To further reveal the variation laws of ultraviolet radiation to provide better service for production and people＇s life, based on observation data of solar ultraviolet radiation obtained by Xilinhot National Climate...To further reveal the variation laws of ultraviolet radiation to provide better service for production and people＇s life, based on observation data of solar ultraviolet radiation obtained by Xilinhot National Climate Observatory in 2007-2012, the variation laws of solar ultraviolet radiation and its relationship with meteorological factors in different cloud conditions in Xilinhote were analyzed by using the mathematical and statistical methods and SPSS 11.5 software. The results showed that the solar ultraviolet radiation had obvious daily, seasonal and annual variations; the solar ultraviolet radiation was weak in the morning and evening but strong at noon; the maximum appeared from June to August, while the minimum appeared in November and December. It had significant correlation with total solar radiation, photosynthetically active radiation, air temperature, air humidity and ground temperature （0-5 cm）. At present, the maximum intensity of ultraviolet radiation （UV-B） was 0.20-1.91 W/m2 from January to March and 0.13-1.43 W/m2 from October to De- cember respectively, which were lower than the safety standard for people and animals （2 W/mZ）. However, the maximum might appear from April to September, ranging from 2.02 to 3.39 W/m2, which was easy to bring a threat and harm to people and animals.展开更多
The output power variability of photovoltaic(PV)power plants(PVPPs)is one of the major challenges for the op-eration and control of power systems.The short-term power variations,mainly caused by cloud movements,affect...The output power variability of photovoltaic(PV)power plants(PVPPs)is one of the major challenges for the op-eration and control of power systems.The short-term power variations,mainly caused by cloud movements,affect voltage magnitude and frequency,which may degrade power quality and power system reliability.Comprehensive analyses of these power variations are crucial to formulate novel control ap-proaches and assist power system operators in the operation and control of power systems.Thus,this paper proposes a simu-lation-based approach to assessing short-term power variations caused by clouds in PV power plants.A comprehensive assess-ment of the short-term power variations in a PV power plant operating under cloud conditions is another contribution of this paper.The performed analysis evaluates the individual impact of multiple weather condition parameters on the magnitude and ramp rate of the power variations.The simulation-based ap-proach synthesizes the solar irradiance time series using three-dimensional fractal surfaces.The proposed assessment ap-proach has shown that the PVPP nominal power,timescale,cloud coverage level,wind speed,period of the day,and shadow intensity level significantly affect the characteristics of the pow-ervariations.展开更多
In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding catalysts.Our objective was to elucidate the mech...In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding catalysts.Our objective was to elucidate the mechanism of snowfall enhancement in stratiform clouds in the Bayanbulak test area of Xinjiang,China.The results indicated that the optimal seeding time was the early stages of weather system development.In this case,the optimal seeding zone was identified as the northwest of the test area,especially near the cloud top(altitudes between 3500 and 4000 m,temperatures range−11 to−15℃),and the ideal concentration of catalyst was with ice crystal density of 1.0×10^(7)kg^(−1)within the target area.Under such conditions,the total precipitation rate in the seeding-affected area increased to 50.1 mm h^(−1).The results also showed that the favorable seeding region was featured by high content of supercooled water and low population of natural ice crystals,where artificial ice crystals could substantially increase the snowfall.This augmentation typically appeared in a unimodal pattern,with the peak formed within 2–3 h after seeding.Seeding in the ice–water mixed zone of a supercooled cloud facilitated rapid ice crystal growth to snow-flake pieces via the Bergeron process,which in turn consumed more supercooled water via collision–coalescence with cloud water droplets.Simultaneously,the intensive consumption of supercooled water impeded the riming process and reduced the formation of graupel particles within the cloud.The dispersion of artificial ice crystals extended over tens of kilometers horizontally;however,in the vertical direction most particles remained approximately 1 km below the seeding layer,due to limited vertical ascent rate in the stratiform clouds restricting upward movement of artificial ice crystals.The above results help better understand the snowfall enhancement mechanism in stratiform clouds and facilitate related weather modification practice.展开更多
