Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2016-948
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
14 Nov 2016
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Use of an observation-based aerosol profile in simulations of a mid-latitude squall line during MC3E: Similarity of stratiform ice microphysics to tropical conditions
Ann M. Fridlind1, Xiaowen Li2,3, Di Wu3,4, Marcus van Lier-Walqui1,5, Andrew S. Ackerman1, Wei-Kuo Tao3, Greg M. McFarquhar6, Wei Wu6, Xiquan Dong7, Jingyu Wang7, Alexander Ryzhkov8, Pengfei Zhang8, Michael R. Poellot9, Andrea Neumann9, and Jason M. Tomlinson10 1NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY, USA
2Morgan State University, Baltimore, MD, USA
3NASA Goddard Space Flight Center, Greenbelt, MD, USA
4Science Systems and Applications, Inc., Lanham, MD, USA
5Columbia University, New York, NY, USA
6University of Illinois, Urbana-Champaign, IL, USA
7University of Arizona, Tucson, AZ, USA
8Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, and National Severe Storms Laboratory, Norman, OK, USA
9University of North Dakota, Grand Forks, ND, USA
10Pacific Northwest National Laboratory, Richland, WA, USA
Abstract. Advancing understanding of deep convection microphysics via mesoscale modeling studies of well-observed case studies requires observation-based aerosol inputs. Here we derive hygroscopic aerosol size distribution input profiles from ground- based and airborne measurements for six convection case studies observed during the Midlatitude Continental Convective Cloud Experiment (MC3E) over Oklahoma. We demonstrate use of the aerosol inputs in mesoscale model simulations of the only well-observed case study that produced extensive stratiform outflow, on 20 May 2011. At well-sampled elevations between −10 and −23 °C over widespread stratiform rain, ice crystal number concentrations are consistently dominated by a single mode near ∼ 400 μm in randomly oriented maximum dimension (Dmax). The ice mass at −23 °C is primarily in a closely collocated mode, whereas a mass mode near Dmax ∼ 1000 μm becomes dominant with decreasing elevation to the −10 °C level, consistent with possible aggregation during sedimentation. However, simulations with and without observation-based aerosol inputs systematically overpredict mass peak Dmax by a factor of 3–5 and underpredict ice number concentration by a factor of 4–10. Previously reported simulations with both two-moment and size-resolved microphysics have shown biases of a similar nature. The observed ice properties are notably similar to those reported from recent tropical measurements. Based on several lines of evidence, we speculate that the microphysics pathways associated with deep tropical convection outflow also occurred in the 20 May MC3E case, likely associated with warm-temperature ice multiplication that is not well understood or well represented in models.

Citation: Fridlind, A. M., Li, X., Wu, D., van Lier-Walqui, M., Ackerman, A. S., Tao, W.-K., McFarquhar, G. M., Wu, W., Dong, X., Wang, J., Ryzhkov, A., Zhang, P., Poellot, M. R., Neumann, A., and Tomlinson, J. M.: Use of an observation-based aerosol profile in simulations of a mid-latitude squall line during MC3E: Similarity of stratiform ice microphysics to tropical conditions, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-948, in review, 2016.
Ann M. Fridlind et al.
Ann M. Fridlind et al.
Ann M. Fridlind et al.

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Short summary
Understanding observed storm microphysics via computer simulation requires measurements of the aerosol on which most hydrometeors form. We prepare aerosol input data for six storms observed over Oklahoma. We demonstrate its use in simulations of a case with widespread ice outflow well-sampled by aircraft. Simulations predict too few ice crystals that are too large. We speculate that microphysics found in tropical storms occurred here, likely associated with poorly understood ice multiplication.
Understanding observed storm microphysics via computer simulation requires measurements of the...
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