The Climatic Characteristics and Change of Haze Days in Henan Province Since 1981
Zhang Fang;Gu Wanlong;Ji Xingjie;Henan Provincial Climate Centre;
Based on meteorological data during 1981- 2010 from 108 ground stations in Henan province,and by using weather factors and weather phenomena data measured at 14: 00 daily,haze days are identified. Change characteristics of haze days of Henan are analyzed on the basis of statistical data of haze days from each station,and the possible reasons are analyzed. Results show that the number of annual haze days in Henan since 1981 increases obviously with an increasing rate of 4. 2 d /10a. The seasonal change of the haze presents the highest number of the winter haze,which account for 46. 2% of the whole year,the haze days in Autumn rank second,and spring and summer are the lowest. The main haze there is mild,which accounted for above 90% of the proportion of the total haze; the haze weather occurred with the relative humidity below 60% and with the visibility less than 3 km; For nearly 30 years,the annual mean wind speed had tended to decrease,the number of annual days with wind force f ≥10 m/s had also decreased,and the number of annual breeze days had obviously risen; Analysis on correlation among haze days,wind speed and precipitation indicates that the number of haze days is obviously negative correlated with wind speed,and is significant negative correlated with precipitation,but related closest with wind speed. In addition,there is a corresponding relationship between the change of haze days and atmospheric pollution emissions caused by human activities. In conclusion,for nearly 30 years the decrease of wind speed might be the main climate reason which the number of haze days increases and meantime the increase of pollution emissions is also one of the possible reasons in Henan.