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
Long-term continuous measurements of particle number size distributions with mobility diameter sizes ranging from 3 to 800 nm were pertbrmed to study new particle formation （NPF） events at Shangdianzi （SDZ）, Mt. T...Long-term continuous measurements of particle number size distributions with mobility diameter sizes ranging from 3 to 800 nm were pertbrmed to study new particle formation （NPF） events at Shangdianzi （SDZ）, Mt. Tai （TS）, and Lin＇an （LAN） stations representing the background atmospheric conditions in the North China Plain （NCP） Central East China （CEC） and Yangtze River Delta （YRD） regions, respectively. The mean formation rate of 3-nm particles was 6.3, 3.7, and 5.8 cm -3 .s-1, and the mean particle growth rate was 3.6, 6.0, and 6.2 nm. h at SDZ, TS, and LAN, respectively. The NPF, event characteristics at the three sites indicate that there may be a stronger source of low volatile vapors and higher condensational sink of pre-existing particles in the YRD region. The formation rate of NPF events at these sites, as well as the condensation sink, is approximately 10 times higher than some results reported at rural/urban sites in western countries. However, the growth rates appear to be 1 2 times higher. Approximately 12%-17% of all NPF events with nucleated particles grow to a climate- relevant size （〉50 nm）. These kinds of NPF events were normally observed with higher growth rate than the other NPF cases. Generally, the cloud condensation nuclei （CCN） number concentration can be enhanced by approximately a factor of 2 6 on these event days. The mean value of the enhancement factor is lowest at LAN （2-3） and highest at SDZ （-4）. NPF events have also been found to have greater impact on CCN production in China at the regional scale than in the other background sites worldwide.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
基金This work was supported by National Basic Research Program of China （No. 2011CB403401）, the National Natural Science Foundation of China （Grant Nos. 41175113 and 41405132）, CAMS Basis Research Project （Nos. 2013Z007 and 2013Y004）. This paper is partially supported by the CMA Innovation Team for Haze-fog Observation and Forecasts. The authors would also like to thank the staff at Shangdianzi, Linan and Mr. Tai for operating and maintaining the instruments and the Leibniz Institute for Tropospheric Research for providing the TDMPS used at the SDZ station.
文摘Long-term continuous measurements of particle number size distributions with mobility diameter sizes ranging from 3 to 800 nm were pertbrmed to study new particle formation （NPF） events at Shangdianzi （SDZ）, Mt. Tai （TS）, and Lin＇an （LAN） stations representing the background atmospheric conditions in the North China Plain （NCP） Central East China （CEC） and Yangtze River Delta （YRD） regions, respectively. The mean formation rate of 3-nm particles was 6.3, 3.7, and 5.8 cm -3 .s-1, and the mean particle growth rate was 3.6, 6.0, and 6.2 nm. h at SDZ, TS, and LAN, respectively. The NPF, event characteristics at the three sites indicate that there may be a stronger source of low volatile vapors and higher condensational sink of pre-existing particles in the YRD region. The formation rate of NPF events at these sites, as well as the condensation sink, is approximately 10 times higher than some results reported at rural/urban sites in western countries. However, the growth rates appear to be 1 2 times higher. Approximately 12%-17% of all NPF events with nucleated particles grow to a climate- relevant size （〉50 nm）. These kinds of NPF events were normally observed with higher growth rate than the other NPF cases. Generally, the cloud condensation nuclei （CCN） number concentration can be enhanced by approximately a factor of 2 6 on these event days. The mean value of the enhancement factor is lowest at LAN （2-3） and highest at SDZ （-4）. NPF events have also been found to have greater impact on CCN production in China at the regional scale than in the other background sites worldwide.
