| 印度洋偶极子中的西极子对西藏高原盛夏降水的影响 |
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| 引用本文： | 罗布,智海,索朗塔杰,胡壮.印度洋偶极子中的西极子对西藏高原盛夏降水的影响[J].干旱区地理,2020,43(4):909-919. |
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| 作者姓名： | 罗布 智海 索朗塔杰 胡壮 |
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| 作者单位： | 1.南京信息工程大学大气科学院,江苏 南京 210044;2.高原大气环境科学研究所,西藏 拉萨 850000;3.西藏那曲地区气象局,西藏 那曲 858200;4.民航西南空管局气象中心,四川 成都 610202 |
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| 基金项目： | 国家重点研发计划“重大自然灾害监测预警与防范”重点专项项目（2018YFC1506002）; 中国气象局成都高原气象研究所开放基金项目（LPM2014005）; 国家科学自然基金（41765012）资助 |
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| 摘 要： | 利用西藏高原地区1987-2016年的逐月夏季降水资料和印度洋偶极子指数资料分析了两者的关系,结果表明：高原地区盛夏降水与表征西印度洋异常海温的西极子指数表现出良好的相关关系,在西极子指数正异常年时高原降水偏多10%~30%,其中高原中部偏多最为显著,而在负异常年时与之相反。分析其机理研究发现,在正西极子异常年,南海和西太暖池区域的深对流加强、西太副高偏西偏南和印度热低压的减弱使得来自热带的水汽更容易深入高原腹地,其次,南亚高压东体异常增强,配合低空异常辐合,都使得高原降水偏多。同时,高原上空局地纬圈环流在高原中部（90 °E附近）上空（400 hPa以上）有异常辐合上升区,使得高原中部更容易发展暖湿切变线、高原低涡等中尺度涡旋低值系统,造成更多的降水。本研究从高原气候变化响应海洋年际变化的角度分析了区域降水的季节差异,可以为高原气候预测提供新的思路。
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| 关 键 词： | 西藏高原 盛夏降水 印度洋偶极子 西极子 OLR |
| 收稿时间： | 2018-10-09 |
Interannual variability of midsummer precipitation over Tibet Plateau associated with the western pole of Indian Ocean Dipole |
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| LUO Bu,ZHI Hai,SUO LangTaJie,HU Zhuang.Interannual variability of midsummer precipitation over Tibet Plateau associated with the western pole of Indian Ocean Dipole[J].Arid Land Geography,2020,43(4):909-919. |
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| Authors: | LUO Bu ZHI Hai SUO LangTaJie HU Zhuang |
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| Institution: | 1.Academy of Atmospheric Sciences of Nanjing University of Information Science and Technology,Nanjing 210044,Jiangsu,China;2.Tibet Institute of Plateau Atmospheric and Environmental Science,Lhasa 850000,Tibet,China;3.Naqu Meteorological Bureau,Naqu 858200,Tibet,China;4.Civil Aviation Southwest Air Traffic Control Bureau Meteorological Center,Chengdou 610202,Sichuan,China |
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| Abstract: | This paper mainly focuses on the relationship between the interannual variation of the seasonal precipitation over the Tibetan Plateau. Based on the observed precipitation between 1987 and 2016,it was found that the western pole of the Indian Ocean dipole （IOD_w） was significantly related with the summer precipitation over the Tibet Autonomous Region,China. In the positive （negative） IOD_w anomaly year,the midsummer precipitation was generally higher （lower） by 10%–30%,being even 40% higher （lower） in the central part of the Tibet Autonomous Region. By analyzing the characteristics of the synthesized circulation and water vapor transmission fields,we found that in the positive （negative） IOD_w years the western Pacific subtropical high was shifted westward （eastward） and southward （northward）,while the Indian cyclone was weaker （stronger） than usual,and reached the Tibetan Plateau. Meanwhile,the amount of water vapor coming from the Bay of Bengal and the South China Sea was abnormally high （low）,there was an anomalous increase （decrease） of the eastern high of the SAH,and an anomalous convergence of the 500 hPa was noted at low altitudes. This resulted in an overall higher （lower） precipitation over the plateau. Moreover,an analysis of the latitudinal circulation over the plateau demonstrated the occurrence of an anomalous convergence and upsurge above 400 hPa over the central part of the plateau （near 90°E）. In this context,warm-wet shear lines,plateau vortexes,and other local convective weather （do not） easily develop over the central part of the plateau,leading to more （less） precipitation. The OLR field confirmed the above conclusions. |
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| Keywords: | Tibet Plateau midsummer precipitation Indian Ocean Dipole western pole OLR |
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