Based on data of number of fog and haze days in Baoji City from 1981 to 2013,the changing trends and mutation of number of fog and haze days in Baoji over the past 33 years were analyzed by using trend coefficient,ten...Based on data of number of fog and haze days in Baoji City from 1981 to 2013,the changing trends and mutation of number of fog and haze days in Baoji over the past 33 years were analyzed by using trend coefficient,tendency rate,linear regression analysis,anomaly percentage,Mann-Kendall mutation test and sliding t test.The results showed that during the 33 years,the number of fog and haze days in Baoji declined by 16.253d/10 a,and there was a cyclical turbulence every 6,15 or 28years.The frequency of fog and haze weather was the highest in winter,followed by spring and autumn,while it was the lowest in summer.According to the anomaly percentage of the number of fog and haze days in 12 months during 1981-2013,the anomaly percentage changed most greatly in July,followed by September,October,April,May,June,August,February and March,but it fluctuated less greatly in January.The number of fog and haze days from 1981 to 2013had obvious mutation trends in a single year and a single season,and mutation types are different.展开更多
For data of atmospheric composition missing, fog and haze days were distinguished based on the standard of meteorological industry Observation and Forecasting Levels of Haze （QX/T113-2010） and four user-defined stan...For data of atmospheric composition missing, fog and haze days were distinguished based on the standard of meteorological industry Observation and Forecasting Levels of Haze （QX/T113-2010） and four user-defined standards, and using data of surface meteorological factors in Fuzhou City, China from 2005 to 2011, temporal distributions of fog and haze days were analyzed respectively to provide methods for fog and haze forecast. The results showed that there were 28.9 fog days and 89.7 haze days per year in Fuzhou. Both fog and haze days were variable, and there might be a day difference of twice to thrice among the years. They were the most in 2007, and then decreased in recent years. Both fog and haze days were more in winter and spring, accounted for 94.1% and 70.1% respectively, while in summer and autumn, they only accounted for 5.9% and 29.9% respectively. In a day, fog mainly occurred from night to early morning, while haze occurred mainly at about noon, which demonstrated that fog and haze are different synoptic phenomena. The mass concentration of PM2.5 in fog days was 34 μg/m^3, while it was 61 μg/m^3 in haze days, and in 22% of haze days it was larger than 75 μg/m3, which was above the national second-grade ambient air quality standard.展开更多
Based on the observation data of the annual number of haze days,rainy days,fog days and gale days,sunshine hours,relative humidity and maximum wind speed at Hangzhou station from 1960 to 2021,the variation characteris...Based on the observation data of the annual number of haze days,rainy days,fog days and gale days,sunshine hours,relative humidity and maximum wind speed at Hangzhou station from 1960 to 2021,the variation characteristics of haze days and meteorological influencing factors were studied by mathematical statistical methods such as Mann-Kendall nonparametric test,sliding T test,wavelet analysis and Pearson correlation two-tailed test.The results show that the annual number of haze days generally showed an upward trend,and the climate tendency rate was 20 d/a;there was a sudden change around 2001,and it changed from stable to rapid growth;the number of haze days was the largest in spring and winter,followed by autumn,while it was the smallest in summer.The annual number of haze days had a strongly significant period of 40 a and a mesoscale variation period of 13 a.The number of haze days was negatively correlated with the number of rainy days,fog days and gale days,sunshine hours,relative humidity and maximum wind speed,which passed the 0.05 significance test.In recent 60 years,the number of rainy days and gale days,relative humidity,and maximum wind speed in Hangzhou have decreased,resulting in the weakening of atmospheric wet deposition capacity and power transmission conditions,which provided favorable meteorological conditions for the increase of haze weather.展开更多
An extensive field experiment for measurement of physical and chemical properties of aerosols was conducted at an urban site in the Chinese Academy of Meteorological Sciences（CAMS） in Beijing and at a rural site in ...An extensive field experiment for measurement of physical and chemical properties of aerosols was conducted at an urban site in the Chinese Academy of Meteorological Sciences（CAMS） in Beijing and at a rural site in Gucheng（GC）, Hebei Province in December 2016. This paper compares the number size distribution of submicron particle matter（PM1, diameter 〈 1 μm） between the two sites. The results show that the mean PM1 number concentration at GC was twice that at CAMS, and the mass concentration was three times the amount at CAMS. It is found that the accumulation mode（100–850 nm） particles constituted the largest fraction of PM1 at GC, which was significantly correlated with the local coal combustion, as confirmed by a significant relationship between the accumulation mode and the absorption coefficient of soot particles. The high PM1 concentration at GC prevented the occurrence of new particle formation（NPF） events, while eight such events were observed at CAMS. During the NPF events, the mass fraction of sulfate increased significantly, indicating that sulfate played an important role in NPF. The contribution of regional transport to PM1 mass concentration was approximately 50% at both sites, same as that of the local emission. However, during the red-alert period when emission control took place, the contribution of regional transport was notably higher.展开更多
基金Supported by the National Natural Science Foundation of China(41071359)
文摘Based on data of number of fog and haze days in Baoji City from 1981 to 2013,the changing trends and mutation of number of fog and haze days in Baoji over the past 33 years were analyzed by using trend coefficient,tendency rate,linear regression analysis,anomaly percentage,Mann-Kendall mutation test and sliding t test.The results showed that during the 33 years,the number of fog and haze days in Baoji declined by 16.253d/10 a,and there was a cyclical turbulence every 6,15 or 28years.The frequency of fog and haze weather was the highest in winter,followed by spring and autumn,while it was the lowest in summer.According to the anomaly percentage of the number of fog and haze days in 12 months during 1981-2013,the anomaly percentage changed most greatly in July,followed by September,October,April,May,June,August,February and March,but it fluctuated less greatly in January.The number of fog and haze days from 1981 to 2013had obvious mutation trends in a single year and a single season,and mutation types are different.
