太湖无锡地区太阳总辐射的气候学计算及特征分析

为了便于研究水气界面辐射传输、水下光辐照度以及湖泊储热量，探讨太湖地区总辐射概况及其变化。文章在概述当前太阳总辐射气候学计算的主要方法及公式基础上，采用最小二乘法，利用上海、南京、杭州3站1961~2000年共40年的历史资料，确定各站的经验系数，然后内插求出太湖无锡地区的经验系数。由此推导出太湖无锡地区太阳总辐射的气候学计算公式，并利用无锡站日照百分率资料求算出近40年到达地面的太阳实际总辐射。然后利用太湖站1998年的太阳总辐射实测资料检验其公式精度，确定公式的可信度。最后对计算值进行分析，阐述了近40年来太湖无锡地区太阳总辐射的变化特征及其原因。研究结果表明:无锡地区太阳总辐射呈下降趋势，而这种下降主要是由于大气中悬浮物增加所致；总辐射年内变化趋势基本上与天文辐射相吻合，但又存在差异，这主要与梅雨的存在有关。

Climatological Calculation and Characteristic Analysis of Global Radiation over Wuxi Region

The variation of global solar radiation reaching the surface over the Wuxi region and its calculation are studied for further understanding of the solar transfer on water air interface and the underwater irradiance. The main methods and formulas for climatological calculation of global radiation are simply discussed. Based on the observation data of global radiation and relative sunshine at Shanghai, Nanjing, Hangzhou stations, the empirical coefficients for these stations are calculated by using the least square method. The coefficient for the Wuxi region is calculated through interpolation from the coefficients of the three stations. The climatological calculation formula, which is suitable for Wuxi region, is brought forward. The global radiation reaching the surface is gained by using the formula and relative sunshine data at Wuxi station in recent 40 years. The formula precision is checked up by use of the observation data from the Taihu Lake ecosystem research station, which is proved to be credible. At last, by analyzing the calculation results, the characteristics and causes of global radiation variation are discussed. The results show that the global radiation has decreased in the past 40 years and the decrease mainly attributed to the increase of suspended matter in the atmosphere. The annual variation of global radiation is basically similar to the extraterrestrial irradiation except some differences in summer. These differences are caused by Meiyu with greater precipitation, cloud cover and less sunshine.