基于雾条件下能见度估算的导线覆冰气象模型

An Icing Conductor Meteorological Model Based on Estimating the Visibility in Fog Condition

在总结分析导线覆冰模型理论框架及其影响导线覆冰增长强度的主要气象因子的基础上,根据四川省二郎山观冰站2006年1月—2009年3月的覆冰观测资料和同期常规气象资料,分析发现覆冰密度仅与气温相关显著,运用非线性回归分析建立了导线覆冰密度模型;利用能见度与液态水含量的转换关系估算了空气中的液态水含量及其输送指标,在此基础上建立了一个以气温、风速等常规气象观测要素为参数的导线覆冰模型,以便于工程应用。对模型拟合结果进行分析,实测冰厚和拟合冰厚之间的相关系数为0.8340,拟合冰厚的均方根误差为28.61 mm。

By using the daily icing data of Erlangshan Mountains in Sichuan Province during three winter seasons provided by Southwest Electric Power Design Institute and related meteorological data, methods of correla- tion analysis, regression analysis are used to study the meteorological factors and icing index associated with the icing over Erlangshan Mountains. From the view of physical concept, the main meteorological factors influencing the strength of icing conductor and the microscopic process of conductor icing are ana- lyzed by the fluid mechanics and thermodynamic principles. The theoretical framework of the rime icing conductor model and the glaze icing conductor model are built. By analyzing icing data and conventional meteorological data, it is found that the icing density is not well correlated with other meteorological ele- ments except for temperature. An icing density model is established by the method of nonlinear regression analysis whose fitting correlation ratio is 0. 5652. This density model can reflect the real icing density. Ac- cording to the relationship between the visibility, extinction coefficient and liquid water, the liquid water content and its transportation can be estimated by the visibility. To choose the most proper scheme for Sichuan mountain climate characteristics, liquid water content estimated by different model is compared using observed data. Combined with the observed icing data, Kunkel scheme is selected for fitting test. As a result, it is found there is a good correlation between the growth of icing thickness and the liquid water content. The conductor icing thickness is decomposed into the rime icing which is formed by horizontal droplet and the glaze icing formed by precipitation. An icing process efficiency index is defined for further transformation of the theoretical models of conductor icing. From physical significance analysis, temperature and wind are main influencing factors of the icing process efficiency index. But the icing process efficiency index is not significantly correlated with temperature and it is related to the wind speed with exponential relationship. Based on these results, an icing conductor model is established to achieve the purpose of engineering application. From the analysis of the model fit- ting results, this icing conductor model can reflect the actual icing conductor on the whole, especially re- flecting the trend well. The correlation coefficient between the icing thickness and fitting thickness is 0. 8340, and the mean square error of icing thickness is 28.61 mm.