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| THE RELATIONSHIP OF THE PRECEDING WINTER MJO ACTIVITIES AND THE SUMMER PRECIPITATION IN YANGTZE-HUAIHE RIVER BASIN OF CHINA | |
| 作者姓名： | 李汀 琚建华 甘薇薇 |
| 作者单位： | College of Resource and Environment and Earth Science, Yunnan University, Kunming 650031 China;;Yunnan Meteorological Administration, Kuming 650034 China;;Sichuan Meteorological Administration, Chengdu 610072 China |
| 基金项目： | Joint Project of Natural Science Foundation of China and Yunnan Province (U0833602) |
| 摘 要： | The first two series(RMM1 and RMM2) of RMM Index(all-Season Real-time Multivariate MJO Index) are computed to obtain the interannual variation of the preceding winter(preceding December to current February) MJO strength,according to which active(or inactive) years of preceding winter MJO are divided.By utilizing the data provided by NCEP/NCAR,CMAP and China’s 160 stations from 1979 to 2008,we studied the preceding winter MJO strength and discovered that the summer precipitation in the basin are of significantly negative correlation,i.e.when the preceding winter MJO is relatively active,the summer precipitation in the basin decreases,and vise verse.We also analyzed the causes.When the preceding winter MJO is relatively active,its release of potential heat facilities Inter-Tropical Convergence Zone(ITCZ) to strengthen and locate northward in winter and propagate northeastward.This abnormal situation lasts from winter to summer.In mid-May,ITCZ jumps northward to the South China Sea,the western Pacific subtropical high withdraws eastward,and the South China Sea summer monsoon sets off and strengthens.In summer,ITCZ propagates to South China Sea-subtropical western Pacific,the zonal circulation of subtropical Pacific strengthens,and a local meridional circulation of the South China Sea to the basin area forms,giving rise to the East Asia Pacific teleconnection wave-train.An East Asian monsoon trough and the Meiyu front show opposite features from south to north,the East Asian summer monsoon strengthens and advances northward.As a result,the summer monsoon is weakened as the basin is controlled by the subtropical high continually,with less rain in summer.On the contrary,when the preceding winter MJO is inactive,ITCZ weakens and is located southward,the subtropical high is located southward in summer,and the basin is in a region of ascending airflow with prevailing southwest wind.The East Asian monsoon trough and EASM weaken so that summer monsoon is reduced in the basin where precipitation increases. |
| 关 键 词： | winter MJO summer precipitation in the basin ITCZ East Asia wave train East Asian Summer Monsoon |
| 收稿时间： | 1/5/2011 12:00:00 AM |
| 修稿时间： | 2011/12/19 0:00:00 |
THE RELATIONSHIP OF THE PRECEDING WINTER MJO ACTIVITIES AND THE SUMMER PRECIPITATION IN YANGTZE-HUAIHE RIVER BASIN OF CHINA |
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| LI Ting,JU Jian-hua and GAN Wei-wei.THE RELATIONSHIP OF THE PRECEDING WINTER MJO ACTIVITIES AND THE SUMMER PRECIPITATION IN YANGTZE-HUAIHE RIVER BASIN OF CHINA[J].Journal of Tropical Meteorology,2012,18(1):32-44. | |
| Authors: | LI Ting JU Jian-hua and GAN Wei-wei |
| Institution: | 1. College of Resource and Environment and Earth Science, Yunnan University, Kunming 650031 China 2. Yunnan Meteorological Administration, Kuming 650034 China 3. Sichuan Meteorological Administration,Chengdu 610072 China |
| Abstract: | The first two series (RMM1 and RMM2) of RMM Index (all-Season Real-time Multivariate MJO Index) are computed to obtain the interannual variation of the preceding winter (preceding December to current February) MJO strength, according to which active (or inactive) years of preceding winter MJO are divided. By utilizing the data provided by NCEP/NCAR, CMAP and China's 160 stations from 1979 to 2008, we studied the preceding winter MJO strength and discovered that the summer precipitation in the basin are of significantly negative correlation, i.e. when the preceding winter MJO is relatively active, the summer precipitation in the basin decreases, and vise verse. We also analyzed the causes. When the preceding winter MJO is relatively active, its release of potential heat facilities Inter-Tropical Convergence Zone (ITCZ) to strengthen and locate northward in winter and propagate northeastward. This abnormal situation lasts from winter to summer. In mid-May, ITCZ jumps northward to the South China Sea, the western Pacific subtropical high withdraws eastward, and the South China Sea summer monsoon sets off and strengthens. In summer, ITCZ propagates to South China Sea-subtropical western Pacific, the zonal circulation of subtropical Pacific strengthens, and a local meridional circulation of the South China Sea to the basin area forms, giving rise to the East Asia Pacific teleconnection wave-train. An East Asian monsoon trough and the Meiyu front show opposite features from south to north, the East Asian summer monsoon strengthens and advances northward. As a result, the summer monsoon is weakened as the basin is controlled by the subtropical high continually, with less rain in summer. On the contrary, when the preceding winter MJO is inactive, ITCZ weakens and is located southward, the subtropical high is located southward in summer, and the basin is in a region of ascending airflow with prevailing southwest wind. The East Asian monsoon trough and EASM weaken so that summer monsoon is reduced in the basin where precipitation increases. |
| Keywords: | winter MJO summer precipitation in the basin ITCZ East Asia wave train East Asian Summer Monsoon |
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