The weather system, meteorological conditions, and microphysics of cloud, fog, and rain droplets are studied during the formation, growth, maintenance, and shedding periods of ice accretion on wires in Enshi, Hubei Pr...The weather system, meteorological conditions, and microphysics of cloud, fog, and rain droplets are studied during the formation, growth, maintenance, and shedding periods of ice accretion on wires in Enshi, Hubei Province in China using 2008/2009 and 2009/2010 winter observations. The comprehensive observations include data of visibility, microphysics of fog and rain droplets, and ice thickness, as well as data from an automated weather station and other routinely recorded meteorological data. The results show that icing occurred during the passage of a cold front, with a high-pressure system and a cold temperature trough at 850 hPa, and a southeasterly at 500 hPa that provided abundant moisture. Ice formation usually started in the evening or early morning, and ice shed around noon the following day when the temperature was -1℃ to 0℃. The averaged liquid water content of the fog droplet was distinctly greater during the growth period than during the other three periods, and there was precipitation during the growth period in each case of ice accretion. The growth rate of the ice thickness was clearly correlated with the liquid water content, with a correlation coefficient of 0.62. Simulations using empirical equations were carried out, and the simulated ice thickness agreed with observations fairly well.展开更多
Several multi-scale numerical simulation experiments were carried out using the mesoscale modeling systems MM5V3.7 and WRFV2.2 for Greater Beijing to estimate the accuracy of WRF and MM5 in simulating the characterist...Several multi-scale numerical simulation experiments were carried out using the mesoscale modeling systems MM5V3.7 and WRFV2.2 for Greater Beijing to estimate the accuracy of WRF and MM5 in simulating the characteristics and variations of mesoscale local circulation in the atmospheric boundary layer of this area. We simulated the horizontal distribution and diurnal variations of temperature and wind fields near the ground and compared them with Automatic Weather System (AWS) data collected from 19 AWS stations in Beijing. Correlation and error analyses were also made. The modeling and statistical results showed that both WRF and MM5 model the temperature field near the ground significantly better than they model the wind field. The temperature field simulated by MM5 is more coincident than that of WRF with the AWS observation records, while WRF does better than MM5 in simulating the wind field, especially under the condition of gusty wind. Neither WRF nor MM5 can capture the fine structure of urban architectural complexity, which is the main error in the wind field simulation. Both models underestimate the land surface temperature at night and overestimate the temperature during the day. All the above results are supported by statistical analysis.展开更多
基金supported by National Key Technology R&D Program of China (Grant No. 2008BAC48B01)National Natural Science Foundation of China (Grant No. 40775012)+1 种基金the Jiangsu Province Qinglan Project for Cloud Fog Precipitation and the Aerosol Research Groupa project funded by the Priority Acadenic Program Development of Jiangsu Higher Education Institutions
文摘The weather system, meteorological conditions, and microphysics of cloud, fog, and rain droplets are studied during the formation, growth, maintenance, and shedding periods of ice accretion on wires in Enshi, Hubei Province in China using 2008/2009 and 2009/2010 winter observations. The comprehensive observations include data of visibility, microphysics of fog and rain droplets, and ice thickness, as well as data from an automated weather station and other routinely recorded meteorological data. The results show that icing occurred during the passage of a cold front, with a high-pressure system and a cold temperature trough at 850 hPa, and a southeasterly at 500 hPa that provided abundant moisture. Ice formation usually started in the evening or early morning, and ice shed around noon the following day when the temperature was -1℃ to 0℃. The averaged liquid water content of the fog droplet was distinctly greater during the growth period than during the other three periods, and there was precipitation during the growth period in each case of ice accretion. The growth rate of the ice thickness was clearly correlated with the liquid water content, with a correlation coefficient of 0.62. Simulations using empirical equations were carried out, and the simulated ice thickness agreed with observations fairly well.
基金supported by National Natural Science Foundation of China (Grant No. 40875004)Urban Meteorology Scientific Research Fund Program of the Institute of Beijing Urban Meteorology, China Meteorological Administration (Grant No. UMRF200702)+2 种基金Public Welfare Special Fund Program (Meteorology) of China Scientific and Technological Ministry (Grant No. GYHY200806020)National Science and Technology Sustain Program (Grant No. 2008BAC37B00)Central Public Welfare Special Fund Program for the Institute and Higher Education (Grant No. IUMKY200701)
文摘Several multi-scale numerical simulation experiments were carried out using the mesoscale modeling systems MM5V3.7 and WRFV2.2 for Greater Beijing to estimate the accuracy of WRF and MM5 in simulating the characteristics and variations of mesoscale local circulation in the atmospheric boundary layer of this area. We simulated the horizontal distribution and diurnal variations of temperature and wind fields near the ground and compared them with Automatic Weather System (AWS) data collected from 19 AWS stations in Beijing. Correlation and error analyses were also made. The modeling and statistical results showed that both WRF and MM5 model the temperature field near the ground significantly better than they model the wind field. The temperature field simulated by MM5 is more coincident than that of WRF with the AWS observation records, while WRF does better than MM5 in simulating the wind field, especially under the condition of gusty wind. Neither WRF nor MM5 can capture the fine structure of urban architectural complexity, which is the main error in the wind field simulation. Both models underestimate the land surface temperature at night and overestimate the temperature during the day. All the above results are supported by statistical analysis.
