文章摘要
亲潮延伸体海区一次海雾过程的观测研究
Observational analysis of a fog event in the Oyashio Extension area
投稿时间:2021-12-10  修订日期:2022-01-14
DOI:
中文关键词: 海雾  观测  暖锋  海洋锋  西北太平洋
英文关键词: sea fog  observations  warm front  SST front  Northwest Pacific
基金项目:国家重点研发计划项目(2019YFC1510102),国家自然科学基金(41975024),山东省气象局课题(SDYBY2018-06,2017sdqxm11)
作者单位邮编
张苏平 中国海洋大学海洋与大气学院 266100
张欣 中国海洋大学海洋与大气学院 266100
时晓曚 青岛市气象台 266100
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中文摘要:
   西北太平洋是全球海雾最多的海域,但由于观测资料匮乏,对开阔大洋上海雾形成机理的个例研究很少。2019年9月12-14日,中国北极科考船“向阳红01号”在亲潮延伸体水域捕捉到一次海雾事件。本文主要利用船载观测数据,分析了海雾形成的物理过程。结果表明,这是一次温带气旋的暖锋和局地海洋锋(海表面温度锋)共同影响下的海雾过程。伴随暖锋的偏南气流将暖湿空气向北输送,在亲潮延伸体区,海面空气增湿效应大于增温效应,导致相对湿度不断增加接近饱和。北上暖空气遇到较冷水域上空的冷空气团,向上爬升形成大范围锋面逆温;局地海洋锋强迫出大气边界层内的次级环流,其下沉支使该锋面逆温层底的高度进一步降低,有利于雾滴局限在近海面成雾,雾区出现于暖锋锋面过后局地海洋锋的冷水侧。这项研究明确了海雾形成过程中作为背景环流的大气暖锋与作为局地强迫项的海洋锋的贡献,可为海雾预报提供新的理论支撑。
英文摘要:
   The northwest Pacific is the most foggy oceanic area in the world. Low visibility in fog affects navigation heavily, yet the synoptic processes of sea fog formation over open oceans remain unclear due to the lack of in-situ observations so far. In September 12-14, 2019, a Chinese arctic research vessel, XiangYanghong 01, captured a fog event in the cold Oyashio Extension (OE) area. The mechanism of the fog formation and maintenance is investigated in the present study based on the in-situ observations. The results show that the fog formation was influenced by both a synoptic-scale warm front in a mid-latitude cyclone system and a local SST front (sea surface temperature front). Warm humid air was transported from south to north along with the warm front, which resulted in the near surface air becoming warmer and wetter in the OE area. The fact that the moistening effect was greater than the heating one led to the relative humidity increasing and close to saturation. On the other hand, the northward warmer air climbed upward when met the colder air mass over the OE water, thus forming a large-scale frontal temperature inversion. The bottom of the inversion dropped further affected by a sinking branch from a vertical circulation in the marine atmospheric boundary layer, and this vertical circulation was very likely to be induced by the local SST front. The lowered inversion was conducive to fog droplets, once formed, to be confined near the sea surface. The fog layer was formed in the warm moist air on the cold flank of the SST front. The contributions of the background atmospheric warm front and the local SST front to fog formation is clarified and a relevant conceptual model is proposed, which are helpful for understanding of the physical processes in the formation of marine fog and for fog forecast in open oceanic area.
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