汪婉婷,管兆勇. 2018. 夏季厄尔尼诺-Modoki和东部型ENSO海表温度异常分布型特征及其与海洋性大陆区域气候异常的联系[J]. 气象学报, 76(1):1-14, doi:10.11676/qxxb2017.081
夏季厄尔尼诺-Modoki和东部型ENSO海表温度异常分布型特征及其与海洋性大陆区域气候异常的联系
The SSTA patterns of El Nio-Modoki and eastern Pacific ENSO and their associations with regional climate variation in the Maritime Continent during boreal summer
投稿时间:2017-02-15  修订日期:2017-07-24
DOI:10.11676/qxxb2017.081
中文关键词:  北半球夏季  太平洋海表温度异常  海洋性大陆地区  气候异常
英文关键词:Boreal summer  Pacific sea surface temperature anomalies  The Maritime Continent  Climate anomalies
基金项目:国家自然科学基金资助项目(41330425、40475028)和江苏省优势学科建设项目(PAPD)。
作者单位E-mail
汪婉婷 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
海南省气象服务中心, 海口, 570203 
 
管兆勇 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 guanzy@nuist.edu.cn 
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中文摘要:
      2007年,Ashok等揭示了赤道太平洋区域存在一种三极型分布海表温度异常并称之为厄尔尼诺-Modoki,同时定义了相应的海表温度异常指数EMI(记为IEM)。在此基础上,利用英国哈得来中心逐月海表温度资料、美国NCEP/NCAR月平均再分析数据集、美国国家海洋和大气管理局(NOAA)逐月降水资料(CMAP),通过在太平洋海表温度异常中扣除厄尔尼诺-Modoki信号后,在Nino1+2区域上定义了东太平洋型海表温度异常指数EPNI(IEPN)。据此,由IEPN和IEM可构成描述热带太平洋海表温度异常变化的一对指数。分析了两个指数相应的海气状态及对海洋性大陆区域气候异常的影响。结果表明,厄尔尼诺-Modoki和东太平洋型海表温度异常及其影响存在显著差异。在北半球夏季,当IEM处于正位相时,热带太平洋海表温度异常呈现“负-正-负”的结构,海洋性大陆大部分区域海表温度异常为负,此时对流层低层太平洋地区辐合,海洋性大陆地区辐散,对流层高层太平洋地区辐散,海洋性大陆地区辐合。对应于辐合辐散中心,存在着自赤道中太平洋分别向赤道东太平洋和海洋性大陆中东部地区的异常垂直环流圈,同时也存在自海洋性大陆西部向印度洋西部的垂直环流。大气在海洋性大陆区域北部加热,南部冷却;在太平洋地区西部加热而东部冷却;在海洋性大陆区域10°N以南降水偏少,而10°N以北降水偏多。当IEPN处于正位相时,热带太平洋海表温度异常呈现“西负东正”分布型,海洋性大陆区域海表温度异常呈现“西正东负”分布,对流层低层海洋性大陆地区辐散中心范围偏大、位置偏东、强度偏强,太平洋地区辐合中心范围偏小、位置偏东,热带环流异常在垂直方向上呈斜压结构,海洋性大陆区域北部大气加热而南部冷却,太平洋地区大气均呈加热正异常,海洋性大陆大部分区域降水均偏少,赤道太平洋降水偏多。以上这些结果有利于深刻理解热带太平洋海表温度异常的特征及其对海洋性大陆区域气候的影响。
英文摘要:
      In 2007, Ashok et al revealed a type of tripole pattern sea surface temperature anomalies (SSTA) in the equatorial Pacific region, known as El Nio-Modoki (EM), and defined the corresponding index EMI of SSTA. On this basis, using the monthly mean sea surface temperature (SST) data from Hadley Centre, the NCEP/NCAR monthly reanalysis, the monthly precipitation, and removing El Nio-Modoki (IEM) from SSTA, we have defined another SSTA index, i.e., EPNI (IEPN), over Nino1+2 to describe the eastern Pacific SSTA events. Using these two indices, IEPN and IEM, a pair of variations of SST anomalies and their influences on climate anomalies over the Maritime Continent (MC) in the tropical Pacific Ocean are investigated. Our results have demonstrated that in boreal summer, when IEM is in its positive phase, the tropical Pacific SSTA show a structure of "negative-positive-negative". Negative SSTAs are observed in most of the MC region. The anomalous convergence in the lower troposphere and anomalous divergence in the upper troposphere are observed in the central Pacific while the anomalous divergence in the lower troposphere and anomalous convergence in the upper troposphere are observed in MC region. Corresponding to the convergence and divergence centers, there are two zonal-vertical circulations from central equatorial Pacific to eastern equatorial Pacific and to central and eastern parts of MC, respectively. A vertical circulation is also observed from western part of MC to western part of India Ocean at the same time. The atmosphere above MC is adiabatically heated in the north and cooled in the south, while it is heated in the west and cooled in the east of the Pacific Ocean. Precipitation in the area south of 10°N is significantly less than normal, whereas it is more than normal in area north of 10°N in the MC region. When IEPN is in its positive phase, the tropical Pacific SSTAs show a distribution of "negative in the west and positive in the east", whereas SSTAs in MC region are "positive in the west and negative in the east". In the lower troposphere, the anomalous divergence center is over MC region and the convergence center is over the equatorial eastern Pacific. The anomalous circulation in the tropical region is baroclinic in vertical and the Walker circulation is anomalously weakened. The atmosphere in MC is also heated adiabatically in the north and cooled in the south while the atmosphere in Pacific is heated in most of the tropical region. Precipitation is less than normal in most part of MC and higher than normal in the equatorial Pacific. These results are helpful for us to better understand the variation features of the tropical Pacific SSTA and their impacts on MC region.
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