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The author:(作者)归海一刀
published in(发表于) 2014/3/25 23:04:27
Beijing air pollution in yellow alert has been issued for the next 3 days sustained heavy pollution

The Beijing News (by Deng Qi) February the city sustained heavy pollution in the past one month, 15 o'clock yesterday, air heavily polluted Beijing air heavily polluted yellow alert has been issued by the Office of the emergency command signals are expected in the next three days of heavy pollution, better this Saturday.

Experts say the pollution is mainly because the inverse effect Wen Jingfeng and southerly.

　　35 monitoring point 33 heavy polluting

20 o'clock yesterday, Centre for environmental monitoring air quality in real time publishing platforms showed that 35 stations in the city, there are 33 sites showed air quality in class five high levels of pollution (PM2.5 24-hour value is 150 micrograms per cubic meter to 250 mg/m), the second serious after the severe pollution levels. East site real-time PM2.5 concentrations of 169 mg/m, 24-hour mean value of 220 μg/m3; Northern Changping real-time PM2.5 concentrations to 208 μg/m, 24 hour mean value of 221 μg/m3.

Beijing, Tianjin and Hebei province environmental Meteorological Center chief forecaster Liao Xiaonong said the pollution haze, this process will have significant diurnal variation, to more serious after nightfall the next day morning, the visibility is not very good. Afternoons, especially the zhousan、SI for two days, visibility improved markedly. Southern region to be more serious in the Beijing, Tianjin and Hebei, Northern light particularly in northern Beijing, Northern Hebei.

Director of the municipal environmental protection monitoring Center said Zhang Dawei, is expected today by the influence of a weak cold air, pollution scenario cannot be completely changed, zhousan、SI pollution worse, heavy pollution situation will continue until Friday. This Friday afternoon into the night, cold air, visibility improved, pollution tends to end, good air quality back to the secondary level is expected on Saturday.

　Dustpan terrain negative stain

From Wednesday to Friday, Beijing's air quality is at a good level. Sunday 23rd, the city gradually transferred to the low pressure system, air quality started to slip. Yesterday afternoon, the air quality of Beijing has reached high levels of pollution levels.

Zhang Dawei said Beijing pollution sources is the superposition of the local emission and regional transport. In addition, the meteorological conditions not conducive to diffusion is the major external factors. The pollution is mainly middle-level warming significantly because of the atmosphere, temperature inversion phenomenon seriously, like a lid cover in the skies above the capital, dispersal ability in vertical direction caused worsening pollution emission easy to accumulate near the ground, prone to heavy pollution. In addition, the southerly easier to carry pollution into Beijing plain area, Beijing, surrounded by the mountain terrain, like pollutants were swept into a dustpan, spread out. Local precipitation in Beijing this Friday, is expected on pollutant removal capabilities are limited.

　　Construction

Visibility in air pollution but not all that bad

Sustained heavy pollution occurred in the course of last month the capital, darkening sky impressive. Air heavily polluted yellow alert has been issued in Beijing yesterday, there are people who consider the sensory pollution seems not so serious.

Zhang Dawei said that compared with the last, the visibility can, in fact, the pollutant concentration levels were low. PM2.5 concentrations and visibility cannot directly draw an equal sign. Determine air pollution levels, PM2.5 monitoring data should be used as a basis rather than based on feeling, or visibility.

He explained that yesterday to reach high levels of pollution, but visibility was not bad, mainly because the air humidity is low. If you have lots of water vapor in the air will produce a dulling effect, thus affecting visibility.

It is understood that the past two days daytime relative humidity is around 40%, relative humidity reached approximately 70% pollution during February.

Pollution was upgraded to Orange alert is unlikely

In late February the capital sustained heavy pollution in the course of a week, Beijing's air pollution was first published the Orange warning signs.

