Analysis Weather Characteristics And Formative Causes Of Heavy Fog In Maotai Airport

Fog weather is an important weather phenomenon that plagues the operation of civil aviation airports.Maotai Airport is located in the southwestern mountainous area with abundant water vapor.It is attacked by fog weather all the year round,which seriously affects the normal operation of the airport.Therefore,this thesis uses the airport self-view data and the reanalysis data of the European Center to study the heavy fog at Maotai Airport,and draw the following conclusions:(1)Airport fog is mainly divided into advection fog,radiation fog and rain fog,and is dominated by advection fog.Advection fog is more common from November to January of the following year,and the daily change is not obvious.Rain fog and radiation fog mostly occur in December.By February of the following year,the diurnal variation of radiation fog was more obvious in winter,and the rain and fog were more obvious in spring and summer;the duration of advection fog was longer than that of the other two fogs,and the minimum visibility was lower than them;good temperature and humidity conditions and wind The field conditions are very favorable for the generation of advective fog.(2)The self-organizing neural network algorithm(SOM)is used to classify the sea level pressure field in the process of advection fog,and 16 types of weather types are obtained.It is found that the SOM1,SOM3 and SOM4 nodes have the most frequent occurrences,and the seasonal variation characteristics of heavy fog on each node are analyzed.,found that autumn and winter are the peak periods of fog.Then combined with the airport self-view data and the water vapor flux analysis of the corresponding nodes,it is found that the visibility variation range corresponding to SOM3 is relatively concentrated,and the visibility is low.The durations of weather patterns corresponding to SOM4 and SOM7 are longer than those of other types.The main sources of water vapor at the airport are the South China Sea and the Bay of Bengal.(3)The characteristics of a typical advective fog event are analyzed from the visibility changes,meteorological elements,mid-low altitude circulation situation field,dynamic conditions and thermal conditions,and the backward trajectory model is used to track the source of the fog water vapor.The results show that: the visibility is extremely low during this heavy fog;the ground wind speed of the airport is suitable,basically at 2-4m/s,and the wind direction is mainly the west-southwest wind;the temperature dew point difference does not change much,and is basically close to 0 ?.The middle and high latitudes in the 500 h Pa altitude layer are stable blocking situation.At the altitudes of 700 h Pa and 850 h Pa,it can be seen that the transportation channel in the southwest direction is the main channel for the process of heavy fog at the airport,and the dry and cold air flow in the northwest is the main reason for the dissipation of the heavy fog;the vertical and horizontal motions in the atmospheric boundary layer are weak,and in the The lower layer is downdraft,and the near-surface horizontal wind speed below 850 h Pa is less than 5m/s;the atmospheric structure is stable,and the temperature inversion phenomenon is more obvious near 850 h Pa.The water vapor during the heavy fog at Maotai Airport was tracked,and it was found that the water vapor mainly came from three directions,namely the nearby Chishui River System,the Bay of Bengal and the Bohai Bay.