华北地区温度和风速对冬季灰霾形成的潜在影响

Potential impacts of temperature and wind on winter haze in North China

针对华北地区灰霾日渐严重的问题,利用1973—2012年地面气象观测数据,从冬季采暖耗能排污和平均风速变化的角度,结合Mann-Kendall法分析了气候变化背景下华北冬季灰霾相关气象因素的长时间尺度演化规律。研究表明,华北大部地区冬季平均风速明显下降,影响大气污染物稀释扩散,容易积累高浓度污染,有助于抬升灰霾发生的频率和强度;除个别地区受气候变化引发极寒事件影响、采暖度日变化趋势持平外,华北各地受长时间尺度上气候变化所致冬季增温效应影响,采暖日和采暖度日整体呈下降趋势,采暖耗能排污减少,有利于降低粉尘污染排放。因华北地区统一采用固定120 d时限的供暖制度,采暖日和采暖度日的下降并没有转化为采暖耗能排污的下降,个别城市采暖度日甚至有所上升。因华北南部及沿海站点计算得到的采暖日明显低于120 d,在这些城市根据天气条件试行灵活供暖,可能明显降低冬季采暖耗能排污,有助于消解雾霾。

Weather observation data of North China from 1973 to 2012 were investigated to analyze long term variation trend of haze related meteorological conditions. The Mann-Kendall test was utilized to analyze their variation trends and mutation points. It is uncovered that there is notable reduction in wind speed during past decades, which is adverse for diffusion of haze and could contribute to escalating frequency and intensity of haze. The escalated surface temperature in winter results in the reduction in heating clay and heating degree days （HDD） and the associated reduction in heating demand and the air pollution under the context of climate change. However, heating degree days in some sites do not decline due to extreme cold waves. The effect of re- duction in Heating days and HDD on heating demand and 120 heating days policy. Moreover, HDD calculated with a a little. Since heating days of warm cities in the south and air pollution in winter has been weakened due to fix fixed date of heating in Beijing and Taiyuan escalates coastal North China are lower mentation of a flexible heating policy in these cities could reduce heating demand and air than 120 days, imple- pollution at large.