为了验证逆康普顿机制的主导过程以及主导过程中软光子的起源,通过文献收集了75个平谱射电类星体(Flat-Spectrum Radio Quasar,FSRQ)多波段的(准)同时数据,并利用对数抛物线函数拟合了频谱能量分布,分析同步峰流量与逆康普顿峰之比和多...为了验证逆康普顿机制的主导过程以及主导过程中软光子的起源,通过文献收集了75个平谱射电类星体(Flat-Spectrum Radio Quasar,FSRQ)多波段的(准)同时数据,并利用对数抛物线函数拟合了频谱能量分布,分析同步峰流量与逆康普顿峰之比和多普勒因子的关系,运用自举法(Bootstrapping)计算了样本的种子因子(Seed Factor,SF)分布,用于调查软光子的起源。分析结果如下:(1)在轻子模型框架下,整个样本与子样本log[U B(νFν)EC/U ext(νFν)syn]和logδ的显著相关性表明,平谱射电类星体的高能辐射优先由外康普顿过程主导。(2)对于相对低同步峰的峰频种群,观测的种子因子分布与理论上尘埃环(Dust Torus,DT)的种子因子范围相交,表明逆康普顿过程中的软光子很可能由尘埃环主导;而对于相对高同步峰的峰频种群,观测的种子因子超过了宽线区(Broad-Line Region,BLR)或尘埃环种子因子的范围,因此无法确定软光子的来源。展开更多
Based on meteorological field and air quality observation data, air pollution process over Pearl River Delta （PRD） in August of 2012 was analyzed. There were five notable pollution processes in this month, in which ...Based on meteorological field and air quality observation data, air pollution process over Pearl River Delta （PRD） in August of 2012 was analyzed. There were five notable pollution processes in this month, in which four pollution processes were related to typhoon. By using meso-scale meteorological model WRF, meteorological characteristics of two pollution processes induced by tropical cyclone were contrasted and analyzed. Results showed that O9 and PMTo concentrations significantly increased in PRD region during Typhoon Haikui period （7 -8 August）, and other pollutant concentrations were also high. However, 03 and PM10 concentrations did not significantly increase during Typhoon Kai-Tak period （16 -17 August）. This kind of concentration difference between two processes was related to typhoon pathway, wind direction and velocity, atmospheric boundary layer height, vertical transport and horizontal divergence field.展开更多
The climatic and environmental effects of atmospheric aerosols are a hot topic in global science community, and radiative properties of the aerosols are one of the important parameters in assessing climatic change. He...The climatic and environmental effects of atmospheric aerosols are a hot topic in global science community, and radiative properties of the aerosols are one of the important parameters in assessing climatic change. Here we studied the black carbon concentration and absorption coefficient measured with aethalometers, scattering coefficient measured with nephelometers, and single scattering albedo derived at an atmospheric composition watch station in Guangzhou from 2004 to 2007. Our main results are as follows. The data of black carbon concentration and absorption coefficients measured with instruments cannot be directly used until they are measured in parallel with internationally accepted instruments for comparison, calibration, and reduction. After evaluation of the data, the result shows that the monthly mean of BC concentration varies 3.1―14.8 μg·m-3 and the concentration decreases by about 1 μg·m-3 in average over the four years; It is higher in the dry season with a multi-year mean of 8.9 μg/m3 and lower in the rainy season with a multi-year mean of 8.0 μg·m-3; The extreme maximum of monthly mean concentration occurred in December 2004 and extreme minimum in July 2007, and a 4-year mean is 8.4 μg·m-3. It is also shown that monthly mean scattering coefficient derived varies 129 -565 Mm-1, monthly mean absorption coefficient 32-139 Mm-1, and monthly mean single scattering albedo 0.71-0.91, with annual mean values of 0.80, 0.82, 0.79 and 0.84 for 2004, 2005, 2006 and 2007, respectively. Three instruments were used to take simultaneous measurements of BC in PM10, PM2.5, and PM1 and the results showed that PM2.5 took up about 90% of PM10 and PM1 accounted for about 68% of PM2.5, and BC aerosols are mainly present in fine particulates. The variability of BC concentrations is quite consistent between the Nancun station (141 m above sea level) and the Panyu station (13 m above sea level), which are 8 km apart from each other. The concentration in higher altitude station (Panyu) is consistently lower than the lower altitude station (Nancun), and the difference of annual mean is about 4 μg·m-3.展开更多
