春季北太平洋风暴轴的年际与年代际变化特征及其与太平洋海温异常的关系

Inter-annual and inter-decadal variability of the spring storm track over the North Pacific and its association with SST anomalies

中文关键词:  风暴轴  海温  海-气关系  太平洋年代际振荡

英文关键词:Storm track  Sea surface temperature  Air-sea relationship  PDO

中文摘要:

      利用20世纪大气再分析资料和欧洲中心海温资料研究了春季西北太平洋风暴轴的年（代）际变化特征以及在不同年代际背景下风暴轴与太平洋海温关系的转变。结果表明，春季西北太平洋风暴轴主要存在两种空间变化模态，即反映其强度变化的第1模态和反映其南北位置变化的第2模态。年代际及以上时间尺度上，风暴轴强度、位置与太平洋海温的关系主要表现为大气对海洋的强迫作用。在不同年代际背景下，风暴轴与太平洋海温的关系则存在明显的年代际转变：1977年以后，风暴轴强度与太平洋海温的关系主要表现为大气对海洋的强迫作用，而在1977年之前则主要表现为海洋对大气的强迫作用，特别是同期冬季日本以东黑潮和黑潮延伸区海温异常的强迫作用；风暴轴南北位置与太平洋海温异常的关系，在1977年以后表现为大气对海洋的强迫作用，主要表现为对北太平洋中部海温的影响，但在1977年以前表现为海洋和大气的共同作用，风暴轴南北位置的变化还与同期的赤道中东太平洋海温异常有关，表明ENSO可能对风暴轴的位置变化存在影响。

英文摘要:

      Based on the 20CR reanalysis data and sea surface temperature (SST) data provided by European Center, the inter-annual (inter-decadal) variability of spring storm track over the North Pacific as well as the inter-decadal change in the relationship between the storm track and North Pacific SST are investigated. Results of Empirical Orthogonal Function (EOF) analysis show that there are two main variation modes for the spring storm track. The first mode represents its intensity variation and the second mode reflects its meridional variation in position. On the inter-decadal time scale, the relationship between the storm track and North Pacific SST anomalies mainly indicates an atmosphere-to-ocean forcing. Under different decadal backgrounds, the inter-annual relationship between the storm track and SST anomalies over the Pacific Ocean exhibits different inter-decadal changes. After 1977, the relationship between the intensity of the storm track and North Pacific SST indicates an atmosphere-to-ocean forcing. Before 1977, however, the relationship reflected an ocean-to-atmosphere forcing that is opposite to the situation after 1977. Specifically, SST anomalies over the Kuroshio Extension imposed strong concurrent forcing on the atmosphere in the spring. On the other hand, the relationship between the meridional position of the storm track and North Pacific SST anomalies after 1977 indicates an atmosphere-to-ocean forcing as the storm track behaves to lead the central North Pacific SST anomalies. However, before 1977, the meridional position of the storm track was also closely related to simultaneous SST anomalies in the equatorial eastern Pacific in the spring, implying ENSO's effect on the position of the storm track.