References

ACP

Atmospheric Chemistry and Physics

ACP

1680-7324

Copernicus GmbH

Göttingen, Germany

10.5194/acp-12-1101-2012

Statistical analysis of an LES shallow cumulus cloud ensemble using a cloud tracking algorithm

Dawe

J. T.

¹ Austin

P. H.

Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver, BC, V6T 1Z4, Canada

26 01 2012

12 2 1101 1119

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.

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A technique for the tracking of individual clouds in a Large Eddy Simulation (LES) is presented. We use this technique on an LES of a shallow cumulus cloud field based upon the Barbados Oceanographic and Meteorological Experiment (BOMEX) to calculate statistics of cloud height, lifetime, and other physical properties for individual clouds in the model. We also examine the question of nature versus nurture in shallow cumulus clouds: do properties at cloud base determine the upper-level properties of the clouds (nature), or are cloud properties determined by the environmental conditions they encounter (nurture). We find that clouds which ascend through an environment that has been pre-moistened by previous cloud activity are no more likely to reach the inversion than clouds that ascend through a drier environment. Cloud base thermodynamic properties are uncorrelated with upper-level cloud properties, while mean fractional entrainment and detrainment rates display moderate correlations with cloud properties up to the inversion. Conversely, cloud base area correlates well with upper-level cloud area and maximum cloud height. We conclude that cloud thermodynamic properties are primarily influenced by entrainment and detrainment processes, cloud area and height are primarily influenced by cloud base area, and thus nature and nurture both play roles in the dynamics of BOMEX shallow cumulus clouds.

References 1

Benner, T C. and Curry, J A.: Characteristics of small tropical cumulus clouds and their impact on the environment, J. Geophys. Res.-Atmos., 103, 28753–28767, 1998.

Blyth, A M., Lasher-Trapp, S G., and Cooper, W A.: A study of thermals in cumulus clouds, Q. J. Roy. Meteorol. Soc., 131, 1171–1190, 2005.

Bony, S. and Dufresne, J.: Marine boundary layer clouds at the heart of tropical cloud feedback uncertainties in climate models, Geophys. Res. Lett., 32, L20806, http://dx.doi.org/10.1029/2005GL023851doi:10.1029/2005GL023851, 2005.

Bretherton, C S. and Smolarkiewicz, P K.: Gravity waves, compensating subsidence and detrainment around cumulus clouds, J. Atmos. Sci., 46, 740–759, 1989.

Brown, A R., Cederwall, R T., Chlond, A., Duynkerke, P G., Golaz, J.-C., Khairoutdinov, M F., Lewellen, D C., Lock, A P., Macvean, M K., Moeng, C.-H., Neggers, R. A J., Siebesma, A P., and Stevens, B.: Large-eddy simulation of the diurnal cycle of shallow cumulus convection over land, Q. J. Roy. Meteorol. Soc., 128, 1075–1093, http://dx.doi.org/10.1256/003590002320373210doi:10.1256/003590002320373210, 2002.

Cahalan, R F. and Joseph, J H.: Fractal statistics of cloud fields, Mon. Weather Rev., 117, 261–272, 1989.

Carpenter, R L., Droegemeier, K K., and Blyth, A M.: Entrainment and detrainment in numerically simulated cumulus congestus clouds. Part I: general results, J. Atmos. Sci., 55, 3417–3432, 1998.

Couvreux, F., Hourdin, F., and Rio, C.: Resolved Versus Parametrized Boundary-Layer Plumes. Part I: A Parameterization-Oriented Conditional Sampling in Large-Eddy Simulations, Bound.-Lay. Meteorology, 134, 441–458, 2010.

Dawe, J T. and Austin, P H.: Interpolation of LES cloud surfaces for use in direct calculations of entrainment and detrainment, Mon. Weather Rev., 139, 444–456, 2011.

de~Rooy, W C. and Siebesma, A P.: A simple parameterization for detrainment in shallow cumulus, Mon. Weather Rev., 136, 560–576, 2008.

Grabowski, W W. and Clark, T L.: Cloud-environment interface instability: rising thermal calculations in two spatial dimensions, J. Atmos. Sci., 48, 527–546, 1991.

Grabowski, W W. and Clark, T L.: Cloud-environment interface instability. Part II: extension to three spatial dimensions, J. Atmos. Sci., 50, 527–546, 1993a.