The upward lightning(UL) initiated from the top of tall buildings(at least above 100 m) is a type of atmospheric discharge. Currently, we understand the nature of the UL from ground observations, but the corresponding...The upward lightning(UL) initiated from the top of tall buildings(at least above 100 m) is a type of atmospheric discharge. Currently, we understand the nature of the UL from ground observations, but the corresponding theoretical research is lacking. Based on an existing bidirectional leader stochastic model, a stochastic parameterization scheme for the UL has been built and embedded in an existing two-dimensional thundercloud charge/discharge model. The ULs simulated from the experiments with two-dimensional high resolution agree generally with the observation results. By analyzing the charge structure of thunderstorm clouds, we determined the in-cloud environmental characteristics that favor the initiation of conventional cloud-to-ground(CG) flashes and analyzed the differences and similarities of some characteristics of the positive and the negative UL. Simulation results indicate that the positive ULs are typically other-lightning-triggered ULs(OLTUL) and are usually a discharge phenomenon between the ground and the lower positive charge region appearing below the main middle negative charge region. The effect of the previous in-cloud lightning(IC) process of space electrical field provides favorable conditions for the initiation of a positive UL. Its entire discharge process is limited, and the branches of the leader are fewer in number as its discharge is not sufficient. A negative UL is generally a discharge phenomenon of the dipole charge structure between the ground and the main negative charge region. The lower temperature stratification and the sinking of the hydrometeors typically initiate a negative UL. Negative ULs develop strongly and have more branches. The OLTUL is initiated mainly during the development stage of a thunderstorm, while the self-triggered UL(STUL) is initiated mainly during the dissipation stage of a thunderstorm.展开更多
基金Supported by Scientific Research Project of Public Welfare Industry(Meteorology)(GYHY201506001-2)~~
文摘To further reveal the variation laws of ultraviolet radiation to provide better service for production and people＇s life, based on observation data of solar ultraviolet radiation obtained by Xilinhot National Climate Observatory in 2007-2012, the variation laws of solar ultraviolet radiation and its relationship with meteorological factors in different cloud conditions in Xilinhote were analyzed by using the mathematical and statistical methods and SPSS 11.5 software. The results showed that the solar ultraviolet radiation had obvious daily, seasonal and annual variations; the solar ultraviolet radiation was weak in the morning and evening but strong at noon; the maximum appeared from June to August, while the minimum appeared in November and December. It had significant correlation with total solar radiation, photosynthetically active radiation, air temperature, air humidity and ground temperature （0-5 cm）. At present, the maximum intensity of ultraviolet radiation （UV-B） was 0.20-1.91 W/m2 from January to March and 0.13-1.43 W/m2 from October to De- cember respectively, which were lower than the safety standard for people and animals （2 W/mZ）. However, the maximum might appear from April to September, ranging from 2.02 to 3.39 W/m2, which was easy to bring a threat and harm to people and animals.
基金supported in part by the Coordenacao de Aperfeicoamento de Pessoal de Nível Superior-Brasil (CAPES)-Finance Code 001UTFPR-Campus Pato Branco, FINEP, SETI, CNPq, and Fundacao Araucária for scholarships and funding
文摘The output power variability of photovoltaic(PV)power plants(PVPPs)is one of the major challenges for the op-eration and control of power systems.The short-term power variations,mainly caused by cloud movements,affect voltage magnitude and frequency,which may degrade power quality and power system reliability.Comprehensive analyses of these power variations are crucial to formulate novel control ap-proaches and assist power system operators in the operation and control of power systems.Thus,this paper proposes a simu-lation-based approach to assessing short-term power variations caused by clouds in PV power plants.A comprehensive assess-ment of the short-term power variations in a PV power plant operating under cloud conditions is another contribution of this paper.The performed analysis evaluates the individual impact of multiple weather condition parameters on the magnitude and ramp rate of the power variations.The simulation-based ap-proach synthesizes the solar irradiance time series using three-dimensional fractal surfaces.The proposed assessment ap-proach has shown that the PVPP nominal power,timescale,cloud coverage level,wind speed,period of the day,and shadow intensity level significantly affect the characteristics of the pow-ervariations.
