1961—2010年贵州冬季路面持续凝冰时间时空分布变化特征

Spatial and temporal variation characteristics of persistent land surface freezing in winter of Guizhou during 1961—2010

利用1961--2010年贵州冬季的日最低地表温度以及日降水资料分析了近50a路面持续凝冰时间的统计特征．结果表明：位于贵州26．5～27．5°N纬度带西部的地区高频发生持续凝冰，每年平均发生6～9次轻级凝冰（持续凝冰1～3d）、3～6次中级凝冰（4～6d）、2～4次重级凝冰（7～11d）和1～2次特重级凝冰（12d以上）．总体来看，在全省范围内各级凝冰发生频次都有不同程度的下降趋势．极端持续凝冰事件集中发生在1月以及2月上半月，且贵州中西部以及西北部阈值在10d以上，受凝冻影响大．

Using daily minimum temperature of land surface and precipitation data in winter of Guizhou province during the period of 1961--2010 ,the characteristics of spatial and temporal variations on the persistent land surface freezing are investigated. Results show that persistent freezing occurred in high frequency in the west part of 26.5- 27.5 ° N regions of Guizhou, including 6-9 slight freezings （ lasting for 1-3 days）, 3-6 moderate freezings （4-6 days）, 2-4 heavy freezings（7-11days） and 1-2 torrential freezings （over 12 days） annually. Overall, there are downward trends in the freezing frequency at different levels in most parts of Guizhou.The extreme events of persistent land surface freezing always occurred in January or the first half of February ,with the thresholds as exceeding 10 days in the central,west and northwest of Guizhou accompanied by serious hazards.