More annual ET than annual Precipitation

[mizukami]

I am getting more annual evapotranspiration than annual precipitation in very dry area (where little precipitation). Now I remember that I was getting water balance error message when I was running CLM, I think indicating this.

I am running offline CLM with external atmospheric forcing (NLDAS) over the upper Colorado River Basin from 1980-2008.

I wonder what I can do to remove this error?

I wonder if changing temporal resolution may help? I ran every 15min but forcing is hourly. I wanted to run hourly, but I got error if I do.

it would be appreciated if anyone could give me comments/suggestions.

 

[slevis]

This may happen in arid areas with lakes or wetlands because lakes and wetlands do not dry out in the current clm. We consider this a feature of the model and not an error. I guess you could remove these water bodies from your surface data to avoid the problem.

Sam Levis

 

[mizukami]

Thanks for the explanation.

I also wondered if ground water contributes to constant ET? I noticed initial condition I used contains large amount of WT (i.e. water in deep soil) it keeps recessing over 20 yeas of simulation. I spun up the model, it get better (but ET still gets greater than precip tiny bit).

naoki

 

[slevis]

The clm hydrology algorithms are explained in great detail in the Technical Description of the CLM, available with other clm documentation on the clm web-page. I expect that the Technical Description addresses the aspects of the hydrology that concern you.

Sincerely,
Sam Levis