We detected a severe haze process in Guangzhou area with lidar and microwave radiometer, performed an inversion to get boundary layer height by wavelet covariance transform, and analyzed the correlation between meteor...We detected a severe haze process in Guangzhou area with lidar and microwave radiometer, performed an inversion to get boundary layer height by wavelet covariance transform, and analyzed the correlation between meteorological factors of boundary layer and visibility from the perspective of dynamical and thermodynamic structures. Our results indicate that the boundary layer height shows significant daily changes, consistent with ground visibility variation. During the cleaning process, the boundary layer height exceeded 1 km; during severe haze, the height was only 500 m. Temperature gradient of 50–100 m, which was 30 h lag, was remarkably correlated with visibility, with the correlation coefficient of 0.77. High layer visibility(255 m) and low layer stability were significantly anticorrelation, and the maximum anticorrelation coefficient was up to-0.76 in cleaning days and-0.49 in haze days. In the related boundary layer meteorological factors, surface ventilation coefficient was linearly correlated with ground visibility, with the greatest correlation coefficient of 0.88. The correlation coefficients of boundary layer height, ground wind velocity, relative humidity and ground visibility were 0.76, 0.67, and-0.77, respectively. There was a strong correlation between different meteorological factors. The dominant meteorological factor during this haze process was surface ventilation coefficient. In the area without boundary layer height sounding, ground visibility and wind velocity could be used to estimate boundary layer height.展开更多
Our analysis of the surface aerosol and ultraviolet(UV) measurements in Pearl River Delta(PRD) region shows that the sur-face UV radiation is reduced by more than 50% due to high aerosol concentrations.This has import...Our analysis of the surface aerosol and ultraviolet(UV) measurements in Pearl River Delta(PRD) region shows that the sur-face UV radiation is reduced by more than 50% due to high aerosol concentrations.This has important impacts on urban eco-system and photochemistry,especially on ozone photochemical production over the region.The quantitative effect of aerosols on surface ozone is evaluated by analyzing surface observations(including ozone,ultraviolet radiation,aerosol radiative pa-rameters) and by using radiative and chemical models.A case study shows that the aerosol concentrations and UV radiation are significantly correlated with ozone concentrations.The correlation coefficient between the aerosol optical depth(AOD) and the PM10 mass concentration is very high,with a maximum of 0.98,and the AOD and UV radiation/ozone is anti-correlated,with a correlation coefficient of -0.90.The analysis suggests that ozone productivity is significantly decreased due to the reduction of UV radiation.The noon-time ozone maximum is considerably depressed when AOD is 0.6,and is further decreased when AOD is up to 1.2 due to the reduction of ozone photochemical productivity.Because the occurring probability of aerosol optical depth for AOD550 nm≥0.6 and AOD340 nm≥1.0 is 47,and 55% respectively during the dry season(October,November,December,January),this heavy aerosol condition explains the low ozone maximum that often occurs in the dry season over the Guangzhou region.The analysis also suggests that the value of single scattering albedo(SSA) is very sensitive to the aerosol radiative effect when the radiative and chemical models are applied,implying that the value of SSA needs to be carefully studied when the models are used in calculating ozone production.展开更多
