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Aerosol Impacts on Meteorological Elements and Surface Energy Budget over an Urban Cluster Region on the Yangtze River Delta

Category: Urban Air Quality

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DOI: 10.4209/aaqr.2017.12.0602
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Xiaolu Ling 1,2, Xiaomen Han1

  • 1 Institute for Climate and Global Change Research, School of Atmospheric Sciences, Nanjing University, Nanjing 210023, China
  • 2 Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing 210023, China

Highlights

  • Aerosol-radiation-meteorology interaction using in-situ data over urban region.
  • Aerosols reduce net radiation with a maximum reduction of 180 W m–2.
  • Northeasterly winds prevail during polluted days with wind speeds 60% lower.
  • Strong wind speed fluctuations lead to the outbreak of air pollution event.

Abstract

The Yangtze River Delta (YRD) is a typical region dramatically influenced by both human activities and a monsoonal climate. Near surface micro-meteorology, radiation and energy fluxes were collected and analyzed at the Lishui field observation site in the suburb of Nanjing to investigate aerosol impacts on the radiation budget and land surface-atmosphere heat, water, and mass exchanges. Based on selected typical polluted/non-polluted days, cluster analysis, composite analysis, and case study were employed. The results indicate that the daily mean surface pressure is 6.6 hPa lower during polluted days compared to that of non-polluted days in Nanjing. Northeasterly winds often prevail during the polluted days with wind speeds 60% lower than those of non-polluted days. Aerosols directly reduce the net radiation flux at the surface with a maximum reduction of 180 W m-2. During the early stage of air pollution events, surface pressure is lower and wind speeds rapidly decrease; during the peak of pollution, a low surface pressure and wind speeds remain, effectively preventing the dispersion of air pollutants. Meanwhile, the temperature often lowers, and the relative humidity subsequently increases. With increases in wind speed and surface pressure, the AQI gradually decreases, and the air pollution event ends.

Keywords

Urban cluster region Meteorological elements Surface energy budget


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