北太平洋海表温度变化及其对北极气温的影响

发布时间：2018-07-22 14:21

【摘要】：在过去几十年里，北太平洋海表温度（SST）随着全球变暖也在发生着显著的变化。本文利用Hadley中心SST资料、美国NCEP/NCAR再分析资料、日本JRA-25再分析资料以及法国卫星海洋存档数据中心Aviso的海表高度（SSH）观测资料，并运用多种统计分析方法，分析了1949-2012年北太平洋海表温度异常（SSTA）标准差的空间和时间分布。深入研究了由标准差时空分布引出的两个方面内容：第一是北太平洋SSTA与SSH之间的时空关系，以及SSTA与通过二维有限脉冲响应（FIR）滤波器所得到SSH的各个分量之间的时空关系；第二是SSTA在冬季变化最剧烈的可能原因是与阿留申低压存在有关，由此研究了冬季阿留申低压协同后期北太平洋SSTA变化对北极夏季表面气温（SAT）的影响。主要结论如下： 1、利用二维FIR滤波器对TOPEX/Poseidon SSH资料进行滤波处理，得到不同时间和空间尺度上的热信号和波信号分量。研究了近20年北太平洋SSH及各个分量与SSTA之间的关系，结果显示：几乎整个北太平洋SSTA与海面高度观测值（zori）有非常好的相关关系；在低纬度地区SSTA与两年周期Rossby波（z24）关系最紧密；而在中纬度地区SSTA则与不传播的海盆尺度热信号（zt）相关关系最显著。利用经验正交函数（EOF）分解和相关分析等方法，进一步研究了zori、zt、z24与SSTA之间的关系。结果显示，SSTA EOF第一模态、zori EOF第二模态、zt EOF第二模态以及z24EOF第一模态均与ENSO存在紧密联系。结合时间系数序列变化的整体趋势和细节来看，z24EOF第一模态时间系数与ENSO的关系最明显，且Ni o3.4指数与z24EOF第一模态时间系数相关关系高达-0.71。得到的结论进一步揭示了北太平洋SSH与SSTA之间紧密的关系，而稳定的两年周期Rossby波信号可能比大气或海洋中其它变量更利于监测ENSO信号，，以及后续的预测研究。 2、通过定义新的阿留申低压强度指数，发现冬季阿留申低压与次年夏季北极SAT相关关系显著，并给出了其中一种解释机制。冬季阿留申低压越弱，次年春季一直到夏季初期北太平洋中纬度海盆内区SST偏高，导致春季、夏季平均经圈环流和500pha位势高度异常：中纬度地区有异常上升运动，异常下沉运动存在于高纬度地区，费雷尔环流减弱，暖空气从高层到低层向北输送，使得北极SAT升高，同时，异常下沉运动绝热增温并且阻止地表热量上传亦对北极气温高有贡献；另一方面中纬度地区位势高度负异常，高纬度地区正异常，南低北高分布型有利于增加白令海峡入流体积通量，亦使北极地区SAT偏高。研究结果揭示了阿留申低压年际变化对北极夏季SAT的调控作用，从而为北极地区甚至北半球的季节预测提供了一个较好的指示作用。
[Abstract]:In the past few decades, sea surface temperature (SST) in the North Pacific Ocean has also changed significantly with global warming. In this paper, we use Hadley Center SST data, American NCEP / NCAR reanalysis data, Japan JRA-25 reanalysis data and sea surface altitude (SSH) observation data of Aviso, and use various statistical analysis methods. The spatial and temporal distributions of the SSTA standard deviation in the North Pacific Ocean from 1949 to 2012 are analyzed. Two aspects derived from the standard deviation spatiotemporal distribution are studied in detail. The first is the spatiotemporal relationship between SSTA and SSH in the North Pacific and the spatiotemporal relationship between SSTA and each component of SSH obtained by two-dimensional finite pulse response (Fir) filter. The second one is that the most severe variation of SSTA in winter is related to the existence of Aleutian low. The influence of SSTA variation in the North Pacific on the summer surface temperature (SAT) of the Arctic is studied. The main conclusions are as follows: 1. Using two-dimensional Fir filter to filter TOPEX / Poseidon SSH data, the thermal and wave components at different time and space scales are obtained. In this paper, we have studied the relationship between the (zori) of the North Pacific and its components in the last 20 years. The results show that there is a very good correlation between the (zori) and the observed values of sea surface height in almost all of the North Pacific. In the low latitudes, the correlation between SSTA and two-year periodic Rossby waves (z24) is the most close, while in the mid-latitudes, the correlation between SSTA and non-propagating basin-scale thermal signals (zt) is the most significant. By means of empirical orthogonal function (EOF) decomposition and correlation analysis, the relationship between zorianztnz24 and SSTA is further studied. The results show that the first mode of SSTA EOF, zori EOF, the second mode of zt EOF, and the first mode of z24EOF are closely related to ENSO. The relationship between the first mode time coefficient of Z24EOF and ENSO is most obvious, and the correlation between Nio3.4 index and Z24EOF first mode time coefficient is as high as -0.71. The obtained results further reveal the close relationship between SSH and SSTA in the North Pacific, and the stable two-year periodic Rossby wave signal may be more conducive to the monitoring of ENSO signals than other variables in the atmosphere or ocean. 2. By defining the new Aleutian low pressure intensity index, it is found that the correlation between the winter Aleutian low pressure and the Arctic SAT in the following summer is significant, and an explanation mechanism is given. The weaker the Aleutian low in winter, the higher the SST in the mid-latitude basin of the North Pacific from the following spring to the beginning of summer, which leads to the anomaly of the mean meridional circulation and 500pha geopotential height in spring. Anomalous subsidence occurs in high latitudes, the Ferrer circulation weakens and warm air flows northward from the upper to the lower levels, which makes the Arctic SATs rise, at the same time, The adiabatic warming of abnormal subsidence motion and stopping the heat transfer from the surface also contribute to the high temperature of the Arctic; on the other hand, the negative anomaly of geopotential height in the mid-latitude region and the positive anomaly in the high latitude area, The south low and north high distribution type is beneficial to increase the Bering Strait inflow volume flux, and also makes the SAT higher in the Arctic region. The results reveal that the interannual variation of Aleutian depression regulates the Arctic summer SAT and thus provides a good indication for seasonal prediction in the Arctic and even in the Northern Hemisphere.
【学位授予单位】：中国气象科学研究院
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P731.11;P461.2

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