北太平洋副热带模态水形成区混合层热动力过程诊断分析  

Diagnostics of mixed-layer thermodynamics in the formation regime of the North Pacific subtropical mode water

作　　者：潘爱军[1,2] 万小芳[1] 刘秦玉[2] 

机构地区：[1]国家海洋局第三海洋研究所环境动力室,福建厦门361005 [2]中国海洋大学物理海洋教育部重点实验室,山东青岛266003

出　　处：《热带海洋学报》2011年第5期8-18,共11页Journal of Tropical Oceanography

基　　金：国家重点基础研究专项(2007CB816002);国家自然科学基金项目(40806013);我国近海物理海洋与海洋气象调查研究项目(908-ZC-I-01);国家海洋局第三海洋研究所基本科研专项资金(海三科2008015)

摘　　要：利用NCEP海洋数据和COADS海气通量资料,通过诊断分析,揭示了海表热力强迫、垂直夹卷、埃克曼平流和地转平流效应在北太平洋副热带模态水形成过程中的贡献。研究表明,在北太平洋副热带3个模态水形成海域冬季混合层降温过程中,海表热力强迫和垂直夹卷效应是主导因素,二者的相对贡献分别约为67%和19%(西部模态水)、53%和21%(中部模态水)、65%和30%(东部模态水);并且在东部模态水形成海域,埃克曼平流和地转平流皆是暖平流效应,而在西部和中部模态水形成海域,仅有地转平流是暖平流效应。进一步的分析表明,海洋平流(地转平流、埃克曼平流)对北太平洋副热带模态水形成海域秋、冬季混合层温度的年际、年代际异常有显著影响,在西部模态水形成海域,海表热力强迫(62%)和地转平流(32%)是导致混合层温度年际、年代际变化的主要因子;在中部模态水形成海域,混合层温度的年际、年代际变化是埃克曼平流(32%)、地转平流(30%)和海表热力强迫(25%)共同作用的结果;相对而言,东部模态水形成海域混合层温度的年际、年代际异常主要受海表热力强迫(67%)控制。Diagnostics of the contributions from the surface heat forcing,vertical entrainment,Ekman advection,and geos-trophic advection to the formation of the North Pacific subtropical mode water are performed using the National Centers for Environmental Prediction（NCEP） ocean data and the Comprehensive Ocean-Atmosphere Data Set（COADS） fluxes.The re-sults suggest that both the surface heat forcing and vertical entrainment dominate the cooling tendency of the wintertime mixed layer in all three mode water formation regions,with relative contributions of 67% and 19% in the North Pacific Sub-tropical Mode Water（NPSTMW） formation region,respectively;53% and 21% in the North Pacific Central Mode Water（NPCMW） formation region,and 65% and 30% in the Eastern Subtropical Mode Water（ESMW） formation region.In addition,both the Ekman and geostrophic advection are warm advection in the ESMW formation region,while only the latter is warm advection in the other two mode water formation regions.Further analysis indicates that on interannual and decadal timescales,contributions from the surface heat forcing and geostrophic advection to the wintertime mixed layer cooling trend are 62% and 32% in the NPSTMW formation region,respectively.In the NPCMW formation region,the interannual and decadal variability derives from the combination of Ekman advection（32%）,geostrophic advection（30%）,and surface heat forcing（25%）.By contrast,the surface heat forcing is the most prominent contributor（67%） in in ESMW formation region.

关 键 词：北太平洋 副热带模态水 混合层 海表热力强迫 海洋平流 垂直夹卷 

分 类 号：P731[天文地球—海洋科学]