Tek Bahadur Chhetri • Tandong Yao • Wusheng Yu • Li Ding • Daniel Joswiak • Lide Tian • Lochan Prasad Devkota • Dongmei Qu
T. B. Chhetri T. Yao W. Yu (&) D. Joswiak L. Tian D. Qu
Key Laboratory of Tibetan Environment Changes and LandSurface Processes, Institute of Tibetan Plateau Research,Chinese Academy of Sciences, Beijing 100101, China
e-mail: yuws@itpcas.ac.cn
T. B. Chhetri
University of Chinese Academy of Sciences, Beijing 100049,China
T. B. Chhetri L. P. Devkota
Central Department of Hydrology and Meteorology, TribhuvanUniversity, Kathmandu, Nepal
L. Ding
Yinchuan Meteorological Administration, Yinchuan 750002,China
Abstract Investigation of temporal variations in the stable d18O and dD isotopes from Kathmandu’s precipitation events shows that the relatively enriched d18O and dD values in the winter (the dry season, dominated by the
westerlies) were positively correlated with temperature, indicating a temperature effect controlling the changes of d18O and dD. However, the d18O and dD values were depleted in the summer (the wet season, dominated by the
Indian monsoon), which were negatively correlated with precipitation amount, indicating an amount effect. In addition, the comparison of stable isotopes in precipitation from Kathmandu and Mawlong (near the Bay of Bengal)
shows that the overall trends of d18O and dD values at Kathmandu generally approximate those at Mawlong. However, there remain many differences between the details of the isotopic changes at Kathmandu versus those at Mawlong. Compared with those at Mawlong, the further rainout effect and the more intense lift effect of the oceanic moisture by the high mountains resulted in the more depleted d18O and dD values in summer precipitation at Kathmandu. A deuterium excess and the local meteoric water lines reveal that evaporation at Kathmandu exceeds that at Mawlong. The data also show that the Indian monsoon activities at Mawlong are more intense than those at Kathmandu.
Keywords Precipitation Stable isotopes Westerlies Indian monsoon Kathmandu Mawlong