GES DISC/USGS Collaboration Leads to More Effective Hydrological Data Analysis
April 17, 2014
The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) is home to North American Land Data Assimilation System (NLDAS) as well as Global Land Data Assimilation System (GLDAS) hydrological data. These data can be downloaded for analysis using the Giovanni visualization tool developed and maintained in part by SESDA team members at GES DISC. These data sets, which include variables such as rain rate, soil moisture, surface runoff, snowfall rate, and total evapotranspiration, are particularly useful for regional hydrological studies, and can be used to analyze the similarities and differences between observations and model data.
The usefulness of NLDAS and GLDAS data has been enhanced by a recent collaboration between the GES DISC and the United States Geological Survey (USGS). The collaboration makes NLDAS and GLDAS areal statistics data available for download via the USGS Geo Data Portal (GDP). Users can access and acquire the data from GDP for specific geographical areas, such as states or countries, or they can input their own area of interest as a “shapefile” and acquire the data for just that specific area. This enhancement makes the data more compatible with Geographical Information Systems (GIS) and more easily incorporated into GIS analyses. More importantly, the ability to use irregularly-shaped boundaries for analysis through the GDP may allow a more accurate representation of these data.
As a demonstration of the difference between a simple analysis of NLDAS data performed using Giovanni and with the GDP, the dramatic impact of Hurricane Irene in 2011 on the state of Vermont was selected. Comparison of two time-series plots (below) shows subtle differences due to the large rectangular area used for the Giovanni plot (right graph) and the ability to restrict the area to just the state of Vermont in the GDP plot (left graph). The graph generated by the GDP data provides a better depiction of Irene’s surface runoff peak within the state of Vermont than the area-wide graph generated using Giovanni.
For more information about this collaboration, check out the GES DISC webpage: http://disc.sci.gsfc.nasa.gov/gesNews/nldas_gldas_gdp_hurricane_irene
