中国西北东部电线积冰气候特征及分区

选取有观测以来至2010年的电线积冰资料及1961-2010年逐日平均气温、最高气温、最低气温、相对湿度及风速资料，对西北东部电线积冰的气候特征以及积冰发生时的天气条件进行分析，探讨积冰形成时的气象要素配置，指出西北东部电线积冰的气候分区。结果表明：① 10月至次年4月为西北东部电线积冰期；积冰类型主要为雾凇和雨凇，其中北部大部地区及陕西西安以雾凇为主，西南部以雨凇为主。② 1 000 m以下地区一般日平均气温在-5～4 ℃，日最低气温在-10～0 ℃，相对湿度在70%以上，风速在0～1 m•s^-1；1 000～2 000 m地区一般日平均气温在-15～4 ℃，日最低气温在-15～0 ℃，相对湿度在70%以上，风速在0～4 m•s^-1；2 000 m以上地区一般日平均气温在-15～0 ℃，日最低气温在-15～-5 ℃，相对湿度在60%以上，风速在0～8 m•s^-1时，最易出现电线积冰现象。③ 从气候角度分析，西北东部电线积冰呈西多东少，山区多于平原的分布格局，海拔较高的西南部及东南部是积冰潜在高发区，西北部、中部及东南部华山周边地区是次高发区，东部大部地区是低发区，并且积冰高发区也是持续冰灾的高发区。

Climatic Characteristics and Distribution of Wire Icing Days in the Eastern Part of Northwest China

In this paper, the climatic characteristics of the wire icing and the real time weather conditions for wire icing occurrence are analyzed using the data of wire icing days from the establishment dates of the meteorological stations to 2010 and the data of daily, daily maximum and minimum temperatures, relative humidity and averaged daily wind speed during the period of 1961-2010, and the distribution of wire icing days is discussed. The results are as follows: (1) Wire icing occurred generally during the period from October to next April in the eastern part of northwest China in the forms of fog glaze mainly in the most northern region and Xi’an and glazed frost in the southwestern part; (2) Wire icing occurred often under the specific weather conditions: It occurred in the regions below 1 000 m. when the averaged daily temperature varied in a range of -5-4 ℃, daily minimum temperature in a range of -10-0 ℃, relative humidity was higher than 70%, and wind speed varied in a range of 0-1 m•s^-1; in the regions with elevation of 1 000-2 000 m, it occurred when the averaged daily temperature varied in a range of -15-4 ℃, daily minimum temperature in a range of -15-0 ℃, relative humidity was higher than 70%, and wind speed varied in a rrange of 0-4 m•s^-1; in the regions above 2 000 m, it occurred when the averaged daily temperature varied in a range of -15-0 ℃, daily minimum temperature in a range of -15--5 ℃, relative humidity was higher than 60%, and wind speed varied in a range of 0-8 m•s^-1； (3) Based on the climatic characteristics, the wire icing in the eastern part of northwest China occurred often in the west but rarely in the east, often in the regions with high altitudes but rarely in the regions with low altitudes. The potential occurrence of wire icing was high in the southwest and southeast, then in the northwest, central region and the region around the Huashan Mountain, and it was low in the east. In addition, the continuous wire icing occurred often in the regions with high occurring frequency of ice disasters.