Zhang Dawei said that compared with previous pollution during, there were no serious last time. Last heating season, emissions intensity, longer duration. This is not a heating season, cumulative effects aren't that big. In addition, the inversion layer tends to be thick in the winter, it is difficult to destroy. Current is alternating periods of winter into spring, inversion layer is less stubborn. As the heating season ends, lower frequency and extent of the contamination. For now, the fouling process mainly in about five levels of severe pollution, upgraded to level orange alert appears six serious contamination is unlikely.

(Original title: the next three days the city sustained heavy pollution)

　　新京报讯 (记者邓琦)2月份京城持续重污染刚过去约一个月，昨日15时，北京市空气重污染应急指挥部办公室发布空气重污染黄色预警信号，预计未来三天重污染持续，本周六转好。

　　专家称本次污染过程主要因为逆温静风及偏南风影响。

　　35个监测点33个重污染

　　昨日20时，市环境监测中心空气质量实时发布平台显示，全市35个监测站点中，有33个站点显示空气质量等级为五级重度污染(pm2.5的24小时均值为150微克/立方米至250微克/立方米)，为仅次于严重污染的第二严重级别。其中东四站点PM2.5实时浓度为169微克/立方米，24小时均值为220微克/立方米；北部昌平的PM2.5实时浓度为208微克/立方米，24小时均值为221微克/立方米。

　　京津冀环境气象中心首席预报员廖晓农表示，这次污染主要以霾为主，此过程中会有比较明显的日变化，即入夜以后到第二天早晨比较严重，能见度不是很好。而午后，尤其是本周三、四两天，能见度会明显好转。京津冀中南部地区比较严重，北部尤其是北京的北部到河北北部相对轻一点。

　　市环保监测中心主任张大伟表示，预计今日受一股弱冷空气影响，污染形势不会彻底改观，本周三、四污染加重，重污染形势将持续至本周五。本周五午后至夜间，受到冷空气影响，能见度转好，污染趋于结束，周六预计空气质量回归至二级良好级别。

　　簸箕地形不利散污

　　从上周三至周五，京城的空气质量均在优良级别。周日23日，全市逐渐转入低压系统，空气质量开始转差。昨日下午，京城空气质量已经达到重度污染级别。

　　张大伟表示，京城每次污染过程来源，都是本地排放和区域传输的叠加。此外，气象条件不利于扩散是主要的外部因素。本次污染主要因为大气中层增温明显，逆温现象严重，就像一个大锅盖罩在京城上空，造成垂直方向上扩散能力转差，近地面的污染排放容易累积，容易形成重污染。此外，偏南风容易携带平原地区的污染入京，北京三面环山的地形，就像污染物被扫进了一个簸箕，扩散不出去。本周五北京局地有降水，预计对污染物清除能力有限。

　　■ 释疑

　　空气重污染但能见度没那么差

　　上个月京城出现的持续重污染过程中，昏暗的天空让人印象深刻。昨日北京发布空气重污染黄色预警，有市民认为感官上污染似乎不那么严重。

　　张大伟表示，跟上次相比，这次能见度还可以，实际上这次的污染物浓度水平并不低。PM2.5浓度水平和能见度不能直接画等号。判断空气污染程度，应以PM2.5的监测数据作为依据，而不是凭感觉或者能见度。

　　他解释称，昨日虽然达到重度污染，但能见度不差，主要因为空气中湿度不大。空气中如果有大量水蒸气，会产生消光作用，从而影响能见度。

　　据了解，近两日白天的相对湿度为40%左右，而2月份污染过程中相对湿度达到了约70%。

　　污染升为橙色预警可能性不大

　　2月末京城持续了一周重污染过程中，北京首次发布了空气重污染橙色预警信号。

　　张大伟表示，跟上次污染过程相比，这次没有上次严重。上次在采暖季，排放强度大，持续时间也长。这次不是采暖季，积累效应没那么大。另外，冬季的逆温层往往比较厚，很难破坏。目前是冬季转入春季交替的时期，逆温层没那么顽固。随着采暖季的结束，污染发生的频率和程度会有所降低。目前看，这次污染过程主要在五级重度污染左右，升级为橙色预警即出现六级严重污染的可能性不大。

(原标题：未来三天 京城持续重污染)

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