Simulating chemistry–aerosol–cloud–radiation–climate feedbacks over the continental U.S. using the online-coupled Weather Research Forecasting Model with chemistry (WRF/Chem) |
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| Authors: | Yang Zhang X-Y Wen CJ Jang |
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| Institution: | 1. Department of Marine, Earth, and Atmospheric Science, North Carolina State University, Campus Box 8208, Raleigh, NC 27695, USA;2. Office of Air Quality Planning and Standards, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA;1. Air Quality Forecasting Lab, North Carolina State University, Raleigh, NC 27695, USA;2. Barons Advanced Meteorological Systems, Raleigh, NC, USA;1. Ocean University of China, Qingdao 266100, Shandong Province, PR China;2. North Carolina State University, Department of Marine, Earth, and Atmospheric Sciences, Campus Box 8208, NCSU, Raleigh, NC 27695, USA;1. Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC, USA;2. ENVIRON International Corporation, Novato, CA, USA;3. Energy Systems Division, Argonne National Laboratory, Argonne, IL, USA;1. Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27606, USA;2. Collaborative Innovation Center for Regional Environmental Quality, Beijing 100084, China;3. Department of Environmental Engineering, Hebei University of Engineering, Handan, Hebei 056038, China;4. Center for Earth System Science, Tsinghua University, Beijing 100084, China;5. The School of Environment, Tsinghua University, Beijing 100084, China;1. Air-Quality Research Division, Environment Canada, Toronto, Canada;2. Meteorological Research Division, Environment Canada, Montreal, Canada;3. Atmospheric Modeling and Analysis Division, Environmental Protection Agency, Research Triangle Park, USA;4. Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, USA;5. University of L''Aquila, L''Aquila, Italy;6. University of Ljubljana, Ljubljana, Slovenia;7. Center of Excellence SPACE-SI, Ljubljana, Slovenia;8. Joint Research Centre, European Commission, Ispra, Italy;9. RSE, Milano, Italy;10. University Murcia, MAR-UMU, Spain;12. Karlsruhe Inst. of Technology, IMK-IFU, Garmisch-Partenkirchen, Germany;13. Air-Quality Research Division, Environment Canada, Montreal, Canada;14. ZAMG, Vienna, Austria;15. Technical Univ. of Madrid, ESMG-UPM, Spain;p. University L''Aquila, CETEMPS, L''Aquila, Italy;1. Air Quality Forecasting Laboratory, North Carolina State University, Raleigh, NC, USA;2. Center for Earth System Science, Tsinghua University, Beijing, 100084, PR China;3. The School of Environment, Tsinghua University, Beijing, 100084, PR China |
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| Abstract: | The chemistry–aerosol–cloud–radiation–climate feedbacks are simulated using WRF/Chem over the continental U.S. in January and July 2001. Aerosols can reduce incoming solar radiation by up to ?9% in January and ?16% in July and 2-m temperatures by up to 0.16 °C in January and 0.37 °C in July over most of the continental U.S. The NO2 photolysis rates decrease in July by up to ?8% over the central and eastern U.S. where aerosol concentrations are high but increase by up to 7% over the western U.S. in July and up to 13% over the entire domain in January. Planetary boundary layer (PBL) height reduces by up to ?23% in January and ?24% in July. Temperatures and wind speeds in July in big cities such as Atlanta and New York City reduce at/near surface but increase at higher altitudes. The changes in PBL height, temperatures, and wind speed indicate a more stable atmospheric stability of the PBL and further exacerbate air pollution over areas where air pollution is already severe. Aerosols can increase cloud optical depths in big cities in July, and can lead to 500–5000 cm?3 cloud condensation nuclei (CCN) at a supersaturation of 1% over most land areas and 10–500 cm?3 CCN over ocean in both months with higher values over most areas in July than in January, particularly in the eastern U.S. The total column cloud droplet number concentrations are up to 4.9 × 106 cm?2 in January and up to 11.8 × 106 cm?2 in July, with higher values over regions with high CCN concentrations and sufficient cloud coverage. Aerosols can reduce daily precipitation by up to 1.1 mm day?1 in January and 19.4 mm day?1 in July thus the wet removal rates over most of the land areas due to the formation of small CCNs, but they can increase precipitation over regions with the formation of large/giant CCN. These results indicate potential importance of the aerosol feedbacks and an urgent need for their accurate representations in current atmospheric models to reduce uncertainties associated with climate change predictions. |
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