This study investigates the cloud macro-and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in ...This study investigates the cloud macro-and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in Shandong province on 21 May 2018,based on the observations from the aircraft,the Suomi National Polar-Orbiting Partnership(NPP)satellite,and the high-resolution Himawari-8(H8)satellite.The aircraft observations show that convection was deeper and radar echoes were significantly enhanced with higher tops in response to seeding in the convective region.This is linked with the conversion of supercooled liquid droplets to ice crystals with released latent heat,resulting in strengthened updrafts,enhanced radar echoes,higher cloud tops,and more and larger precipitation particles.In contrast,in the stratiform cloud region,after the Silver Iodide(AgI)seeding,the radar echoes become significantly weaker at heights close to the seeding layer,with the echo tops lowered by 1.4–1.7 km.In addition,a hollow structure appears at the height of 6.2–7.8 km with a depth of about 1.6 km and a diameter of about 5.5 km,and features such as icing seeding tracks appear.These suggest that the transformation between droplets and ice particles was accelerated by the seeding in the stratiform part.The NPP and H8 satellites also show that convective activity was stronger in the convective region after seeding;while in the stratiform region,a cloud seeding track with a width of 1–3 km appears 10 km downstream of the seeding layer 15 minutes after the AgI seeding,which moves along the wind direction as width increases.展开更多
Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four ...Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four flights were analyzed. The vertical distributions of aerosol optical properties including aerosol scattering coefficients（σsc）, absorption coefficients（σab）,Angstr？m exponent（α）, single scattering albedo（ω）, backscattering ratio（βsc）, aerosol mass scattering proficiency（Q sc） and aerosol surface scattering proficiency（Q sc′） were obtained. The mean statistical values of σsc were 77.45 Mm-1（at 450 nm）, 50.72 Mm-1（at 550 nm）, and32.02 Mm-1（at 700 nm）. The mean value of σab was 7.62 Mm-1（at 550 nm）. The mean values ofα, βsc and ω were 1.93, 0.15, and 0.91, respectively. Aerosol concentration decreased with altitude. Most effective diameters（ED） of aerosols were less than 0.8 μm. The vertical profiles of σsc,, α, βsc, Q sc and Q sc′ showed that the aerosol scattering properties at lower levels contributed the most to the total aerosol radiative forcing. Both α and βsc had relatively large values, suggesting that most aerosols in the observational region were small particles. The mean values of σsc, α, βsc, Q sc, Q sc′, σab and ω at different height ranges showed that most of the parameters decreased with altitude. The forty-eight hour backward trajectories of air masses during the observation days indicated that the majority of aerosols in the lower level contributed the most to the total aerosol loading, and most of these particles originated from local or regional pollution emissions.展开更多
基金supported by the National Key Research and Development Project(Grant No.2019YFA0606803,2016YFA0601704)the National Natural Science Foundation of China(Grant No.41925022)+1 种基金the Innovation and Development Project of China Meteorological Administration(CXFZ2022J036)the Science and Technology Development Fund of Hubei Meteorological Bureau(Grant No.2017Y06,2017Y07,2016Y06,2019Y10).
文摘This study investigates the cloud macro-and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in Shandong province on 21 May 2018,based on the observations from the aircraft,the Suomi National Polar-Orbiting Partnership(NPP)satellite,and the high-resolution Himawari-8(H8)satellite.The aircraft observations show that convection was deeper and radar echoes were significantly enhanced with higher tops in response to seeding in the convective region.This is linked with the conversion of supercooled liquid droplets to ice crystals with released latent heat,resulting in strengthened updrafts,enhanced radar echoes,higher cloud tops,and more and larger precipitation particles.In contrast,in the stratiform cloud region,after the Silver Iodide(AgI)seeding,the radar echoes become significantly weaker at heights close to the seeding layer,with the echo tops lowered by 1.4–1.7 km.In addition,a hollow structure appears at the height of 6.2–7.8 km with a depth of about 1.6 km and a diameter of about 5.5 km,and features such as icing seeding tracks appear.These suggest that the transformation between droplets and ice particles was accelerated by the seeding in the stratiform part.The NPP and H8 satellites also show that convective activity was stronger in the convective region after seeding;while in the stratiform region,a cloud seeding track with a width of 1–3 km appears 10 km downstream of the seeding layer 15 minutes after the AgI seeding,which moves along the wind direction as width increases.
基金supported partially by the Ministry of Science and Technology of China under its national key project on global change studies (No.2013CB955804)the Special Fund for doctorate programs in Chinese Universities (No.20113228110002)+1 种基金the Public Meteorology Special Foundation of MOST (No.GYHY201306065)the Shanxi Meteorological Bureau Key Research Projects (No.SXKZDTC20140605)
文摘Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four flights were analyzed. The vertical distributions of aerosol optical properties including aerosol scattering coefficients（σsc）, absorption coefficients（σab）,Angstr？m exponent（α）, single scattering albedo（ω）, backscattering ratio（βsc）, aerosol mass scattering proficiency（Q sc） and aerosol surface scattering proficiency（Q sc′） were obtained. The mean statistical values of σsc were 77.45 Mm-1（at 450 nm）, 50.72 Mm-1（at 550 nm）, and32.02 Mm-1（at 700 nm）. The mean value of σab was 7.62 Mm-1（at 550 nm）. The mean values ofα, βsc and ω were 1.93, 0.15, and 0.91, respectively. Aerosol concentration decreased with altitude. Most effective diameters（ED） of aerosols were less than 0.8 μm. The vertical profiles of σsc,, α, βsc, Q sc and Q sc′ showed that the aerosol scattering properties at lower levels contributed the most to the total aerosol radiative forcing. Both α and βsc had relatively large values, suggesting that most aerosols in the observational region were small particles. The mean values of σsc, α, βsc, Q sc, Q sc′, σab and ω at different height ranges showed that most of the parameters decreased with altitude. The forty-eight hour backward trajectories of air masses during the observation days indicated that the majority of aerosols in the lower level contributed the most to the total aerosol loading, and most of these particles originated from local or regional pollution emissions.
