冬季黑潮延伸体海区海洋锋强度变化及其与北太平洋风暴轴的关系

发布时间：2018-05-23 09:20

本文选题：黑潮延伸体 + 海洋锋　；参考：《大气科学》2017年06期

【摘要】：利用英国哈德莱中心(Hadley Center)1949~2014年表层海温资料,将黑潮延伸体海区海温经向梯度的大值区域的平均值定义为黑潮延伸体及其北部海洋锋强度指数(KEFI),利用数据分析方法研究了各季节KEFI的变化特征及其与北太平洋风暴轴的关系。分析表明,各季节的KEFI存在明显的年际和年代际变化特征,同时在冬季与北太平洋瞬时方差有显著正相关,两者在风暴轴主体位置的相关性最为显著,并且这种相关性在KEFI超前一个月时就所显现,同时对后期风暴轴也有一定影响,即冬季黑潮延伸体海区海洋锋的强度会影响风暴轴区域瞬时方差的变化。之后主要分析了这种影响的可能机制,发现在冬季KEFI高值年,由于海洋锋两侧的热量输送差异更加明显,导致海洋锋附近的近表面气温经向梯度增强,维持了近表面的斜压性,促进涡动热量的向极输送和海洋锋南侧的向上输送,有利于瞬时涡旋的发展。另外大尺度环流场与冬季黑潮延伸体海洋锋也有关系,具体表现为,在海洋锋强年,阿留申低压加深,副热带高压略有加强,对应的对流层低层位势高度场在40°N以北有负变高,以南有正变高,同时高空极锋急流加强,副热带西风急流减弱加宽北抬,海洋锋偏弱年的变化则相反。因此,冬季黑潮延伸体及其北部的海洋锋主要通过两侧海表热量输送差异不断产生气温梯度,进而维持斜压性以促进上层风暴轴的发展。
[Abstract]:Using Hadley Center data of surface sea surface temperature (SST) from 1949 to 2014 in the Hadley Center, UK, In this paper, the mean value of the large area of sea surface temperature meridional gradient in the Kuroshio extensional area is defined as Kuroshio extensional body and its northern oceanic front intensity index (KEFI). The variation characteristics of KEFI in each season and its relationship with the North Pacific storm track are studied by using the data analysis method. The analysis shows that the KEFI of each season has obvious interannual and Interdecadal variation characteristics, and there is a significant positive correlation between the KEFI and the instantaneous variance of the North Pacific in winter, and the correlation between them is the most significant in the main position of storm track. Moreover, the correlation appears one month ahead of KEFI and has a certain effect on the later storm track, that is, the strength of the oceanic front in the Kuroshio extension area in winter will affect the variation of the instantaneous variance of the storm track region. After that, the possible mechanism of this influence is mainly analyzed. It is found that in the high value year of KEFI in winter, the difference of heat transfer between the two sides of the ocean front is more obvious, which leads to the enhancement of the meridional gradient of the near surface temperature near the ocean front, which maintains the baroclinic property of the near surface. It is beneficial to the development of instantaneous vortex to promote the polar transport of vortex heat and the upward transport of ocean front to the south. In addition, the large-scale circulation field is also related to the oceanic front of the Kuroshio extensional body in winter. In the strong year of the oceanic front, the Aleutian low pressure deepens, the subtropical high is slightly strengthened, and the corresponding lower tropospheric potential height field increases negatively to the north of 40 掳N. At the same time, the upper polar front jet is strengthened, the subtropical westerly jet is weakened and widened, and the oceanic front is weaker and weaker. Therefore, the winter Kuroshio extensional body and its northern oceanic front mainly produce temperature gradient through the difference of heat transport between the two sides of the sea surface, and then maintain baroclinic to promote the development of upper storm track.
【作者单位】：中国气象科学研究院;中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室(LASG);
【基金】：国家自然科学基金项目41490642(41490640)、41665004~~
【分类号】：P731;P732

【相似文献】