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Jerome M. Schmidt, Piotr J. Flatau, and Paul R. Harasti

1. Introduction One of the more clearly recognizable meteorologically based radar signals is that of the radar reflectivity bright band that forms within mixed-phased stratiform cloud systems near the melting level. After one of the initial studies of the phenomenon by Ryde (1946) , research has focused on the radar attributes, microphysical processes, and environmental factors governing the structure of this particular feature ( Atlas 1954 ; Austin and Bemis 1950 ; Battan 1973 ; Fabry and

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Matthew D. Shupe, Pavlos Kollias, P. Ola G. Persson, and Greg M. McFarquhar

liquid water due to the lower saturation vapor pressure of ice (the Bergeron–Findeisen mechanism) and thus will fully glaciate the cloud if the total condensate supply rate does not exceed the rate of ice diffusional growth. However, in addition to vertical motions, other conditions support the growth of liquid water, making the exact mechanisms and feedbacks in operation in these clouds unclear. In the Arctic, extensive stratiform mixed-phase cloud layers are observed ( Herman and Goody 1976 ) and

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Jonathan L. Petters, Jerry Y. Harrington, and Eugene E. Clothiaux

1. Introduction Boundary layer stratiform clouds are persistent and prevalent ( Klein and Hartmann 1993 ), imparting a strong negative forcing to the earth’s radiative budget ( Chen et al. 2000 ). The representation of these clouds in current climate models is relatively poor, leading to large uncertainty in climate projections [ Randall et al. 2007 ; Intergovernmental Panel on Climate Change (IPCC)]. This problem is exacerbated by the sensitivity of stratiform clouds to perturbations in

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Greg M. McFarquhar, Michael S. Timlin, Robert M. Rauber, Brian F. Jewett, Joseph A. Grim, and David P. Jorgensen

( Wakimoto et al. 2004 ). In addition to making dual- and quad-Doppler measurements ( Jorgensen et al. 1996 ) of the convective lines and stratiform regions, the NOAA P-3 executed 17 spiral descents on 11 days to document the vertical variability of cloud microphysical structure in the stratiform regions behind the convective lines. In this paper, vertical profiles of hydrometeor shapes, sizes, phases, and concentrations above, within, and below the melting layer of the stratiform regions of MCSs

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Paloma Borque, Edward P. Luke, Pavlos Kollias, and Fan Yang

; Yang et al. 2016 ; Grabowski et al. 2018 ). Most previous observational studies (e.g., Albrecht 1989 ; Baker 1993 ; Terai et al. 2012 ; Mann et al. 2014 ; Hudson and Noble 2014 ; Jung et al. 2016 ) and modeling efforts (e.g., Nicholls 1987 ; Austin et al. 1995 ; Delobbe and Gallée 1998 ; Feingold et al. 2013 ) of marine shallow clouds have focused on the effect that cloud condensation nuclei number concentration has on precipitation production in stratiform clouds. Feingold et al. (1999

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Sonia Lasher-Trapp, Sarah Anderson-Bereznicki, Ashley Shackelford, Cynthia H. Twohy, and James G. Hudson

wintertime clouds, and it is possible that some factors act in some cases but not in others. Song and Marwitz (1989) noted that the SLD cases reported by Politovich (1989) had very low droplet concentrations, like those found in maritime stratiform clouds, suggesting that SLD formed by a very efficient warm-rain process (fewer drops compete less for the available vapor and grow much more quickly to sizes capable of initiating collisions and coalescence, given enough time). Several additional studies

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Tsuyoshi Koshiro, Seiji Yukimoto, and Masato Shiotani

1. Introduction Low stratiform clouds (LSCs) are mainly observed over the ocean and have a large negative radiative effect due to their relatively high albedo and cloud-top temperature, which is only slightly below the sea surface temperature (SST). Because of their significant potential impact on Earth’s energy balance, variations in the LSC amount and related climate parameters have been intensively investigated at various time scales. In particular, the empirical seasonal relationship with

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Gijs de Boer, Edwin W. Eloranta, and Matthew D. Shupe

; Pinto 1998 , hereafter P98 ). Previous studies have shown that from late spring to midfall, low-level clouds to make up over half of the Arctic cloud fraction ( Curry and Ebert 1992 ). Many of these clouds are mixed-phase 1 stratiform decks that persist over extended time periods (e.g., Shupe et al. 2006 , hereafter S06 ; Rogers et al. 2001 ; Curry et al. 1996 ). Ice formed in the mixed-phase layer grows and precipitates out. Supercooled liquid contained in these clouds increases surface

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Sergey Y. Matrosov

such as stratiform ones that exhibit readily identifiable melting-layer features in ARM radar measurements. Stratiform precipitation events typically result in lower-to-moderate rainfall rates R and show only modest variability in R and in the vertical profiles of nonattenuated reflectivity. During such events, MMCR signals usually are not completely attenuated except in the vicinity of cloud tops where reflectivity values are generally very low. Measurements from ARM microwave radiometers

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Yefim L. Kogan, Zena N. Kogan, and David B. Mechem

, R. , 2005 : Drizzle in stratiform boundary layer clouds. Part II: Microphysical aspects. J. Atmos. Sci. , 62 , 3034 – 3050 . Wood , R. , P. R. Field , and W. R. Cotton , 2002 : Autoconversion rate bias in stratiform boundary layer cloud parameterizations. Atmos. Res. , 65 , 109 – 128 . APPENDIX Calculation of Gamma Function Parameters The following expressions follow from the definition of moments of the gamma function (7) : Subtracting (A2) from (A1) provides the value

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