1960～2016年江西省霾日变化特征及气候成因分析

Spatiotemporal characteristics of the annual change of haze days and their relations with climatic factors during 1960～2016 in Jiangxi,China

利用江西省1960～2016年82个气象站水平能见度、相对湿度和天气现象等资料,重建了江西省霾日序列,分析了江西省霾日数的年际变化特征,并通过霾日数与降水日数、大风日数和静风日数的相关关系,探讨了不同季节霾日数年际变化的气候成因.结果表明:1960～2016年江西省霾日数表现为在1970s有明显偏高、1980年后显著增加趋势(0.53d/a),赣北地区霾日多且增加速率快.四季霾日数均有增加,其中秋季贡献最大(0.21d/a,P<0.001),春季其次(0.12d/a,P<0.001),冬季霾日数最多,但年际趋势并不显著(0.10d/a,P>0.05),夏季年均霾日数较低,增加幅度最小(0.09d/a,P<0.001).过去几十年降水日数减少(-0.26d/a,P>0.05)导致大气湿沉降能力减弱,以及大风日数减少(-0.33d/a,P<0.01)和静风日数增加(1.73d/a,P<0.01)导致大气扩散能力降低,为江西省霾日增加提供了有利气候背景.但主要气候成因因季节不同:春季霾日数增加的主要气候成因是大风日数减少(r=-0.48,P<0.01),与其他要素的关系不显著;夏季亦与大风日数减少显著相关(r=-0.50,P<0.01),同时与静风日数增加显著相关(r=0.37,P<0.05);秋季受大风日数减少、静风日数增加以及降水日数减少共同影响,导致秋季霾日增加速率最快;冬季霾日数仅与降水日数显著相关(r=-0.36,P<0.05),但由于冬季降水日数变化趋势不明显(-0.26d/a,P>0.05),冬季霾日数变化不显著.

Based on horizontal visibility, relative humidity and weather phenomena obtained from 82 meteorological stations in Jiangxi Province from 1960~2016, haze days were reconstructed and the temporal variations were analysed. Additionally, the attributions of the variation were identified according analysis of the correlation of haze days with precipitation days, high wind days and breeze days. The results showed that the haze days had an obvious peak in the 1970s, followed by an increasing trend since 1980 (0.53d/a, P<0.001). Among the four seasons, increasing haze days in autumn (0.21d/a, P<0.001) contributed most to the annual increasing rate, followed by spring (0.12d/a, P<0.001). In winter, although most haze days happened, the increasing trend was insignificant (0.10d/a, P>0.05). While summer has the least increasing amplitude (0.09d/a, P<0.001). In the past decades, the reduction of atmospheric deposition ability caused by less precipitation days (-0.26d/a, P>0.05), and the reduction of atmospheric diffusion ability caused by fewer high wind days (-0.33d/a, P<0.01) but higher breeze days (1.73d/a, P<0.01), provided advantages for haze increase. However, the main attribution varied between seasons. The major reason for haze increase in spring was the reduction in high wind days (r=-0.48, P<0.01). While in summer, it had significant correlation with both high wind days (r=-0.50, P<0.01) and breeze days (r=0.37, P<0.05). In autumn, haze increase was affected by fewer high wind days, higher breeze days and less precipitation days, leading to the highest increasing rate among four seasons. In winter, haze days has a better correlation with precipitation days (r=-0.36, P<0.05) whose trend was insignificant (-0.26d/a, P>0.05). Thus, winter haze days has an insignificant trend during.