Grabowski, W W. and Clark, T L.: Cloud-environment interface instability. Part III: direct influence of environmental shear, J. Atmos. Sci., 50, 3821–3828, 1993b.

Heus, T., Jonker, H. J J., den Akker, H. E. A V., Griffith, E J., Koutek, M., and Post, F H.: A statistical approach to the life cycle analysis of cumulus clouds selected in a virtual reality environment, J. Geophys. Res.-Atmos., 114, D06208, http://dx.doi.org/10.1029/2008JD010917doi:10.1029/2008JD010917, 2009.

Holland, J Z. and Rasmusson, E M.: Measurement of the atmospheric mass, energy, and momentum budgets over a 500-kilometer square of tropical ocean, Mon. Weather Rev., 101, 44–57, http://dx.doi.org/10.1175/1520-0493(1973)101<0044:MOTAME>2.3.CO;2doi:10.1175/1520-0493(1973)101<0044:MOTAME>2.3.CO;2, 1973.

Jiang, H., Xue, H., Teller, A., Feingold, G., and Levin, Z.: Aerosol effects on the lifetime of shallow cumulus, Geophys. Res. Lett., 33, L14806, http://dx.doi.org/10.1029/2006GL026024doi:10.1029/2006GL026024, 2006.

Jiang, H., Feingold, G., Jonsson, H H., Lu, M.-L., Chuang, P Y., Flagan, R C., and Seinfeld, J H.: Statistical comparison of properties of simulated and observed cumulus clouds in the vicinity of Houston during the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS), J. Geophys. Res.-Atmos., 113, D13205, http://dx.doi.org/10.1029/2007JD009304doi:10.1029/2007JD009304, 2008.

Kain, J S. and Fritsch, J M.: A one-dimensional entraining/detraining plume model and its application in convective parameterization, J. Atmos. Sci., 47, 2784–2802, 1990.

Khairoutdinov, M F. and Randall, D A.: Cloud resolving modeling of the ARM summer 1997 IOP: model formulation, results, uncertainties, and sensitivities, J. Atmos. Sci., 60, 607–625, 2003.

Klaassen, G P. and Clark, T L.: Dynamics of the cloud-environment interfact and entrainment in small cumuli: two-dimensional simulations in the absence of ambient shear, J. Atmos. Sci., 42, 2621–2642, 1985.

Mann, H B. and Whitney, D R.: On a Test of Whether one of Two Random Variables is Stochastically Larger than the Other, Annals of Mathematical Statistics, 18, 50–60, http://dx.doi.org/10.1214/aoms/1177730491doi:10.1214/aoms/1177730491, 1947.

Medeiros, B. and Stevens, B.: Revealing differences in GCM representations of low clouds, Clim. Dyn., 36, 385–399, 2011.

Medeiros, B., Stevens, B., Held, I M., Zhao, M., Williamson, D L., Olson, J G., and Bretherton, C S.: Aquaplanets, climate sensitivity, and low clouds, J. Climate, 21, 4974–4991, 2008.

Nakagawa, S.: A farewell to Bonferroni: the problems of low statistical power and publication bias, Behavioral Ecology, 15, 1044–1045, http://dx.doi.org/10.1093/beheco/arh107doi:10.1093/beheco/arh107, 2004.

Neggers, R. A J., Siebesma, A P., and Jonker, H. J J.: A Multiparcel Model for Shallow Cumulus Convection, J. Atmos. Sci., 59, 1655–1668, 2002.

Neggers, R. A J., Duynkerke, P G., and Rodts, S. M A.: Shallow cumulus convection: a validation of large-eddy simulation against aircraft and Landsat observations, Q. J. Roy. Meteorol. Soc., 129, 2671–2696, 2003a.

Neggers, R. A J., Jonker, H. J J., and Siebesma, A P.: Size statistics of cumulus cloud populations in large-eddy simulations, J. Atmos. Sci., 60, 1060–1074, 2003b.

Neggers, R. A J., Neelin, J D., and Stevens, B.: Impact mechanisms of shallow cumulus convection on tropical climate dynamics, J. Climate, 20, 2623–2642, 2007.

Norris, J R.: Low cloud type over the ocean from surface observations. Part II: geographical and seasonal variations, J. Climate, 11, 383–403, 1988.

Perneger, T V.: What's wrong with Bonferroni adjustments, The British Medical Journal, 316, 1236, 1998.

