Connecting regional aerosol emissions reductions to local and remote precipitation responses
<p>The unintended climatic implications of aerosol and precursor emission reductions implemented to protect public health are poorly understood. We investigate the precipitation response to regional changes in aerosol emissions using three coupled chemistry–climate models: NOAA Geophysical...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-08-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/18/12461/2018/acp-18-12461-2018.pdf |
| Summary: | <p>The unintended climatic implications of aerosol and precursor
emission reductions implemented to protect public health are poorly
understood. We investigate the precipitation response to regional changes in
aerosol emissions using three coupled chemistry–climate models: NOAA
Geophysical Fluid Dynamics Laboratory Coupled Model 3 (GFDL-CM3), NCAR
Community Earth System Model (CESM1), and NASA Goddard Institute for Space
Studies ModelE2 (GISS-E2). Our approach contrasts a long present-day control
simulation from each model (up to 400 years with perpetual year 2000 or 2005
emissions) with 14 individual aerosol emissions perturbation
simulations (160–240 years each). We perturb emissions of sulfur dioxide
and/or carbonaceous aerosol within six world regions and assess the
significance of precipitation responses relative to internal variability
determined by the control simulation and across the models. Global and
regional precipitation mostly increases when we reduce regional aerosol
emissions in the models, with the strongest responses occurring for sulfur
dioxide emissions reductions from Europe and the United States.
Precipitation responses to aerosol emissions reductions are largest in the
tropics and project onto the El Niño–Southern Oscillation (ENSO).
Regressing precipitation onto an Indo-Pacific zonal sea level pressure
gradient index (a proxy for ENSO) indicates that the ENSO component of the
precipitation response to regional aerosol removal can be as large as 20 %
of the total simulated response. Precipitation increases in the Sahel in
response to aerosol reductions in remote regions because an anomalous
interhemispheric temperature gradient alters the position of the
Intertropical Convergence Zone (ITCZ). This mechanism holds across multiple
aerosol reduction simulations and models.</p> |
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| ISSN: | 1680-7316 1680-7324 |