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The Dependence of Cirrus Gamma Size Distributions Expressed as Volumes in N(sub 0)-Lambda-Mu Phase Space and Bulk Cloud Properties on Environmental Conditions: Results from the Small Ice Particles in Cirrus Experiment (SPARTICUS)The variability of cirrus ice microphysical properties is investigated using observations obtained during the Small Particles in Cirrus (SPARTICUS) campaign. An existing approach that represents a size distribution (SD) as a single gamma function using an ellipsoid of equally realizable solutions in (N(sub 0), lambda, mu) phase space is modified to automatically identify multiple modes in SDs and characterize each mode by such an ellipsoid. The modified approach is applied to ice crystals with maximum dimension D greater than15 micrometers collected by the 2-D stereo and 2-D precipitation probes on the Stratton Park Engineering Company Learjet. The dependencies of N(sub 0), mu, and lambda from each mode, total number concentration, bulk extinction, ice water content (IWC), and mass median maximum dimension D(sub mm) as a function of temperature T and cirrus type are then analyzed. The changes in the observed codependencies between N(sub 0), mu, and lambda, bulk extinction, IWC, and D(sub mm) with environmental conditions indicate that particles were larger at higher T during SPARTICUS. At most two modes were observed in any SD during SPARTICUS, with the average boundary between them at 115 micrometers, similar to past studies not using probes with shatter mitigating tips and artifact removal algorithms. The bimodality of the SDs increased with T. This and the differences in N(sub 0), mu, and lambda between the modes suggest that particles with smaller D nucleated more recently than particles with larger D, which grew via vapor deposition and aggregation. Because smaller crystals, whose concentrations are uncertain, make marginal contributions to higher order moments, the use of higher moments for evaluating model fields is suggested.
Document ID
20160003591
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Jackson, Robert C. (Illinois Univ. at Urbana-Champaign Urbana, IL, United States)
McFarquhar, Greg M. (Illinois Univ. at Urbana-Champaign Urbana, IL, United States)
Fridlind, Ann M. (NASA Goddard Inst. for Space Studies New York, NY United States)
Atlas, Rachel (Chicago Univ. Chicago, IL, United States)
Date Acquired
March 22, 2016
Publication Date
October 9, 2015
Publication Information
Publication: Journal of Geophysical Research: Atmospheres
Volume: 120
Issue: 19
Subject Category
Meteorology and Climatology
Report/Patent Number
GSFC-E-DAA-TN30558
Funding Number(s)
CONTRACT_GRANT: DE-SC0006988
CONTRACT_GRANT: DE-SC0014065
WBS: WBS 199008.02.04.10.Q765.13
CONTRACT_GRANT: DE-SC0008500
CONTRACT_GRANT: DE-SC0001279
Distribution Limits
Public
Copyright
Other
Keywords
Ellipsoids
Ice
Variability
Moisture content