| 杨梅,李岩瑛,朱陵晶.河西走廊东部近57年不同等级冷空气时空变化特征及寒潮分析[J].沙漠与绿洲气象,2022,16(5):87~93 |
| 河西走廊东部近57年不同等级冷空气时空变化特征及寒潮分析 |
| Spatio-temporal variation characteristics of cold air at different levels in eastern Hexi Corridor and cold wave forecast |
| 投稿时间：2021-10-20 修订日期：2022-03-31 |
| DOI：10.12057/j.issn.1002-0799.2022.05.012 |
| 中文关键词: 降温日数 不同等级冷空气 时空变化特征 寒潮 河西走廊东部 |
| 英文关键词:cooling days cold air at different levels temporal and spatial variations cold wave Eastern Hexi Corridor |
| 基金项目:国家自然科学基金面上项目（41975015）资助 |
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| 中文摘要: |
| 利用河西走廊东部5个国家气象观测站1961—2017年的日最低气温，统计分析其5个等级冷空气的时空变化和降温幅度，并用NCEP月平均500 hPa位势高度场、风场分析本地寒潮显著极端年的特征。结果表明:(1)冷空气年均日数:Ⅰ级最多，Ⅳ和Ⅴ级基本接近，Ⅲ级最少。空间分布Ⅰ级偏北沙漠区少、中部平原区多；其余四级分布均为偏北沙漠区偏多。时间分布Ⅱ、Ⅳ和Ⅴ级春季4—5月最多，夏季最少；Ⅲ级集中在夏季7—8月；Ⅰ级月季出现频率接近，夏季8月略多。(2)年降温日数Ⅴ和Ⅳ级呈明显减少趋势，Ⅰ～Ⅲ级线性不明显，但Ⅰ和Ⅱ级增多。年均降温频数的年代际差异不大，整体呈先降后升，但其主要周期有差异。(3)平均降温幅度季节变化只有Ⅴ级明显，Ⅳ级相近，而Ⅰ～Ⅲ级最大分别出现在春季、秋季和夏季；Ⅴ级24 h、48 h、72 h最大降温幅度分别为9.9、12.2、14.3 ℃。(4)寒潮次数有12个极端年，显著偏多(少)年寒潮天数差异10月最大，夏季较小。河西走廊东部500 hPa位势高度场在显著偏多年为明显的西北气流控制，配合负距平中心；乌拉尔山脊前有极地干冷空气输送有利于寒潮天气发生。偏少年以纬向平直西风气流为主，有明显的正距平高度，冷空气下滑少降温不易发生。 |
| 英文摘要: |
| Based on the observed daily minimum air temperature at five national meteorological stations in eastern Hexi Corridor during 1961 to 2017,we statistically analyzed the cold air at five levels spatio-temporal distributions and cooling range.The characteristics of the local extreme cold wave analyzed by applying the monthly mean 500 hPa geopotential height field,wind field circulation data from NCEP.Results showed the annual average days of cold air were the most in level I,V and IV levels were close,and the least in level III.The spatial distribution was less in northern desert area and more in central plain area of level I.The other four levels were basically similar,the northern desert areas were more.The time distribution of II,IV and V levels were most in April and May in spring,which was least in summer.The level III was concentrated in July and August.The frequency of level I in each month was close but a little more in August.The linear trend of the annual cooling days that V and IV levels decreased obviously,while level I~III was not obvious,but I and II levels increased.The interdecadal variation of the average annual cooling frequency was not significant,and the decreased first and then increased,but its main cycle was different.In the seasonal variation of the average cooling range only level V was obvious,IV was similar,while I~III levels were the largest in spring,autumn,spring and summer.The maximum temperature drop of V were 9.9,12.2 and 14.3 ℃ for 24 h, 48 h and 72 h.During the study period,there were 12 extreme years in cold wave,and the difference of cold wave days in more (less) years was the largest in October,but smaller in summer.During the positive-anomaly years,the 500 hPa geopotential height field under the obvious?northwest flows control with a negative anomaly center.Meanwhile the Urals Ridge transfered the polar dry and cold air to the was conducive to the cold wave.During the negative-anomaly years,the straight westerly controlled the study area,and with obvious positive anomaly height.Cold air down less where cooling disaster weather was not easy to occur. |
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