喜马拉雅山中段北坡对流层中上部大气降水化学的高程分布特征

1997年夏季在希夏邦马峰北坡达索普冰川区(28°33′N,85°44′E)海拔5800m～7000m区间对4次降雪过程进行了系统的采样工作,目的是认识全球偏远地区对流层中上部大气成分的高程分布特征.达索普冰川区夏季4次降水中,局地大陆性气团降水SO₄^2-、NO₃^-、Ca²⁺和Mg²⁺之间存在显著的正相关性,而海洋性气团降水4种离子之间的相关性变化较大,说明在夏季低尘埃阶段大气中各种离子的主导来源处在短期的(如数天)变化中.这种离子主导来源的变化同时也影响了降水中离子的高程分布特征.总体上达索普冰川区夏季降水中NO₃^-、Ca²⁺、Mg²⁺浓度随海拔的升高呈减小趋势,SO₄^2-浓度则为增大趋势.

Elevation Distribution of Precipitation Chemistry in Middle/Upper Troposphere in Summer, the Northern Slope of Central Himalayas

During 1997 summer, fresh snow samples were collected from four snowfall events from the elevation of 5800 to 7000 m in the Dasuopu Glacier region on the northern slope of Mt. Xixabangma (28 degrees 33'N, 85 degrees 44'E), in order to understand the elevation distribution of the middle/upper tropospheric components in the remote region. The correlation between SO4(2-), NO3-, Ca2+ and Mg2+ in precipitation differs with type of air mass, indicating the dominant sources of ions vary in short-term (e.g. several days) during summer low dust period. In general, with elevation increases, the concentrations of NO3-, Ca2+ and Mg2+ decreases, while SO4(2-) increases, which are influenced by the variation of dominant sources of ions.