全球典型低云区中各类低云云量与水平温度平流关系的单点个例分析

选取欧洲中心40年再分析资料(ERA40)中2001年7月的775hPa和925hPa等压面上的风场和温度场资料与ISCCP同时段的低云资料,利用条件概率方法(云频数)和逐日演变的动态方法分析全球典型低云区单点的云量与水平温度平流的关系.结果表明:全球典型低云区单点上各种云的云量与水平温度平流之间的关系是十分复杂的,在某种平流下各种云均有可能出现,某种云也能在不同的平流下出现.全球典型低云区单点云量与水平温度平流的逐日演变没有明显的同步性.因此,从已知的水平温度平流条件来预报各类低云云量是没有充分的观测事实作为依据的.

Case Study on the Relationship Between Various Low Cloud Amounts and Horizontal Temperature Advection in Global Typical Low Cloud Regions

The data of wind fields and temperature fields from ERA40 and low cloud amount from ISCCP in July,2001 is used to analyze the relationship between cloud amount(hereafter,CA) and horizontal temperature advection(hereafter,HTA)at grid points in global typical low cloud regions(hereafter,GTLCRs)with conditional probability method(cloud frequency) and the daily evolution method.It is founded that the relationship between CA and HTA at grid points in GTLCRs is very complex.Different types of cloud are likely to appear in some kind of HTA and some sort of cloud appears exclusively under the conditions of different HTAs.The daily evolutions of various CAs are not synchronous with the daily evolution of HTAs.As a result,there are not sufficient evidences to support the view that various low cloud amounts are decided by the known cases of HTAs.