ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-11-9607-2011 Cloud-base vertical velocity statistics: a comparison between an atmospheric mesoscale model and remote sensing observations Tonttila J. 1 3 O'Connor E. J. 1 2 Niemelä S. 1 Räisänen P. 1 Järvinen H. 1 Finnish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland Meteorology Department, University of Reading, Reading, UK Division of Atmospheric Sciences, Department of Physics, University of Helsinki, Helsinki, Finland 22 03 2011 11 3 9607 9633 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys-discuss.net/11/9607/2011/acpd-11-9607-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/11/9607/2011/acpd-11-9607-2011.pdf

The statistics of cloud-base vertical velocity simulated by the non-hydrostatic mesoscale model AROME are compared with Cloudnet remote sensing observations at two locations: the ARM SGP site in Central Oklahoma, and the DWD observatory at Lindenberg, Germany. The results show that, as expected, AROME significantly underestimates the variability of vertical velocity at cloud-base compared to observations at their nominal resolution; the standard deviation of vertical velocity in the model is typically 4–6 times smaller than observed, and even more during the winter at Lindenberg. Averaging the observations to the horizontal scale corresponding to the physical grid spacing of AROME (2.5 km) explains 70–80% of the underestimation by the model. Further averaging of the observations in the horizontal is required to match the model values for the standard deviation in vertical velocity. This indicates an effective horizontal resolution for the AROME model of at least 4 times the physically-defined grid spacing. The results illustrate the need for special treatment of sub-grid scale variability of vertical velocities in kilometer-scale atmospheric models, if processes such as aerosol-cloud interactions are to be included in the future.

 References Ackerman,~T P., Stokes,~G.: The atmospheric radiation measurement program, Phys. Today, 56, 38–44, http://dx.doi.org/10.1063/1.1554135doi:10.1063/1.1554135, 2003. Bechtold,~P., Cuijpers,~J W M., Mascart,~P., and Trouilhet,~P.: Modelling of trade wind cumuli with a~low-order turbulence model: toward a~unified description of Cu and Sc clouds in meteorological models,~J. Atmos. Sci., 52, 455–463, 1995. Clothiaux,~E E., Moran,~K P., Martner,~B E., Ackerman,~T P., Mace,~G G., Uttal,~T., Mather,~J H., Widener,~K B., Miller,~M A., and Rodriguez D J.: The atmospheric radiation measurement program cloud radars: operational modes,~J. Atmos. Ocean. Tech., 16, 819–827, 1999. Clothiaux,~E E., Ackerman,~T P., Mace,~G G., Moran,~K P., Marchand,~R T., Miller,~M A., and Martner,~B E.: Objective determination of cloud heights and radar reflectivities using a~combination of active remote sensors at the ARM CART sites,~J. Appl. Metorol., 39, 645–665, 2000. Clothiaux,~E E., Miller,~M.A, Perez,~R C., Turner,~D D., Moran,~K P., Martner,~B E., Ackerman,~T P., Mace,~G G., Marchand,~R T., Widener,~K B., Rodriguez,~D J., Uttal,~T., Mather,~J H., Flynn,~C J., Gaustad,~K L., and Ermold,~B.: The ARM Millimeter Wave Cloud Radars (MMCRs) and the Active Remote Sensing of Clouds (ARSCL) Value Added Product (VAP), DOE Tech. Memo. ARM VAP-002.1, available at: http://www.arm.gov/publications/vaps, last access: 21 March 2011, 2001. Cuxart,~J., Bougeault,~P., and Redelsperger,~J L.: A~turbulence scheme allowing for mesoscale and large eddy simulations,~Q J Roy. Meteor. Soc., 126, 1–30, 2000. Duynkerke,~P G., Jonker,~P J., Chlond,~A., Van Zanten,~M C., Cuxart,~J., Clark,~P., Sanchez,~E., Martin,~G., Lenderink,~G., and Teixeira,~J.: Intercomparison of three- and one-dimensional model simulations and aircraft observations of stratocumulus, Bound.