Abstract: A foggy weather process at Hubei International Logistics Core Hub Airport on December 1st to 2nd, 2016, was analyzed by using the data of regular observation, regional automatic observation station and NCEP 1°×1° reanalyzed data. The results showed that the process of fog appeared under the cooperation of the high, middle, low level weather system, and has obvious characteristics of radiation fog. In the fog stage, the 10 m wind on the ground was dominated by a partial east wind with a wind speed of less than 1.0 m/s. The situation that wind speed increased or the wind direction turned to a northerly wind facilitated the dissipation of fog. The vorticity and divergence of the lower troposphere was small, and the middle and lower layers were dominated by downdraft. The relative humidity of groud surface was maintained at about 5 g/kg, and the temperature dew point difference was about 3 °C. The sharp increase in temperature dew point difference can indicate the dissipation of fog. Before the appearance of heavy fog, the low-level relative humidity was maintained more than 60%, a relatively dry areas with relative humidity of less than 20% was maintained between 800 hPa and 600 hPa; There was an inversion layer or neutral layer junction near 950 hPa to 900 hPa, and there was a cold advection at the lower level and a warm advection at the middle and upper levels, the cold advection increased from the ground to the height, then the upper layer turned into the tendency that the cold advection decreased with height and the warmer advection increased with height. The cold flow near 900 hPa decreased with height, forming a stable structure with warm and cold in a smaller range.

Key words: fog, downdraft, inversion layer, upper-layer dry and lower-layer wet, Hubei International Logistics Core Hub Airport