热带太平洋海温变率模态的结构特征分析
发布时间：2019-04-08 10:50
【摘要】：本文针对去趋势的Hadley中心1958-2008年月平均海温数据,采用季节联合正交经验分解(SEOF)的分析方法,揭示了热带太平洋海温异常变率的两个主要季节演变模态。SEOF-1为年际变率模态,主周期为3年和5年,反映了传统的ENSO模态,与全球海洋、表现热通量、大气环流及降水异常都具有明显的遥相关,全球性影响显著。SEOF-2为年代际变率模态,主周期为10-12年,包含有赤道中太平洋和副热带东北太平洋两个不同步的暖异常中心、以及东太平洋的冷异常中心。该年代际变率模态的全球遥相关分布具有明显的局地性特征,主要集中于热带及北太平洋区域。本文较为细致地分析了模态的结构特征及各部分之间的关系。研究发现：副热带东北太平洋暖异常中心海温距平计算的指数、及由赤道纬向反位相的冷暖异常差值计算的指数都与SEOF-2模态时间序列的相关性较高,同时与ENSO相对独立,但两指数之间相关性非常弱,具有一定的独立性；两个指数都具有一定的稳定性,即ENSO信号存在与否不影响指数本身的变化规律,也不影响两指数之间及与SEOF-2时间序列的相关关系；另外,两个指数各自能够单独回归出SEOF-2模态中的一部分海温异常形态,副热带东北太平洋海温异常指数能回归得到该模态中大部分的暖异常,尤其是赤道中太平洋及副热带东北太平洋的两个暖中心十分明显,赤道纬向反位相结构海温异常指数则能回归得到该模态中赤道纬向反位相变化部分,尤其是东太平洋冷异常明显,而且两指数回归的海温异常的合成与原模态十分相近,说明该模态很有可能是两种具有不同性质的海温异常模态的合成或者伴随发生的结果,暗示了该模态具有被再分解的可能性。利于傅利叶滤波方法从原始海温异常中滤掉了8年以下的高频振荡,对剩余的以年代际低频变率为主的热带太平洋海温异常再次进行SEOF分解,得到两个具有不同特性的年代际变率模态。第一模态主周期12-15年,表现为中东太平洋赤道及两侧的三角形区域内同时增暖,位于赤道中太平洋及副热带东北太平洋位置各有一个暖异常中心,由于该模态呈现出经向的双暖中心结构,定义此模态为热带太平洋年代际变率经向模态(Tropical Pacific interdecadal meridional mode, TPDMM),此模态与副热带东北太平洋海温指数在时间变化及海温异常形态分布上都十分相似;第二模态最突出的周期为20年左右,表示为赤道东太平洋为较强的冷异常,中太平洋为相对较弱的暖异常,该模态表现为赤道纬向的冷暖异常反位相结构,故定义此模态为热带太平洋年代际变率纬向模态(Tropical Pacific interdecadal zonal mode, TPDZM),同样,此模态与赤道纬向反位相结构海温指数回归的海温模态及时间序列对应关系也非常良好。进一步的研究发现这两个再分解得到的年代际模态都具有现实的意义,TPDMM模态的全球遥相关分布呈现出“类ENSO (ENSO-like)"形态,而且与ENSO的时间序列也具有协同变化的特点,暗示TPDMM可能是ENSO在年代际之间的调整产生的结果；TPDZM则反映了热带太平洋海温平均态的变化。
[Abstract]:In this paper, the two main seasonal evolution modes of the sea surface temperature anomaly rate in the tropical Pacific are revealed by the analysis method of the seasonal joint orthogonal empirical decomposition (SEOF) for the average sea temperature data of the Hadley center, which is going to the trend, from 1958 to 2008. SEOF-1 is the interannual variability mode, the main period is 3 years and 5 years, the traditional ENSO mode is reflected, and the global ocean, the performance heat flux, the atmospheric circulation and the precipitation anomaly have obvious remote correlation, and the global influence is remarkable. SEOF-2 is an interdecadal variability mode with a main cycle of 10-12 years, including two non-synchronized warm anomaly centers in the Pacific and subtropical North-East Pacific in the equator, and a cold anomaly center in the Eastern Pacific. The global teleconnection distribution of interdecadal variability mode has obvious local characteristics, mainly in the tropical and northern Pacific region. In this paper, the structural characteristics of the modal and the relation between the parts are analyzed in detail. It is found that the index of the SST anomaly in the warm anomaly center in the North-East Pacific Ocean and the index of the cold and warm anomaly of the equatorial zonal inversion phase are higher than that of the SEOF-2 mode time series, while the correlation with the ENSO is very weak, but the correlation between the two indices is very weak, The two indexes have certain stability, that is, the presence or absence of the ENSO signal does not affect the change law of the index itself, nor does it affect the correlation between the two indexes and the SEOF-2 time series; in addition, the two indexes can be respectively returned to a part of the sea surface temperature anomaly in the SEOF-2 mode, and the SST anomaly index in the northeast Pacific of the subtropical zone can be returned to obtain most of the warm anomalies in the mode, especially the two warm centers of the Pacific and the subtropic Pacific in the equator are very obvious, The temperature anomaly index of the equatorial zonal reverse-phase structure can be regressed to obtain the variation of the equatorial latitudinal inversion in this mode, especially the cold anomaly of the eastern Pacific, and the anomaly of the sea surface temperature of the two-index regression is very similar to that of the original mode. It is suggested that the mode is likely to be the combination of two sea surface temperature anomaly modes with different properties or the result of the occurrence, which implies that the mode has the possibility of re-decomposition. The method is beneficial to the Fourier-leaf filtering method to filter out the high-frequency oscillation below 8 years from the original sea temperature anomaly, and again carry out SEOF decomposition on the rest of the tropical Pacific sea surface temperature anomaly, which is dominated by the inter-time low-frequency variability, to obtain two interdecadal variability modes with different characteristics. the main period of the first mode is 12-15 years, and the main period of the first mode is 12-15 years, This mode is defined as the meridional mode (TPDMM) of the interdecadal variability of the tropical Pacific. This mode is very similar to that of the Pacific SST in the north-east of the subtropical zone. The most prominent period of the second mode is about 20 years. It is indicated that the equatorial eastern Pacific is a relatively weak cold anomaly, and the middle and the Pacific are relatively weak warm and abnormal, the mode is the equatorial zonal cold and warm abnormal reverse phase structure, so this mode is defined as the tropic Pacific interdecadal zontal mode (TPDZM) in the tropical Pacific. The relationship between the modal and the time series of the sea surface temperature index regression with the equatorial zonal inversion is also very good. The further study found that the interdecadal mode of the two re-decomposition has the real meaning, and the global teleconnection distribution of the TPDMM mode presents the "ENSO-like" form, and the time series with the ENSO also has the characteristic of cooperative change, It is suggested that the TPDMM may be the result of the adjustment of the ENSO between the ages, and the TPDZM reflects the change of the mean state of the sea surface temperature in the tropical Pacific.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P731.11
