| CHARACTERISTICS OF MIDDLE EAST JET STREAM DURING SEASONAL TRANSITION AND ITS RELATION WITH INDIAN SUMMER MONSOON ONSET? |
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| 引用本文： | 倪东鸿,孙照渤,李忠贤,曾 刚,邓伟涛.CHARACTERISTICS OF MIDDLE EAST JET STREAM DURING SEASONAL TRANSITION AND ITS RELATION WITH INDIAN SUMMER MONSOON ONSET?[J].热带气象学报(英文版),2014,20(3):208-217. |
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| 作者姓名： | 倪东鸿 孙照渤 李忠贤 曾 刚 邓伟涛 |
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| 作者单位： | Key Laboratory of Meteorological Disaster of Ministry of Education and Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044 China |
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| 基金项目： | Project of Natural Science Foundation of China （41205035, 40905045, 40775059）; National Basic Research and Development Program of China （2013CB430202）; NSF of Jiangsu Higher Education Institutions （13KJB170013）; Special Scientific Research Fund of Public Welfare Industries of China （GYHY201306028）; Qing Lan Project; Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions （PAPD） |
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| 摘 要： | By using the NCEP/NCAR pentad reanalysis data from 1968 to 2009, the variation characteristics of Middle East jet stream(MEJS) and its thermal mechanism during seasonal transition are studied. Results show that the intensity and south-north location of MEJS center exhibit obvious seasonal variation characteristics. When MEJS is strong, it is at 27.5°N from the 67 th pentad to the 24 th pentad the following year; when MEJS is weak, it is at 45°N from the 38 th pentad to the 44 th pentad. The first Empirical Orthogonal Function(EOF) mode of 200-hPa zonal wind field shows that MEJS is mainly over Egypt and Saudi Arabia in winter and over the eastern Black Sea and the eastern Aral Sea in summer. MEJS intensity markedly weakens in summer in comparison with that in winter. The 26th-31 st pentad is the spring-summer transition of MEJS, and the 54th-61 st pentad the autumn-winter transition. During the two seasonal transitions, the temporal variations of the 500-200 hPa south-north temperature difference(SNTD) well match with 200-hPa zonal wind velocity, indicating that the former leads to the latter following the principle of thermal wind. A case analysis shows that there is a close relation between the onset date of Indian summer monsoon and the transition date of MEJS seasonal transition. When the outbreak date of Indian summer monsoon is earlier than normal, MEJS moves northward earlier because the larger SNTD between 500-200 hPa moves northward earlier, with the westerly jet in the lower troposphere over 40°-90°E appearing earlier than normal, and vice versa.
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| 关 键 词： | 大气科学 气候学 气候类型 热带气象学 |
| 修稿时间： | 2014/5/19 0:00:00 |
CHARACTERISTICS OF MIDDLE EAST JET STREAM DURING SEASONAL TRANSITION AND ITS RELATION WITH INDIAN SUMMER MONSOON ONSET |
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| NI Dong-hong,SUN Zhao-bo,LI Zhong-xian,ZENG Gang and DENG Wei-tao.CHARACTERISTICS OF MIDDLE EAST JET STREAM DURING SEASONAL TRANSITION AND ITS RELATION WITH INDIAN SUMMER MONSOON ONSET[J].Journal of Tropical Meteorology,2014,20(3):208-217. |
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| Authors: | NI Dong-hong SUN Zhao-bo LI Zhong-xian ZENG Gang and DENG Wei-tao |
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| Institution: | Key Laboratory of Meteorological Disaster of Ministry of Education and Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044 China |
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| Abstract: | By using the NCEP/NCAR pentad reanalysis data from 1968 to 2009, the variation characteristics of Middle East jet stream (MEJS) and its thermal mechanism during seasonal transition are studied. Results show that the intensity and south-north location of MEJS center exhibit obvious seasonal variation characteristics. When MEJS is strong, it is at 27.5°N from the 67th pentad to the 24th pentad the following year; when MEJS is weak, it is at 45°N from the 38th pentad to the 44th pentad. The first Empirical Orthogonal Function (EOF) mode of 200-hPa zonal wind field shows that MEJS is mainly over Egypt and Saudi Arabia in winter and over the eastern Black Sea and the eastern Aral Sea in summer. MEJS intensity markedly weakens in summer in comparison with that in winter. The 26th-31st pentad is the spring-summer transition of MEJS, and the 54th-61st pentad the autumn-winter transition. During the two seasonal transitions, the temporal variations of the 500-200 hPa south-north temperature difference (SNTD) well match with 200-hPa zonal wind velocity, indicating that the former leads to the latter following the principle of thermal wind. A case analysis shows that there is a close relation between the onset date of Indian summer monsoon and the transition date of MEJS seasonal transition. When the outbreak date of Indian summer monsoon is earlier than normal, MEJS moves northward earlier because the larger SNTD between 500-200 hPa moves northward earlier, with the westerly jet in the lower troposphere over 40°-90°E appearing earlier than normal, and vice versa. |
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| Keywords: | Middle East jet stream seasonal transition characteristics thermal effect onset date of Indian summer monsoon |
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