2000-2015年华北地区8月极端干旱的异常环流型及其波活动特征 |
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作者姓名: | 徐玮平 孟祥新 伯忠凯 邢雅敏 |
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作者单位: | 山东省气候中心,山东济南250031;淄博市临淄区气象局,山东淄博255400 |
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基金项目: | 山东省气象局科研项目(2020SDQN03)。 |
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摘 要: | 利用1961-2015年华北地区54个国家级气象观测站夏季8月逐日降水资料和2000-2015年欧洲中期天气预报中心(ECMWF)再分析数据,研究了华北地区8月极端干旱的异常环流型及原因.结果 表明:华北地区极端干旱事件以年际变化为主,2000-2015年华北地区极端干旱年在中高纬500 hPa高度距平场上存在“-、+...
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关 键 词: | 极端干旱 地表2 m温度 大气环流 波通量 |
收稿时间: | 2020/11/17 0:00:00 |
Anomalous circulation patterns and wave activity characteristics of extreme drought in North China in August from 2000 to 2015 |
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Authors: | XU Weiping MENG Xiangxin BO Zhongkai XING Yamin |
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Institution: | (Shandong Climate Center, Jinan 250031, China;Linzi Meteorological Bureau of Zibo, Zibo 255400, China) |
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Abstract: | Based on the daily precipitation data of 54 national meteorological observation stations in North China in August from 1961 to 2015 and reanalysis data from the European Center for Medium-Range Weather Forecasts(ECMWF)from 2000 to 2015,this paper investigates the anomalous circulation patterns and causes of the extreme drought in August in North China.The results are as follows.The extreme drought events in North China show interannual variations.During the extreme drought years in North China from 2000 to 2015,there is an abnormal wave train structure of“-,+,-,+”in the geopotential height anomaly field at 500 hPa in the mid-high latitudes.There is a strong anticyclonic anomaly over the western Ural Mountains which makes the warm ridge move northward,the strong anticyclonic anomaly over Lake Baikal strengthens the upper-level ridge and enlarges its influence range at the same time,and such anomalous circulation situation impels the cold and dry northwest airflow in front of the upper-level ridge to be transported to North China.Western Europe is a key area for the wave activity flux in the mid-high latitudes of the Northern Hemisphere,where the surface temperature at 2 m presents a significantly increasing trend,and the vertical wave activity flux TNZ at 500 hPa corresponding to this key area also increases significantly.Due to the abnormal thermal forcing,EU wave trains are excited,low-level energy is transmitted upward,and high-level energy is dispersed outward,which strengthens the warm ridge over the western Ural Mountains,causing anomalous circulation patterns in the mid-high latitudes and frequent extreme drought events in North China. |
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Keywords: | extreme drought surface temperature at 2 m atmospheric circulation wave flux |
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