王悦,管兆勇,方陆俊,汪婉婷. 2017. 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]. 气象学报, ():-, doi:10.11676/qxxb2017.044
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
Relationships between the Maritime Continent climate and equatorial central Pacific SSTA during boreal summer: direct and indirect links
投稿时间:2016-10-28  最后修改时间:2017-01-19
DOI:10.11676/qxxb2017.044
中文关键词:  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
英文关键词:Key Words the Maritime Continent, CP-type SSTA pattern, arc-path vertical circulation, direct and indirect connections
基金项目::国家自然科学基金资助项目(43130425,40475028)和江苏省优势学科建设项目(PAPD)
作者单位E-mail
王悦 南京信息工程大学 709612202@qq.com 
管兆勇 南京信息工程大学 guanzy@nuist.edu.cn 
方陆俊 杭州市气象局 610552890@qq.com 
汪婉婷 南京信息工程大学 wangwanting1992@126.com 
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中文摘要:
      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)以及英国哈德莱中心海表温度月平均资料,采用Kao定义CP型ENSO指数的方法(2009),给出了夏季CP型海温(SST)异常指数,并分析了中部型ENSO和海洋性大陆区域(MC)气候的联系。结果表明,当夏季CP型SST正异常事件发生时,MC的核心区域(中太平洋)区域出现显著降水和气温负(正)异常,此时MC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。MC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,MC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MC区域东部辐散(辐合)偏弱,而MC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MC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CP型SST正异常的维持,并由此通过反Walker环流圈促进MC区域下沉运动增强。此为MC与中太平洋间的直接联系,可由Bjerkness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。MC与中太平洋间的间接联系主要表现在由赤道外低纬和中纬地区均存在的沿弧形路径上的垂直环流而建立的MC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Hadley环流有关,还与热带和中纬度的Rossby波动有关。这些结果有利于人们深刻认识CP型ENSO对MC地区气候的影响机理以及与热带外环流异常的联系。
英文摘要:
      Abstract:[Data]Using the monthly mean data from NCEP/NCAR Reanalysis, the NOAA precipitation data, and the sea surface temperature from Hadley Center over period of 1979-2015,[Method and objective]we have calculated the summer CP-type sea surface temperature anomaly (SSTA) index by employing the EOF-regression method proposed by Kao (2009). Based on this CP-type SSTA index, we have examined the relationships between CP-type ENSO and the Maritime Continent climate anomalies during boreal summer, and investigated how the equatorial Pacific SSTA forcing links to the climate in MC.[Results and conclusion]Our results show that when positive CP-type SSTA events occur in summer, there is significantly negative (positive) precipitation and temperature anomalies in the key region of MC (Pacific). Meanwhile, in the part of MC region, large negative (positive) heating anomalies are observed, which drives the atmosphere to descend (ascend) there. The anomalous diabatic heating free of latent heat release is also negative (positive) there, thereby facilitating the 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 are observed almost symmetrical about the equator in the lower (upper) troposphere between MC region and the Pacific, inducing the divergence (convergence) to be weaker in the eastern part of MC region and stronger in the western part of the region. The positive SSTA in equatorial central Pacific and atmospheric cooling anomalous in the key region of MC induce the anomalous westerly to be intensified, which in turn induces the SSTA in central equatorial Pacific to be warmer. This process explained by the Bjerkness mechanism facilitates an anomalous anti-Walker circulation between MC and equatorial central Pacific, which directly links the SSTA forcing in equatorial central Pacific to climate anomalies in MC region. In region between Peruvian coast and equatorial central Pacific, an anomalous Walker circulation is observed, which can also be explained by the Bjerkness mechanism. On the other hand, different from those direct connections as mentioned above, MC and the central Pacific regions are linked indirectly by vertical circulation along curve paths in the lower and middle latitudes outside 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 tropical region and the quasi-stationary Rossby waves in mid-latitudes. [Implication] These results are helpful for our better understanding how the CP-type ENSO influences not only the climate anomalies in MC region but also the circulation anomalies outside tropical region during boreal summer.
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