Wavelet analysis of properties of marine boundary layer mesoscale cellsobserved from AMSR-E

Abstract

Marine boundary layer clouds over the colder regions of the ocean often organize into closed or open mesoscale cellular convection (MCC) with cell sizes between 10 and 100 km, modulating cloud water path (CWP), precipitation, and albedo (Agee et al., 1973). MCC is associated with significant mesoscale variations of moisture (∼10% relative humidity perturbation), temperature, and winds (Rothermel & Agee, 1980). MCClike patterns can be simulated in large-eddy simulations, weather, and climate models with horizontal grid resolutions of O (10 km) or less (e.g., Boutle & Abel, 2012). To evaluate their skill requires good documentation and understanding of MCC cloud morphology and scale, of co-variability between observable quantities within closed and open cells, and of the sensitivity of closed and open MCC to potential environmental controlling factors across different boundary-layer cloud regions.There is a 50-year history of MCC observations from in situ and satellite measurements that has advanced our understanding and provided local data that has been used for model comparisons. MCC was first observed by the first weather satellites in the early 1960s (Agee, 1984). MCC covers extensive regions over the eastern subtropical oceans (Muhlbauer et al., 2014;Wood & Hartmann, 2006), with closed cells forming near the coast and open cells occurring toward the warm oceans (Atkinson & Zhang, 1996;Muhlbauer et al., 2014). Closed and open cells can be considered as different stages of the stratocumulus to cumulus transition (Wood, 2012), which is often associated with the advection of clouds over a warmer ocean surface

The Role of Mesoscale Cloud Morphology in the Shortwave Cloud Feedback

“…Open, closed, and disorganized MCC as identified by WH6 have distinct radiative (I. L. and microphysical (Muhlbauer et al, 2014;Zhou et al, 2021;Danker et al, 2022) properties, consistent with other MCC studies (e.g., Painemal et al, 2010;Wood, 2012;Terai et al, 2014;Bretherton et al, 2019;Watson-Parris et al, 2021;Kang et al, 2022). We utilize the updated MIDAS dataset and CF vs. albedo diagrams (following earlier studies Bender et al, 2011;Engstrom et al, 2015b;Feingold et al, 2016;Bender et al, 2017;Feingold et al, 2017) or more disorganized clouds (e.g., trade Cu) in the subtropics (e.g., Wyant et al, 1997;Yamaguchi et al, 2017;Eastman et al, 2021Eastman et al, , 2022.…”

“…For example, open and closed mesoscale cellular convective (MCC) organization that dominate subtropical stratocumulus (Sc) cloud decks and marine cold-air outbreaks (Muhlbauer et al, 2014;Mohrmann et al, 2021) are distinctly different from the more disorganized cumulus (Cu) cloud structures in the tropical trade-winds (Stevens et al, 2019). The radiative properties of mesoscale morphology patterns differ even for the same cloud areal coverage (I. L. , indicating microphysical and macrophysical differences between organization structures (consistent with Painemal et al, 2010;Wood, 2012;Terai et al, 2014;Muhlbauer et al, 2014;Bretherton et al, 2019;Zhou et al, 2021;Watson-Parris et al, 2021;Kang et al, 2022). The occurrence of cloud morphology patterns is strongly connected to environmental factors (e.g., Atkinson & Zhang, 1996;Wood, 2012;Muhlbauer et al, 2014;Bony et al, 2020;Schulz et al, 2021;Mohrmann et al, 2021;Narenpitak et al, 2021).…”

“…At zeroth order, the mean optical thickness and extent of low cloud strongly affect global albedo (Engstrom et al, 2015b). However, low clouds encompass different morphology patterns with regionally varied mesoscale features (e.g., large-scale structures O∼100 km of clouds with typical cell sizes O∼20-80 km, Wood & Hartmann, 2006;Zhou et al, 2021;Stevens et al, 2019). For example, open and closed mesoscale cellular convective (MCC) organization that dominate subtropical stratocumulus (Sc) cloud decks and marine cold-air outbreaks (Muhlbauer et al, 2014;Mohrmann et al, 2021) are distinctly different from the more disorganized cumulus (Cu) cloud structures in the tropical trade-winds (Stevens et al, 2019).…”