绍兴地区灰霾天气历史变化特征及成因分析

The Analysis of Historical Change and Causal Factors of Haze Weather in Shaoxing Region

利用绍兴地区各台站建站以来观测资料,对绍兴地区灰霾天气的历史变化进行分析。结果表明,绍兴地区逐年平均灰霾日数总体呈上升趋势,特别是2011-2012年,灰霾日数占历年总数的35.2%。灰霾日数12月最多,8月最少;灰霾天气中,风速≤3.0m/s时,出现概率最大,为67.0%;当风向为NNE时,出现概率最大,为16.0%,SE时,出现概率最低,仅为1.6%。年日照时数与灰霾天数呈弱的负相关。5个县中绍兴和诸暨灰霾日较其它县市偏多,可能与其工业化程度强有关。除城市工业化发展等因素外,灰霾的观测判别标准的变化是其中一个重要原因,如按照目前灰霾的判别标准,重新统计历年可能出现的天数,2000年后年平均灰霾天数比70年代增幅仅为41%,远远低于实际增幅704%。早期判别标准不统一、阈值偏低造成灰霾天数记录偏少。

Using observational data from meteorological stations,we analyzed the historical changes of haze weath er in Shaoxing area since the establishment of these stations.The result shows that the average haze days esca lated with years.Especially in 2011-2012,the haze days accounted 35.2% of the total number of calendar years.Haze days maximize in December and minimize in August.The occurrence probability of haze weather is highest when the wind velocity ≤3.0m/s,explicitly 67.0%,and when the wind direction is NNE,explicitly 16.0%,however,when the wind direction is SE,the occurrence probability is the least,only 1.6%.The nega tive correlation between the annual sunshine hours and the hazes days is not so palpable.In addition to the de velopment of urban industrialization,factors such as the evolvement of haze’s observation and discrimination stan dard can also be influential.For example,if we count the possible number of haze days in the current stan dard,the annual average haze days after 2000 grow only 41% when compared with that of 1970s,far lower than the actual increase of 704%.Standard is not uniform in early days,and the inadequate threshold leads to the inadequate records of haze days.