PROGRESS IN GEOGRAPHY ›› 2012, Vol. 31 ›› Issue (11): 1452-1459.doi: 10.11820/dlkxjz.2012.11.005

• Original Articles • Previous Articles     Next Articles

Contributions of Local Moisture to Precipitations in Western China

MA Qian, ZHANG Mingjun, WANG Shengjie, WANG Baolong, MA Xuening   

  1. College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, China
  • Received:2012-04-01 Revised:2012-08-01 Online:2012-11-25 Published:2012-11-25

Abstract: Based on stable isotope data of precipitations and lakes on the Tibetan Plateau and Tianshan-Altay areas, contributions of secondary evaporation and evaporative vapors to local precipitations are estimated. (1) The stable isotope data show that values of both δ18O and d-excess decreases from Hetian to Altay in summer monsoon (June to September), suggesting that in the area secondary evaporation has a greater effect in summer monsoon, while in Tibetan plateau area the stable isotope composition of hydrogen and oxygen increases along the water vapor trajectory in both summer monsoon and winter monsoon (October to May), contributed mainly by evaporative vapors from surface water bodies throughout the year. (2) The estimation of evaporation rate indicates that in Tianshan-Altay area the secondary evaporation happens at all times, and it has greater effect in summer monsoon, with rates from 13% to 20% and an average rate of 16.7%, and less effect in winter monsoon, with an average rate of 4.3%. (3) Using a vapor contribution rate model, contributions from moisture advection, evaporative vapors from surface water bodies, and transpiration from plants are calculated. Moisture advection generally contributes the biggest part, greater than 50%, while evaporative vapors contribute the smallest part, with an overall rate of 10%. Transpiration has a contribution rate in between.

Key words: advection moisture, local moisture, secondary evaporation, stable isotope, western China