I think they are more or less doing the method of mark stock here, just in a grid based instead of image based…
Mark scales up image 16x and reduces -ad to 4, 8, 16 (instead of 2048 or more) and then he downsamples.
I think climate studio does the same simulation 2000 times for each point, but with ad 1(or 2). and then picks the average/highest/sum result out of the 2000.
Could be interesting to experiment with.