祁连山-黑河流域水循环中的大气过程

利用气象台站探空资料、地面观测资料和NCEP/NCAR再分析气候资料,分析了祁连山-黑河流域水循环中的大气过程,结果表明:受西风带波动影响的水汽来源贫乏是此区大气水汽含量少的原因之一;水汽输送通量辐散是此区大气水汽含量少的原因之二;就年平均而言,祁连山-黑河流域大气水汽含量仅为高湿的江南地区的20%,为半干旱区的华北中部的约40%;高海拔的祁连山区因降水效率高,地面蒸发量小,地表水物质易于聚积形成径流;黑河流域因降水效率低,降水量值与地面蒸发量值相当,对地表水的贡献很小。在祁连山黑河流域25°×25°区域上空,大气年输入水量为6678亿m3,输出为6502亿m3,净输入水量为176亿m3;输入水汽呈逐年减少的趋势。20世纪70～80年代有明显的下降,近40年来祁连山黑河流域的气温在升高,大气中的水汽含量在减少,降水量的减少将难以避免。

Atmospheric hydrologic cycle over the Qilian-Heihe Valley

The atmospheric hydrologic cycle over the Qilian-Heihe Valley are analyzed by using the observed data of meteorological stations and the NCEP/NCAR monthly mean data from 1958 to 1997.Some significant results are showed.The sparse water vapor source is reason one of little water vapor in atrmsphere over the Valley,and the water vaporflux divergence is reason two of that.The higher precipitation efficiency and less evaporation are prone to accumulate water substance into runoff over the higher Qilian Mountain than the lower Heihe Vale.The lower precipitation efficiency make less precipitation amount over Heihe Vale and correspond with evaporation armunt so as to contribute quite smallness for runoff.In the atrmsphere column over the area of 2.5°×2.5°,the annual influent water vapor amount is 6678×10⁸m³,the annual effluent water vapor amount is 6502×10⁸m³,and the net water vapor amount is 176×10⁸m³.Over theqlian-Heihe Valley,it is inevitable that the precipitation amount will be reduced because the influent water vapor is reducing along with air temperature rising year after year.