四川高速公路封道强浓雾特征及其成因分析

Characteristics and Causal Analysis of Dense Fogs for Expressway in Sichuan

利用2006—2013年四川高速公路强浓雾封道资料及气象资料,分析了造成四川高速公路封道的强浓雾特征,并通过天气环流条件和气象要素特征分析,研究了形成封道强浓雾的气象成因。结果表明：四川高速公路强浓雾封道主要出现在11月至次年1月,主要在清晨05：00—08：00开始,08：00—11：00结束,持续时间一般为0-9h。均压场是封道强浓雾的地面环流条件,低层为高压环流控制,高空环流条件为西北气流型和平直西风气流型。夜间辐射降温明显,地面到近地层风速弱、湿度大及存在逆温层,有利于封道强浓雾的出现。

Using the fog data of expressway in Sichuan and meteorological data from 2006 to 2013,the characteristics of dense fogs which made the expressway in Sichuan close and the corresponding causes are analyzed.The main conclusions are as follows：dense fogs leading to road closure mainly occur from November to the following January,mostly starting in the period of 05：00to 08：00in the early morning,usually ending from 08：00to 11：00in the morning,with the duration of road closure basically being 0to 9hours.There is generally an evenly distributed pressure field while dense fog occurs,and the low levels are controlled by high pressure circulation.The upper-level circulation conditions of dense fogs can be classified into two patterns：northwest flow and straight westerly flow.The meteorological conditions beneficial to the formation of dense fogs include significant radiation cooling at night,weak wind and high humidity from the ground to the near surface layer,and temperature inversion at the surface layer.