Is the isotopic composition of tropical rain a paleo-tempestology proxy – PaleoTempesto

Rainfall projections in the tropics are subject to large uncertainty. Past rainfall changes offer insight into how rainfall responds to climate changes. However, rainfall reconstructions diverge in some regions depending on whether they are based on the water isotopic composition or on other proxies. The goal of this project is to address this long-standing enigma. Our hypothesis is that isotopic proxies are more sensitive to the type of storms from which the rain falls, than to the rate of the rainfall. To check this hypothesis, we will investigate how the type of storm impacts the water isotopic composition, based on storm-resolving simulations evaluated against in-situ and satellite observations. We will implement a representation of this impact in the LMDZ general circulation model to address the role of the type of storm on isotopic variations at the climatic scale. We will combine paleoclimate simulations with this model with existing isotopic and non-isotopic proxies to quantify the role of the storm type on isotopic variations at the paleoclimatic scale. Hopefully this project will lead to a new paradigm in the interpretation of isotopic proxies. It will also build bridges between the storm and paleoclimate communities.