恩施州气象站雾日变化趋势及原因分析

选取恩施州8个国家气象站1960~2015年地面气象观测资料,利用相关、线性倾向估计、M-K突变检验等方法对该地雾日变化趋势进行分析,并对雾日变化原因进行初步探寻。结果表明:2000~2015年恩施州各站雾日空间分布较1960~1999年发生了较大变化,SW-NE向带状大值中心被切断,出现了NW-SE向的雾日小值分布带;近56年除宣恩年雾日持续减少外,各站年雾日均在20世纪60、70年代突变后增多,20世纪末期减少并于2012年再次突变,州西南部最先增减、西北部其次、东部最慢,特别是近16年来年雾日显著减少,州北部站点(–40~–20 d·(10 a)~(–1))减少比南部(约–4 d·(10 a)~(–1))快;各站雾日变化和风速均呈负相关,和相对湿度均呈正相关,而气温和降水对不同站点雾日变化的影响则存在差异;近16年恩施州低山山地(恩施、来凤、宣恩、建始)雾日减少主要和气温升高、风速增加有关,中山山地(咸丰、利川)雾日减少主要与相对湿度减少有关。

VARIATION OF FOG AND THE UNDERLYING MECHANISMS BASED ON METEOROLOGICAL OBSERVATION STATIONS IN ENSHI

Based on the observed data from eight meteorological observation stations in Enshi area from 1960 to 2015,fog variations and the underlying mechanisms were analyzed by using correlation analysis,linear tendency estimation method,and the Mann-Kendall mutation test (M-K test).The spatial distribution of fog in Enshi during 2000 to 2015 was different from that during 1960 to 1999,with a maximum center of fog being cut off from southwest to northeast,and a minimum center of fog from southwest to northeast.In the last 56 years,except for the continuously decreasing fog days in Xuanen,annual fog days the other stations increased after a shift in 1960s and 1970s,and then decreased in the late period of 20th Century,followed by a shift in 2012.The changes started in southwest of Enshi,followed by northwest,and then east.The fog in Enshi significantly reduced in the recent 16 years,and fog in the north area decreased (-40-20 d·(10a)-1) much more quickly than in south area (-4d·(10a)1).And the influence of temperature and precipitation on fog days is different from station to station.During the last 16 years,the reduction of fog days in low mountain was related to temperature and wind speed,while related to the humidity in middle mountain.