Abstract:

Using ERA5 reanalysis data, ground observation data from the China Meteorological Administration, and satellite remote sensing monitoring data, an analysis was conducted on a wide-area sea fog event accompanied by an extratropical cyclone entering the Yellow Sea and East China Sea from April 19 to 22, 2023. The results indicated that the sea fog primarily occurred in the western and northern parts of the cyclone that moves into the sea, with advection cooling fog in the Yellow Sea and frontal fog in the East China Sea. During the occurrence of the Yellow Sea fog, the temperature difference between air and sea ranged from 0 ℃ to 2 ℃, while in the East China Sea, the air temperature was lower than the sea temperature during the sea fog event. The formation of the Yellow Sea fog was mainly due to the warm and moist air from the south converging and then condensing on the cooler sea surface. In contrast, the East China Sea fog was frontal fog formed under the effect of weak cold air in the rear of the cyclone, providing the main moisture source for the occurrence and maintenance of this sea fog process. During the sea fog event, the cloud water content significantly increased in the vertical direction, and the fog development height formed by the south wind was greater than that formed by the north wind.

Key words: Sea fog, Extratropical cyclone, Air-sea temperature difference, Inversion layer