The UV attenuation due to atmospheric aerosols in Guangzhou was quantitatively assessed using surface ultraviolet radiation (UV,295-385 nm) observation,sun photometer and radiation models.Observations showed that the ...The UV attenuation due to atmospheric aerosols in Guangzhou was quantitatively assessed using surface ultraviolet radiation (UV,295-385 nm) observation,sun photometer and radiation models.Observations showed that the annual average value of aerosol optical depth (AOD) was 1.19 in UV spectral region of 340 nm,the annual average occurrence frequency of aerosol optical depth AOD 340 nm >1.0 was 55%,and the annual average attenuation rate of surface UV direct radiation of 340 nm was 68%.It was proven in the observation of surface UV radiation and model evaluation that annual average attenuation of UV due to atmosphere was 75%,and that reached 72% in the dry season (October,November,December and January);while average attenuation of UV due to atmospheric aerosols reached 62% in the dry season.It was indicated that very significant UV attenuations due to atmospheric aerosols existed in Guangzhou urban agglomeration,and at least half of UV radiation was attenuated due to atmospheric aerosols.Such large-amplitude attenuation will have a significant impact on urban ecosystem and species chemical cycles,especially photochemical reaction processes.展开更多
基金Supported by National Natural Science Foundation,China(41275100)Public Sector(Meteorological)Scientific Research Project,China(GYHY201306042,GYHY201406031)
文摘Based on meteorological field and air quality observation data, air pollution process over Pearl River Delta （PRD） in August of 2012 was analyzed. There were five notable pollution processes in this month, in which four pollution processes were related to typhoon. By using meso-scale meteorological model WRF, meteorological characteristics of two pollution processes induced by tropical cyclone were contrasted and analyzed. Results showed that O9 and PMTo concentrations significantly increased in PRD region during Typhoon Haikui period （7 -8 August）, and other pollutant concentrations were also high. However, 03 and PM10 concentrations did not significantly increase during Typhoon Kai-Tak period （16 -17 August）. This kind of concentration difference between two processes was related to typhoon pathway, wind direction and velocity, atmospheric boundary layer height, vertical transport and horizontal divergence field.
基金Supported by Natural Science Foundation of China (Grant Nos. U0733004,40375002, 40418008, 40775011)National High Technology R & D Program of China (Grant Nos. 2006AA06A306 and 2006AA06A308)National Basic Research Program of China (Grant No. 2005CB422207)
文摘The climatic and environmental effects of atmospheric aerosols are a hot topic in global science community, and radiative properties of the aerosols are one of the important parameters in assessing climatic change. Here we studied the black carbon concentration and absorption coefficient measured with aethalometers, scattering coefficient measured with nephelometers, and single scattering albedo derived at an atmospheric composition watch station in Guangzhou from 2004 to 2007. Our main results are as follows. The data of black carbon concentration and absorption coefficients measured with instruments cannot be directly used until they are measured in parallel with internationally accepted instruments for comparison, calibration, and reduction. After evaluation of the data, the result shows that the monthly mean of BC concentration varies 3.1―14.8 μg·m-3 and the concentration decreases by about 1 μg·m-3 in average over the four years; It is higher in the dry season with a multi-year mean of 8.9 μg/m3 and lower in the rainy season with a multi-year mean of 8.0 μg·m-3; The extreme maximum of monthly mean concentration occurred in December 2004 and extreme minimum in July 2007, and a 4-year mean is 8.4 μg·m-3. It is also shown that monthly mean scattering coefficient derived varies 129 -565 Mm-1, monthly mean absorption coefficient 32-139 Mm-1, and monthly mean single scattering albedo 0.71-0.91, with annual mean values of 0.80, 0.82, 0.79 and 0.84 for 2004, 2005, 2006 and 2007, respectively. Three instruments were used to take simultaneous measurements of BC in PM10, PM2.5, and PM1 and the results showed that PM2.5 took up about 90% of PM10 and PM1 accounted for about 68% of PM2.5, and BC aerosols are mainly present in fine particulates. The variability of BC concentrations is quite consistent between the Nancun station (141 m above sea level) and the Panyu station (13 m above sea level), which are 8 km apart from each other. The concentration in higher altitude station (Panyu) is consistently lower than the lower altitude station (Nancun), and the difference of annual mean is about 4 μg·m-3.
