Using a global aerosol model adjoint to unravel the footprint of spatially-distributed emissions on cloud droplet number and cloud albedo

• Published in: Geophysical research letters Vol. 39; no. 24
• Main Authors: Karydis, V. A., Capps, S. L., Moore, R. H., Russell, A. G., Henze, D. K., Nenes, A.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 28.12.2012; American Geophysical Union; John Wiley & Sons, Inc
• Subjects: adjoint; aerosol; Atmosphere; Atmospheric aerosols; Atmospheric sciences; Chemistry; Climate change; Clouds; droplet; Earth; Earth sciences; Earth, ocean, space; emissions; Exact sciences and technology; modeling; Physics; source; Western U.S; Southeastern U.S; United States; Central Europe; Europe; Eastern U.S; models; projects; sensitivity analysis; aerosols; droplets; simulation; fine-grained materials; precursors; concentration; global; clouds; North America; Precursor; Sulfur dioxide; parametrization; Nitrogen dioxide; Long-range transport; albedo; Anthropogenic factor
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2012GL053346

The adjoints of the GEOS‐Chem Chemical Transport Model and a comprehensive cloud droplet parameterization are coupled to study the sensitivity of cloud droplet number concentration (Nd) over US regions and Central Europe to global emissions of anthropogenic fine mode aerosol precursors. Simulations reveal that the Nd over the midwestern and southeastern US is mostly sensitive to SO2 emissions during August, and to NH3 emissions during February. Over the western US, Nd is mostly sensitivity to SO2 and primary organic aerosol emissions. In Central Europe, Nd is most sensitive to NH3 and NOx emissions. As expected, local emissions strongly affect Nd; long‐range transport, however, is also important for the western US and Europe. Emissions changes projected for the year 2050 are estimated to have the largest impacts on cloud albedo andNd over Central Europe during August (42% and 82% change, respectively) and western US during February (12% and 36.5% change, respectively). Key Points Adjoint modeling unravels the impact of aerosol on cloud properties Long range transport of aerosol has important impacts on clouds Future emissions will impact droplet number mostly central Europe