Hi all, I'm trying to calculate the average water contents of atmospheric column from the model output. I used water budget equation which says the change in water contents can be due to advection  terms in the left hand side and that must equal to E-P in the right hand side. The rate of change with time for long period is small and negligible. I integrated the equation vertically from surface pressure up 100  mb. When I did the calculation I got unbalance result, the difference is in order of multiple of 10 even multiple of 100. Any one knows why the water budget not balanced in the model? regards /A