Variations in annual accumulation recorded in a Laohugou ice core from the northeastern Tibetan Plateau and their relationship with atmospheric circulation

Abstract

Annual accumulation was reconstructed for a period from 1960 to 2006 using a 21.2-m ice core from the firn basin of Laohugou (LHG) Glacier No. 12 on the northeastern Tibetan Plateau (TP). Significant periodicity of LHG accumulation variations was identified as a quasi-3-year period in accordance with the oscillation of precipitation in the northwestern China, especially the Hexi Corridor. Furthermore, the relationships of LHG accumulation with atmospheric circulation and moisture sources were investigated. LHG accumulation was positively correlated with the 500-hPa geopotential height and pressure in Central Asia, as well as the autumn Northern Atlantic Oscillation, suggesting that the Westerlies may transport moisture to the LHG region and enhance precipitation. In addition, a negative relationship between LHG accumulation and meridional wind indicated that an intense Mongolian cyclone caused by a strong meridional wind in the region could block Arctic air masses from the LHG region. Moisture fluxes and backward air mass trajectories suggested that moisture might originate from Central Asia, Southern and the inland TP. The relationship between LHG accumulation and atmospheric circulation provides an opportunity to reconstruct the history of atmospheric circulation using a deep ice core record.