The first China-US joint dust field experiment was carried out by Lanzhou University, Chinese Academy of Sciences, China Me- teorological Administration, and University of Maryland, the Department of Energy （DOE）, U...The first China-US joint dust field experiment was carried out by Lanzhou University, Chinese Academy of Sciences, China Me- teorological Administration, and University of Maryland, the Department of Energy （DOE）, USA, from April to June, 2008. The observation sites are located at Zhangye National Climatological Observatory, Semi-Arid Climate and Environment Observatory of Lanzhou University （SACOL）, and Jingtai with the Mobile Facilities of SACOL. The measurements of Particle Soot Absorp- tion Photometer and TSI Integrating Nephelometer are used to analyze the aerosol absorption and scattering characteristics over Zhangye. The results are： the aerosol absorption, total scattering, and backscattering coefficients present similar diurnal variation trends with their bi-peaks at 08：00 and 22!00, and they are generally higher in nighttime than in daytime. Their monthly average coefficient is the highest in April, and the!l drops in succession in May and June. Frequency analysis of aerosol single scattering albedo （SSA） shows that the magnitudes＇0f SSA at 450, 550, and 700 nm are mainly within 0.7q3.9. The maximum frequency of SSA at 450 and 700 nm distribute at 0.8, and at 0.85 for 550 nm. The averages of SSA at 450, 550, and 700 nm are 0.72, 0.75, and 0.68, respectively.展开更多
Year-round measurements of the mass concentration and optical properties of fine aerosols （PM2s） from June 2009 to May 2010 at an urban site in Beijing were analyzed. The annual mean values of the PM2.5 mass concent...Year-round measurements of the mass concentration and optical properties of fine aerosols （PM2s） from June 2009 to May 2010 at an urban site in Beijing were analyzed. The annual mean values of the PM2.5 mass concentration, absorption coefficient （Ab）, scattering coefficient （Sc） and single scattering albedo （SSA） at 525 nm were 67 ± 66 μg/m^3, 64 ± 62 Mm^-1, 360±405 Mm^-1 and 0.82±0.09, respectively. The bulk mass absorption efficiency and scattering efficiency of the PM2.5 at 525 nm were 0.78 m^2/g and 5.55 m^2]g, respectively. The Ab and Sc showed a similar diurnal variation with a maximum at night and a minimum in the afternoon, whereas SSA displayed an opposite diurnal pattern. Significant increases in the Ab and Sc were observed in pollution episodes caused by the accumulation of pollutants from both local and regional sources under unfavorable weather conditions. Aerosol loadings in dust events increased by several times in the spring, which had limited effects on the Ab and Sc due to the low absorption and scattering efficiency of dust particles. The frequency of haze days was the highest in autumn because of the high aerosol absorption and scattering under unfavorable weather conditions. The daily PM2.5 concentration should be controlled to a level lower than 64 μg/m^3 to prevent the occurrence of haze days according to its exponentially decreased relationship with visibility.展开更多
We briefly introduce our recent work on the spectral evolution of energetic protons, the beam property of accelerated electrons, the gamma-ray flare classification, the temporal features of the annihilation line, the ...We briefly introduce our recent work on the spectral evolution of energetic protons, the beam property of accelerated electrons, the gamma-ray flare classification, the temporal features of the annihilation line, the hard X-ray delayed events, the hydrodynamic process, and the continuum emission in solar flares.展开更多
基金supported by the National Natural Science Foundation of China (41075104)the Fundamental Research Funds for the Central Universities of Lanzhou University (lzujbky-2011-5)
文摘The first China-US joint dust field experiment was carried out by Lanzhou University, Chinese Academy of Sciences, China Me- teorological Administration, and University of Maryland, the Department of Energy （DOE）, USA, from April to June, 2008. The observation sites are located at Zhangye National Climatological Observatory, Semi-Arid Climate and Environment Observatory of Lanzhou University （SACOL）, and Jingtai with the Mobile Facilities of SACOL. The measurements of Particle Soot Absorp- tion Photometer and TSI Integrating Nephelometer are used to analyze the aerosol absorption and scattering characteristics over Zhangye. The results are： the aerosol absorption, total scattering, and backscattering coefficients present similar diurnal variation trends with their bi-peaks at 08：00 and 22!00, and they are generally higher in nighttime than in daytime. Their monthly average coefficient is the highest in April, and the!l drops in succession in May and June. Frequency analysis of aerosol single scattering albedo （SSA） shows that the magnitudes＇0f SSA at 450, 550, and 700 nm are mainly within 0.7q3.9. The maximum frequency of SSA at 450 and 700 nm distribute at 0.8, and at 0.85 for 550 nm. The averages of SSA at 450, 550, and 700 nm are 0.72, 0.75, and 0.68, respectively.
基金supported by the National Basic Research Program of China(2014CB441202)the National Natural Science Foundation of China(Nos.41175131 and 41305128)the Special Scientific Research Funds for Environment Protection Commonweal Section(No.201409027)
文摘Year-round measurements of the mass concentration and optical properties of fine aerosols （PM2s） from June 2009 to May 2010 at an urban site in Beijing were analyzed. The annual mean values of the PM2.5 mass concentration, absorption coefficient （Ab）, scattering coefficient （Sc） and single scattering albedo （SSA） at 525 nm were 67 ± 66 μg/m^3, 64 ± 62 Mm^-1, 360±405 Mm^-1 and 0.82±0.09, respectively. The bulk mass absorption efficiency and scattering efficiency of the PM2.5 at 525 nm were 0.78 m^2/g and 5.55 m^2]g, respectively. The Ab and Sc showed a similar diurnal variation with a maximum at night and a minimum in the afternoon, whereas SSA displayed an opposite diurnal pattern. Significant increases in the Ab and Sc were observed in pollution episodes caused by the accumulation of pollutants from both local and regional sources under unfavorable weather conditions. Aerosol loadings in dust events increased by several times in the spring, which had limited effects on the Ab and Sc due to the low absorption and scattering efficiency of dust particles. The frequency of haze days was the highest in autumn because of the high aerosol absorption and scattering under unfavorable weather conditions. The daily PM2.5 concentration should be controlled to a level lower than 64 μg/m^3 to prevent the occurrence of haze days according to its exponentially decreased relationship with visibility.
基金the National Natural Science Foundation of China (Grant Nos. 19525308, 9883002, 49990451, 10173027) Ministry of Science and Technology of China(G2000078402).
文摘We briefly introduce our recent work on the spectral evolution of energetic protons, the beam property of accelerated electrons, the gamma-ray flare classification, the temporal features of the annihilation line, the hard X-ray delayed events, the hydrodynamic process, and the continuum emission in solar flares.
