青藏高原东北部强冷空气次数变化特征及其影响

摘要

Based on the data from the national meteorological stations in the northeastern Qinghai-Tibet Plateau, the occurrence frequencies of monthly, quarterly and annual strong cold air for each station and the entire region from 1961 and 2015 are calculated, and then we analyzes the characteristics of strong cold air and its influences with the climate diagnosis method.It is found:In terms of spatial scale, from 1961 to 2015, there were strong cold air averagely in 20 stations collected throughout a year, 11 stations in spring, 17 stations in summer, 12 stations in autumn and 8 stations in winter, showing a significant decline.In terms of time scale, from 1961 to 2015, the annual occurrence frequency of strong cold air influencing the northeast Qinghai-Tibet Plateau decreased by 0.401 per 10 years, showing an obvious decrease tendency.In addition, the occurrence frequencies of strong cold air in summer and autumn in this region decreased by 0.094 and 0.119 per 10 years, respectively, also presenting a significant decline.However, the annual strong cold air events in spring and winter were decreased by 0.087 and 0.076 time per 10 years, respectively, without significant decline.Moreover, the occurrence frequency of strong cold air in the northeastern Qinghai-Tibet Plateau showed a significant decline from 1983 to 2014 and insignificant decline from 1962 to 1982.With respect to its influence, the annual occurrence frequency of strong cold air in the northeastern Qinghai-Tibet Plateau reduced due to the significant increase of average minimum temperature and a significant decrease in the number of strong wind days from 1961 to 2015.%基于青藏高原东北部68个国家气象站资料, 统计了1961-2015年各站和全区月、季、年强冷空气的次数资料, 利用气候诊断方法分析了强冷空气的变化特征及其影响, 结果表明:在空间尺度上, 1961-2015年强冷空气次数全年20站、春季11站、夏季17站、秋季12站、冬季8站, 呈显著的减少趋势.在时间尺度上, 1961-2015年以来, 青藏高原东北部年平均强冷空气次数每10年减少0.401次, 呈显著的减少趋势;该区域夏季和秋季平均强冷空气次数每10年分别减少0.094、0.119次, 也呈显著的减少趋势, 春季和冬季每10年分别减少0.087、0.076次, 减少的趋势不显著.在时段尺度上, 青藏高原东北部年平均强冷空气次数1983-2014年呈显著减少趋势, 而1962-1982年仅存在减少的趋势.1961-2015年青藏高原东北部年平均强冷空气次数减少是由年平均最低气温显著升高和年大风日数显著减少而导致的.