New answers tagged modelling
The analysis is done by the Goddard Institute for Space Studies. You can find more information on the methodology at the GISS Surface Temperature Analysis (GISTEMP) website.
David Tarboton does a good job of breaking it down at http://hydrology.usu.edu/taudem/taudem5/help53/D8FlowDirections.html basically as does Jenson. Jenson, S. K., and J. O. Domingue. 1988. "Extracting Topographic Structure from Digital Elevation Data for Geographic Information System Analysis." Photogrammetric Engineering and Remote Sensing 54 (11): ...
You might want to have a look at these Matlab functions http://www.mathworks.com/matlabcentral/fileexchange/50124-topotoolbox More specificaly, you can generate a flow accumulation matrix using DEM = GRIDobj('YourRaster.tif'); FD = FLOWobj(DEM,'preprocess','carve'); A = flowacc(FD); cheers
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