Temporal and spatial characteristics of haze days with different intensities and the climatic factors during 1961—2013 in Liaoning Province
Cui Ya · Acta Scientiae Circumstantiae · 2015
Temporal and spatial characteristics of haze days with varied intensity and the possible climatic factors have been analyzed by applying meteorological data from 52 surface weather stations in Liaoning Province between 1961 and 2013. In terms of spatial distribution,there is a high-value center located in Shenyang City and two sub-high-value centers in the southwest of Jinzhou City and in the east of Chaoyang City,where annual total haze events generally exceed 50 days. The number of haze days in the western and northeastern mountainous areas is the lowest with less than 10 days a year.Haze events are more frequently observed in winter and autumn,accounting for over 60% of annual total,followed by summer and least frequently in spring. Averaged number of annual haze days in Liaoning Province have a significant increasing trend of 3. 5 d / decade during 1961—2013. Days with slight,mild and moderate haze increase significantly,but the days with severe haze have no significant change. Unfavorable climate conditions exacerbated the occurrence of haze events. Significantly negative correlation is found between haze days and precipitation days,and the precipitation days show an obvious decreasing trend in the province,probably reducing the wet-depositing capacity of atmospheric pollutants. On the other hand,the reduced mean wind speed and strong wind days lead to the reduction of pollutants diffusion capacity.