本文编号：2454516
[Abstract]:In this paper, the two main seasonal evolution modes of the sea surface temperature anomaly rate in the tropical Pacific are revealed by the analysis method of the seasonal joint orthogonal empirical decomposition (SEOF) for the average sea temperature data of the Hadley center, which is going to the trend, from 1958 to 2008. SEOF-1 is the interannual variability mode, the main period is 3 years and 5 years, the traditional ENSO mode is reflected, and the global ocean, the performance heat flux, the atmospheric circulation and the precipitation anomaly have obvious remote correlation, and the global influence is remarkable. SEOF-2 is an interdecadal variability mode with a main cycle of 10-12 years, including two non-synchronized warm anomaly centers in the Pacific and subtropical North-East Pacific in the equator, and a cold anomaly center in the Eastern Pacific. The global teleconnection distribution of interdecadal variability mode has obvious local characteristics, mainly in the tropical and northern Pacific region. In this paper, the structural characteristics of the modal and the relation between the parts are analyzed in detail. It is found that the index of the SST anomaly in the warm anomaly center in the North-East Pacific Ocean and the index of the cold and warm anomaly of the equatorial zonal inversion phase are higher than that of the SEOF-2 mode time series, while the correlation with the ENSO is very weak, but the correlation between the two indices is very weak, The two indexes have certain stability, that is, the presence or absence of the ENSO signal does not affect the change law of the index itself, nor does it affect the correlation between the two indexes and the SEOF-2 time series; in addition, the two indexes can be respectively returned to a part of the sea surface temperature anomaly in the SEOF-2 mode, and the SST anomaly index in the northeast Pacific of the subtropical zone can be returned to obtain most of the warm anomalies in the mode, especially the two warm centers of the Pacific and the subtropic Pacific in the equator are very obvious, The temperature anomaly index of the equatorial zonal reverse-phase structure can be regressed to obtain the variation of the equatorial latitudinal inversion in this mode, especially the cold anomaly of the eastern Pacific, and the anomaly of the sea surface temperature of the two-index regression is very similar to that of the original mode. It is suggested that the mode is likely to be the combination of two sea surface temperature anomaly modes with different properties or the result of the occurrence, which implies that the mode has the possibility of re-decomposition. The method is beneficial to the Fourier-leaf filtering method to filter out the high-frequency oscillation below 8 years from the original sea temperature anomaly, and again carry out SEOF decomposition on the rest of the tropical Pacific sea surface temperature anomaly, which is dominated by the inter-time low-frequency variability, to obtain two interdecadal variability modes with different characteristics. the main period of the first mode is 12-15 years, and the main period of the first mode is 12-15 years, This mode is defined as the meridional mode (TPDMM) of the interdecadal variability of the tropical Pacific. This mode is very similar to that of the Pacific SST in the north-east of the subtropical zone. The most prominent period of the second mode is about 20 years. It is indicated that the equatorial eastern Pacific is a relatively weak cold anomaly, and the middle and the Pacific are relatively weak warm and abnormal, the mode is the equatorial zonal cold and warm abnormal reverse phase structure, so this mode is defined as the tropic Pacific interdecadal zontal mode (TPDZM) in the tropical Pacific. The relationship between the modal and the time series of the sea surface temperature index regression with the equatorial zonal inversion is also very good. The further study found that the interdecadal mode of the two re-decomposition has the real meaning, and the global teleconnection distribution of the TPDMM mode presents the "ENSO-like" form, and the time series with the ENSO also has the characteristic of cooperative change, It is suggested that the TPDMM may be the result of the adjustment of the ENSO between the ages, and the TPDZM reflects the change of the mean state of the sea surface temperature in the tropical Pacific.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P731.11
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