利用JRA55大气再分析资料和TRMM卫星降水资料,分析了2002年夏季(5~8月)华南地区降水的低频振荡特征,重点揭示了对其影响显著的中高纬大气季节内振荡的环流结构及演变。小波和功率谱分析表明,2002年夏季华南降水表现为主周期为10~30 d的...利用JRA55大气再分析资料和TRMM卫星降水资料,分析了2002年夏季(5~8月)华南地区降水的低频振荡特征,重点揭示了对其影响显著的中高纬大气季节内振荡的环流结构及演变。小波和功率谱分析表明,2002年夏季华南降水表现为主周期为10~30 d的准双周低频振荡。典型低频降水事件及合成分析指出,准双周降水的强(弱)变化除了受低空西北太平洋副热带高压西伸进入(东移退出)南海的影响以外,还显著地依赖于中高纬地区高空大气环流的季节内振荡。在对流层高层,中高纬度地区存在一支自大西洋经欧亚大陆的气旋—反气旋相间排列的低频波列。该波列在欧亚大陆地区向东南传播,当异常反气旋和气旋分别位于青藏高原和华北上空时,这种偶极型环流之间的高空辐散场有利于华南地区上升运动的发展,因而华南降水偏强;反之,华南降水偏弱。研究还表明,低频波列南移造成了对流层异常温度平流和副热带高层异常绝对涡度的变化,使得华南地区上升与下沉运动交替出现以及相应的经向环流圈反转,从而导致华南准双周振荡干湿位相的转换。局地异常感热加热对干湿位相转换也起一定作用。时滞相关分析发现,当青藏高原地区500 h Pa位势高度异常场超前于华南异常降水4 d(即位相差为1/4周期)时,二者出现显著正相关,表明青藏高原地区500 h Pa位势高度异常对预测华南地区季节内降水变化有潜在的应用价值。展开更多
In this paper, we discussed the features of atmospheric circulations over Eurasia as a response to sea surface temperature anomalies （SSTAs） over the tropical Indian Ocean, the equatorial Pacific, Kuroshio and the N...In this paper, we discussed the features of atmospheric circulations over Eurasia as a response to sea surface temperature anomalies （SSTAs） over the tropical Indian Ocean, the equatorial Pacific, Kuroshio and the North Atlantic. Our results are shown as follows： （1） CAM3.0, driven by the combined SSTAs over the four oceanic regions, can simulate well the features of anomalous atmospheric circulations over Eurasia in January 2008, indicating that the effects of the SSTAs over these four regions were one of the key causes of the anomalous systems over Eurasia. （2） The SSTAs over each key region contributed to the intensification of blocking over the Urals Mountains and a main East Asian trough. However, the influence of the SSTAs over individual oceanic regions differed from one another in other aspects. The SSTAs over the North Atlantic had an impact on the 500-hPa anomalous height （Z500A） over the middle-high latitudes and had a somewhat smaller effect over the low latitudes. For the warm SSTAs over Kuroshio, the subtropical high was much stronger, spread farther north than usual, and had an anomalous easterly that dominated the northwest Pacific Ocean. The warm SSTAs over the tropical Indian Ocean could have caused a negative Z500A from West Asia to Middle Asia, a remarkably anomalous southwesterly from the Indian Ocean to the south of China and an anomalous anticyclone circulation over the South China Sea-Philippine Sea region. Because of the La Nifia event, the winter monsoon was stronger than normal, with an anomalously cooler northerly over the southeastern coastal areas of China. （3） The combined effects of the SSTAs over the four key regions were likely more important to the atmospheric circulation anomalies of January 2008 over Eurasia than the effects of individual or partly combined SSTAS. This unique SSTA distribution possibly led to the circulation anomalies over Eurasia in January 2008, especially the atmospheric circulation anomalies over the subtropics, which were more similar to those of the winter E1 Nifio events than to the circulation anomalies following La Nifia.展开更多
文摘利用JRA55大气再分析资料和TRMM卫星降水资料,分析了2002年夏季(5~8月)华南地区降水的低频振荡特征,重点揭示了对其影响显著的中高纬大气季节内振荡的环流结构及演变。小波和功率谱分析表明,2002年夏季华南降水表现为主周期为10~30 d的准双周低频振荡。典型低频降水事件及合成分析指出,准双周降水的强(弱)变化除了受低空西北太平洋副热带高压西伸进入(东移退出)南海的影响以外,还显著地依赖于中高纬地区高空大气环流的季节内振荡。在对流层高层,中高纬度地区存在一支自大西洋经欧亚大陆的气旋—反气旋相间排列的低频波列。该波列在欧亚大陆地区向东南传播,当异常反气旋和气旋分别位于青藏高原和华北上空时,这种偶极型环流之间的高空辐散场有利于华南地区上升运动的发展,因而华南降水偏强;反之,华南降水偏弱。研究还表明,低频波列南移造成了对流层异常温度平流和副热带高层异常绝对涡度的变化,使得华南地区上升与下沉运动交替出现以及相应的经向环流圈反转,从而导致华南准双周振荡干湿位相的转换。局地异常感热加热对干湿位相转换也起一定作用。时滞相关分析发现,当青藏高原地区500 h Pa位势高度异常场超前于华南异常降水4 d(即位相差为1/4周期)时,二者出现显著正相关,表明青藏高原地区500 h Pa位势高度异常对预测华南地区季节内降水变化有潜在的应用价值。
基金Special Funds for Public Welfare of China (GYHY(QX) 2008-06-005)Science and Technology Innovation Program of Jiangsu Province (CX09B_221Z)
文摘In this paper, we discussed the features of atmospheric circulations over Eurasia as a response to sea surface temperature anomalies （SSTAs） over the tropical Indian Ocean, the equatorial Pacific, Kuroshio and the North Atlantic. Our results are shown as follows： （1） CAM3.0, driven by the combined SSTAs over the four oceanic regions, can simulate well the features of anomalous atmospheric circulations over Eurasia in January 2008, indicating that the effects of the SSTAs over these four regions were one of the key causes of the anomalous systems over Eurasia. （2） The SSTAs over each key region contributed to the intensification of blocking over the Urals Mountains and a main East Asian trough. However, the influence of the SSTAs over individual oceanic regions differed from one another in other aspects. The SSTAs over the North Atlantic had an impact on the 500-hPa anomalous height （Z500A） over the middle-high latitudes and had a somewhat smaller effect over the low latitudes. For the warm SSTAs over Kuroshio, the subtropical high was much stronger, spread farther north than usual, and had an anomalous easterly that dominated the northwest Pacific Ocean. The warm SSTAs over the tropical Indian Ocean could have caused a negative Z500A from West Asia to Middle Asia, a remarkably anomalous southwesterly from the Indian Ocean to the south of China and an anomalous anticyclone circulation over the South China Sea-Philippine Sea region. Because of the La Nifia event, the winter monsoon was stronger than normal, with an anomalously cooler northerly over the southeastern coastal areas of China. （3） The combined effects of the SSTAs over the four key regions were likely more important to the atmospheric circulation anomalies of January 2008 over Eurasia than the effects of individual or partly combined SSTAS. This unique SSTA distribution possibly led to the circulation anomalies over Eurasia in January 2008, especially the atmospheric circulation anomalies over the subtropics, which were more similar to those of the winter E1 Nifio events than to the circulation anomalies following La Nifia.
