【摘要】 利用环渤海地区(35°～42.5°N、116°～123.5°E) 2002-2017年地面气象站逐日实况观测资料和2014-2017年空气污染物资料,对环渤海及其四类地区能见度小于5 km的天气及成因进行了分析.结果表明,环渤海地区低能见度年均发生日数空间分布不均匀,京津地区、华北平原及山东半岛南部较多,北部山区及人口密度较小的县城较少. 1～5 km等级的低能见度日数年变化特征为双峰型,夏冬季多、春秋季少.除海滨城市外, 0～1 km等级的低能见度日数年变化特征为单峰型,冬季多、夏季少. 08:00最易出现低能见度天气,主要是雾、霾、降水等天气现象引起,易发生在相对湿度大于80%的情况下.发生低能见度时,平均风速较小、平均风向为东南风.低能见度与空气质量指数呈负相关,且与w(PM2.5)的相关性最大.更多还原

【Abstract】 Daily surface meteorological observation data from 2002 to 2017 and air pollutant data from2014 to 2017 were used to analyze the processes and causes for visibility below 5 km in the Bohai Rim region(35°-42.5°N, 116°-123.5°E). The results showed that the spatial distribution of days with low visibility was uneven; the number of low-visibility days was high in the Beijing-Tianjin region, North China Plain and southern Shandong Peninsula and low in northern mountainous areas where the population density was low. The annual variation characteristics of the number of days whose visibility was between1-5 km is bimodal, i.e. more in summer and winter and less in spring and autumn. The annual variation characteristics of the number of days whose visibility was between 0-1 km were unimodal, most occurring in winter except the coastal cities. The diurnal variation of visibility was high at 08:00. Low-visibility weather was likely to occur when the relative humidity was over 80% and the average speed of wind was low with a southeast direction. Fog, haze and precipitation were the important factors affecting visibility. And low visibility had a negative relationship with air quality index and was most relevant to mass concentration of PM2.5.更多还原