Plant, R. S.: Statistical properties of cloud lifecycles in cloud-resolving models, Atmos. Chem. Phys., 9, 2195–2205, http://dx.doi.org/10.5194/acp-9-2195-2009doi:10.5194/acp-9-2195-2009, 2009.

Randall, D., Krueger, S., Bretherton, C., Curry, J., Duynkerke, P., Moncrieff, M., Ryan, B., Starr, D., Miller, M., Rossow, W., Tselioudis, G., and Wielicki, B.: Confronting models with data: the GEWEX cloud systems study, B. Am. Meteorol. Soc., 84, 455–469, http://dx.doi.org/10.1175/BAMS-84-4-455doi:10.1175/BAMS-84-4-455, 2003.

Romps, D M. and Kuang, Z.: Nature versus Nurture in Shallow Convection, J. Atmos. Sci., 67, 1655–1666, 2010.

Shaffer, J P.: Multiple Hypothesis Testing, Annual Reviews of Psychology, 46, 561–584, 1995.

Siebesma, A P. and Cuijpers, J. W M.: Evaluation of parametric assumptions for shallow cumulus convection, J. Atmos. Sci., 52, 650–666, 1995.

Siebesma, A P., Bretherton, C S., Brown, A., Chlond, A., Cuxart, J., Duynkerke, P G., Jiang, H., Khairoutdinov, M., Lewellen, D., Moeng, C.-H., Sanchez, E., Stevens, B., and Stevens, D E.: A large eddy simulation intercomparison study of shallow cumulus convection, J. Atmos. Sci., 60, 1201–1219, http://dx.doi.org/10.1175/1520-0469(2003)60<1201:ALESIS>2.0.CO;2doi:10.1175/1520-0469(2003)60<1201:ALESIS>2.0.CO;2, 2003.

Stevens, B., Ackerman, A S., Albrecht, B A., Brown, A R., Chlond, A., Cuxart, J., Duynkerke, P G., Lewellen, D C., Macvean, M K., Neggers, R. A J., Sanchez, E., Siebesma, A P., and Stevens, D E.: Simulations of trade wind cumuli under a strong inversion, J. Atmos. Sci., 58, 1870–1891, 2001.

Tiedtke, M., Heckley, W A., and Slingo, J.: Tropical forecasting at ECMWF: The influence of physical parametrization on the mean structure of forecasts and analyses, Q. J. Roy. Meteorol. Soc., 114, 639–664, http://dx.doi.org/10.1002/qj.49711448106doi:10.1002/qj.49711448106, 1988.

vanZanten, M C., Stevens, B., Nuijens, L., Siebesma, A P., Ackerman, A S., Burnet, F., Cheng, A., Couvreaux, F., Jiang, H., Khairoutdinov, M., Kogan, Y., Lewellen, D C., Mechem, D., Nakamura, K., Noda, A., Shipway, B J., Slawinska, J., Wang, S., and Wyszogrodzki, A.: Controls on precipitation and cloudiness in simulations of trade-wind cumulus as observed during RICO, Journal of Advances in Modeling Earth Systems, 3, M06001, http://dx.doi.org/10.1029/2011MS000056doi:10.1029/2011MS000056, 2011.

Wyant, M., Bretherton, C., and Blossey, P.: Subtropical low cloud response to a warmer climate in an superparameterized climate model: part I. regime sorting and physical mechanisms, Journal of Advances in Modeling Earth Systems, 1, 7, http://dx.doi.org/10.3894/JAMES.2009.1.7doi:10.3894/JAMES.2009.1.7, 2009.

Zhao, G. and Girolamo, L D.: Statistics on the macrophysical properties of trade wind cumuli over the tropical western Atlantic, J. Geophys. Res.-Atmos., 112, D10204, http://dx.doi.org/10.1029/2006JD007371doi:10.1029/2006JD007371, 2007.

Zhao, M. and Austin, P H.: Life cycle of numerically simulated shallow cumulus clouds. Part I: transport, J. Atmos. Sci., 62, 1269–1290, http://dx.doi.org/10.1175/JAS3414.1doi:10.1175/JAS3414.1, 2005a.

Zhao, M. and Austin, P H.: Life cycle of numerically simulated shallow cumulus clouds. Part II: mixing dynamics., J. Atmos. Sci., 62, 1291–1310, http://dx.doi.org/10.1175/JAS3415.1doi:10.1175/JAS3415.1, 2005b.