Chemistry of snow deposited during the summer monsoon and in the winter season at Baishui glacier No. 1, Yulong mountain, China

The glaciers on Yulong mountain (5596 m a.s.l.), China, are the southernmost in mainland Eurasia. The largest is Baishui glacier No. 1. Up to 90% of the annual precipitation there falls in summer, when warm moisture-rich air masses associated with the southwest monsoon reach the area from the Indian Ocean. The winter climate is influenced by air masses with a continental origin and by the southern branch of the westerlies. The snow that accumulates on Baishui glacier No. 1 includes marine aerosols associated with the summer monsoon, and dust brought in winter from central/west Asia, Africa or the Thar Desert area. Studies in May 2006 at two sites, one in the accumulation area (4900 m) and one in the ablation area (4750 m), revealed differences between the ionic composition of the snow that had accumulated in the 2005/06 winter and that of the snow which had been deposited during the preceding summer monsoon. Differences in the chemistry of the summer-accumulated snow at the two sites probably reflected local differences in ablation and elution rates, rather than differences in ion supplies. Differences in the chemistry of the winter-accumulated snow may reflect the influence of up-valley winds, which bring more crustal material to the lower site.