| 夏季海洋性大陆区域气候与赤道太平洋中部型海温异常的直接和间接联系 |
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| 引用本文： | 王悦,管兆勇,方陆俊,汪婉婷.夏季海洋性大陆区域气候与赤道太平洋中部型海温异常的直接和间接联系[J].Acta Meteorologica Sinica,2017,75(4):552-563. |
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| 作者姓名： | 王悦 管兆勇 方陆俊 汪婉婷 |
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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, 气象灾害预报预警与评估协同创新中心, 气候与环境变化国际合作联合 实验室, 南京, 210044,南京信息工程大学气象灾害教育部重点实验室, 气象灾害预报预警与评估协同创新中心, 气候与环境变化国际合作联合 实验室, 南京, 210044,杭州市气象局, 杭州, 310051,南京信息工程大学气象灾害教育部重点实验室, 气象灾害预报预警与评估协同创新中心, 气候与环境变化国际合作联合 实验室, 南京, 210044 |
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| 基金项目： | 国家自然科学基金项目（41330425、40475028）和江苏省优势学科建设项目（PAPD）。 |
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| 摘 要： | 利用1979-2015年NCEP/NCAR月平均再分析资料、美国国家海洋和大气管理局（NOAA）的月平均降水资料（CMAP）以及英国哈得来中心海表温度月平均资料，采用2009年Kao等定义的中部型ENSO指数，给出了夏季中部型海表温度（SST）异常指数，并分析了中部型ENSO和海洋性大陆（MC）区域气候的联系。结果表明，当夏季中部型海表温度正异常事件发生时，海洋性大陆核心区域（中太平洋）出现显著降水和气温负（正）异常，此时海洋性大陆核心区域有明显的负（正）热源异常，大气受冷却（加热）而下沉（上升），同时潜热释放之外的非绝热加热表现为负（正）异常，易于导致降水负（正）异常。海洋性大陆区域与中太平洋间主要通过水平环流和垂直环流建立联系。（1）中部型ENSO指数显著正异常时，在对流层低（高）层，海洋性大陆区域和中太平洋间存在由关于赤道的对称气旋性（反气旋性）环流对而形成的直接联系，并使得海洋性大陆区域东部辐散（辐合）偏弱，而海洋性大陆区域西部辐散（辐合）偏强。（2）在垂直剖面上，赤道中太平洋海表温度的正异常和海洋性大陆核心区域的大气异常冷却有利于促使该地区低层赤道西风异常增强并进而利于中部型海表温度正异常的维持，并由此通过反沃克环流圈促进海洋性大陆区域下沉运动增强。此为海洋性大陆与中太平洋间的直接联系，可由皮叶克尼斯机制进行解释。而位于中太平洋与秘鲁地区的异常垂直环流亦可用这一机制进行解释。海洋性大陆与中太平洋的间接联系主要表现在由赤道外低纬和中纬度地区均存在的沿弧形路径上的垂直环流而建立的海洋性大陆与中太平洋地区的联系上。这些弧形垂直剖面上的垂直环流不仅与局地哈得来环流有关，还与热带和中纬度的罗斯贝波动有关。这些结果有利于深刻认识中部型ENSO对海洋性大陆区域气候的影响机理以及与热带外环流异常的联系。
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| 关 键 词： | 海洋性大陆 中部型海温异常 弧形垂直环流 直接和间接联系 |
| 收稿时间： | 2016/11/11 0:00:00 |
| 修稿时间： | 2017/4/10 0:00:00 |
Relationship between the Maritime Continent climate anomalies and equatorial central Pacific SSTA during boreal summer:Direct and indirect links |
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| WANG Yue,GUAN Zhaoyong,FANG Lujun and WANG Wanting.Relationship between the Maritime Continent climate anomalies and equatorial central Pacific SSTA during boreal summer:Direct and indirect links[J].Acta Meteorologica Sinica,2017,75(4):552-563. |
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| Authors: | WANG Yue GUAN Zhaoyong FANG Lujun and WANG Wanting |
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| Institution: | Key Laboratory of Meteorological Disaster of Ministry of Education, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, International Joint Laboratory on Climate and Environment Change, Nanjing University of Information Science & Technology, Nanjing 210044, China,Key Laboratory of Meteorological Disaster of Ministry of Education, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, International Joint Laboratory on Climate and Environment Change, Nanjing University of Information Science & Technology, Nanjing 210044, China,Hangzhou Meteorological Bureau, Hangzhou 310051, China and Key Laboratory of Meteorological Disaster of Ministry of Education, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, International Joint Laboratory on Climate and Environment Change, Nanjing University of Information Science & Technology, Nanjing 210044, China |
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| Abstract: | Using the monthly mean data from NCEP/NCAR Reanalysis, the NOAA precipitation data, and the sea surface temperature from Hadley Center over the period of 1979-2015, we calculated the summer CP-type sea surface temperature anomaly (SSTA) index by employing the EOF-regression method proposed by Kao in 2009. Based on this CP-type SSTA index, we examined the relationship between CP-type ENSO and the Maritime Continent (MC) climate anomalies during boreal summer. Our results show that when positive CP-type SSTA occur in summer, there exist significantly negative (positive) precipitation and temperature anomalies in the key region of MC (central Pacific). Meanwhile, large negative (positive) heating anomalies are observed in the MC region, leading to descending (ascending) motions there. The anomalous diabatic heating other than latent heat release is also negative (positive) there, facilitating negative (positive) precipitation. The MC region and the central Pacific are linked by the horizontal and vertical circulations. When the CP-type ENSO index is significantly positive, a pair of cyclonic (anticyclone) circulations almost symmetrical about the equator are observed in the lower (upper) troposphere between MC region and the Pacific, inducing weaker than normal divergence (convergence) in the eastern part of MC region and stronger than normal divergence (convergence) in the western part of the region. Positive SSTAs in the equatorial central Pacific and atmospheric cooling anomalies in the key region of MC induce the anomalous westerly to further intensify, which in turn induces stronger warm SSTAs in central equatorial Pacific. This process can be explained by the Bjerknes mechanism and facilitates anomalous anti-Walker circulation between MC and the equatorial central Pacific, which directly links the SSTA forcing in equatorial central Pacific to climate anomalies in MC region. In the region between Peruvian coast and equatorial central Pacific, an anomalous Walker circulation is observed, which can also be explained by the Bjerknes mechanism. On the other hand, different to those direct connections mentioned above, MC and the central Pacific regions are linked indirectly by the vertical circulation along curve paths in the lower and middle latitudes outside the equatorial zone. Those vertical circulations along arc/curve paths are not only related to anomalous local Hadley circulations, but also related to the Rossby wave patterns in the tropical region and the quasi-stationary Rossby waves in the mid-latitudes. These results are helpful for better understanding how the CP-type ENSO influences not only the climate anomalies in MC region, but also circulation anomalies outside the tropical region during boreal summer. |
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| Keywords: | Maritime Continent CP-type SSTA pattern Arc-path vertical circulation Direct and indirect connections |
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