| 中国南海夏季风强、弱年多尺度相互作用能量学特征 |
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| 引用本文： | 杨悦,徐邦琪,何金海.中国南海夏季风强、弱年多尺度相互作用能量学特征[J].气象学报,2016,74(4):556-571. |
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| 作者姓名： | 杨悦 徐邦琪 何金海 |
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| 作者单位： | 南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心, 南京, 210044 |
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| 基金项目： | 国家自然科学基金（41375100）、国家重点基础研究发展计划973项目（2015CB453200）、江苏省杰出青年基金（BK20140046）、教育部科学技术研究项目（2013014A）。 |
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| 摘 要： | 中国南海夏季风为东亚季风的主要系统之一，其具有多重尺度特征，除季节平均环流场外，低频（季节内振荡）和高频（天气尺度）扰动也十分活跃，各尺度系统存在明显的年际变化。该研究使用ERA-Interim和NCEP/NCAR两套再分析资料，从季风平均动能（MKE）诊断的角度出发，探讨了1979-2010年中国南海夏季风环流年际变化的能量来源及其和扰动场的相互作用过程。结果表明:中国南海夏季风对流活跃年份，中国南海南部（12°N以南）及中南半岛一带为季风平均动能显著增强区，此与南亚季风区西风急流的增强并向东延伸有关；中国南海北部（12°N以北）及西太平洋为气旋性环流盘踞，季风槽加深。中国南海南部季风平均动能增强的能量源自于扰动动量通量与平均环流的相互作用，强季风年，平均环流失去较少的动能给扰动场（亦即平均环流保留较多的动能）。通过进一步探讨高频（<10 d）及低频（10-90 d）扰动场与平均环流不同分量的（散度、涡度、风垂直切变）相互作用过程，发现季风平均动能的增长主要来自于<10 d扰动与季风平均散度和涡度的相互作用。中国南海北部季风槽区季风平均动能的维持来自于大气热源和平均上升运动的相互作用，但同时有较多的季风平均动能向扰动动能转换，有利于扰动的成长。因此，强季风年，中国南海北部热带气旋生成数目增多，夏季北传的季节内振荡也增强，导致中国南部沿海及华南地区出现较多的灾害天气。
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| 关 键 词： | 中国南海夏季风 尺度相互作用 年际变化 动能诊断 |
| 收稿时间： | 2015/10/21 0:00:00 |
| 修稿时间： | 2016/4/26 0:00:00 |
Energetic characteristics of multi-scale interaction in the strong and weak years of South China Sea summer monsoon |
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| YANG Yue,HSU Pangchi and HE Jinhai.Energetic characteristics of multi-scale interaction in the strong and weak years of South China Sea summer monsoon[J].Acta Meteorologica Sinica,2016,74(4):556-571. |
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| Authors: | YANG Yue HSU Pangchi and HE Jinhai |
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| Institution: | Key Laboratory of Meteorological Disaster, Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEME), Nanjing University of Information Science and Technology, Nanjing 210044, China |
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| Abstract: | The South China Sea (SCS) summer monsoon is one of the major systems for the East Asian monsoon. It consists of multi-scale features. In addition to seasonal mean circulation, low-frequency (intraseasonal oscillation) and high-frequency (synoptic-scale) eddies are both active and demonstrate significant interannual variability. This study investigated the energy sources for the interannual variability of monsoon circulation and its interactions with eddies during 1979-2010 using two reanalysis datasets, i.e. the ERA-Interim and the NCEP/NCAR. Results show that during the years with enhanced convections in the SCS summer monsoon, the mean kinetic energy (MKE) strengthened over the southern SCS (south of 12°N) and Indochina. The increase in MKE is associated with the eastward extension of a strengthened westerly jet in the Indian summer monsoon region. In the northern SCS (north of 12°N) and western Pacific, an anomalous cyclonic circulation appeared, which is related to the deepening of monsoon trough. The enhanced MKE in the southern SCS is supported by interactions between eddy momentum fluxes and mean circulation. The monsoon mean flows lost less kinetic energy to eddies (i.e., mean flows retain more kinetic energy) during strong monsoon years. Interactions between the high-frequency (<10 d) and low-frequency (10-90 d) eddies with different components (divergent part, rotational part, and vertical wind shear) of mean flows were further examined. It is found that the interactions between <10 d eddies and monsoon divergent flows play a major role in producing positive MKE anomaly. The MKE in the monsoon trough over the northern SCS is maintained by the interaction between atmospheric heating and ascending motion anomaly. Meanwhile, the enhanced MKE is converted to eddy kinetic energy that is favorable for the growth of eddies. As a result, tropical cyclones and northward-propagating intraseasonal oscillation were both active over the northern SCS during strong monsoon years, which often lead to disastrous weather events in southern China. |
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| Keywords: | South China Sea summer monsoon Scale interaction Interannual variability Energetic of mean kinetic energy |
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