output variable Zwt in clm5.0 running single point cases

[Mesmer]

i want to ask if there is someone that can give me informations about this variable Zwt (water table)?? what input variables can influence it ? if it is possible to give an initial value or to edit his function ? what and where is the datasheet that describe it ? i'm interested on it . how it changes in time . i have attached a pdf file where you can find three graphs of water table in three different years that come from my simulation. There is not a great seasonal change ,why??

thank you

 

[oleson]

From the CLM technical note (2.7. Hydrology — ctsm release-clm5.0 documentation):

"where the water table

is determined by finding the first soil layer above the bedrock depth (section 2.2.2.2) in which the volumetric water content drops below a specified threshold. The default threshold is set to 0.9."

If your water table is that deep (~8m) with not much seasonal variation, then it implies a dry site with not much seasonality in precip.

For typical seasonal variation in CLM5 ZWT over different regions of the world, go to this diagnostics page, select set3, and then the last column for a given region (Hydrology):

LND_DIAG Diagnostic Plots

If you want to change the initial value or the formulation of ZWT then search for instances of zwt in the code.