Atmos. Chem. Phys. Discuss., 12, 29607-29655, 2012
www.atmos-chem-phys-discuss.net/12/29607/2012/
doi:10.5194/acpd-12-29607-2012
© Author(s) 2012. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Assessing the mineral dust indirect effects and radiation impacts on a simulated idealized nocturnal squall line
R. B. Seigel, S. C. van den Heever, and S. M. Saleeby
Department of Atmospheric Science, Colorado State University, 1371 Campus Delivery, Fort Collins, CO, 80523, USA

Abstract. Mineral dust is arguably the most abundant aerosol species in the world and it plays a large role in aerosol indirect effects (AIEs). This study assesses and isolates the individual responses in a squall line that arise (1) from radiation, (2) from dust altering the microphysics, as well as (3) from the synergistic effects between (1) and (2). To accomplish these tasks, we use the Regional Atmospheric Modeling System (RAMS) set up as a cloud-resolving model (CRM). The CRM contains aerosol and microphysical schemes that allow mineral dust particles to nucleate as cloud drops and ice crystals, replenish upon evaporation and sublimation, be tracked throughout hydrometeor transition, and scavenge by precipitation and dry sedimentation.

Factor separation is used on four simulations of the squall line in order to isolate the individual roles of radiation (RADIATION), microphysically active dust (DUST MICRO), and the nonlinear interactions of those factors (SYNERGY). Results indicate that RADIATION acts to increase precipitation, intensify the cold pool, and enhance the mesoscale organization of the squall line due to changes in microphysics beginning from cloud top cooling. Conversely, DUST MICRO decreases precipitation, weakens the cold pool, and weakens the mesoscale organization of the squall line due to an enhancement of the warm rain process. SYNERGY shows little impact on the squall line, except near the freezing level, where an increase in mesoscale organization takes place. The combined effect of the mineral dust AIE due to both DUST MICRO and SYNERGY is to weaken the squall line.


Citation: Seigel, R. B., van den Heever, S. C., and Saleeby, S. M.: Assessing the mineral dust indirect effects and radiation impacts on a simulated idealized nocturnal squall line, Atmos. Chem. Phys. Discuss., 12, 29607-29655, doi:10.5194/acpd-12-29607-2012, 2012.
 
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