Questions about Atmosphere series

(1) About the “EVAP” in atmosphere series, what kind of ET is it? Is it potential ET, actual ET, or pan evaporation?(2) How does this “EVAP” be used in the EFDC? Does the “RAIN - EVAP” to calculate the net income into the waterbody from air? If so, then I suppose Question(1) is for the “actual ET”? Or it is not used, if I open the Temperature Module?(3) If I want to input “Relative Humidity” instead of “Wet Bulb ATM Temp”, I should make “IRELH=1”. However, I can’t find where to set this. What should I do?(4) What does “CLOUD = FRACTIONAL CLOUD COVER” mean? Does “0” means the day is sunny and there is no cloud?

(1) EVAP is just open water surface evaporation and has nothing to do with transpiration which is the process by which porewater is transported to and evaporated from the leaves of plants. It could be pan evaporation, or based on some other method for calculating evaporation, or really whatever you define it as in the ASER.INP file. You always have the option to have EFDC+ compute evaporation based on the predicted latent heat flux. The options on the first tab of the temperature module lay out what your options for computing evaporation are.(2) RAIN - EVAP would generally be true if you provided an EVAP value in ASER.INP, but as I said that is not a required field in ASER.INP if you don’t have that information. You have the option to choose if you want EFDC+ to use the values in that column of ASER.INP or not.(3) If you have activated the temperature module, you can specify this in the series editor (see attached image) for the ASER.INP file.(4) Cloud = 0 indicates no cloud cover, Cloud = 1 indicates full cloud cover. Valid values are any real number between 0 and 1.