| 梅雨期高位涡源区及其传播过程 |
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| 引用本文： | 赵亮,丁一汇.梅雨期高位涡源区及其传播过程[J].应用气象学报,2008,19(6):697-709. |
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| 作者姓名： | 赵亮 丁一汇 |
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| 作者单位： | 1.中国气象科学研究院, 北京 100081 |
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| 基金项目： | 科技部国际合作项目"区域气候变化的监测、模拟和影响研究"
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国家重点基础研究发展计划项目
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"十一五"国家科技支撑项目
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| 摘 要： | 分析了气候平均意义下梅雨前期及期间东亚地区等熵位涡（isentropic potential vorticity，简称IPV）的源区和演变过程。结果表明:梅雨发生前，东亚地区对流层高层经向位涡梯度减弱，而后这里的IPV开始向南延伸出高值带，形成“舌区”。同期对流层低层，经向位涡梯度出现反向，与南边位涡梯度大值带形成经向偶极子型并伴随梅雨发生发展。梅雨期40°N，120°E附近对流层顶折叠处有明显的位涡输送和质量交换。用10~90 d带通滤波和超前相关追踪IPV异常源区和传播路径发现，345 K的IPV异常场和梅雨期前后降水异常的相关系数最大值出现在前者超前后者10 d左右，位置在贝加尔湖东侧，这里是影响梅雨期降水的位涡源区。其向南输送高位涡空气主要在梅雨发生前的6月10日左右，高位涡异常空气沿2 PVU等位涡面以东北—西南路径向南输送，在2 PVU面最陡峭处堆积，然后穿越物质面快速下沉侵入40°N以南，并在对流层呈扇状铺开。因而，贝加尔湖东侧可能是影响梅雨的主要冷空气源区，是梅雨降水中期预报的一个关键区。
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| 关 键 词： | 等熵位涡 梅雨 超前相关 位涡源区 |
| 收稿时间： | 2008-02-18 |
Sources and Transfer of High Isentropic Potential Vorticity During Meiyu Period |
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| Zhao Liang and Ding Yihui.Sources and Transfer of High Isentropic Potential Vorticity During Meiyu Period[J].Quarterly Journal of Applied Meteorology,2008,19(6):697-709. |
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| Authors: | Zhao Liang and Ding Yihui |
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| Institution: | 1.Chinese Academy of Meteorological Sciences, Beijing 1000812.Nanjing University of Information Science & Technology, Nanjing 2100443.The Second Artillery 96162 Corps Meteorological Observatory, PLA, Ganzhou 3410004.National Climate Center, Beijing 100081 |
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| Abstract: | The climatological mean sources and evolutions of isentropic potential vorticity(IPV)during Meiyu period are studied. Compared to the factors in the isobaric coordinate system during the Meiyu period, potential vorticity on the isentropic surface shows clearer "trough" and "ridge", and it is found that there are two high IPV "tongue" areas near the east of Lake Baikal and the southeast of Karafuto in the lower troposphere during the Meiyu period. And pentad IPV evolutions show that the regions where the meridional IPV gradient(MIPVG)weakens in the upper troposphere could be the entrance of high IPV air invading. Before the Meiyu rainy season the MIPVG obviously weakens in upper troposphere over East Asia, then high IPV contours begin to extend equatorward forming "tongue" area. Simultaneously, in lower troposphere MIPVG appears to reverse, shaping local north south dipole between low and high MIPVG. Evident potential vorticity transports and mass exchanges exist at tropopause near 40°N, 120°E during Meiyu period where the tropopause easily folds. By using 10—90 day bandpass and lead/lag correlation analysis, the sources and paths of high IPV anomalies are further investigated and traced. The results show that high IPV anomalies originate from the lower stratosphere and upper troposphere of the high latitude, and the maximum correlation coefficients between IPV anomalies and rainfall anomaly on 345 K isentropic surface before, during and after Meiyu period appear when the former leads the latter by about 10 days, near 55°N, 130°E in the east of Lake Baikal which is an important source of high IPV influencing the rainfall during Meiyu period. On June 10 before Meiyu, the high IPV air is transferred primarily southward along the NE—SW direction at 2 PVU surface from the high IPV source and accumulates near the steepest areas of this surface, developing upward, then crosses downward to the tropopause, and partly invades the south of 40°N when the IPV anomalies fields are typical longitudinal mode. However, in the troposphere it becomes a distribution of latitudinal mode spreading out like a fan. On 315 K isentropic surface, high IPV anomalies invade later than those in the upper troposphere, and are also transferred southward along the NE—SW direction from the high IPV source region near 45°N in the lower troposphere to the Meiyu areas since about June 18. As a result, the region on the east of Lake Baikal is possibly a main source area of cold air influencing Meiyu and key region to make the medium term forecast of Meiyu precipitation. |
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| Keywords: | isentropic potential vorticity Meiyu lead correlation IPV source |
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