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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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Alexander Khain, M. Pinsky, and A. Korolev

1. Introduction Mixed-phase stratiform and stratocumulus clouds cover enormous areas across the globe. They play a crucial role in the planet radiative equilibrium and contribute significantly to precipitation formation. The phase composition of clouds affects the radiation transfer (e.g., Oshchepkov and Isaka 1997 ) and is important for climate formation processes (e.g., Wilson and Ballard 1999 ; Wilson 2000 ). Due to the importance of mixed-phase stratiform clouds and their

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Stanley G. Benjamin, Eric P. James, Ming Hu, Curtis R. Alexander, Therese T. Ladwig, John M. Brown, Stephen S. Weygandt, David D. Turner, Patrick Minnis, William L. Smith Jr., and Andrew K. Heidinger

call this a stratiform cloud-hydrometeor (SCH) DA technique since it is for stratiform clouds only (convective clouds treated through radar DA; Weygandt et al. 2021, manuscript submitted to Wea. Forecasting ) and since it directly updates prognostic cloud hydrometeor fields. It has been applied and refined in NOAA hourly updated models as an option within the NOAA GSI DA system ( Kleist et al. 2009 ) and applied to the NOAA 3-km High-Resolution Rapid Refresh (HRRR; Dowell et al. 2021, manuscript

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