| 秋季热带印度洋偶极子年际振荡对长江上游径流量多寡的影响分析 |
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| 引用本文： | 庞轶舒,秦宁生,罗玉,王春学,周斌.秋季热带印度洋偶极子年际振荡对长江上游径流量多寡的影响分析[J].高原气象,2021(2):353-366. |
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| 作者姓名： | 庞轶舒 秦宁生 罗玉 王春学 周斌 |
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| 作者单位： | 中国气象局成都高原气象研究所/高原与盆地暴雨旱涝灾害四川省重点实验室;四川省气候中心 |
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| 基金项目： | 国家自然科学基金项目(41772173);中国气象局成都高原气象研究所创新团队项目(BROP202043);中国气象局气候变化专项(CCSF202034);四川省科技计划项目(2019YJ0620);高原与盆地暴雨旱涝灾害四川省重点实验室科技发展基金项目省重点实验室项目(2018-青年-06)。 |
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| 摘 要： | 利用年际增量、小波分析和回归分析等方法深入分析了秋季热带印度洋偶极子(Tropical Indian Ocean Dipole,TIOD)年际振荡对次年长江上游年径流量的影响特征及其物理机理。结果表明,长江上游年径流量和秋季TIOD均具有显著的年际振荡特征,在20世纪80年代以前和90年代之后尤为明显。两者的滞后相关系数为0.42,通过了99.9%的显著性检验,即秋季TIOD较前一年增强(减弱),有利于次年长江上游径流量较前一年偏多(少)。秋季TIOD对次年长江上游年径流量多寡的影响,是通过调制降水,尤其是夏季降水来实现的。当秋季TIOD增强时,赤道印度洋海温呈东西"-+"分布,其中偏暖区延伸至南北纬20°,偏冷区与西太平洋的偏冷区相通。赤道印度洋至西太平洋上空激发出增强的Walker型环流,中心位于印度洋正上方。随着时间的发展,暖性Kelvin波产生并向东传播,印度洋偏暖区以及冷暖海温差异中心东移。至次年夏季,西印度洋暖海温中心移动至东印度洋边缘至南海区域,偏冷海区东退至日界线附近。印度洋上空增强的Walker型环流消失,高层转为偏东气流与105°E附近加强爬升的气流相连。与此同时,105°E以东的Walker环流加强,高层为西风,400 hPa以下为深厚的东风区。高低空环流相互耦合并配合科氏力的影响,赤道以北副热带地区负涡度增强,西太平洋副热带高压偏大偏强,异常反气旋北扩,系统外围的西南气流加强南海和孟湾水汽的输送,使得次年夏季长江上游全流域处于水汽辐合上升区,降水显著偏多,从而影响了长江上游年径流量的多寡。
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| 关 键 词： | 印度洋偶极子 长江上游 年径流量 年际增量 |
Analysis on Effect of Tropical Indian Ocean Dipole Inter-Annual Oscillation on Annual Variation of Runoff in the Upper Reaches of Yangtze River |
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| PANG Yishu,QIN Ningsheng,LUO Yu,WANG Chunxue,ZHOU Bin.Analysis on Effect of Tropical Indian Ocean Dipole Inter-Annual Oscillation on Annual Variation of Runoff in the Upper Reaches of Yangtze River[J].Plateau Meteorology,2021(2):353-366. |
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| Authors: | PANG Yishu QIN Ningsheng LUO Yu WANG Chunxue ZHOU Bin |
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| Institution: | (Institute of Plateau Meteorology,China Meteorological Administration,Chengdu/Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province,Chengdu 610072,Sichuan,China;Sichuan Climate Center,Chengdu 610072,Sichuan,China) |
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| Abstract: | In this paper,the influence of Tropical Indian Ocean Dipole(TIOD)oscillation in autumn on the annual runoff in the upper reaches of the Yangtze river in the following year and the corresponding physical mechanism were analyzed by means of interannual increment,wavelet analysis and regression analysis. The results show that both the autumn TIOD and annual runoff of the upper Yangtze River have significant interannual oscillation characteristics,especially before the 1980 s and after the 1990 s. Their hysteresis correlation coefficient is0. 42,passing the significance test of 99. 9%. In other words,autumn TIOD was strengthened(weakened)compared with the previous year,which is conducive to the increase(decrease)of runoff in the upper reaches of the Yangtze river in the next year. Such a relationship can be realized through the modulation of autumn TIOD on precipitation,especially the summer precipitation. When TIOD is strengthened in autumn,the SST of the equatorial Indian Ocean shows an east-west "-+" distribution,in which the warmer zone extends to 20°N/S,and the colder zone stretches to the western Pacific Ocean. An enhanced Walker circulation is stimulated over the equatorial Indian Ocean to the western Pacific Ocean,centered directly over the Indian Ocean. With the development of time,the warm Kelvin wave generates and propagates to the east,and the center of the warm and cold sea temperature difference in the Indian Ocean moves to the east. In the following summer,the warm SST center of the western Indian Ocean moves to the edge of the eastern Indian Ocean to the South China Sea,while the cold area retreats to date line. The enhanced Walker circulation over Indian Ocean disappeared while the westerly of its upper layer turns to easterly and links to enhanced climbing airflow near 105°E. At the same time,the Walker Cell over the east of 105°E is strengthened,of which the upper level is westerly and the region below 400 hPa is easterly airflow. With the Coupling of high-and low-level circulation and cooperation with the Coriolis force,the negative vorticity increases in the subtropical zone of Northern Hemisphere,which lead to a larger and stronger West Pacific Subtropical High and northward expansion of corresponding anomalous anticyclone accordingly.Southwest airflow around this circulation system strengthens the water vapor transportation from the South China Sea and Bay of Bengal to the whole upper reaches of the Yangtze River in summer. Water vapor convergence rises and the precipitation significantly is more,which affects the variation of annual runoff in the upper reaches of the Yangtze River. |
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| Keywords: | Tropical Indian Ocean Dipole the upper Yangtze River annual runoff annual increment |
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