Revisiting the Inherent Assumptions Made When Heavy Water Isotopologues Are Used to Investigate Convective Heating Profiles

Abstract Previous studies have demonstrated that we can use the depletion of heavy water isotopologues (HDO and O) within precipitation as proxies to the vertical profiles of convective heating. We further tested this using isotopic analysis of rainfall over the eastern Pacific during the OTREC2019 field campaign to determine if the vertical profile over the region is top‐ or bottom‐heavy. While a composite of the station observations within the domain shows results consistent with previous studies, there are significant spatial variations across individual stations. This is corroborated by isotope‐enabled Weather Research and Forecasting simulations that span the domain of the OTREC2019 field campaign. The trends of heavy‐isotope depletion are also not consistent even when we attempt to account for the impacts of horizontal advection in our moisture budget analysis, implying that certain assumptions we made in order to use the depletion of heavy isotopologues as a proxy to convective heating profiles may not apply on a local level.