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Ocean-atmosphere interaction over sea surface temperature front along Kuroshio Extension and North Pacific subtropical front.

沿黑潮延伸带和北太平洋副热带锋的海表温度锋面的海洋-大气相互作用。

基本信息

批准号：
17340137
负责人：
TANIMOTO Youichi
金额：
$ 10.36万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

Over the western North Pacific east of the Japan, sea surface temperature (SST) shows a steep front across the Kuroshio Extension (KE). The SST gradient near the KE is 5℃/200 km through seasons, therefore changes in SST are very large in that region. In the present study, we conducted global positioning system (GPS) radio sonde atmospheric soundings across the front in July 2005 (January 2006) as a research cruise of research vessel (R/V) Roger Revelle, Scripps Institute of Oceanography (R/V Hakuho-maru, Ocean Research Institute, University of Tokyo).In early summer, whilst the lower atmosphere overlying the KE region exhibits synoptic disturbances, SST front is nearly the same for several weeks during the cruise due the large inertia of the ocean. Analyses of the atmospheric soundings and ceilometer measurement show that the vertical structure of atmospheric boundary layer is modified across the front. In case of warm/moist (cold/dry) air mass overlying the KE region, a cloud regime shift from cumulus to low-level stratus, occasionally to fog (from stratus with solid cloud deck to broken stratus scattering with lower cloud base) is observed across warm-to-cold SST.In deep winter, the near surface is always unstable because of warm ocean and cool/dry atmosphere. Hence, the main inversion is formed at the top of well-mixed layer. Temporal variation of the mixed layer top (MLT), which is mostly corresponding to the observed cloud base, is well correlated with surface heat flux. The lag correlation becomes the maximum when the flux leads by 5-12 hours the MLT. After a passage of synoptic storm, the surface heat flux occasionally exceeded 800W m^<-2> and thereby the stratus and stratocumulus were formed at the MLT.These observational findings indicate that the marine atmospheric boundary layer is modified by the spatial changes in SST along the KE front even though the overlying atmosphere displays its synoptic distrubances.

在日本以东的北太平洋西部，海表温度（SST）在黑潮延伸体（KE）上表现出一个陡峭的锋。KE附近的SST季节梯度为5 ℃/200 km，因此该区域的SST变化非常大。在本研究中，我们于2005年7月在锋面进行了全球定位系统（GPS）无线电探空仪大气探测（2006年1月）作为斯克里普斯海洋研究所Roger Revelle号研究船的研究巡航（东京大学海洋研究所"白凤丸"号研究船）。在初夏，当覆盖在KE区域上的低层大气表现出天气扰动时，由于海洋的大惯性，SST锋在巡航期间的几个星期几乎相同。对大气探测和云高仪观测资料的分析表明，锋面附近的大气边界层垂直结构发生了改变。在KE区上覆盖暖湿（冷）干气团时，在暖-冷SST上，云型由积云向低层层云转变，有时也会出现雾（从具有实心云面的层云向具有低云底的破碎层云散射）。因此，主要的逆温层形成在混合层的顶部。混合层顶（MLT）的时间变化与地面热通量有很好的相关性，它主要对应于观测到的云底。当流量超前MLT 5 - 12小时时，滞后相关性达到最大值。在一次天气风暴过后，海面热通量偶尔超过800 W/m~2，从而在MLT形成层云和层积云.这些观测结果表明，尽管上覆大气表现出天气性的不均匀性，但海洋大气边界层仍受沿着KE锋SST空间变化的影响.<-2>