基金Supported by the Scientific Research Project of the Bayingol Mongolian Autonomous Prefecture in Xinjiang(202318)China Meteorological Administration(CMA)Weather Modification Centre Innovation Team Project(WMC2023IT01)CMA Key Innovation Team Project(CMA2022ZD10).
文摘In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding catalysts.Our objective was to elucidate the mechanism of snowfall enhancement in stratiform clouds in the Bayanbulak test area of Xinjiang,China.The results indicated that the optimal seeding time was the early stages of weather system development.In this case,the optimal seeding zone was identified as the northwest of the test area,especially near the cloud top(altitudes between 3500 and 4000 m,temperatures range−11 to−15℃),and the ideal concentration of catalyst was with ice crystal density of 1.0×10^(7)kg^(−1)within the target area.Under such conditions,the total precipitation rate in the seeding-affected area increased to 50.1 mm h^(−1).The results also showed that the favorable seeding region was featured by high content of supercooled water and low population of natural ice crystals,where artificial ice crystals could substantially increase the snowfall.This augmentation typically appeared in a unimodal pattern,with the peak formed within 2–3 h after seeding.Seeding in the ice–water mixed zone of a supercooled cloud facilitated rapid ice crystal growth to snow-flake pieces via the Bergeron process,which in turn consumed more supercooled water via collision–coalescence with cloud water droplets.Simultaneously,the intensive consumption of supercooled water impeded the riming process and reduced the formation of graupel particles within the cloud.The dispersion of artificial ice crystals extended over tens of kilometers horizontally;however,in the vertical direction most particles remained approximately 1 km below the seeding layer,due to limited vertical ascent rate in the stratiform clouds restricting upward movement of artificial ice crystals.The above results help better understand the snowfall enhancement mechanism in stratiform clouds and facilitate related weather modification practice.
基金supported by the National Key Basic Research Development Program of China (Grant No. 2014CB441403)the National Natural Science Foundation of China (Grant Nos. 41175003 & 41475003)
文摘The upward lightning(UL) initiated from the top of tall buildings(at least above 100 m) is a type of atmospheric discharge. Currently, we understand the nature of the UL from ground observations, but the corresponding theoretical research is lacking. Based on an existing bidirectional leader stochastic model, a stochastic parameterization scheme for the UL has been built and embedded in an existing two-dimensional thundercloud charge/discharge model. The ULs simulated from the experiments with two-dimensional high resolution agree generally with the observation results. By analyzing the charge structure of thunderstorm clouds, we determined the in-cloud environmental characteristics that favor the initiation of conventional cloud-to-ground(CG) flashes and analyzed the differences and similarities of some characteristics of the positive and the negative UL. Simulation results indicate that the positive ULs are typically other-lightning-triggered ULs(OLTUL) and are usually a discharge phenomenon between the ground and the lower positive charge region appearing below the main middle negative charge region. The effect of the previous in-cloud lightning(IC) process of space electrical field provides favorable conditions for the initiation of a positive UL. Its entire discharge process is limited, and the branches of the leader are fewer in number as its discharge is not sufficient. A negative UL is generally a discharge phenomenon of the dipole charge structure between the ground and the main negative charge region. The lower temperature stratification and the sinking of the hydrometeors typically initiate a negative UL. Negative ULs develop strongly and have more branches. The OLTUL is initiated mainly during the development stage of a thunderstorm, while the self-triggered UL(STUL) is initiated mainly during the dissipation stage of a thunderstorm.
