Abstract
Decadal hemispheric Weather Research and Forecast-Community Multiscale
Air Quality simulations from 1990 to 2010 were conducted to examine the
meteorology and air quality responses to the aerosol direct radiative
effects. The model's performance for the simulation of hourly surface
temperature, relative humidity, wind speed, and direction was evaluated
through comparison with observations from NOAA's National Climatic Data
Center Integrated Surface Data. The inclusion of aerosol direct
radiative effects improves the model's ability to reproduce the trend in
daytime temperature range which over the past two decadeswas increasing
in eastern China but decreasing in eastern U.S. and Europe. Trends and
spatial and diurnal variations of the surface-level gaseous and particle
concentrations to the aerosol direct effect were analyzed. The inclusion
of aerosol direct radiative effects was found to increase the
surface-level concentrations of SO2, NO2, O-3, SO42-, NO3-, and
particulate matter 2.5 in eastern China, eastern U.S., and Europe by
1.5-2.1%, 1-1.5%, 0.1-0.3%, 1.6-2.3%, 3.5-10.0%, and 2.2-3.2%,
respectively, on average over the entire 21 year period. However,
greater impacts are noted during polluted days with increases of
7.6-10.6%, 6.2-6.7%, 2.0-3.0%, 7.8-9.5%, 11.1-18.6%, and 7.2-10.1%,
respectively. Due to the aerosol direct radiative effects, stabilizing
of the atmosphere associated with reduced planetary boundary layer
height and ventilation leads to an enhancement of pollution.
Consequently, the continual increase of aerosol optical depth (AOD) in
eastern China leads to an increasing trend in the air quality feedback
which exacerbates air pollution, while emission reductions in eastern
U.S. and Europe result in a declining trend in both AODs and feedback
which make the air pollution control strategies more effective.
