| 东亚夏季气候主要模态的年际变化及其机理 |
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| 引用本文： | 胡增臻.东亚夏季气候主要模态的年际变化及其机理[J].海洋学报,1999,21(6):26-39. |
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| 作者姓名： | 胡增臻 |
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| 作者单位： | 中国科学院大气物理研究所, 大气科学和地球流体力学数值模拟国家重点实验室, 北京100080 |
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| 基金项目： | 国家重中之重课题!“我国短期气候预测系统的研究”96－908－04－03－3，国家自然科学基金!49505069和49705045 |
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| 摘 要： | 主要研究了东亚(中国和日本)夏季气候(降水和气温)主要模态的年际变化及其机理。研究发现,中国区域夏季降水和气温的大尺度年际变化间有很强的耦合:大范围多(少)雨对应大范围低(高)温。奇异值分解的第一个模态的长期变化主要反映了长江中下游地区降水逐年增加(变湿)的趋势而气温逐年降低(变冷)的趋势。在70年代中期以后,长江中下游地区降水和气温耦合变化的准两年分量明显增强。研究表明,影响长江中下游地区夏季降水和气温年际变化的大尺度环流背景异常十分相似,即主要是两个遥相关型:太平洋-日本(PJ)型和欧亚型遥相关型。与夏季东亚梅雨异常相联系的长江中下游地区降水和气温异常是中高纬度干冷空气和低纬度暖湿空气相互作用的结果。热带西太平洋海表温度异常和相关的对流活动的年际变化通过PJ型对东亚地区夏季降水和气温的年际变化产生十分显着的影响。西太平洋对流活动与北半球大气环流遥相关的相互作用有明显的季节性。PJ型不仅是夏季西太平洋对流活动与北半球夏季热带外地区500hPa高度场年际变化耦合相互作用的最重要模态,而且也是两者各自变化的一个十分重要的模态。1984年夏季北半球500hPa位势高度主振荡型分析表明存在着能量从热带西太平洋向东亚北部的PJ型的振荡传播。低纬度的影响可传播到70°N,同时也存在能量从高纬度向低纬度的传播.即从极地传播到70°N。高纬度和低纬度的影响在70°N附近汇合。
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| 关 键 词： | 东亚夏季气候 耦合模态 准两年变化 遥相关型 |
| 收稿时间： | 1998/1/16 0:00:00 |
| 修稿时间： | 1998/11/2 0:00:00 |
Interannual variability of summer climate modeover East Asia and its mechanism |
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| Hu Zengzhen.Interannual variability of summer climate modeover East Asia and its mechanism[J].Acta Oceanologica Sinica (in Chinese),1999,21(6):26-39. |
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| Authors: | Hu Zengzhen |
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| Institution: | LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100080 |
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| Abstract: | Interannual variability of the dominated summer climate(rainfall and temperature)patterns over East Asia(China and Japan)and its mechanism are studied. It is found that there is a strong coupling between the large-scale summer rainfall and temperature variations in China on the interannual time-scale. Large-scale above (below) normal rainfall variation generally corresponds to large-scale below(above) normal temperature variation. The long-term variation of the first pattern of singulu value decomposition mainly reflects the increasing(wetting) trend of rainfall and decreasing (cooling) trend of temperature year by year over the middle reach of Chartgjiang River. The component of quasi-biennial oscillation variation is intensified after the middle of 1970s in the coupling variation of rainfall and temperature. It is noticeable that the summer rainfall variation is the exactly biennial oscillation variation in the middle reach of Changjiang River and the Great Bend of Huanghe River after the middle of 1980s. Therefore, there is a trend of time scale shortening in the interannual variation of the summer rainfall in the middle reach of Changjiang River and the Great Bend of Huanghe River. It is found that the large-scale background anomaly in affecting the rainfall and temperature anomalies along the middle and lower reaches of Changjiang River is coherent, that is,the two teleconnection pattetns:the Pacific-Japan(PJ) and Eurasia teleconnection patterns. The rainfall and temperature anomalies along the middle and lower reaches of Changjiang River,connected with the plum rain anomaly in East Asia in summer, is the result of the interaction between the cold and dry air from the temperate and high latitudes and the warm and moist air from the low latitudes. The interannual variations of sea surface temperature anomaly and the connected convective activity in the tropical western Pacific affect significantly the interannual variations of the summer rainfall and temperature in East Asia through the PI teleconnection pattern. There is obvious seasonality of the interaction between the convective activity over the western Pacific and the teleconnection patterns of the general circulation in the Northern Hemisphere (NH).The PJ pattern is not only the most important pattern in the coupled interaction between the interannual variabilities of the convection over the western Pacific and the extratropical general circulation in the NH summer, but also the dominant pattern in the variations for themselves. Through the principal oscillation pattern analysis of the 500 hPa geopotential height in the NH summer of 1984,it is indicated that the energy can propagate from the tropical western Pacific to the northern part of East Asia through the PJ-like oscillation. The impact from the low latitudes can reach 70°N. At the same time,there is also the propagation of energy from the high latitudes to the low latitudes, that is, from the North Pole to 70°N. The impacts from the low latitudes and from the high latitudes are converged around 70°N. |
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| Keywords: | Summer climate over East Asia coupled mode quasi-biennial oscillation teleconnection pattern |
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