Analysis of fog at Xianyang Airport based on multi-source ground-based detection data

In order to improve the accuracy of fog forecast at Xianyang Airport, microwave radiometer, wind profiling radar and other equipment are utilized to detect fog. With the long term detection data from the equipment mentioned above, this paper analyzes the altitudinal-temporal variation characteristics of wind, temperature, and relative humidity during fog weather. It also tallies up the variation characteristics of the three meteorological factors at different heights as visibility and time changes. The findings are listed as follows. During autumn and winter, fog usually appears between 22:00 BT and 13:00 BT next day at Xianyang Airport, with relatively stable atmospheric structure. During fog, when the height is below 300 m, the average relative humidity is > 75%, and the average horizontal wind speed is < 3 m/s, along with a weak downdraft. In September and October, there is mainly southwest wind at low levels during fog weather, the height of radiation inversion layer within 300 m. In November, December and January, it is mainly northeast wind at low levels during fog, with rather thick radiation inversion layer. When the visibility is 1500 m in mist, if the temperature drops by 3 degrees C and the relative humidity rises by 9% in September and October, the visibility decreases to < 1000 m accordingly; if the temperature drops by 6 degrees C in November (or it drops 8 degrees C in December and January), the inversion layer thickens, the relative humidity increases by 15%, then the visibility reduces to < 1000 m. These findings can provide scientific basis to improve the accuracy of fog forecast at Xianyang Airport.