-Lay. Meteorol., 92, 453–487, 1999. Feingold,~G., Frisch,~A S., Stevens,~B., and Cotton,~W R.: On the relationship among cloud turbulence, droplet formation and drizzle as viewed by Doppler radar, microwave radiometer and lidar,~J. Geophys. Res., 104, 22195–22203, 1999. Fouquart,~Y. and Bonnel,~B.: Computations of solar heating of the Earth's atmosphere: a~new parameterization, Beitr. Phys. Atmos., 53, 35–62, 1980. Frisch,~A S., Lenschow,~D H., Fairall,~C W., Schubert,~W H., and Gibson,~J S.: Doppler radar measurements of turbulence in marine stratiform cloud during ASTEX,~J. Atmos. Sci., 52, 2800–2808, 1995. Geerts,~B. and Miao,~Q.: The use of millimeter doppler radar echoes to estimate vertical air velocities in the fair-weather convective boundary layer,~J. Atmos. Ocean. Technol., 22, 225–246, 2005. Geleyn,~J.-F., Catry,~B., Bouteloup,~Y., and Brozkova,~R.: A~statistical approach for sedimentation inside a~microphysical precipitation scheme, Tellus A, 60, 649–662, 2008. Ghan,~S J., Leung,~L R., Easter,~R C., and Abdul-Razzak,~H.: Prediction of cloud droplet number in a~general circulation model,~J. Geophys. Res., 102, 21777–21794, 1997. Ghate,~V P., Albrecht,~B A., and Kollias,~P.: Vertical velocity structure of nonprecipitating continental boundary layer stratocumulus clouds,~J. Geophys. Res., 115, D13204, http://dx.doi.org/10.1029/2009JD013091doi:10.1029/2009JD013091, 2010. Guo,~H., Liu,~Y., Daum,~P H., Senum,~G I., and Tao,~W.-K.: Characteristics of vertical velocity in marine stratocumulus: comparison of large eddy simulations with observations, Environ. Res. Lett., 3, 045020, http://dx.doi.org/10.1088/1748-9326/3/4/045020doi:10.1088/1748-9326/3/4/045020, 2008. Hogan,~R J., Grant,~A L., Illingworth,~A J., Pearson,~G N., and O'Connor,~E J.: Vertical velocity variance and skewness in clear and cloud-topped boundary layers as revealed by Doppler lidar,~Q J Roy. Meteor. Soc., 135, 635–643, 2009. Hoose,~C., Kristjánsson,~J E., Arabas,~S., Boers,~R., Pawlowska,~H., Puygrenier,~V., Siebert,~H., and Thouron,~O.: Parameterization of in-cloud vertical velocities for cloud droplet activation calculations in coarse-grid models: analysis of observations and cloud resolving model results, 13th Conference on Atmospheric Raditation, Portland, OR, USA, 28 June–2 July 2010, Presentation 6.4, available at: http://ams.confex.com/ams/pdfpapers/170866.pdf, last access: 21 March 2011, 2010. Illingworth,~A J., Hogan,~R J., O'Connor,~E J., Bouniol,~D., Brooks,~M E., Delano\"e,~J., Donovan,~D P., Eastment,~J D., Gaussiat,~N., Goddard,~J W F., Haeffelin,~M., Klein Baltink,~H., Krasnov,~O A., Pelon,~J., Piriou,~J.-M., Protat,~A., Russchenberg,~H W J., Seifert,~A., Tompkins,~A M., van Zadelhoff,~G.-J., Vinit,~F., Willén,~U., Wilson,~D R., and Wrench,~C L.: Cloudnet: continuous evaluation of cloud profiles in seven operational models using ground-based observations, B. Am. Meteorol. Soc., 88, 883–898, 2007. Ivanova,~I T. and Leighton,~H G.: Aerosol-cloud interactions in a~mesoscale model, part I: sensitivity to activation and collision-coalescence,~J. Atmos. Sci., 65, 289–308, 2008. Khairoutdinov,~M F., Krueger,~S K., Moeng,~C.-H., Bogenschutz,~P A., and Randall,~D A.: Large-eddy simulation of deep maritime tropical convection,~J. Adv. Model. Earth Syst., 1(15), 13~pp., 2009. Khvorostyanov,~V I. and Curry,~J A.: Terminal velocities of droplets and crystals: power laws with continuous parameters over the size spectrum,~J. Atmos. Sci., 59, 1872–1884, 2002. Kollias,~P. and Albrecht~B.: The turbulence structure in a~continental stratocumulus cloud from millimeter-wavelength radar observations,~J. Atmos. Sci., 57, 2417–2434, 2000. Kollias,~P. and Albrecht~B.: Vertical velocity statistics in fair-weather cumuli at the ARM TWP Nauru Climate Research Facility,~J. Clim., 23, 6590–6604, 2010. Kollias,~P., Albrecht,~B., Lhermitte,~R., and Savtchenko,~A.: Radar observations of