AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Effects of Aerosol Direct Feedback Effects on Surface Ozone and PM2.5 in Continental USA in 2005 by a Two-Way Coupled WRF-CMAQ Model
CHOWDHURY MONIRUZZAMAN, Jared Bowden, Saravanan Arunachalam, University of North Carolina, Chapel Hill
Abstract Number: 322 Working Group: Regional and Global Air Quality and Climate Modeling
Abstract Aerosol or particulate matter (PM) in air scatters and absorbs radiation from sun which blocks incoming short-wave radiation reaching earth surface, known as aerosol direct effects (ADEs), thus affecting ozone (O3) photolysis reaction and surface temperature which in turn affects PM concentration. The changed PM concentration further affects chemistry and meteorology by ADEs through a feedback cycle. The aerosol direct feedback effects (ADFEs) are neglected in traditional air quality models (where meteorology is used as input and not affected by chemistry). In this study, a coupled Weather Research and Forecasting - Community Multiscale Air Quality (WRF-CMAQ) modeling system was used to determine the ADFEs on surface O3 and PM2.5 change as well as change of meteorological variables such as short-wave radiation (SWR) at surface, temperature at 2 m (T2) and planetary boundary layer (PBL) height in continental USA in a 36-km grid domain for the year 2005. The novelty of this new application is that the WRF fields were driven using the global-scale NASA’s Modern Era Reanalysis for Research and Applications (MERRA) meteorological data. We found that ADFEs cause annual perturbation of domain average of O3 and PM2.5 by -0.4 ppb (daily range -23 to +22) and +0.28 micro-g/m3 (daily range -32 to +25) respectively in 2005 in continental USA. ADFEs perturb the meteorological variables: SWR, T2, and PBL (domain-wide annual average) by -7.37 W/m2, -0.47 K and -21 m respectively. We also found that as high as 60% of PM2.5 increases by the ADFEs during summer were caused by secondary organic aerosol increase. We extended this application to assess the incremental air quality impacts due to a single source sector – aircraft emissions during landing and takeoff (LTO) cycles – and found that ADFEs in this coupled WRF-CMAQ application decrease aircraft-attributable surface O3 and PM2.5 change by 21% and 23% respectively.