基金supported by the National Basic Research Program of China(Grant No.2011CB403403)the National Natural Science Foundation of China(Grant Nos.41205123,41375156,1175117)Guangdong Provincial Natural Science Foundation(Grant No.10151008019000004)
文摘We detected a severe haze process in Guangzhou area with lidar and microwave radiometer, performed an inversion to get boundary layer height by wavelet covariance transform, and analyzed the correlation between meteorological factors of boundary layer and visibility from the perspective of dynamical and thermodynamic structures. Our results indicate that the boundary layer height shows significant daily changes, consistent with ground visibility variation. During the cleaning process, the boundary layer height exceeded 1 km; during severe haze, the height was only 500 m. Temperature gradient of 50–100 m, which was 30 h lag, was remarkably correlated with visibility, with the correlation coefficient of 0.77. High layer visibility(255 m) and low layer stability were significantly anticorrelation, and the maximum anticorrelation coefficient was up to-0.76 in cleaning days and-0.49 in haze days. In the related boundary layer meteorological factors, surface ventilation coefficient was linearly correlated with ground visibility, with the greatest correlation coefficient of 0.88. The correlation coefficients of boundary layer height, ground wind velocity, relative humidity and ground visibility were 0.76, 0.67, and-0.77, respectively. There was a strong correlation between different meteorological factors. The dominant meteorological factor during this haze process was surface ventilation coefficient. In the area without boundary layer height sounding, ground visibility and wind velocity could be used to estimate boundary layer height.
基金supported by National Natural Science Foundation of China (Grant Nos. 40875090, 40375002, 40775011)Natural Science Foundation of Guangdong Province (Grant No. 7035008)Tropical Marine Meteorological Science Foundation (Grant No. 200502)
文摘Our analysis of the surface aerosol and ultraviolet(UV) measurements in Pearl River Delta(PRD) region shows that the sur-face UV radiation is reduced by more than 50% due to high aerosol concentrations.This has important impacts on urban eco-system and photochemistry,especially on ozone photochemical production over the region.The quantitative effect of aerosols on surface ozone is evaluated by analyzing surface observations(including ozone,ultraviolet radiation,aerosol radiative pa-rameters) and by using radiative and chemical models.A case study shows that the aerosol concentrations and UV radiation are significantly correlated with ozone concentrations.The correlation coefficient between the aerosol optical depth(AOD) and the PM10 mass concentration is very high,with a maximum of 0.98,and the AOD and UV radiation/ozone is anti-correlated,with a correlation coefficient of -0.90.The analysis suggests that ozone productivity is significantly decreased due to the reduction of UV radiation.The noon-time ozone maximum is considerably depressed when AOD is 0.6,and is further decreased when AOD is up to 1.2 due to the reduction of ozone photochemical productivity.Because the occurring probability of aerosol optical depth for AOD550 nm≥0.6 and AOD340 nm≥1.0 is 47,and 55% respectively during the dry season(October,November,December,January),this heavy aerosol condition explains the low ozone maximum that often occurs in the dry season over the Guangzhou region.The analysis also suggests that the value of single scattering albedo(SSA) is very sensitive to the aerosol radiative effect when the radiative and chemical models are applied,implying that the value of SSA needs to be carefully studied when the models are used in calculating ozone production.
基金supported by the National Natural Science Foundation of China(41175117,40875090and40375002)the National Basic Research Program(2011CB403403)+1 种基金the Science and Technology Foundation of Guangdong Province(2010A030200012)the Science and Technology Innovation Team Plan of Guangdong Meteorological Bureau(201103)
文摘The UV attenuation due to atmospheric aerosols in Guangzhou was quantitatively assessed using surface ultraviolet radiation (UV,295-385 nm) observation,sun photometer and radiation models.Observations showed that the annual average value of aerosol optical depth (AOD) was 1.19 in UV spectral region of 340 nm,the annual average occurrence frequency of aerosol optical depth AOD 340 nm >1.0 was 55%,and the annual average attenuation rate of surface UV direct radiation of 340 nm was 68%.It was proven in the observation of surface UV radiation and model evaluation that annual average attenuation of UV due to atmosphere was 75%,and that reached 72% in the dry season (October,November,December and January);while average attenuation of UV due to atmospheric aerosols reached 62% in the dry season.It was indicated that very significant UV attenuations due to atmospheric aerosols existed in Guangzhou urban agglomeration,and at least half of UV radiation was attenuated due to atmospheric aerosols.Such large-amplitude attenuation will have a significant impact on urban ecosystem and species chemical cycles,especially photochemical reaction processes.
