伴随冬季北太平洋副热带海洋锋强度变化的大气扰动异常及对中纬度大气平均场的影响

发布时间：2018-01-09 10:24

本文关键词：伴随冬季北太平洋副热带海洋锋强度变化的大气扰动异常及对中纬度大气平均场的影响　出处：《中国科学:地球科学》2016年12期 　论文类型：期刊论文

【摘要】：中纬度海洋热力状况异常影响大气主要通过两种途径:非绝热加热的直接强迫作用和大气瞬变涡旋反馈的间接强迫作用,而后者的作用并没有被很好地认识.为了进一步理解间接强迫作用的物理机制,本文利用观测资料分析和区域大气模式模拟,研究了伴随冬季北太平洋副热带海洋锋强度变化的中纬度大气场异常,特别是对流层中高层不同频率的涡旋扰动活动的异常.实际观测和数值试验结果均表明,当北太平洋副热带海表面温度锋偏强时,其上空的中纬度大气经向温度梯度增强;对应此时的大气斜压性增强,且中纬度大气西风急流整层加速;然而增强的大气斜压性并不对应一致性增强的大气涡旋扰动活动.中纬度大气的涡旋扰动根据其生命周期,进一步划分为高频(2~7天)和低频(10~90天)涡旋扰动.研究结果表明偏强的北太平洋副热带海洋锋对应着增强的中纬度大气高频涡旋扰动和减弱的低频涡旋扰动;其中,中纬度大气高频扰动活动的增强,将有利于削弱中纬度大气经向温度梯度,从而减弱中纬度大气斜压性;而高频扰动对纬向风倾向项的正贡献,有利于中纬度急流中心北侧及下游区域的西风加速,形成中纬度西风相当正压结构的增强;大气低频扰动的减弱,对中纬度大气纬向风倾向项产生负贡献,不利于急流的纬向均匀化,而其热力强迫异常则有利于维持中纬度对流层中层大气的经向温度梯度.
[Abstract]:Mid latitude Ocean Thermodynamic Anomaly of atmospheric effects mainly through two ways: direct forcing of diabatic heating and atmospheric transient indirect forcing vortex feedback, the latter effect has not been well understood. In order to further understand the physical mechanism of indirect forcing, by using observation data analysis and model of regional atmospheric modeling study on the change of winter, with the subtropical North Pacific Ocean Front intensity of mid latitude atmospheric anomalies, especially abnormal upper troposphere vortex with different frequency disturbance. The actual observation and numerical results show that when the subtropical North Pacific sea surface temperature fronts is strong, its over the mid latitude atmosphere was enhanced to the temperature gradient; the corresponding atmospheric baroclinicity enhancement, and mid latitude westerly jet atmospheric whole layer acceleration; however enhanced atmospheric baroclinicity does not correspond to a Induced by atmospheric vortex enhanced disturbance. Vortex midlatitude atmosphere disturbance according to the life cycle, further divided into high frequency and low frequency (2~7 days) (10~90 day) vortex disturbances. The research results show that the strong side of the subtropical North Pacific Ocean Front corresponds to enhanced mid latitude air high frequency disturbance and reduced frequency of vortex among them, the vortex disturbance; enhanced midlatitude atmosphere disturbance activities, will be conducive to weaken the mid latitude atmospheric meridional temperature gradient, which weakens the mid latitude atmospheric baroclinicity; while the high frequency disturbance is contribution to the zonal wind tendency item, is conducive to the mid latitude jet Center North and the downstream region of the westerly acceleration, the formation of enhancement the westerly equivalent barotropic structure; weakened atmospheric low-frequency disturbance, the negative contribution to the mid latitude atmospheric zonal wind tendency, is not conducive to rapid zonal uniformity, which is beneficial to the abnormal thermal forcing The meridional temperature gradient of middle troposphere in middle latitude is maintained.

【作者单位】：中国气象局-南京大学气候预测研究联合实验室南京大学大气科学学院;气象灾害教育部重点实验室南京信息工程大学;
【基金】：国家自然科学基金项目(批准号:41330420,41275068) 国家重大基础研究计划项目(编号:2012CB956002,2016YFA0600303) 江苏省科技厅面上项目(编号:SBK2015020577) 气象灾害教育部重点实验室(南京信息工程大学)开放课题项目(编号:KLME1501)资助
【分类号】：P461.2;P732.6
【正文快照】： 1引言冬季北太平洋海盆,至少存在两条主要的纬向延伸的海表面温度(S S T)经向梯度带状大值区.其中偏南的一条位于2 8°N~3 2°N附近,跨越整个北太平洋海盆,被记为北太平洋副热带海洋锋区(S T F Z)(N a k a m u r a等,1 9 9 7;N a k a m u r a和K a z m i n,2 0 0 3).副热

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