yfan1@uni-goettingen_de
New Member
dear all,When creating own atmosphere forcing data for CLM, several of the 8 variables (PSRF, RH, SHUM, TBOT, WIND) are specified "at the lowest atm level". Could anyone tell me the definition of "lowest atm level"? Initially, I confused this with the observational height (ZBOT). I thought ZBOT was the atmospheric reference height, and that was the lowest atm level where these atm variables are measured. Later I noticed that in CLM4.0 ZBOT is the atmospheric reference height assumed to be the height above z0+d (roughness length, displacement height) for all surface types. It determines an atm surface layer of constant thickness (e.g. 30m) where the fluxes are calculated.I can keep the default value 30m for ZBOT. However, I am still unclear what is the "lowest atm level" for measuring the PSRF, RH, SHUM, TBOT, WIND variables.Thank you very much for explanation,Yuanchao