# SK_MC_GRACE_Greenland
The data set comprises sensitivity kernels (SKs) of different mass change estimators from Level-2 gravimetry data from the Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow-On missions as discussed in the 2023 Journal of Geodesy publication 'The sensitivity kernel perspective on GRACE mass change estimates'.
The SKs are given as a set of spherical harmonic (SH) coefficients.
Sensitivity kernels are included for each of the four methods of mass change estimates for each of the eight Greenland ice drainage basins, both described in the article.
For the ice drainage basins the definition by Zwally et al. (2012) is used.
Zwally, H. Jay, Mario B. Giovinetto, Matthew A. Beckley, and Jack L. Saba, 2012, Antarctic and Greenland Drainage Systems, GSFC Cryospheric Sciences Laboratory, Available at
https://earth.gsfc.nasa.gov/cryo/data/polar-altimetry/antarctic-and-greenland-drainage-systems.
## SK_MC_GRACE_Greenland.nc
The NetCDF file includes following variables:
* SK - 4-D variable [`4x9x4186x4`] of the SKs.
Each SK is given in the standard format for SH coefficients (3rd and 4th dimension of `SK`; degree `n` and order `m` in the first and second column, respectively; cosine coefficient `C_nm` and sine coefficient `S_nm` given in the third and fourth column, respectively).
SKs are given for the four methods of mass change estimation (1st dimension of `SK`), numbered as in the article for the eight ice drainage basins (and their combination under number nine) (2nd dimension of `SK`).
* C_00 - 2-D variable [`4x9`] of degree-0 coefficients for each of the SKs. Empirically derived and used in the article for illustration purposes.
Given for the four methods of mass change estimation (1st dimension of `C_00`) for the eight ice drainage basins (and their combination) (2nd dimension of `C_00`).
## MATLAB example script
The following example script shows how to retrieve one specific SK (Method I, whole Greenland ice sheet) from the NetCDF file:
```
% read SK variable
SK = ncread('SK_MC_GRACE_GreenlandIceSheet.nc', 'SK');
% read C_00 variable
C_00 = ncread('SK_MC_GRACE_GreenlandIceSheet.nc', 'C_00');
% get the SK (Eta) for Method 2 for the whole Greenland ice sheet
i_method = 2;
i_basin = 9;
Eta = squeeze(SK(i_method,i_basin,:,:));
% replace C_00 for illustration purposes
Eta(1,3) = C_00(i_method,i_basin);
```
This work is licensed under CC-BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/).