[Variations of Stable Isotope in Precipitation and Its Atmospheric Circulation Effect in Chongqing]

Variations of hydrogen and oxygen in stable isotopes and deuterium excess in precipitation as well as their relationship with precipitation,temperature and ENSO (El Niño/La Niño-Southern Oscilation) were analyzed by using 100 daily precipitation stable isotope data from April to October, 2015. The result showed that:① The equation of local meteoric water line (LMWL) was established:δD=8.28δ¹⁸O+12.34, the intercept and slope of which were greater than the global meteoric water 1ine (GMWL) but was similar to most of the southern China monsoon region.② Both stable isotopes and deuterium excess in precipitation indicated obvious seasonal variation in the monsoon region, high in summer and low in winter. This was attributed to the difference in moisture sources in different seasons. ③ In addition, no significant correlation was detected between δ¹⁸O values in precipitation with temperature and precipitation (r=0.03; r=0.12). But it was sensitive to atmospheric circulation effect, and was positively correlated with ENSO.δ¹⁸O values in precipitation and deuterium excess in precipitation clearly recorded the La Niño and El Niño conversion process between 2014 and 2015. During the El Niño event, the δ¹⁸O and d values became obvious on the high side, and the changes were the opposite during La Niño.