Note on stratocumulus instability

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With the exception of a few numerical modeling studies (e.g. Oliver et al., 1978), investigations of the stratocumulus-topped planetary boundary layer have evolved from Lilly’s (1968) mixed-layer approach (e.g. Schubert, 1976; Deardorff, 1976; Kraus and Schaller, 1978; Schubert et al., 1979a,b). In a discussion of the stability of these cloud decks, Lilly (1968) introduced the concept of moist convective instability, which occurs when very dry air is entrained into the cloud’s top, and becomes negatively buoyant (with respect to the cloud) while becoming saturated. Lilly asserted that this would happen when the difference across the cloud top of moist static energy is negative; Le., when hc > hu, where subscripts “c” and “u” refer to the cloud and upper (clear) air respectively. (Lilly (1968) actually discussed the problem in terms of wet bulb potential temperature, which is equivalent to moist static energy for purposes of this discussion.)DOI: 10.1111/j.2153-3490.1981.tb01736.x
  • References (9)

    Deardorff, J. W. 1976. On the entrainment rate of a stratocumulus-topped mixed layer. Quart. J. Roy. Met. SOC.102,563-582.

    Deardorff, J . W. 1980. Cloud top entrainment instability. J.Atmos. Sci. 37, 131-147.

    Kraus, H. and Schaller, E. 1978. Steady-state characteristics of inversions capping a well-mixed PBL. Boundary-Layer Met. 14,83-104.

    Lilly, D. K. 1968. Models of cloud-topped mixed layers under a strong inversion. Quart. J. Roy. Met. SOC9.4, 292-309.

    Oliver, D. A., Lewellen, W. S. and Williamson, G. G. 1978. The interaction between turbulent and radiative transport in the development of fog and lowlevel stratus. J. Atmos. Sci. 35,301-3 16.

    Randall, D. A. 1980. Conditional instability of the first kind upside-down.J.Atmos. Sci. 37, 125-130.

    Schubert, W. H. 1976. Experiments with Lilly's cloudtopped mixed layer model. J. Atmos. Sci. 33, 436- 446.

    Schubert, W. H., Wakefield, J. S., Steiner, E. J. and Cox, S . K. 1979a. Marine stratocumulus convection. Part I: Governing equations and horizontally homogenous solutions. J. Atmos. Sci. 36, 1286- 1307.

    Schubert, W. H., Wakefield, J. S., Steiner, E. J. and Cox, S. K. 1979b. Marine stratocumulus convection. part 11: Horizontally inhomogenous solutions. J . Atmos. Sci. 36, 1308-1324.

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