An "on-the-fly" (OTF) subsetting service for North American Land Data Assimilation Systems (NLDAS) products has just been released to the public. Users of this service can subset the NLDAS products by parameter and/or spatial region before downloading the data from the Mirador
data search and access tool.
This OTF subset service may effectively mitigate the common usage issues associated with huge data volumes, limited data storage, and variable Internet speed. Also, since the NLDAS data are archived as hourly files, the temporal range is accommodated in the Mirador search criteria, thus allowing subsetting by time.
For example, a user selects three days of NLDAS Phase 2 (NLDAS-2) data from Mirador by entering the begin date and the end date of the desired time range. Then the user proceeds by clicking on the Search GES-DISC button. On the next screen, the user clicks Select All, followed by Add Selected Files to Cart. The following screen will appear:
Then, from the list of Available Services, the user can select Subset Spatially and/or by Parameter, which leads to a new page that allows parameter selection and the spatial region-of-interest to subset. In the current example, the user selects Subset Spatially and/or by Parameter for “NLDAS Primary Forcing (NLDAS_FORA0125_H.002),” which leads to a page for the NLDAS_FORA0125_H.002 parameter and spatial selections, shown below:
After the user has specified the spatial region and selected the parameters of interest, clicking the Submit Selected Criteria button leads to an updated page listing all selected data sets (three in this example) and services, shown below:
From the updated page, the user can continue selecting Subset Spatially and/or by Parameter for another data set, or click the Continue to Shopping Cart button. If the latter option is chosen, then the user sees all selected files in the shopping cart, shown below:
The Checkout button leads to a batch download interface for the subsetted files. The subsetted data are in the GRIB format, same as that of the original NLDAS products.