RELATIONSHIPS BETWEEN AN ICE CORE RECORDS FROM SOUTHERN TIBETAN PLATEAU AND ATMOSPHERIC CIRCULATION OVER ASIA
青藏高原南部冰芯记录与大气环流的关系*

Hydrogen isotope (δD) and annual accumulation records covering the period A.D. 1952~1998 were reconstructed using a 29.5m ice core from the col of the Lanong Glacier (5850m a.s.l.) on the eastern saddle of Mt. Nyainqêntanglha (NQ), Southern Tibetan Plateau (TP). Using NCEP/NCAR Reanalysis data, we explore the relationships between the annual δD and accumulation records from the ice core and primary components of the climate system. Linear correlation analysis between δD and climate components indicates that δD variations are correlated with summer precipitation, winter surface pressure, and geopotential height in both winter and summer over the South Asian and TP region. Summer precipitation and δD are negatively correlated over regions of northern India and the Bay of Bengal, while a positive correlation exists over the north of TP. This is consistent with the amount effect controlling δD values during the summer monsoon season. A negative relationship between δD and winter surface pressure over central Asia suggests that high pressure acts as a barrier against winter moisture transport with higher δD values from the Westerlies. Negative correlations between δD and geopotential height in both summer and winter over Asia indicate that stronger atmospheric circulation over Asia corresponds to lower δD values. Linear correlation analysis between annual accumulation and climate components for the 47 year overlap periods indicates that annual accumulation variations are closely correlated with sea surface and 500hPa air temperature over the North Indian Ocean and atmospheric circulation (surface pressure and geopotential height) over Asia. An Intensification of atmospheric circulation and increase of sea surface and air temperatures, resulting in intensified moisture availability and moisture transport, have been a major cause for the increase of ice core accumulation over the Mt. NQ region since the 1980s. Associations between atmospheric circulation and the NQ δD and accumulation records found in this study can be applied to future studies utilizing longer ice core records to reconstruct atmospheric circulation farther back in time.