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Schmidt, JM, Flatau PJ, Yates RD.  2014.  Convective cells in altocumulus observed with a high-resolution radar. Journal of the Atmospheric Sciences. 71:2130-2154.   10.1175/jas-d-13-0172.1   AbstractWebsite

Very-high-resolution Doppler radar observations are used together with aircraft measurements to document the dynamic and thermodynamic structure of a dissipating altocumulus cloud system associated with a deep virga layer. The cloud layer circulation is shown to consist of shallow vertical velocity couplets near cloud top and a series of subkilometer-scale Rayleigh-Benard-like cells that extend vertically through the depth of the cloud layer. The subcloud layer was observed to contain a number of narrow virga fall streaks that developed below the more dominant Rayleigh-Benard updraft circulations in the cloud layer. These features were discovered to be associated with kilometer-scale horizontally orientated rotor circulations that formed along the lateral flanks of the streaks collocated downdraft circulation. The Doppler analysis further reveals that a layer mean descent was present throughout both the cloud and subcloud layers. This characteristic of the circulation is analyzed with regard to the diabatic and radiative forcing on horizontal length scales ranging from the Rayleigh-Benard circulations to the overall cloud layer width. In particular, linear analytical results indicate that a deep and broad mesoscale region of subsidence is quickly established in middle-level cloud layers of finite width when a layer-wide horizontal gradient in the cloud-top radiative cooling rate is present. A conceptual model summarizing the primary observed and inferred circulation features of the altocumulus layer is presented.

O
Markowicz, KM, Flatau PJ, Remiszewska J, Witek M, Reid EA, Reid JS, Bucholtz A, Holben B.  2008.  Observations and modeling of the surface aerosol radiative forcing during UAE(2). Journal of the Atmospheric Sciences. 65:2877-2891.   10.1175/2007jas2555.1   AbstractWebsite

Aerosol radiative forcing in the Persian Gulf region is derived from data collected during the United Arab Emirates (UAE) Unified Aerosol Experiment (UAE(2)). This campaign took place in August and September of 2004. The land -sea-breeze circulation modulates the diurnal variability of the aerosol properties and aerosol radiative forcing at the surface. Larger aerosol radiative forcing is observed during the land breeze in comparison to the sea breeze. The aerosol optical properties change as the onshore wind brings slightly cleaner air. The mean diurnal value of the surface aerosol forcing during the UAE2 campaign is about -20 W m(-2), which corresponds to large aerosol optical thickness (0.45 at 500 nm). The aerosol forcing efficiency [i. e., broadband shortwave forcing per unit optical depth at 550 nm, W m(-2) (tau(500))(-1)] is -53 W m(-2) (tau(500))(-1) and the average single scattering albedo is 0.93 at 550 nm.