation is forced by a combination of National Oceanic and Atmospheric Administration/National Center for Environmental Prediction’s Global Data Assimilation System (GDAS) atmospheric analysis fields, spatially and temporally disaggregated Global Precipitation Climatology Project (GPCP) precipitation fields, and observation based downward shortwave and longwave radiation fields derived using the method of the Air Force Weather Agency's AGRicultural METeorological modeling system (AGRMET). This data set supersedes GLDAS-1 products, in which improvements are made in the use of GPCP and the disaggregation scheme, and quality control for the AGRMET dataset. The GPCP 1-degree Daily (1DD) dataset is used and disaggregated to 3-hourly intervals, whereas GLDAS-1 used the NOAA Climate Prediction Center Merged Analysis of Precipitation (CMAP) pentad dataset and disaggregated to 6-hourly. The gaps and irregularity in the AGRMET shortwave downward flux are alleviated by additional filtering and bias correction to the Surface Radiation Budget (SRB) dataset. Furthermore, the spatial aggregation scheme of GDAS dataset is revised in GLDAS-2.1. The simulation started on 1 January 2000 using the conditions from the GLDAS-2.0 simulation and was forced with GDAS and the disaggregated GPCP. The AGRMET radiation forcing is added for 1 March 2001 onwards. The simulation uses the common GLDAS data sets for land water mask (MOD44W: Carroll et al., 2009) and elevation (GTOPO30), as well as the Noah model default land cover (Modified IGBP MODIS 20-category classification) and soil texture (Hybrid STATSGO/FAO) datasets. The GLDAS-2.1 data are archived and distributed in NetCDF format.

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