CDO

Hello

I am calculating seasonal precipitation means from my climate model outputs over a region (252x252 cells) using the following series of formula:

selmon,1,2,12 - e.g. for choosing the dec-feb season.
selyear,2008,2009 - to choose a period
timsum - to sum the precipitation
divc,181(number of days in the period) - to have the average daily precipitation.

When mapping I found that all cells over my area of interest where nice looking number e.g. 2.000, 1.500, 1.225 etc. but most often the same over larger areas creating maps with virually no variation. I therefore went back and investigated the original output data, which for the hourly outputs had large variations with many decimals e.g. 0.093750, 0.15625, 0.12500, 0.21875, 0.37500, 0.28125 (storm event) for a specific cell I choose for investigation.

In the above example the result after 'timsum' is 384mm (reasonable result). However, when i divide by the number of days the result is = 2.000, which is wrong - it is really 2.1215. Also all the nabour cells had a value of 2.000. AND, when using the same row of calculations after selecting that one cell to begin with, the result is 2.1215.

Therefore; what is going on? Is there some sort of smoothing/interpolation over the area or?

The same pattern is visible when I use mulc,0.0055 (the same as divc,181).

Thanks

Morten