Research On The Spatial-temporal Characteristics And Forecasting Methods Of Heavy Fog In Liaoning Province

Fog is a severe weather phenomenon closely related to the spatial and temporal distribution characteristics.The causes for the mechanisms of fog are complex.Accurate forecast of fog is very important to guarantee the safety of air and sea transportation.every three hour fog event and corresponding meteorological elements of 60 observation stations in Liaoning province in January 1,2004,-2013,December 30 th,23 hours and ten years,are analyzed in detail on the frequency distribution,multi-year trend,seasonal characteristics and characteristic values of the heavy fog events in Liaoning province.On the basis of the construction of multiple linear regression equations,the physical components of heavy fog events are attributable to the spatial distribution characteristics of the heavy fog events in Liaoning area in 2004-2013.The results shows:The number of heavy fog events in southern Liaoning is significantly larger than that in the eastern and western regions.The highest value can exceed 200 times,while the eastern and western regions are only dozens of times.According to the season,in terms of frequency,the performance of spring and summer is more consistent(only the intensity is different),the autumn and winter are more consistent(both are both bi-directional gradient decreasing).In addition,there are more frequent fog events in the southern Liaodong Peninsula no matter which season.The number of autumn in the whole province is obviously higher than that in the other three seasons.The frequency of heavy fog event occurred in 08 days in spring and autumn,and was the highest at 11,14 and 05 respectively.The number of fog days in spring,summer and autumn is not significant in three seasons.Winter is the largest interannual difference in heavy fog events.In the low value year of heavy fog,the Liaodong Peninsula in the wind field of 1000 hPa is controlled by abnormal north wind,and the specific wet field's specific humidity is negative,but in the high value year of the heavy fog,it is controlled by the abnormal southerly wind,and the specific humidity of the abnormal wet field is positive.Too much wind speed is not conducive to the occurrence and development of fog events.The EOF analysis of the frequency of the heavy fog events shows that the fog frequency in Liaoning province has a good consistency in both the annual and seasonal angles.In some cases,there is still a reverse phase contrast between East and West or south to north.In addition,the heavy fog event in the southeast of Liaodong Peninsula is obviously stronger than that in the northwest.It may also be related to the geographical location of the sea.In winter,visibility is positively correlated with temperature,negatively related to dew point temperature and positive correlation with wind speed.In summer,there areregional differences in the correlation between the three variables in western,central and eastern regions.In addition,specific humidity and saturated specific humidity have less influence on visibility in the West and Central areas,but are very important to the eastern part of Liaoning.Great impact,this is particularly significant in the summer.According to the different regions and seasons,different regression models are given,through the actual application test of the heavy fog event in 2016,the accuracy rate of the southern region in winter can reach more than 90%,and the application effect of the northern region in the north of the summer is not so good.