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

To interpret the climatic signals of precipitation/speleothem δ¹⁸O, it is critical to identify the importance of the factors affecting the precipitation δ¹⁸O. This study presents new stable isotope data for precipitation δ¹⁸O and δD in the site of Shenqi cave, southwest China, from November-2015 to October-2016 (the “Super-El Niño” event), to investigate the regional-scale climate forcing on precipitation δ¹⁸O. The precipitation δ¹⁸O, δD 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 δ¹⁸O fluctuations in our study area at least on seasonal timescales. Combined with the seasonal-monthly variations of the IsoGSM δ¹⁸O, GPCP/CRU rainfall and NCEP/NCAR moisture fluxes, we detected that the super-El Niño 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.