Lorentz curve fittings are applied to frequency distributions of the concentrations of O3, CO, NOx and SO2 recorded at the Jinsha regional atmospheric background station （JSH） from June 2006 to July 2007, and the pe...Lorentz curve fittings are applied to frequency distributions of the concentrations of O3, CO, NOx and SO2 recorded at the Jinsha regional atmospheric background station （JSH） from June 2006 to July 2007, and the peak concentrations of these species for the different seasons are obtained. The peak concentrations are considered to be representative of different background levels for certain processes. The peak concentrations are compared with the corresponding mean （median） concentrations, and the suitability and limitations of the mean （median） values as the background levels are discussed. The mean （median） values might represent the background concentrations in the region under some circumstances, but in other cases these values often underestimate or overestimate the true background concentrations owing to the transport of pollutants and other factors. The effects of air masses transported from different regions on the pollutant background concentrations are obtained by analyzing the 72-hour backward trajectories of air masses 100m above the ground at JSH, These trajectories are estimated using the HYSPLIT model and then clustered for the measurement period. The spatial distribution and seasonal variations of trajectories and the corresponding mean concentrations of O3, SO〉 NOx and CO for different clusters are analyzed. After filtering the seasonal changes in pollutant concentrations, the relative influences of air masses from different regions are obtained. The results show that JSH can be used to obtain the atmospheric background information of different air masses originating from or passing over the Yangtze River Delta, Central South China and the Jianghan Plain. Air masses from Central China, South China, and the western Yangtze River Delta contribute significantly to O3 at JSH. Air masses from the north and northeast of JSH （i.e., the Jianghan Plain, Huang-Huai Plain and North China Plain） and the south （Central South China） contribute significantly to SO2, CO and NOx concentra展开更多
为了分析单站区域电离层总电子含量(total electron content, TEC)模型的适用范围和精度,基于2~15阶次球谐函数,分别建立了欧洲区域16个单站区域电离层TEC模型,生成了区域格网TEC,并与欧洲定轨中心(Center for Orbit Determination in E...为了分析单站区域电离层总电子含量(total electron content, TEC)模型的适用范围和精度,基于2~15阶次球谐函数,分别建立了欧洲区域16个单站区域电离层TEC模型,生成了区域格网TEC,并与欧洲定轨中心(Center for Orbit Determination in Europe,CODE)、国际全球导航卫星系统服务组织(International Global Navigation Satellite System Service, IGS)和全球GNSS监测评估系统(International GNSS Monitoring and Assessment System, iGMAS)等全球电离层产品比较分析。结果表明,基于低阶(2×2阶或3×3阶)球谐函数建立的单站区域电离层TEC模型,以单站为中心,在经纬度10°×10°范围以内(半径小于600 km),电离层TEC精度与CODE、iGMAS和IGS等全球电离层产品的TEC精度相当,约为1.0 TECU,实现了在一定区域内(半径小于600 km)利用单站建立电离层TEC模型替代全球电离层TEC模型,高效地为区域内单频用户提供高精度的电离层延迟改正。展开更多
随着我国气象事业的不断发展,相关设施的建设及气象设备的更新需要投入大量技术人员在工地作业。为了严守安全生产红线,以现代化信息技术加强相关施工区域站的人员安全监管势在必行。文章基于YOLOv5(You Only Look Once version 5)目标...随着我国气象事业的不断发展,相关设施的建设及气象设备的更新需要投入大量技术人员在工地作业。为了严守安全生产红线,以现代化信息技术加强相关施工区域站的人员安全监管势在必行。文章基于YOLOv5(You Only Look Once version 5)目标检测算法训练的安全帽佩戴检测算法,可以实时检测工作人员的安全帽佩戴情况,在保障施工现场人员安全、减少安全事故发生方面具有积极作用。展开更多
基金supported by National Basic Research Program of China (Grant No. 2005CB4222002)Project of China Meteorological Administration (Grant No. GYHY[QX]200706005)National Natural Science Foundation of China (Grant No. 40705042)
文摘Lorentz curve fittings are applied to frequency distributions of the concentrations of O3, CO, NOx and SO2 recorded at the Jinsha regional atmospheric background station （JSH） from June 2006 to July 2007, and the peak concentrations of these species for the different seasons are obtained. The peak concentrations are considered to be representative of different background levels for certain processes. The peak concentrations are compared with the corresponding mean （median） concentrations, and the suitability and limitations of the mean （median） values as the background levels are discussed. The mean （median） values might represent the background concentrations in the region under some circumstances, but in other cases these values often underestimate or overestimate the true background concentrations owing to the transport of pollutants and other factors. The effects of air masses transported from different regions on the pollutant background concentrations are obtained by analyzing the 72-hour backward trajectories of air masses 100m above the ground at JSH, These trajectories are estimated using the HYSPLIT model and then clustered for the measurement period. The spatial distribution and seasonal variations of trajectories and the corresponding mean concentrations of O3, SO〉 NOx and CO for different clusters are analyzed. After filtering the seasonal changes in pollutant concentrations, the relative influences of air masses from different regions are obtained. The results show that JSH can be used to obtain the atmospheric background information of different air masses originating from or passing over the Yangtze River Delta, Central South China and the Jianghan Plain. Air masses from Central China, South China, and the western Yangtze River Delta contribute significantly to O3 at JSH. Air masses from the north and northeast of JSH （i.e., the Jianghan Plain, Huang-Huai Plain and North China Plain） and the south （Central South China） contribute significantly to SO2, CO and NOx concentra
文摘为了分析单站区域电离层总电子含量(total electron content, TEC)模型的适用范围和精度,基于2~15阶次球谐函数,分别建立了欧洲区域16个单站区域电离层TEC模型,生成了区域格网TEC,并与欧洲定轨中心(Center for Orbit Determination in Europe,CODE)、国际全球导航卫星系统服务组织(International Global Navigation Satellite System Service, IGS)和全球GNSS监测评估系统(International GNSS Monitoring and Assessment System, iGMAS)等全球电离层产品比较分析。结果表明,基于低阶(2×2阶或3×3阶)球谐函数建立的单站区域电离层TEC模型,以单站为中心,在经纬度10°×10°范围以内(半径小于600 km),电离层TEC精度与CODE、iGMAS和IGS等全球电离层产品的TEC精度相当,约为1.0 TECU,实现了在一定区域内(半径小于600 km)利用单站建立电离层TEC模型替代全球电离层TEC模型,高效地为区域内单频用户提供高精度的电离层延迟改正。
文摘随着我国气象事业的不断发展,相关设施的建设及气象设备的更新需要投入大量技术人员在工地作业。为了严守安全生产红线,以现代化信息技术加强相关施工区域站的人员安全监管势在必行。文章基于YOLOv5(You Only Look Once version 5)目标检测算法训练的安全帽佩戴检测算法,可以实时检测工作人员的安全帽佩戴情况,在保障施工现场人员安全、减少安全事故发生方面具有积极作用。
