西北太平洋边缘海区海面变化多尺度解析及空间分异

利用MODWT对西北太平洋边缘海区8站位1965~2005年验潮序列进行多尺度分解,讨论了该区域海面变化多尺度波动特征及空间分异。结果显示年周期组分振幅随纬度增大而逐渐增大,半年周期组分振幅以中国沿岸最大,其余站位相对较小。年际尺度的波动中ENSO信号与1~2年尺度的准周期波动存在模态混叠现象,表现为对序列构形和不同时段的相关关系的影响。利用ICA方法从小波分解的年际尺度和信号中分离出的ENSO信号,表明不同纬度海面对ENSO事件的响应整体上呈现向高纬衰减的变化特征。基于小波相似性的分析结果显示,低纬各站海面对ENSO在各尺度上均呈现出显著的负相关,而中高纬地区则呈现出正相关。1980年之前和之后中高纬地区的海面对ENSO的响应出现了显著的差异,这可能与ENSO自身频率的调整有关。

Multi-scale analysis of sea-level change and its spatial characteristics in northwest Pacific Ocean marginal seas

In this paper, MODWT multi-scale decomposition methods are used to decompose the monthly average tidal records of eight tidal gauge stations in northwest Pacific Ocean marginal seas during 1965~2005. Furthermore, multi-scale fluctuation and spatial differentiation characteristics in these areas are discussed. The results indicate that all the stations are identified with annual fluctuating periods, and their change scopes in south of Zhapo, China coast and north of Kanmen are 50 mm, 70~90 mm and 65 mm, respectively. The change scopes of semiannual periods in three China coast tide gauges vary from 50 to 60 mm, which is larger than those of other gauges. When the change scopes of the inter-annual oscillations decrease from low latitude to high latitude, the scopes in Cube, Legaspi and Inchon are about 65 mm, while it decreases to about 45 mm in other stations. Mode mixing, which is mainly manifested as series configuration and phase difference at different time spans, is predominantly combined with ENSO signal and quasi-periodic oscillations of 1~2 years. The mode mixing signals can be clearly extracted by using ICA method, and the ENSO signal extracted by ICA filtering can be compared well with MEI index. The responses of sea level to ENSO in different stations decrease from low to high latitude, which are manifested by the amplitude of ENSO signal. Wavelet semblance analysis is introduced to analyze the correlation between ENSO signal and MEI index. The results show that sea levels of low latitude zone are mainly negatively correlated with ENSO at each scale, while sea levels of high latitude zone are mainly positively correlated. In mid-high latitude zone, the responses of sea level to ENSO are significantly different before 1980 and hereafter, which might be related to the frequency change of ENSO. The responses of sea level to ENSO show remarkable particularity at about 80-month scale during 1982~1983 and 1997~1998, which are identified as the two strongest ENSO events during the 20th century. The comprehensive analysis of this relative long-time scale may be helpful to the further understanding of the mechanism and process of these two strongest ENSO events.