Water Isotopologues Long-Term Continuous Rainfall Monitoring Contribution for Modeling Present Climate: Information Obtained from Different Time Scale Observations

Abstract

Rainfall isotopic composition has been continuously monitored at the central portion of the São Paulo state (Brazil) in different sampling time scales since 2013. The integration of different meteorological data, such as surface data from meteorological stations, HYSPLIT trajectories, reanalysis and ERA-interim data, has led to observed different conclusions based on the isotopic observation time scale. The amount effect in tropical areas is important for isotopic monthly data, explaining classical effects on monthly data, such as seasonality (high (low) isotopic composition during the dry (wet) period). Based on a daily scale, the interpretation is more complex, leading to controls on isotopic composition related to moisture source/transport and convective activity, as well as some local factors. Using microrain radar with GOES-16 imagery to identify the rainfall type, we were able to understand the cloud microphysics and sub-cloud processes responsible for rain isotope composition variation during the event. This combination of isotopic data may provide substantial subsidies and information for coupling isotopic data in GCMs. The incorporation of water isotopes into GCMs has enabled a more comprehensive evaluation of the water cycle and improvements in hydrometeorological simulations. This contribution has provided new insights into present, past, and future climate.