Correlation between δ~(18)O in the Monsoonal Precipitation and Some Astronomy-Atmosphere-Ocean Events

There are varied factors that control the variations of stable isotope in precipitation in different locations under different climatic conditions. The isotopic contents in precipitation in monsoonal regions vary complicatedly. The 36-year isotopic data in precipitation at New Delhi, an IAEA/WMO station in southwest monsoon region, has been used to compare with the indices of some Astronomy-Atmosphere-Ocean events, such as solar activities, atmospheric wind speeds and the ENSO events. The results suggest that the changing trend of δ~(18)O in monsoonal precipitation, as a result of temperature effect, is significantly agreed with that of sunspots. In addition, variation of the ratio of temperature to precipitation positively correlates with that of the δ~(18)O in precipitation . A teleconnection between the isotopic variation in precipitation at New Delhi and ENSO events is found, resulting from the interactions of coupled air-sea systems in tropical Indian Ocean and Pacific Ocean, which is ascribed to the precipitation amount effect. At the height of 500 hPa, evaporation of cloud droplets and the exchange between the cloud droplets and the monsoonal vapors may be the major reasons of a positive correlation betweenδ~(18)O and wind velocity at the height of 500 hPa. The temperature effect and the precipitation amount effect strengthen the correlation.