草温与露点温度对结露和结霜指示性分析

利用密云国家基准气候站和电白国家基准气候站2009—2010年自动站的观测记录和人工结露、结霜观测资料,以及平谷国家一般气象站2010年12月至2011年5月自动站的观测记录和天气现象自动化观测资料,分析了结露、结霜与地面气象要素关系。结果表明:诸多气象要素中,草温和草温与露点温度差对露或霜结成具有指示性作用;电白站95.0%结露发生在日最小草温与露点温度差<1.1℃时,密云站95.0%结露发生在日最小草温与露点温度差<1.2℃时,密云站95.0%结霜发生在日最小草温与露点温度差<1.3℃时;结露主要发生在最低草温0.5℃以上,从平谷站自动天气现象观测资料分析可以看出结露发生在0℃以上,结霜发生在0℃以下;很多情况,百叶箱高度上的空气中的水汽含量并未达到饱和,而贴地(或贴近地物)的空气中的水汽含量达到饱和;日最小草温与露点温度差<3.1℃时,电白、密云站不出现露、霜的比率分别是16.8%和11.7%;因土壤湿度南方比北方大,草温与露点温度差为正的比例南方较北方大。

Indicative Analysis of Grass Temperature and Dew Point Temperature to the Occurrence of Dew and Frost

Based on the data of dew and frost from 2009 to 2010 recorded by automatic weather station (AWS),manual observation data in Miyun and Dianbai National Reference Climatological Stations and the AWS records and the weather observation data of Pinggu Ordinary Climatological Station from December 2010 to May 2011,the relationships between surface meteorological factors and dew or frost were analyzed. The results show that;the grass temperature and the difference between grass temperature and dew-point temperature can be an indicator of dew and frost;95.0%dews occur in the conditions of the difference being<1.1℃in Dianbai Station,and 95.0%dews and 95.0%frosts occur when the difference is<1.2℃and<1.3℃respectively in Miyun Station.Dew mainly occurs when the minimum grass temperature is -0.5℃,from the analysis of automatic present weather observation data in Pinggu Station,it can be seen that dew occurs when the temperature is above zero,while frost occurs when the temperature is below zero.In many cases,the water-vapor content of atmosphere at the height of thermometer-screen is not saturated,while the water-vapor content of groud-hugging(or close to the surface features)atmosphere is saturated.In the conditions of the difference between the minimum grass temperature and the dew-point temperature in a day being<3.1℃,the proportion of no dew and frost is 16.8%and 11.7%in the two stations.The proportion of positive difference between grass temperature and dew-point temperature in the South China is larger than that in the North China because the soil moisture in the South China is larger than that in the North China.