Hydrologic Loading Time Series Documentation

Here you will find extended documentation (beyond our web services' API documentation) for our production web services. Full documentation for the hydrologic modeling can be found here.

Hydrologic Loading Displacement Time Series

Expanded documentation describing parameter options for the hydrologic loading web service is provided below.

• Station (“station”)

  Loading displacement time series are available for locations at selected stations (identified by 4-character ID) processed by the GAGE/PBO Analysis Centers. Stations are chosen based on their position in the GLDAS and NLDAS grids. The GLDAS grid is global with 1º grid squares, while the NLDAS grid covers the conterminous United States with 0.125º grid squares. Both models only provide loads for “continental crust”, with no data for grid squares that are considered “oceanic crust”. Stations along the coastline and on islands may be located within oceanic grid squares, with no load data available. Such stations do not have the loading time series calculated.

• Start Time (“starttime”)

  Start time for time series in ISO 8601 format: YYYY-MM-DDThh:mm:ss. Entering just the YYYY-MM-DD date field is sufficient.

• End Time (“endtime”)

  End time for time series in ISO 8601 format: YYYY-MM-DDThh:mm:ss. Entering just the YYYY-MM-DD date field is sufficient.

• Model (“model”)

  Loading displacement time series are generated for multiple Land Surface Models (LSMs). A Land Surface Model may be produced for either the Global Land Data Assimilation System (GLDAS) or the National Land Assimilation System (NLDAS). GLDAS and NLDAS are projects that oversee multiple LSMs, which which in turn are generated by different groups using the same data with variations on how soil moisture and vegetation-based water storage are treated.

  The Noah models uses a 4-layered soil model to 2-meter depths and a single vegetation parameter for each grid cell.

  The Mosaic models allow for multiple vegetation types in each grid cell (though in North America water stored in vegetation is negligible). It uses a 3-layer soil model extend to depths of 3.5 meters.

  The Variable Infiltration Capacity (VIC) model does not include a vegetation term and uses a 3-layer soil model extending to depths of 1.9 meters.

• Results (“Response Body”)

  The output of the web service, in addition to providing header information, includes the date and model displacement component time series in meters with column headers Date, DispN, DispE, DispU.

Acknowledgements and Attribution

These hydrologic displacement models were generated at UNAVCO with funding through the GAGE Facility with support from the National Science Foundation (NSF) and National Aeronautics and Space Administration (NASA) under NSF Cooperative Agreement No. EAR-1261833.

The hydrologic environmental files used as the basis of our load model were based on data from NASA's Earth Science Division, archived and distributed by the Goddard Earth Sciences (GES) Data and Information Services Center (DISC).