| 基于风场季节变率的高原季风指数算法的改进及对比 |
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| 引用本文： | 张少波,吕世华,赵勇,杨显玉.基于风场季节变率的高原季风指数算法的改进及对比[J].气象学报,2019,77(2):315-326. |
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| 作者姓名： | 张少波 吕世华 赵勇 杨显玉 |
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| 作者单位： | 1.成都信息工程大学大气科学学院 高原大气与环境四川省重点实验室 气候与环境变化联合实验室, 成都, 610225 |
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| 基金项目： | 高原大气与环境四川省重点实验室开放课题（PAEKL-2018-Y2）、国家自然科学基金项目（41775016、41875102）、成都信息工程大学引进人才启动项目（KYTZ201737）。 |
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| 摘 要： | 关于青藏高原季风，现有研究分别从近地层的热低压、气旋式环流切变以及风场的涡度和散度等角度定义了高原季风指数，但现有指数均更多地关注高原空间场的对比，而没有考虑风场的冬、夏转换特征。因此，在之前的工作中，基于风场季节变率指数，从高原近地层冬、夏风场对比的角度定义了一种新的高原季风指数，这里对该指数进行改进和简化，以便于其的进一步推广。为了验证改进的效果，使用ERA-interim再分析数据计算高原季风指数，并比较了不同高原季风指数年变化和年际变化的差异及其与夏季降水相关的差异。结果表明:（1）改进后的高原季风指数物理含义清楚，弥补了原指数计算复杂的不足。（2）物理基础的差异使得新指数在8月达到峰值，不同于其他指数在6月达到峰值。整体而言，不同高原季风指数和高原降水的年变化特征均有较高的一致性。（3）新指数能够较好地表征高原季风与高原夏季降水东、西反相的相关系数分布特征，且不同于其他指数在高原一致的相关系数分布特征，对于高原地区降水，尤其是高原东南部人口相对密集地区的降水预测具有较好的指示意义。
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| 关 键 词： | 高原季风指数 夏季降水 指数对比 |
| 收稿时间： | 2018/1/29 0:00:00 |
| 修稿时间： | 2018/9/30 0:00:00 |
An improvement of the Plateau monsoon index based on seasonal variation of wind and its comparison with other indexes |
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| ZHANG Shaobo,L&#; Shihu,ZHAO Yong and YANG Xianyu.An improvement of the Plateau monsoon index based on seasonal variation of wind and its comparison with other indexes[J].Acta Meteorologica Sinica,2019,77(2):315-326. |
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| Authors: | ZHANG Shaobo L&#; Shihu ZHAO Yong and YANG Xianyu |
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| Institution: | School of Atmospheric Sciences/Plateau Atmosphere and Environment Key Laboratory of Sichuan Province/Joint Laboratory of Climate and Environment Change, Chengdu University of Information Technology, Chengdu 610225, China,School of Atmospheric Sciences/Plateau Atmosphere and Environment Key Laboratory of Sichuan Province/Joint Laboratory of Climate and Environment Change, Chengdu University of Information Technology, Chengdu 610225, China;Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China;Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044, China,School of Atmospheric Sciences/Plateau Atmosphere and Environment Key Laboratory of Sichuan Province/Joint Laboratory of Climate and Environment Change, Chengdu University of Information Technology, Chengdu 610225, China and School of Atmospheric Sciences/Plateau Atmosphere and Environment Key Laboratory of Sichuan Province/Joint Laboratory of Climate and Environment Change, Chengdu University of Information Technology, Chengdu 610225, China |
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| Abstract: | When considering the Tibetan Plateau (TP) monsoon, different TP monsoon indexes have been defined from various perspectives, such as the near surface layer thermal low, the cyclonic circulation shear, the vorticity and divergence of wind field, etc. However, these existing indexes are more concerned of the spatial contrast of the variable and have not considered the characteristics of wind field change between the summer and winter. To address this issue, a new TP monsoon index has been proposed based on seasonal variation of winds in the author''s previous work. The new index is further improved and simplified in the present paper. The ERA-interim reanalysis data is used to calculate six different TP monsoon indexes. Annual and inter-annual variations of the six indexes and their correlation coefficients with summer precipitation are compared. The results show that the algorithm for the calculation of the new TP monsoon index is simple but with clear physical meaning. Due to differences in the physics considered, the new TP monsoon index peaks in August, which is different to other indexes that peak in June. In general, characteristics of annual variations of different monsoon indexes and precipitation agree well with each other. The correlation coefficient between the new TP monsoon index and summer precipitation shows opposite signs between the western and eastern TP, while a consistent positive correlation coefficient distribution can be found on the TP between other TP monsoon indexes and summer precipitation. Above all, the new TP monsoon index shows a satisfactory result especially in the southeastern part of TP, which is a relatively densely populated area. Thereby, this new index has potential application value in the summer precipitation prediction over the TP. |
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| Keywords: | Plateau monsoon index Summer precipitation Index comparison |
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