updrafts, downdrafts, and turbulence in fair-weather cumuli,~J. Atmos. Sci., 58, 1750–1766, 2001. %Lafore,~J P., Stein,~J., Asencio,~N., Bougeault,~P., Ducrocq,~V., Duron,~J., Fischer,~C., Hereil,~P., Mascart,~P., Pinty,~J P., Redelsperger,~J L., Richard,~E., and Vila-Guerau de Arellano,~J.: The meso-NH atmospheric simulation system, Part I: adiabatic formulation and control simulations, Ann. Geophys., 16, 90–109, 1998. % ### SELF-REFERENCE ### Lafore,~J P., Stein,~J., Asencio,~N., Bougeault,~P., Ducrocq,~V., Duron,~J., Fischer,~C., Héreil,~P., Mascart,~P., Masson,~V., Pinty,~J P., Redelsperger,~J L., Richard,~E., and Vilà-Guerau~de~Arellano,~J.: The Meso-NH Atmospheric Simulation System. Part I: adiabatic formulation and control simulations, Ann. Geophys., 16, 90–109, http://dx.doi.org/10.1007/s00585-997-0090-6doi:10.1007/s00585-997-0090-6, 1998. Le Moigne,~P.: SURFEX scientific documentation, online documentation available at: http://www.cnrm.meteo.fr/surfex/doc_exter/surfex_scidoc.pdf, last access: 21 March 2011, 2009. Liu,~Y., Geerts,~B., Miller,~M., Daum,~P., and McGraw,~R.: Threshold radar reflectivity for drizzling clouds, Geophys. Res. Lett., 35, L03807, http://dx.doi.org/10.1029/2007GL031201doi:10.1029/2007GL031201, 2008. Lohmann,~U., Feichter,~J., Chuang,~C C., and Penner,~J E.: Prediction of the number of cloud droplets in the ECHAM GCM,~J. Geophys. Res., 104, 9169–9198, 1999. Lu,~M.-L., Sorooshian,~A., Jonsson,~H H., Feingold,~G., Flagan,~R C., and Seinfeld,~J H.: Marine stratocumulus aerosol-cloud relationships in the MASE-II experiment: precipitation susceptibility in Eastern Pacific marine stratocumulus,~J. Geophys. Res., 114, D24203, http://dx.doi.org/10.1029/2009JD012774doi:10.1029/2009JD012774, 2009. Mlawer,~E J., Taubman,~S J., Brown,~P D., Iacono,~M J., and Clough,~S A.: Radiative transfer for inhomogeneous atmospheres: RRTM, a~validated correlated-$k$ model for the long wave,~J. Geophys. Res., 102, 16663–16682, 1997. Morcrette,~J.-J.: Radiation and cloud radiative properties in the ECMWF operational weather forecast model,~J. Geophys. Res., 96D, 9121–9132, 1991. O'Connor,~E J., Hogan,~R J., and Illingworth,~A J.: Retrieving stratocumulus drizzle parameters using doppler radar and lidar,~J. Appl. Meteorol., 44, 14–27, 2005. Pergaud,~J., Masson,~V., Malardel,~S., and Couvreux,~F.: A~parameterization of dry thermals and shallow cumuli for mesoscale numerical weather prediction, Bound.-Lay. Meteorol., 132, 83–106, 2009. Pinty,~J P. and Jabouille,~P.: A~mixed-phase cloud parameterization for use in a~mesoscale non-hydrostatic model: simulations of a~squall line and of orographic precipitation, Preprints of Conference on Cloud Physics, Amer. Meteor. Soc., Everett, WA, 217–220, 1998. Rodts,~S M A., Duynkerke,~P G., and Jonker,~H J J.: Size distributions and dynamical properties of shallow cumulus clouds from aircraft observations and satellite data,~J. Atmos. Sci., 60, 1895–1912, 2003. Rogers,~R R.: A~short course in cloud physics, Pergamon Press, Oxford, UK, 266~pp., 1976. Seity,~Y., Brousseau,~P., Malardel,~S., Hello,~G., Bénard,~P., Bouttier,~F., Lac,~C., and Masson,~V.: The AROME-france convective scale operational model, Mon. Weather Rev., D24203, http://dx.doi.org/10.1175/2010MWR3425.1doi:10.1175/2010MWR3425.1, 2010. Skamarock,~W C.: Evaluating mesoscale NWP models using kinetic energy spectra, Mon. Weather Rev., 132, 3019–3032, 2004. Snider,~J R., Guibert,~S., Brenguier,~J.-L., and Putaud,~J.-P.: Aerosol activation in marine stratocumulus clouds: 2. Köhler and parcel theory closure studies,~J. Geophys. Res., 108(D15), 8629, http://dx.doi.org/10.1029/2002JD002692doi:10.1029/2002JD002692, 2003. Zhu,~P. and Zuidema,~P.: On the use of PDF schemes to parameterize sub-grid clouds, Geophys. Res. Lett., 36, L05807, http://dx.doi.org/10.1029/2008GL036817doi:10.1029/2008GL036817, 2009.