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气象:2016,42(6):756-763
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河西走廊东部强降温变化特征和典型环流型
(1.甘肃省武威市气象局,武威 733099;2.甘肃省民勤县气象局,民勤 733300)
Change Characteristic and Typical Circulation Type of Strong Cooling in Eastern Hexi Corridor
(1.Wuwei Meteorological Office of Gansu Province, Wuwei 733099;2.Minqin Meteorological Station of Gansu Province, Minqin 733300)
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投稿时间:2014-12-13    修订日期:2016-02-01
中文摘要: 利用河西走廊东部1961—2010年5个气象站日最低气温观测资料,计算了50 a强降温24 h(48 h)最低气温下降≥8(10)℃、最低气温≤4℃次数,采用统计学方法系统分析了该区域强降温的时空分布以及强度等气候特征,然后利用1991—2010年ECMWF 500 hPa(2.5°×2.5°)数值预报格点资料,分析了该地强降温的环流特征,最后研究了强降温次数与大气环流特征量的关系。结果表明,受地形地貌、地表植被以及山脉阻挡的影响,河西走廊东部强降温次数的地域分布存在明显差异,海拔较高的山区和北部沙漠边缘强降温次数明显多于绿洲平原区。强降温天气具有明显的区域性特征,随着强降温站数的增多,强降温的次数在减少;24和48 h强降温年代、年次数总体呈减少趋势,其强降温次数时间序列均存在4~6 a的准周期变化,但未出现突变现象。强降温天气主要发生在1—5和9—12月,4月强降温次数最多。各强度强降温次数的变率较大,随着降温强度的增大,强降温次数迅速减少,24 h强降温强度呈较弱减弱趋势,48 h强降温强度呈较弱增强趋势。河西走廊东部强降温天气的典型环流形势分为西北气流型和偏北气流型两大类,其中西北气流型次数多于偏北气流型。河西走廊东部月强降温次数与表征高空冷空气的强度和移动路径的大气环流特征量表现为显著的正相关,说明河西走廊东部强降温次数与高空冷空气的强度和移动路径的关系密切,高空冷空气的强度和移动路径是强降温预测的强信号。
Abstract:Using daily lowest temperature observation data of five meteorological stations in the east of Hexi Corridor during 1961-2010, the number of strong cooling [the lowest temperature drop rate is ≥ 8 (10)℃ and the minimum temperature is ≤ 4℃ in 24(48 h) in recent 50 years] was calculated. Climatic characteristics of spatio temperal distribution and intensity of strong cooling were systematically analyzed with statistical methods. Then the ECMWF 500 hPa numerical forecast grid data (2.5°×2.5°) from 1991 to 2010 was used to analyze the strong cooling circulation features in this region. Finally, relations between strong cooling times and atmospheric circulation characteristics were studied. The results show that strong cooling times distribute differently in eastern Hexi Corridor and it is more obviously in high elevation mountains and northern desert edge than in oasis plain area due to the block of terrain, vegetation and mountains. Strong cool weather has obvious regional characteristics, and the times reduces with the increase of strong cooling station number. The decadal and annual times of strong cooling show a decreasing trend, and time series of strong cooling times has 4-6 year quasi periodic variation, but no mutations. Such weather occurs mainly from January to May and from September to December, but most in April. Times of strong cooling with different intensities varies greatly reducing rapidly with the increase of cooling intensity. Intensity of 24 h strong cooling has a weak reducing tendency, while that of 48 h strong cooling shows a slightly increasing trend. Typical circulation of strong cooling weather in eastern Hexi Corridor is divided into two categories, including northwest airflow type and northern airflow type, and the number of northwest airflow type is more than that of northern airflow type. A significantly positive correlation exists between monthly strong cooling times and circulation characteristics including high altitude cold air strength and cold air moving path, which means that a close relationship exists between strong cooling times and the high level cold air strength and cold air moving path. Intensity and moving path of high level cold air are strong signals for the forecasting of strong cooling weather.
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基金项目:国家自然科学基金项目(41305134)和甘肃省气象局第七批“十人计划”共同资助
引用文本:
杨晓玲,丁文魁,马中华,刘蓉,2016.河西走廊东部强降温变化特征和典型环流型[J].气象,42(6):756-763.
YANG Xiaoling,DING Wenkui,MA Zhonghua,LIU Rong,2016.Change Characteristic and Typical Circulation Type of Strong Cooling in Eastern Hexi Corridor[J].Meteor Mon,42(6):756-763.