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Data Rods (Time Series Data)

Data Rods for Hydrology Community

The way NASA earth science data are typically archived (by time steps, one step per file, often containing multiple variables) is not optimal for their access by the hydrology community, particularly if the data volume and/or number of data files are large. To enhance the access to and use of these data, the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) adopted two approaches, in a project supported by the NASA ACCESS Program: (1) optimally reorganize two large hydrological data sets as time series, for more efficient access and (2) integrate the time series data (aka “data rods”) into hydrology community tools, such as Consortium of Universities for the Advancement of Hydrologic Science, Inc. Hydrologic Information System (CUAHSI HIS), EPA BASINS (Better Assessment Science Integrating point & Non-point Sources), and, under development, Data Rods Explorer on the Tethys Platform (developed by Brigham Young University). This ACCESS project has thus far resulted in the reorganization and archiving (as data rods) of a set of water cycle related variables (Table 1) from the North American and Global Land Data Assimilation Systems (NLDAS and GLDAS, respectively). In addition to their access provided by the hydrology community tools, selected data rods variables can be searched and accessed through Mirador, the GES DISC search and access user interface, and all data rods variables can be accessed via Web services developed by GES DISC.

Table 1 lists variables reorganized as time series (data rods), along with sample URLs of the Web service for each variable.

The Web service currently accepts five keywords: variable, location, startDate, endDate, and type. Table 2 describes the Key-Value-Pair (KVP) syntax of the Web service. The startDate and endDate are optional, with the data/time of the first and last time steps, respectively, as default.  All sample URLs for "plot", without specifying startDate and endDate, return time series of entire data range.  All sample URLs for NLDAS Primary Forcing "asc2" and GLDAS "asc2", with startDate and endDate specified,  return time series in two-column ASCII format for the specified time range.  The sample URLs for  NLDAS Noah "asc2",  with only startDate specified, return time series, in two-column ASCII format, from the specified date/time to end of the available data. .

Basic characteristics of the NLDAS and GLDAS data are described in Table 3.

All grids over water have been masked out, so no data rods are generated for these grids. If a specified location is over water or beyond the data domain, the Web service will return an error message. The land/sea mask data can be accessed from (for NLDAS) and (for GLDAS).

Table 1. Variables reorganized as time series 

Data Product  Short Name
 Description  Unit
    Sample URL 




 APCPsfc  Precipitation hourly total  kg/m^2  plot  asc2
 DLWRFsfc  Surface DW longwave radiation flux  W/m^2  plot  asc2
 DSWRFsfc  Surface DW shortwave radiation flux  W/m^2  plot  asc2
 PEVAPsfc  Potential evaporation  kg/m^2  plot  asc2
 SPFH2m  2-m above ground specific humidity  kg/kg  plot  asc2
 TMP2m  2-m above ground temperature  K  plot  asc2
 UGRD10m  10-m above ground zonal wind  m/s  plot  asc2
 VGRD10m  10-m above ground meridional wind  m/s  plot  asc2







 EVPsfc  Total evapotranspiration  kg/m^2  plot  asc2
 GFLUXsfc  Ground heat flux  w/m^2  plot  asc2
 LHTFLsfc  Latent heat flux  w/m^2  plot  asc2
 SHTFLsfc  Sensible heat flux  w/m^2  plot  asc2
 SSRUNsfc  Surface runoff (non-infiltrating)  kg/m^2  plot  asc2
 BGRIUNdfc  Subsurface runoff (baseflow)  kg/m^2  plot  asc2
 SOILM0-10cm  0-10 cm soil moisture content  kg/m^2  plot  asc2
 SOILM0-100cm  0-100 cm soil moisture content  kg/m^2  plot  asc2
 SOILM0-200cm  0-200 cm soil moisture content  kg/m^2  plot  asc2
 SOILM10-40cm  10-40 cm soil moisture content  kg/m^2  plot  asc2
 SOILM40-100cm  40-100 cm soil moisture content  kg/m^2  plot  asc2
 SOILM100-200cm  100-200 cm soil moisture content  kg/m^2  plot  asc2
 TSOIL0-10cm  0-10 cm soil temperature  K  plot  asc2







 Evap  Total Evapotranspiration  kg/m^2/s  plot  asc2
 precip  Precipitation rate  kg/m^s/hr  plot  asc2
 Rainf  Rain rate  kg/m^2/s  plot  asc2
 Snowf  Snow rate  kg/m^2/s  plot  asc2
 Qs  Surface Runoff  kg/m^2/s  plot  asc2
 Qsb  Subsurface Runoff  kg/m^2/s  plot  asc2
 SOILM0-100cm  0-100 cm top 1 meter soil moisture content  kg/m^2  plot  asc2
 SOILM0-10cm  0-10 cm layer 1 soil moisture content  kg/m^2  plot  asc2
 SOILM10-40cm  10-40 cm layer 2 soil moisture content  kg/m^2  plot  asc2
 SOILM40-100cm  40-100 cm layer 3 soil moisture content  kg/m^2  plot  asc2
 Tair  Near surface air temperature  K  plot  asc2
 TSOIL0-10cm  Average layer 1 soil temperature  K  plot  asc2
 Wind  Near surface wind magnitude  m/s  plot  asc2



 Table 2. Key-Value-Pair (KVP) syntax


Value Convention











GEOM:POINT(lon, lat)*

location=GEOM:POINT(-100.2, 29.89)


yyyy-mm-ddThh (default is the 1st time step)



yyyy-mm-ddThh (default is the last time step)




type=plot (output time series plot)


type=asc2  (output 2-column ASCII)


type=ascii (output 4-column ASCII)


type=netcdf (output netcdf, just a prototype)

 * If a specified (lon, lat) is not exactly on a grid point, the Web service returns a time series of a nearest grid .

 Table 3. Basic characteristics of NLDAS and GLDAS data








Spatial resolution

0.125o x 0.125o

0.125o x 0.125o

0.25o x 0.25o

Spatial coverage

125W ~ 63W, 25N ~ 53N

125W ~ 63W, 25N ~ 53N

180W~180E, 60S ~ 90N

Origin grid

(-124.9375, 25.0625)

(-124.9375, 25.0625)

(-179.875 , -59.875)

Array X-index

000  ~ 223

000  ~ 223

000  ~  600

Array Y-index

000  ~ 464

000  ~ 464

0000  ~ 1440

Temporal resolution




Temporal coverage

1979-01-01T13  - present

1979-01-02T01 ~ present

2000-02-24T00 ~ present

Valid hour values

00, 01, 02, 03,  ….., 22, 23

00, 01, 02, 03,  ….., 22, 23

00, 03, 06, 09, 12, 15, 18, 21


About 4 days

About 4 days

About 2 months






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Last updated: Nov 10, 2016 03:25 PM ET