Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 9 2 2009 10.5194/acpd-9-10549-2009 http://www.atmos-chem-phys-discuss.net/9/10549/2009/ http://www.atmos-chem-phys-discuss.net/9/10549/2009/acpd-9-10549-2009.html http://www.atmos-chem-phys-discuss.net/9/10549/2009/acpd-9-10549-2009.pdf 10549 10574 2009-04-30 Analytical treatment of ice sublimation and test of sublimation parameterisations in two-moment ice microphysics models K. Gierens klaus.gierens@dlr.de S. Bretl Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany We derive an analytic solution to the spectral growth/sublimation equation for ice crystals and apply it to idealised cases. The results are used to test parameterisations of the ice sublimation process in two-moment bulk microphysics models. Although it turns out that the relation between number loss fraction and mass loss fraction is not a function since it is not unique, it seems that a functional parameterisation is the best that one can do in a bulk model. Testing a more realistic case with humidity oscillations shows that artificial crystal loss can occur in simulations of mature cirrus clouds with relative humidity fluctuating about ice saturation. Brenguier, J. L.: Parameterization of the condensation process: A theoretical approach. J. Atmos. Sci., 48, 264–282, 1991. Harrington, J. Y., Meyers, M. P., Walko, R. L., and Cotton, W. R.: Parameterization of ice crystal conversion processes due to vapor deposition for mesoscale models using double-moment basis functions. Part I: Basic formulation and parcel model test, J. Atmos. Sci., 52, 4344–4366, 1995. Jawitz, J. W.: Moments of truncated continuous univariate distributions, Adv. Water Resour., 27, 269–281, 2004. Koenig, L.: Numerical modeling of ice deposition, J. Atmos. Sci., 28, 226–237, 1971. Morrison, H. and Grabowski, W. W.: A novel approach for representing ice microphysics in models: description and tests using a kinematic framework, J. Atmos. Sci., 65, 1528–1548, 2008. Sedunov, Y. S.: Physics of Drop Formation in the Atmosphere, Wiley & Sons, 234~pp., 1974. Spichtinger, P. and Gierens, K. M.: Modelling of cirrus clouds – Part 1a: Model description and validation, Atmos. Chem. Phys., 9, 685–706, 2009. Tompkins, A. M.: A prognostic parameterization for the subgrid–scale variability of water vapor and clouds in large-scale models and its use to diagnose cloud cover, J. Atmos. Sci., 59, 1917–1942, 2002. Wacker, U. and Herbert, F.: On the mathematical simulation of non-equilibrium cloud condensation rates, Meteorol. Rundsch., 36, 141–144, 1983.