grace | bundle

Tools for manipulating and analysing GRACE level-2 data

balaji devaraju
devaraju at ife uni-hannover de

Reading GRACE data

In order to read the data, just download the data from the GRACE data repository to a folder. Provide the name of the folder to the readgrace function.

% Script for reading GRACE spherical harmonic data

pth = '/path/where/GRACE/data/is/stored/';

% Code for the different data types
code = { 'GAA', ... % Non-tidal atmosphere
         'GAB', ... % Non-tidal ocean
         'GAC', ... % GAA + GAB
         'GAD', ... % Ocean bottom pressure
         'GSM', ... % GRACE monthly static field
         'GSD'};    % Monthly formal errors

% read data
for k = 1:length(code)
    eval([lower(code{k}), ' = readgrace(pth, ', code{k}, ');']);
end

% The output is a ten column cell-array
% [organisation]    - UTCSR (CSR, Texas); EIGEN (GFZ Potsdam); JPLEM (JPL)
% [release]         - Release 4 or 5
% [code]            - GAA, GAB, GAC, GAD, GSM, GSMSD
% [year]            - Year
% [month]           - Month as computed by the program is not very reliable.
%                     The best to ascribe time tag for the GRACE data is the 
%                     'start_day' of the monthly solution.
% [days]            - [start_day end_day total_days]
%                     The days that were used to compute the monthly solution.
% [version]         - Indicates whether the solution is a regularized data
%                     due to problematic data (missing GPS data, repeat orbits,
%                     battery problems, etc.)
% [lmax]            - Maxximum degree of spherical harmonic expansion
% [data]            - Spherical harmonic coefficients in [C\S] format
% [errors]          - Formal errors of the spherical harmonic coefficients