基于自动站资料的苏州灰霾天气分析

Observation and analysis of haze characteristics in Suzhou based on automatic station data

利用苏州2010∽2013年的逐时气象和大气成分观测资料,对苏州灰霾天气特征进行了统计分析,研究发现：苏州灰霾的小时频率为30.7%,灰霾等级以轻微灰霾为主,干霾占总灰霾的比例为85.6%.2013年12月灰霾小时频率最高,达82.3%.灰霾小时频率有明显的日变化特征,峰值出现在上午8：00时,达36.3%,14：00∽16：00时,灰霾频率最低,约为25%左右;灰霾期间,PM10、PM2.5、PM1.0和散射系数分别是非灰霾期间的1.72、2.07、1.88和2.58倍.采用不同的灰霾日标准,苏州年均灰霾日数在94∽243之间,相差极大.灰霾频率和气象条件有密切关系,灰霾频率最高的相对湿度区间为70%∽80%,重度霾最多出现在90%∽95%的相对湿度条件下;随风速增加,灰霾频率逐渐下降,在西北风向下,灰霾频率最大.大气消光以颗粒物散射消光为主,约占总消光的82%左右,黑碳的吸收消光约占13%左右.

The characteristics of haze weather in Suzhou were analyzed based on the hourly data from 2010 to 2013. The results show that the hourly frequency of haze is 30.7%（mostly slight haze）, with the maximum haze frequency of 82.3% which is occurred in December of 2013. The ratio of dry haze to total haze is 85.6%. The hourly haze frequency shows obviously daily variation, the peak at 08：00a.m. can reach 36.3%,and the minimum at 14：00∽16：00p.m. is approximately 25%. During the haze time, the values of PM10, PM2.5, PM1.0 and scatter coefficient are 1.72, 2.07, 1.88 and 2.58 times of that in no-haze time. The average haze day is in the range of 94 to 243 of one year because of the different standard for haze day. The meteorological conditions have significant influence on the haze frequency. When the relatively humidity is in the range of 70%∽80%, the haze frequency is the biggest, but heavy haze are often occurred in the relatively humidity range of 90%∽95%. Haze frequency of NW wind direction is the biggest and decrease gradually with the increase of wind speed. Particle scattering extinction is the most part of atmospheric extinction and accounted for about 82%, followed by absorption extinction of black carbon which is 13%.