1957—2016年杭州市大气能见度变化特征分析

Temporal Dynamic of Visibility Characteristics of Hangzhou during 1957—2016

【目的】探究杭州市大气能见度变化特征。【方法】基于1957-2016年(缺失1965—1972年数据)的监测数据,利用均值计算、Ridit值分析、累计百分比等方法对杭州市大气能见度变化特征进行分析。【结果】(1)1957—2016年平均大气能见度为10.05 km,变化趋势为-0.231 km/a;(2)大气能见度最高值出现在夏季,最低值出现在冬季,而春、秋两季的大气能见度处于夏、冬季之间且监测均值较为接近,处于夏季与冬季之间;(3)"好"(≥20 km)和"差"(<4 km)的大气能见度出现频率展示出了不同的变化特征;(4)杭州市在1956—1987年,Ridit值均大于0.5,在1987—1995年,Ridit值接近0.5,1996—2015年Ridit值处于0.5以下,而2016年Ridit值大于0.5;(5)20%、50%和80%位数的大气能见度在1957—2016年均处于下降趋势。【结论】整体而言杭州市大气能见度处于下降趋势,而2010年以后出现了下降放缓,在2016年呈现出一定的上升趋势,表明近年来杭州市对大气污染物的治理起到一定效果。

【Objective】The objective of the study was to explore the temporal dynamic of atmosphericvisibility in Hangzhou.【Methods】Based on the monitoring data from1957to2016(except1965-1972),the characteristics of atmospheric visibility were analyzed.【Results】淤The average atmospheric visibili原ty in1957-2016was10.05km and the trend was-0.231km/year;于The highest atmospheric visibilityappeared in the summer but the lowest value appeared in the winter.Additionally,while the mean val原ues of atmospheric visibility were similar between spring and autumn;盂The rate of atmospheric visibilityof"good"(逸20km)and"bad"(<4km)showed different variations;榆The Ridit value of Hangzhou washigher than0.5in1957-1987,was close to0.5in1987-1995,was below0.5in1996-2015,andwas higher than0.5in2016;虞the atmospheric visibility of20%,50%and80%exhibited a downwardtrend over1957-2016.【Conclusion】In general,the visibility of Hangzhou declined.The downward trend was slow after2010.In2016,the variation of visibility showed a certain upward trend.The results suggest原ed that recent measures have been playing a significant role in controlling air pollutants in Hangzhou.