新疆准噶尔盆地冬季系统性降水研究Ⅱ．理论探讨

根据对北疆盆地冬季冷锋降水个例的观测分析，建立一个二维动力场给定、微物理时变的冷云模式。模式考虑了云水、云冰、雪、霰和水汽五种水元间16个微物理过程。本文用其研究了无扰动层状云、发生泡区和高空引晶自然播撒作用于层状云和飞机播撒层状云的降水发展过程，并用一维模式作一些模拟补充。模拟表明，无扰动层状云内液水丰富、冰粒子少，降水不充分。高空引晶自然播撒能大大加强层状云降水。低层发生泡既产生更多的云水又提供大量冰晶，对增加降水有双重作用。模拟得出各个过程中不同部位的各微物理过程相对重要性的时间演变，清楚地解释了观测发现的一些主要降水特征。对层状云飞机播撒同样能加强降水形成，播撒后主要增水区约10公里宽且有最大剂量限制。泡区人工播撒可进一步增加降水，而在自然播撒区再作人工播撒效果不好。

A Study of the Frontal Snowfall in Zhungeer Basin of Xinjiang in Winter Part II: Theoretical Discussion

A two-dimensional cloud model including detail microphysics is presented. The precipitation processes of stratiform clouds with or without small-mesoscale disturbances (such as generated cells and natural seeding etc.) and artificial seeding are simulated. The results are compared with observations calulations indicate that in the undisturbant stratiform clouds there exists plentiful supercooled liquid water can not transform to snowfall due to lack of sufficient ice crystals, but when the disturgbances act on the stratiform clouds, there will be a great deal of precipitation. Artificial seeding in the stratiform clouds or the disturbant regions of generated cells can increase snowfall in a large amounts. Mechanisms of the precipitation and artificial enhancement is discussed