靠近迭代法获取湿球温度初探
Preliminary Study on Calculating Wet Ball Temperature Using a Near Iterative Method
中文摘要：
主要探讨了通过靠近查询、迭代求算获取自动气象站湿球温度的方法。以戈夫--格雷奇（Goff-Gratch）公式为基础，编制了湿球未结冰条件下，气温t位于0～48 ℃，间隔为3 ℃的小型湿度查算表，其中包含：每个t值对应湿球温度tw、水汽压e、相对湿度U、气压订正参数n。它可帮助满足自动气象站资料已知t1、 e1，批量求算tw1的工作。首先将t1、e1表与小型湿度查算表进行联表靠近查询，再以t、 e、 tw为基础， e不变，对tw进行步长为正负0.1的迭代计算。迭代过程中， t随着tw的值不断变化。令变化中的湿球温度为t′w，相应的气温为t′，当| t′-t1|为最小值时， t′w便是所求的湿球温度tw1，为提高精度，也可对tw1进行适当订正。
中文关键词：
湿球温度，靠近查询，迭代求算
KeyWords：
wet ball temperature, close to query, iterative calculation
Abstract：
This paper mainly discusses the method of obtaining the wet ball temperature of automatic weather station by close query and iterative calculation. Based on the Gof-Gratch formula, a small humidity check scale with temperature at 0~48 ℃ and intervals of 3 ℃ under unfrozen conditions is prepared. This check scale includes wet ball temperature tw, vapor pressure e, relative humidity U, and pressure correction parameter n at each t value. The small humidity checklist can enable the calculation of tw1 in batch using automatic weather station data such as t1 and e1. First, the t1 and e1 tables are linked to the small humidity checklist to make a close query. Secondly, an iterative calculation of tw with a step length of ±0.1 is performed using t, e, and tw values while keep e value unchanged. During this iteration, t changes with the value of tw. Assume that the temperature of the changing wet ball is t′w and the corresponding air temperature is t′. The t′w is the solution of wet ball temperature tw1 when | t′-t1| reaches the minimum value. In order to improve the accuracy, tw1 can be adjusted appropriately.