Covariability between tree-ring-based precipitation reconstructions in Northwest China and the sea-surface temperature of the Indian and Pacific Oceans

Abstract

We investigated the coherent variability between precipitation variations in NW China and the sea-surface temperatures of the Indian and Pacific Oceans, using both instrumental data and tree-ring-based precipitation reconstructions. Major coherent hydroclimatic variations in NW China were identified based on the first 2 leading singular value decomposition modes. The modes include the 'southern Xinjiang' pattern, the 'coherent NW-SE' pattern with positive or negative loadings over both the northwestern and southeastern parts and the 'NW-SE dipole' pattern, with inverse correlation patterns between them. The southerly winds near the western boundary of NW China and Lake Balkhash during the early stage of the Indian summer monsoon influence the hydroclimate variability in western NW China (Xinjiang area). The East Asian summer monsoon variability is related to the hydroclimate of eastern NW China, which is modulated by the El Niño Southern Oscillation, geopotential heights in northeastern Asia and over the Philippine Sea, as well as the western Subtropical Pacific High. The strength of the geopotential height in northeastern Asia may be related to the 'coherent NW-SE' pattern, while the inverse relationships between the Pacific Decadal Oscillation and Indian summer monsoon and westerlies may account for the 'NW-SE dipole'. © Inter-Research 2011.