Projects
Mesoscale organization of marine stratocumulus |
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Zhou and Bretherton, 2021 applies for the first time the two-dimensional wavelet analysis to a full year of passive microwave retrievals from Advanced Microwave Scanning Radiometer for Earth Observing System. Together with a machine-learning classification of cell type, this allows the statistical characteristics of open and closed mesoscale cellular convection of various scales, and its relation to water vapor path, rain rate, and potential environmental controlling factors to be analyzed across a very large set of cases.
Zhou and Bretherton, 2019 investigates the mechanisms that promote mesoscale closed cellular organization in well-mixed non-drizzling stratocumulus-topped marine boundary layers. LES simulations show that the mesoscale closed-cell stratocumulus organization is driven by positive feedback from cloud-induced mesoscale perturbations of longwave radiative cooling that amplifies boundary-layer humidity perturbations. A conceptual model for closed-cell stratocumulus as a mesoscale wavelength hydrodynamic instability in which mesoscale moist and dry anomalies spontaneously grow is presented.
Zhou et al., 2018 designs a unique group of nudging numerical experiments that bypasses the influence of large-scale meterological conditions (surface and entrainment fluxes) and slow manifold of boundary-layer depth equillibrium on mesoscale organization of marine stratocumulus. This study reveals that moisture stratification of drizzling stratocumulus plays a dominant role increasing its organization scale.
Zhou et al., 2017 explores the impact of cloud droplet number concentration upon the emergence and scale growth of mesoscale features in the stratocumulus-topped marine boundary layer. One of the key conclusions of this study is that mesoscale organization of drizzling stratocumulus is not driven by the spatial variability of the subcloud moist cold pools, which may distinguish them from dry cold pools associated with deeper convection.
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