Evolutionary Characteristics of a Persistent Dense Fog Esipode in Northern Leeside of Tianshan Mountains based on Multi-source Data
The persistent dense fog episode that occurred from December 9 to 13,2019 in the northern regions of Xinjiang along the Tianshan Mountains was analyzed based on routine meteorological data,automated weather observing system(AWOS)data,and microwave radiometer data.The results showed that:(1)The occurrence of the dense fog episode coincided with the dominance of an upper ridge system in the region,accompanied by a persistent eastward extension of warm advection at lower levels and uniform surface pressure behind the cold high-pressure system in Mongolia.(2)The melting snow,which was the result of surface temperature rising in the days before the dense fog episode,provided favorable conditions for the formation of dense fog.The combination of weak winds,abundant saturated moist air near the surface,the stable stratification,and the low-lying topography of the Junggar Basin made it difficult for dense fog to dissipate.(3)Near-surface radiation cooling was conducive to the maintenance and strengthening of the inversion layer beneficial to the dense fog.(4)The multi-channel visible and infrared channel difference images of the FY-4A satellite could monitor the formation,maintenance and dissipating of dense fog during the day and night.
Northern leeside of Tianshan Mountainsdense fogAWOSinversion layerBrunt-Vaisala frequency