| 天气型对北京地区近地面臭氧的影响 |
| 摘要点击 3157 全文点击 2763 投稿时间：2009-04-09 修订日期：2009-06-04 |
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| 中文关键词 臭氧 天气型 山谷风 光化学污染 北京 |
| 英文关键词 ozone synoptic type mountain and valley winds photochemical pollution Beijing |
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| 中文摘要 |
| 臭氧（O3）是夏秋季北京城市大气光化学污染物中的首要气态污染物,气象因素是影响其浓度水平和变化规律的主要因子之一.2008年7月～2008年9月, 在北京市4个站点进行了臭氧、氮氧化物（NOx）和一氧化碳（CO）浓度的同步连续观测,并对同期天气型进行了分类比对分析.结果显示,观测期间,北京地区处于低压前部（主要是蒙古气旋）和高压前部的比例分别为42%和20%,分别是造成臭氧浓度高值和低值的主要背景场.处于低压前部控制时,高温、低湿以及局地环流形成的山谷风造成区域臭氧累积,小时最大值（体积分数）高达102.2×10-9,并随气压的升高以3.4×10-9 Pa-1的速率降低, 山谷风风向的转变决定了臭氧浓度最大值出现时间,峰值出现在14:00左右；处于高压前部控制时,低温、高湿以及系统性北风造成区域臭氧低值,小时最大值（体积分数）仅为49.3×10-9,系统性北风将臭氧峰值出现时刻推后到16:00左右.北京地区臭氧光化学污染呈现出区域一致性,并与天气型有较好相关,关注天气型结构和演变对预报大气光化学污染具有重要意义. |
| 英文摘要 |
| Ozone (O3), influenced by meteorological factors, is a primary gaseous photochemical pollutant during summer to fall in Beijing’s urban ambient. Continuous monitoring during July to September in 2008 was carried out at four sites in Beijing. Analyzed with synoptic type, the results show that the ratios of pre-low cylonic (mainly Mongolia cyclone) and pre-high anticylonic to total weather conditions are about 42% and 20%, illustrating the high-and low-ozone episodes, respectively. At the pre-low cylonic conditions, high temperature, low humidity, mountain and valley winds caused by local circulation induce average hourly maximum ozone concentration (volume fraction) up to 102.2×10-9, negative correlated with atmospheric pressure with a slope of -3.4×10-9 Pa-1. The time of mountain wind changed to valley wind dominates the diurnal time of maximum ozone, generally around 14:00.At the pre-high anticylonic conditions, low temperature, high humidity and systematic north wind induce average hourly maximum ozone concentration (volume fraction) only 49.3×10-9, the diurnal time of maximum ozone is deferred by continuous north wind till about 16:00.The consistency of photochemical pollution in Beijing region shows that good correlation exists between synoptic type and ozone concentration. Therefore, getting an eye on the structure and evolution of synoptic type is of great significances for forecasting the photochemical pollution. |
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