Reply to Comment on “On the Estimation of Potential Evaporation Under Wet and Dry Conditions” by Jozsef Szilagyi

Abstract

The commentary by Jozsef Szilagyi (referred to as JS-2022 hereafter) questioned the estimation of wet surface temperature (T ws ) in Tu and Yang (2022) (TY-2022 hereafter), which adopted the method of Yang and Roderick (2019) (YR-2019 hereafter). The argument outlined in the commentary is mainly based on: (a) the T ws estimates from TY-2022 and YR-2019 are unphysically low, and can be often lower than air temperature and the wet-bulb temperature; (b) the low T ws estimates from TY-2022 and YR-2019 would lead to a negative sensible heat that is unrealistic under a normal atmosphere. However, neither of the above two arguments is correct since JS-2022 interpreted the results of TY-2022 and YR-2019 based on the JS-2022 framework (i.e., Szilagyi & Jozsa, 2008; referred to as SJ-2008 hereafter) instead of the framework of TY-2022 and YR-2019. The underlying key issue is that the framework of SJ-2008 assumes a constant net radiation (R n ), while the framework of TY-2022 and YR-2019 allows R n change with surface wetting/drying.

Reply to Comment on “Potential Evaporation and the Complementary Relationship” by Jozsef Szilagyi

“…In contrast, S17 assumed a constant R n and argued that the decreased R ln may be counterbalanced by the increased R sn due to less cloud cover as the surface becomes drier (see S23 and Szilagyi (2022) for details). However, numerical experiments indicated that the shortwave transmissivity remained largely unchanged with varying atmospheric humidity (see Figure S2 in Tu & Yang, 2022 and the detailed reply in Yang et al, 2022). Therefore, a perfect offset between changes in R sn and R ln is unlikely to be the normal case and the idea that R n changes with surface wetting/drying is the more physically valid circumstance.…”

“…In addition, S23 questioned the estimation of wet surface temperature (T ws ) in T23 and S23 argued that the estimated T ws in T23 are sometimes unphysically low (lower than the wet-bulb temperature). However, as we replied to Dr Szilagyi's previous comments (please see Szilagyi, 2022 andYang et al, 2022), this argument of S23 is based on the framework of S17 (assuming a constant R n ) instead of the framework of T23 (and also YR19). The fact that T23 and YR19 are able to recover the observed T ws has already demonstrated that the T ws in T23 and YR19 is physically attainable.…”

“…The fact that T23 and YR19 are able to recover the observed T ws has already demonstrated that the T ws in T23 and YR19 is physically attainable. Please see our previous reply to Szilagyi (2022) for further details (Yang et al, 2022).…”