Isotope variations in precipitation and environmental drivers in Anshun during strong El Niño events

Extreme weather triggered by El Niño events poses a serious threat to the economy and society. 2015 was one of the years with the highest average global temperatures since the El Niño event was recorded. During this period, many parts of the globe experienced frequent extreme weather events. Isotope values in precipitation are important for understanding extreme climates. Therefore, in this work, 140 stable isotope data from precipitation events in the Anshun area from 2015–2016 (including El Niño and La Niña events) were combined with related meteorological data to analyze the characteristics of hydrogen and oxygen isotopes in atmospheric precipitation, as well as their relationships with precipitation, temperature, and atmospheric circulation. The results show that ① the equations of the atmospheric precipitation lines in the study area are δD=8.70δ18O+19.55 (El Niño period) and δD=8.60δ18O+17.23 (La Niña period), which indicate that the atmospheric precipitation in the El Niño period was affected mainly by oceanic water vapor and that there was an imbalance of isotopes in atmospheric precipitation during the La Niña period, with the phenomenon of secondary evaporation. ② isotopes show seasonal variations that are high in the dry seasons and low in the rainy seasons, which are due mainly to the differences in water vapor sources and air mass properties of precipitation in different seasons. ③ The correlation between δ18O and temperature and precipitation in atmospheric precipitation in the study area is not significant, but the correlation can respond sensitively to changes in the ENSO.