青藏高原人工水汽通道对西北地区夏季降水及环流的影响——Ⅱ.对月降水量的模拟试验

采用数值天气预报模式对月降水量进行模拟．探讨“空中调水”的可能性问题，即观察在青藏高原上打开一些通道对我国西部地区夏季降水将产生何种影响。这里，我们讨论１９９８年６月和７月两月累计雨量的模拟。结果表明，如果在高原中部开一个通道，夏季的暖湿气流可以沿通道向北输送，使得通道内的水汽含量有所增加，在通道中部中心地段，６、７两月份月降水量约增加５０～２００ ｍｍ，亦即在局部地区有明显增雨效果，但除此局部地区之外几无影响，且在入口和出口地区降水反而减少，水汽也不能输送到西北地区。在高原西部打开通道几乎无影响。对模拟环流的分析表明，开凿通道后，仍难于改变高原周围的环流形势，尤其是塔里木盆地上空的下沉气流没有大改变，因而．即使有部分水汽能够到达高原以北．仍很难增加该区域大范围的降水。

Impact of Artificial Water Vapor Channel on the Tibetan Plateau on Rainfall in Northwest China Part II: Numerical Simulation for Monthly Precipitation Amount

In Part I of this work, the numerical simulation experiments of some cases in rainy season of 1998 have been conducted. In this paper (i.e., Part II), the numerical simulation experiments of monthly precipitation amount of June and July, 1998 were made. Based on the study, the probability of the influence of man-made water vapor channel on the Tibetan Plateau on the precipitation amount in Northwest China will be evaluated, again. The results show that the distribution of the precipitation has been changed after the above-mentioned channels were made. In the middle channel, the precipitation amount increased somewhat, and in the entrance and exit area of the channel, the precipitation de-creased. The precipitation increased in Northwest China except the upper reaches of the Yangtze River has not been found. Therefore, it is still a problem to be studied continuously.