The Seasonally Altered Atmosphere Moisture Circulations With Rainfall and Rainfall Isotopes in Southwest China

To interpret the climatic signals of precipitation/speleothem delta O-18, it is critical to identify the importance of the factors affecting the precipitation delta O-18. This study presents new stable isotope data for precipitation delta O-18 and delta D in the site of Shenqi cave, southwest China, from November-2015 to October-2016 (the "Super-El Nino " event), to investigate the regional-scale climate forcing on precipitation delta O-18. The precipitation delta O-18, delta D and d-excess have an obvious seasonality, relatively low values in the wet season and high in the dry season. The further analysis of seasonally altered LMWL and moisture circulations suggested that changes in atmosphere moisture circulations would be the key factor underlying the precipitation/speleothem delta O-18 fluctuations in our study area at least on seasonal timescales. Combined with the seasonal-monthly variations of the IsoGSM delta O-18, GPCP/CRU rainfall and NCEP/NCAR moisture fluxes, we detected that the super-El Nino of 2016 have changed the distributions of monthly rainfall in wet season through the Western Pacific Subtropical High, but not mainly the precipitation isotopic compositions and moisture circulations in our study area.