陕西省冬季霾天气的背景环流与欧亚大陆积雪深度的联系

Relationship between the Associated Background Circulations of the Winter Haze Days in Shaanxi Province and the Snow Depth in Eurasia

基于1980-2017年陕西省地面气象观测站观测资料、NCEP/NCAR月平均再分析资料和日本JRA-55再分析陆地雪深资料,对1980-2016年陕西冬季霾日数的时空变化及可能原因进行了分析。根据陕西冬季霾日数偏多年与偏少年的高度场环流背景,研究了影响陕西省冬季霾日数的主要环流系统。对欧亚大陆积雪深度分布对于陕西省冬季霾日数的影响进行了探讨。研究表明:(1)乌拉尔山地区的500 hPa高度场负(正)异常中心,是有利于陕西省冬季霾日数增多(减少)的大气背景环流,影响陕西省霾日数变化的海平面气压存在地中海地区与中亚至西伯利亚地区反位相变化的特征。(2)欧洲地区积雪深度增加(减小),会造成陕西省冬季霾日数的减少(增多)的气象条件。(3)欧亚大陆积雪深度分布与陕西省冬季霾日数的相关呈现欧洲地区与西伯利亚地区反位相的分布,冬季积雪深度指数与陕西省冬季霾日数相关大于0.41,积雪深度指数正(负)异常会造成乌拉山地区位势高度负(正)异常,不利于(有利于)冷空气向东亚移动,造成有利于陕西省冬季霾日数的增多(减少)的气象条件。

Based on daily observations from ground-level stations,monthly NCEP/NCAR reanalysis dataset and JRA-55 snow depth dataset,the interannual variation characteristics of haze days in Shaanxi province and the variations reason were analyzed.According to the background of the height field circulations of winter haze days in Shaanxi province,the main circulations systems affecting the number of winter haze days in Shaanxi province were studied.Meanwhile,the impact of the snow depth in Eurasia on the number of winter haze days was discussed.The main conclusions were as follows:(1)The negative(positive)anomaly center of the atmospheric circulations at 500 hPa over the Ural mountains is the background circulation of the increase(reduction)of the haze days in Shaanxi province in winter.The meteorological conditions conductive to the increase(reduction)of the haze days in Shaanxi province in winter was characterized by the opposite phase of sea level pressure between the Mediterranean and central Asia to Siberia.(2)The increase(decrease)of the snow depth in Europe could build up some meteorological conditions conductive to the decrease(increase)of the haze days in Shaanxi province in winter.(3)The correlations between the snow depth in Eurasia and the number of winter haze days in Shaanxi province showed an inverse distribution between Europe and west Siberia,the correlation coefficient between snow depth index and haze days in Shaanxi Province was greater than 0.41,the positive(negative)snow depth index could cause the negative(positive)height anomaly of the circulations over the Ural mountains,which will lead to the weakening(strengthening)of the cold air moving to East Asia and the meteorological conditions conducive to the increase(decrease)of the haze days in Shaanxi province in winter.