持续大雾对日光温室蔬菜的致灾效应分析

Disaster-inducing effects of lasting heavy fog on greenhouse vegetables

2007年12月下旬,河北省中南部平原地区的日光温室蔬菜大面积受灾,损失惨重。灾情发生的主要气象环境因素为:长期高湿、寡照、低温,系高空平直西风环流不利于较强冷空气南下和地面冷高压东南部弱冷空气不断扩散的稳定形势下形成持续大雾天气所致。大雾前期低层偏南气流持续输送水汽、水汽通量的连续辐合、低层切变过境为持续大雾天气的形成创造了有利的低层湿度条件,逆温层的形成与维持为持续大雾天气的产生创造了有利的层结条件,夜间偏北微风少云的天气利于雾滴的形成,而强冷空气的入侵是持续大雾天气结束的主要原因。提出了持续大雾天气预报的着眼点及日光温室蔬菜的防灾措施。

In the late December 2007,the greenhouse vegetables underwent serious damage over the central and southern plains of Hebei Province,leading to a considerable reduction of vegetable production.The main weather environment causing this disaster is the persistent heavy frog,which resulted from the long-duration of high humidity,lack of sunshine and low temperature.The high level westerly wind,preventing the cold air from high latitude intruding the plain,and the cold air spreading from the surface high pressure are suitable for the formation of heavy fog.In the early stage of the heavy fog,the low-level southerly wind,the water vapor convergence and the low-level shear provided good water vapor condition for the fog.The formation and maintenance of the temperature inversion produce the favorable stratification condition.Small northerly wind at night and little cloud are suitable for the formation of droplet.The strong cold air intrusion is the main cause for the persistent heavy fog.This work presents key points for persistent fog prediction and the disaster prevention measures for greenhouses vegetables.