基金Supported by the Key Project of Science and Technology Department of Fujian Province,China in 2012(2012Y0009)
文摘For data of atmospheric composition missing, fog and haze days were distinguished based on the standard of meteorological industry Observation and Forecasting Levels of Haze （QX/T113-2010） and four user-defined standards, and using data of surface meteorological factors in Fuzhou City, China from 2005 to 2011, temporal distributions of fog and haze days were analyzed respectively to provide methods for fog and haze forecast. The results showed that there were 28.9 fog days and 89.7 haze days per year in Fuzhou. Both fog and haze days were variable, and there might be a day difference of twice to thrice among the years. They were the most in 2007, and then decreased in recent years. Both fog and haze days were more in winter and spring, accounted for 94.1% and 70.1% respectively, while in summer and autumn, they only accounted for 5.9% and 29.9% respectively. In a day, fog mainly occurred from night to early morning, while haze occurred mainly at about noon, which demonstrated that fog and haze are different synoptic phenomena. The mass concentration of PM2.5 in fog days was 34 μg/m^3, while it was 61 μg/m^3 in haze days, and in 22% of haze days it was larger than 75 μg/m3, which was above the national second-grade ambient air quality standard.
基金Supported the Key Project of Zhejiang Meteorological Bureau(2019ZD14).
文摘Based on the observation data of the annual number of haze days,rainy days,fog days and gale days,sunshine hours,relative humidity and maximum wind speed at Hangzhou station from 1960 to 2021,the variation characteristics of haze days and meteorological influencing factors were studied by mathematical statistical methods such as Mann-Kendall nonparametric test,sliding T test,wavelet analysis and Pearson correlation two-tailed test.The results show that the annual number of haze days generally showed an upward trend,and the climate tendency rate was 20 d/a;there was a sudden change around 2001,and it changed from stable to rapid growth;the number of haze days was the largest in spring and winter,followed by autumn,while it was the smallest in summer.The annual number of haze days had a strongly significant period of 40 a and a mesoscale variation period of 13 a.The number of haze days was negatively correlated with the number of rainy days,fog days and gale days,sunshine hours,relative humidity and maximum wind speed,which passed the 0.05 significance test.In recent 60 years,the number of rainy days and gale days,relative humidity,and maximum wind speed in Hangzhou have decreased,resulting in the weakening of atmospheric wet deposition capacity and power transmission conditions,which provided favorable meteorological conditions for the increase of haze weather.
基金Supported by the National Key Project of Ministry of Science and Technology of China(2016YFC0203306 and 2016YFC0203305)Chinese Academy of Meteorological Sciences Basic Research Fund(2017Z011,2016Z001,and 2016Y004)
文摘An extensive field experiment for measurement of physical and chemical properties of aerosols was conducted at an urban site in the Chinese Academy of Meteorological Sciences（CAMS） in Beijing and at a rural site in Gucheng（GC）, Hebei Province in December 2016. This paper compares the number size distribution of submicron particle matter（PM1, diameter 〈 1 μm） between the two sites. The results show that the mean PM1 number concentration at GC was twice that at CAMS, and the mass concentration was three times the amount at CAMS. It is found that the accumulation mode（100–850 nm） particles constituted the largest fraction of PM1 at GC, which was significantly correlated with the local coal combustion, as confirmed by a significant relationship between the accumulation mode and the absorption coefficient of soot particles. The high PM1 concentration at GC prevented the occurrence of new particle formation（NPF） events, while eight such events were observed at CAMS. During the NPF events, the mass fraction of sulfate increased significantly, indicating that sulfate played an important role in NPF. The contribution of regional transport to PM1 mass concentration was approximately 50% at both sites, same as that of the local emission. However, during the red-alert period when emission control took place, the contribution of regional transport was notably higher.
