| 青藏高原风季大风集中期、集中度及环流特征 |
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| 引用本文： | 姚慧茹,李栋梁.青藏高原风季大风集中期、集中度及环流特征[J].中国沙漠,2019,39(2):122-133. |
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| 作者姓名： | 姚慧茹 李栋梁 |
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| 作者单位： | 1. 南京信息工程大学 大气科学学院/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044;2. 天津市气象灾害防御技术中心, 天津 300202 |
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| 基金项目： | 国家重点研发计划项目（2018YFC1507101）；国家公益性行业（气象）科研专项（GYHY201506001-1）；国家重点基础研究发展计划项目（2013CB956004）；国家自然科学基金项目（91337109，41305080）；江苏省普通高校研究生科研创新计划项目（KYLX_0830）；江苏高校优势学科建设工程资助项目（PAPD） |
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| 摘 要： | 利用青藏高原气象台站逐日最大风速数据和JRA-55再分析资料,通过引入集中期和集中度的概念,分析了1971—2012年高原大风在风季的分布形态及其环流背景。结果表明:青藏高原的大风天气在春季(3—5月)最多,在夏末秋初(8—10月)最少。1971—2012年,大风日数以14 d/10a的速度减少,同时大风日数的年较差也在缩小。大风集中期随纬度增大而延后,并且在近42年大体呈提前的趋势,从3月底4月初提前至2月底3月初。大风集中度则有增大的趋势,并取决于大风日数,大风日数越多,集中度越低。高原大风集中期受到急流系统经向位移的制约,2月和3月北非和西亚地区的副热带急流以及4月中层西风带偏南时,伴随着副热带气压偏低,青藏高原春季大风天气偏多,大风集中期偏晚。反之,大风天气偏少,集中期偏早。大风集中度的大小则与中亚和高原地区2—4月副热带急流强度有关,2月和4月副热带急流偏弱、3月急流偏强时,大风日数集中在3月,集中度较高。反之,集中度较低。春季(3月)高原大风天气是冷、暖空气系统共同作用的结果,高原东部的大风天气多受北方冷空气系统影响,高原西部的大风天气多受南方暖空气系统影响、以西南风为主。
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| 关 键 词： | 青藏高原 大风日数 集中期 集中度 |
| 收稿时间： | 2018-02-27 |
| 修稿时间： | 2018-04-27 |
The Gale Concentration Period and Degree over the Tibetan Plateau and Related Atmospheric Circulation during the Windy Period |
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| Yao Huiru,Li Dongliang.The Gale Concentration Period and Degree over the Tibetan Plateau and Related Atmospheric Circulation during the Windy Period[J].Journal of Desert Research,2019,39(2):122-133. |
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| Authors: | Yao Huiru Li Dongliang |
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| Institution: | 1. College of Atmospheric Science/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044, China;2. Meteorological Disaster Prevention Technology Center of Tianjin, Tianjin 300202, China |
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| Abstract: | Based on the daily maximum wind speed data of 47 stations in the Tibetan Plateau and JRA-55 reanalysis data, by using the concept of concentration period and concentration degree, the concentration of gales over the Tibetan Plateau and related atmospheric circulation during windy period from 1971 to 2012 are analyzed. The results show that the gales over the Tibetan Plateau occur mostly in spring (from March to May) and occur least from August to October. There is a declining trend of the gale days during 1971-2012 with a rate of -14 d/10a, and the annual range of the gale days is also reduced. The gale concentration period (GCP) over the Plateau is usually delayed with latitude and is moving up earlier in the recent 42 years, which is from the early April to early March. The gale concentration degree (GCD) has an increase tendency, and it depends on the number of gale days. The more the gale days are, the lower the concentration degree is. GCP is affected by the meridional displacement of the subtropical jet stream. In February and March, when the subtropical jet stream in North Africa and Western Asia and the low-level westerly belt in April tended to be southerly, along with the lower pressure in the subtropical region, there is more gale days over the Tibetan Plateau and GCP is delayed; Otherwise, GCP is advanced. GCD is related to the intensity of the subtropical jet stream in Central Asia and Tibetan Plateau from February to April. When the subtropical jet in February and April is weak and the jet in March is strong, the gale days over the plateau are concentrated in March and the GCD is high, and vice versa. In spring, especially in March, the occurrence of gales over the Tibetan Plateau is the result of the interaction of cold and warm air system. The gales in the eastern plateau are affected mostly by the cold air from the North, while the gales in the west of the plateau are influenced by the warm air from the South, which is dominated by the southwest wind. |
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| Keywords: | Tibetan Plateau gale days concentration period concentration degree |
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