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Han Z.,CAS Institute of Atmospheric Physics | Xie Z.,CAS Institute of Atmospheric Physics | Xie Z.,Fujian Meteorological Science Institute | Wang G.,CAS Institute of Earth Environment | And 2 more authors.
Atmospheric Environment | Year: 2016

A volatility basis set approach with chemical aging mechanism has been incorporated into a regional air quality model system (RAQMS) and used to investigate the distribution of organic aerosols (OA) over east China in April 2009, with focus on secondary organic aerosols (SOA) in fine particle and relative contributions from a series of anthropogenic and biogenic VOC precursors. The comparison between the VBS approach prediction and observation at four sites in east China demonstrates a significant improvement in SOA and OA concentrations compared with the traditional two-product model, which predicts very low SOA level. The average value of secondary organic carbon (SOC) for all sites predicted by the VBS approach with chemical aging is 2.8 μgC m-3, quite close to the estimated value of 3.3 μgC m-3. The SOC fraction of organic carbon (OC) also increases from just 5% predicted by the two-product model to 33% by the VBS approach with aging, close to the estimated fraction of 32%, suggesting a more realistic and precise representation of SOA formation by the VBS approach. The enhanced SOC prediction further improve OC prediction, reducing the normalized mean bias from -43% to -18%. The VBS approach with aging predicts SOA concentration in PM2.5 of 5-10 μg m-3 over most parts of east China. The predicted ASOA concentrations vary from 5.0 to 7.5 μg m-3 in the Pearl River Delta, the Yangtze River Delta and the wide areas north of the Yangtze River. BSOA is predicted to be 1.0-2.5 μg m-3 across the regions from southeast China to the middle reaches of the Yangtze River and the Yellow River. Prediction with the VBS approach exhibits that ASOA becomes dominant component of SOA, which is more realistic as compared to the BSOA dominance by the two-product model. The domain-average surface POA and SOA concentrations predicted by the VBS approach with aging over east China are 4.86 μg m-3 and 4.45 μg m-3, with the SOA fraction of total OA and the ASOA fraction of SOA being 48% and 85%, respectively. This indicates the comparable contributions to OA from SOA and POA, and the predominant contribution of ASOA to SOA over east China in springtime. The mean SOA concentrations over east China produced from aromatics, alkanes, alkenes, isoprene, monoterpene and sesquiterpene are predicted to be 2.44, 0.57, 0.8, 0.17, 0.42 and 0.06 μg m-3, respectively, which contribute 55%, 13%, 18%, 4%, 9% and 1% of the total SOA. Aromatics are the dominant contributors to SOA formation. © 2015 Elsevier Ltd. Source

Lin W.,Fujian Meteorological Science Institute | Lin C.,Fujian Meteorological Science Institute | Chen B.,Fujian Meteorological Science Institute | Yu Y.,Fujian Meteorological Science Institute
Journal of Natural Disasters | Year: 2014

In this study, the V-3θ diagrams obtained from radiosonde data during 2002-2011 were used to analyze the V-3θ structure characteristics before and after the occurrence of hails, which provide references to hail forecast. There are some characteristics of the V-3θ structure before the occurrence of hails; there exists thicker cooling layer in the high part of aerosphere, whose altitude is the same as the hail particles forming area detected by reflectivity cross-section product; the whole aerosphere is in obvious heterogeneous structure; cooling stratus cloud and wasp waist often happen, especially before large-scale hail disasters, and the3θ curves flex acutely as well; the hail happening is accompanied by a roll-flow wind field, which in northwest Fujian is northwester uplayer and southeaster underlayer, or a configuration of northwester uplayer and southwester underlayer; the three θ curves present steady structure with right inclination and no cooling layer, and the wind field become reverse roll-flow after hail finishes. Source

Lin W.,Fujian Meteorological Science Institute | Wang H.,Fujian Meteorological Science Institute | Xie Z.,Fujian Meteorological Science Institute | Chen B.,Fujian Meteorological Science Institute | Yu Y.,Fujian Meteorological Science Institute
Journal of Natural Disasters | Year: 2016

The low visibility weather with haze or fog in Fuzhou was classified based on synoptic chart, surface weather observations and sounding date from 2006 to 2011. The visibilities, durations and vertical structures were analyzed to establish the seasonal model of low visibility weather: compared with summer and autumn, the days of haze or fog are more, the durations are longer, and the visibilities are lower in winter and spring; As cold air moving frequently in winter, the haze or fog often happens in transformed cold high or warm zone before cold air coming, and radiation fog easily appears in cold ridge; The low visibility weather relates to variation of southwesterly flow in spring, which frequently happens before upper trough, in warm convergent zone or south of low-vortex shear; In summer, the low visibility weather relates to the position of subtropical high pressure zone, so its duration is shorter, and its haze happens within the zone and fog on its edge; The number of low visibility weather days in autumn is the least one, which just appears as overdue typhoon or early cold air. © 2016, Science Press. All rights reserved. Source

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