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Here you will find global grids of loading derived from the GLDAS water storage model (http://disc.sci.gsfc.nasa.gov/services/grads-gds/hydrology/documentation/hydro_doc.shtml)

This is a GGFC Operational Product.

The data here are updated quarterly at a minimum.

The 3-dimensional displacements have been derived using the method originally outlined in van Dam and Wahr [1987]. (van Dam, T. and J. Wahr, Displacements of the Earth's surface due to atmospheric loading:  Effects on Gravity and Baseline Measurements, J. Geophys. Res., 92, 1281-1286, 1987.)

Specifics include:

  1. GLDAS soil moisture and snow water equivalent is used
  2. The data are given monthly

For more information on the GLDAS mass model, the user is referred to http://disc.sci.gsfc.nasa.gov/hydrology/documentation.

PLEASE NOTE:  Time series for any individual grid location contain a long-term trend. Users are advised to remove this trend from their data before interpreting the results.

The data provided here are first organized by reference frame. Within each reference frame directory the data are organized by year, then by day.  Each day file contains 2 epochs of data at the following epochs: 06, 18.

Each individual file contains the global (2.5 deg.  X 2.5 deg) 3-dimensional surface displacement (in mm) for the epoch corresponding to the file name.

Each file can be read using the following algorithm (or something equivalent) where dvt is surface displacement to the north,dvl is surface displacement to the east, and du is surface displacement in the radial direction:

do imo=1,12
read(iunit,1001) chyr,cmo,cref
1001 format(a4,1x,a4,1x,a2)
do ilon=1,144
rlon=(ilon-1)*2.5
do ilat=1,73
rlat=90.-(ilat-1)*2.5
read(unit,1002) vt(ilon,ilat),vl(ilon,ilat),du(ilon,ilat)
1002  format(3(f10.4,2x))
end do
end do
end do

chyr=year in character format
cmo=mon in character format
cref=reference frame in character formatr
rlon=longitude of data point
rlat=latitude of data point

You may use the program, gldas_tseries.f, to extract the data for a single latitude and longitude.  The program will need to be adapted to your particular needs.  However, before altering the program, please compile on your system and confirm that you obtain the results similar to those in stjo.cws. Details are inserted as comments in the fortran file.

Anyone using this data set is requested to use the following citation:
van Dam, T., 2010, Updated October 2010.  GLDAS derived monthly, global surface
displacements at 2.5 x 2.5 degree spacing.  Data set accessed YYYY-MM-DD at http://geophy.uni.lu/ggfc-hydrology.html

For questions regarding this data set, please contact T. van Dam, tonie.vandam @ uni.lu