基于255 m气象塔天津地区污染天气高空风特征研究

基于2016年4月—2017年3月天津地区地面、255 m气象塔和风廓线监测数据,结合数值模拟,研究天津污染天气分析中高空风特征,以期进一步提高污染天气预报准确率.结果表明:高空风速和风向分析对污染天气趋势判断有重要作用,如冠层以上高度风速、300~1500 m风向对PM2.5污染程度的指示效果好于近地面同类数据;在选取高空风速指标时,应尽量避免边界层顶附近高度风速数据选取,如使用300 m和600 m风速和作为指标要好于300、600和900 m风速和作为指标.而其是否有利于污染扩散判断的临界阈值为10~15 m·s-1,小于10 m·s-1时水平扩散条件不利于污染物扩散,大于15 m·s-1时有利于污染物扩散.分析高空风向时,需要考虑输送高度和Ekman螺线的影响,与地面不同,300~1500 m高空风分析时,有利于出现污染天气的风向为西风、西南风和南风,而地面仅为南风和西南风;当1500 m高度呈现东风、偏东风和东南风时,天津地区受来自渤海的气流影响明显,污染气象条件有利于污染物扩散,空气质量以良好为主.

The Characteristics of high-altitude wind about the analysis of pollution weather by 255 meters meteorological tower in Tianjin

Based on the monitoring data of ground, 255 meter meteorological tower and wind profile, combined numerical simulation in Tianjin area during April 2016 to March 2017, researched on characteristics of upper air wind about the analysis of pollution weather in Tianjin. The result showed:The analysis of wind speed and direction at high altitude played an important role in judging the trend of pollution weather, Such as wind speed at 80 meters and wind speed during 300~1500 m, choosing data analyzed, the wind speed data near the top of the boundary layer was avoided, Such as using the sum of wind speed at 300 m and 600 m was better than the sum of the wind speed at 300 m, 600 m and 900 m, Statistical displayed when the index was less than 10 m·s^-1, the horizontal diffusion condition was not conducive to the diffusion of pollutants, when the index was larger than 15 m·s^-1, the horizontal diffusion condition was favorable to the diffusion of pollutants. In the analyzed of high altitude wind direction, it was necessary to consider the influence of the conveying height and the Ekman spiral, It was different from the ground, when wind direction during 300~1500 m were analyzed, the wind direction which was favorable to the polluted weather was westerly wind, southwest wind and south wind, but the ground were only southerly and southwest wind, When the wind direct at 1500 m were East and Southeast, Tianjin area were affected by air mass from Bohai, the pollution meteorological condition was advantageous to the pollutant diffusion, air quality was good.