Abstract:

Abstract:Based on the hourly snowfall data from 3 automatic weather stations in Urumqi during the period of 2011-2015, the diurnal variation characteristics of snowfall in different regions of Urumqi were analyzed. The results show that during 2011-2015, the accumulated snowfall, accumulated frequency and the frequency of snowfall with different grades in the urban area of Urumqi were greater than those in the suburb and mountainous areas in winter. The intensity of hourly snowfall was the largest in urban area, followed by suburb area and the smallest in mountainous area. The average duration of light snow in urban, suburban and mountainous areas was not obvious. The average duration of moderate snow in the suburb was the shortest. The average duration of moderate snow in the urban and mountain area was longer. The average duration of heavy snow was the shortest in suburb, followed by urban area and longest in mountain area. The average duration of snowstorm was the shortest in urban area, the second shortest in suburb, and the longest in mountain area. The amplitude of snowfall intensity in daytime was larger than that in night. The snowfall and frequency in mountain area were characterized by a single peak from afternoon to the evening. Except for 21:00, the hourly snowfall and snowfall frequency in the urban area were more than those in suburb and mountainous areas. The intensity of snowfall in the urban area was stronger than that in suburb from evening to early morning. The intensity of snowfall in the urban area was stronger than that in mountain area in the morning. The short duration  snow (1-6 h) in urban and suburban areas was prone to occuring at night and in the morning , the long duration snowfall (more than 6 h) was easy to appear in the morning and evening. The short duration and long duration snow in the mountain area was easy to appear in the afternoon and evening. The snowfall in urban area began in the early morning or early afternoon and ended at noon. The snowfall in the suburb area began at midnight and ended in the morning. The snowfall in the mountain area started in the afternoon and ended in the late evening.

Key words: snow, hourly snowfall, diurnal variations, Urumqi

摘要：

基于2011—2015年乌鲁木齐市城区、郊区和山区3个国家观测站称重式固态降水逐时观测资料，分析了乌鲁木齐市不同区域冬季降雪的日变化特征。结果表明：近5 a冬季乌鲁木齐市城区累计降雪量、累计降雪频次和各量级降雪频次均大于郊区和山区。小时最大降雪量城区最大、郊区次之、山区最小。小雪平均持续时间各区差异不大，中雪郊区最短、城区和山区略长；大雪郊区最短、城区其次、山区最长；暴雪城区最短、郊区其次、山区最长。各区降雪强度白天波动振幅均大于夜间，山区累计降雪量和降雪频次在傍晚前后（17:00—21:00）的单峰特征明显。除21:00外，城区逐时降雪量和降雪频次均大于郊区和山区；降雪强度在傍晚至凌晨时段强于郊区，在上午时段强于山区。城区和郊区短历时降雪（1~6 h）的最大降雪易出现在夜间和清晨；长历时降雪（超过6 h）易出现在上午和傍晚；山区短历时和长历时降雪的最大降雪均易出现在下午至傍晚。城区降雪过程多在清晨和午后开始，中午结束；郊区降雪过程多在前半夜开始，上午结束；山区降雪多为午后开始，傍晚至前半夜结束。

关键词: 降雪, 小时降水, 日变化, 乌鲁木齐