ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-10127-2011 Moisture and dynamical interactions maintaining decoupled Arctic mixed-phase stratocumulus in the presence of a humidity inversion Solomon A. 1 2 Shupe M. D. 1 2 Persson P. O. G. 1 2 Morrison H. 3 CIRES, University of Colorado, Boulder, Colorado, USA Earth System Research Laboratory/NOAA, Boulder Colorado, USA MMM/NESL/NCAR, Boulder, Colorado, USA 07 10 2011 11 19 10127 10148 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.net/11/10127/2011/acp-11-10127-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/10127/2011/acp-11-10127-2011.pdf

Observations suggest that processes maintaining subtropical and Arctic stratocumulus differ, due to the different environments in which they occur. For example, specific humidity inversions (specific humidity increasing with height) are frequently observed to occur near cloud top coincident with temperature inversions in the Arctic, while they do not occur in the subtropics. In this study we use nested LES simulations of decoupled Arctic Mixed-Phase Stratocumulus (AMPS) clouds observed during the DOE Atmospheric Radiation Measurement Program's Indirect and SemiDirect Aerosol Campaign (ISDAC) to analyze budgets of water components, potential temperature, and turbulent kinetic energy. These analyses quantify the processes that maintain decoupled AMPS, including the role of humidity inversions. Key structural features include a shallow upper entrainment zone at cloud top that is located within the temperature and humidity inversions, a mixed layer driven by cloud-top cooling that extends from the base of the upper entrainment zone to below cloud base, and a lower entrainment zone at the base of the mixed layer. The surface layer below the lower entrainment zone is decoupled from the cloud mixed-layer system. Budget results show that cloud liquid water is maintained in the upper entrainment zone near cloud top (within a temperature and humidity inversion) due to a down gradient transport of water vapor by turbulent fluxes into the cloud layer from above and direct condensation forced by radiative cooling. Liquid water is generated in the updraft portions of the mixed-layer eddies below cloud top by buoyant destabilization. These processes cause at least 20% of the cloud liquid water to extend into the inversion. The redistribution of water vapor from the top of the humidity inversion to its base maintains the cloud layer, while the mixed layer-entrainment zone system is continually losing total water. In this decoupled system, the humidity inversion is the only source of water vapor for the cloud system, since water vapor from the surface layer is not efficiently transported into the mixed layer. Sedimentation of ice is the dominant sink of moisture from the mixed layer.

 References Abdul-Razzak, H. and Ghan, S. J.: A parameterization of aerosol activation 2. Multiple aerosol types, J. Geophys. Res., 105, 6837–6844, 2000. Ackerman, A. S., Kirkpatrick, M. P., Stevens, D. E., and Toon, O. B.: The impact of humidity above stratiform clouds on indirect aerosol climate forcing, Nature, 432, 1014–1017, 2004. Albrecht, B. A., Penc, R. S., and Schubert, W. H.: An observational study of cloud-topped mixed layers, J. Atmos. Sci., 42, 800–822, 1985. Albrecht, B. A., Jensen, M. P., and Syrett, W. J.: Marine boundary layer structure and fractional cloudiness, J. Geophys. Res., 100, 209–214, 1995. Avramov, A., Ackerman, A. S., Fridlind, A. M., van Diedenhoven, B., Botta, G., Aydin, K., Verlinde, J., Korolev, A., Strapp, J. W., McFarquhar, G. M., Jackson, R., Brooks, S. D., Glen, A., and Wolde, M.: Towards ice formation closure in Arctic mixed-phase boundary layer clouds during ISDAC, J. Geophys. Res., in press, http://dx.doi.org/10.1029/2011JD015910doi:10.1029/2011JD015910, 2011. Bretherton, C. S., Blossey, P. N., and Uchida, J.: Cloud droplet sedimentation, entrainment efficiency, and subtropical stratocumulus albedo, Geophys. Res. Lett., 34, L03813, http://dx.doi.org/10.1029/2006GL027648doi:10.1029/2006GL027648, 2007. Brost, R. A., Wyngaard, J. C., and Lenschow, D. H.: Marine stratocumulus layers. Part II: Turbulence budgets, J. Atmos. Sci., 39, 818–836, 1982. Chen, F. and Dudhia, J.: Coupling an advanced land-surface/ hydrology model with the Penn State/ NCAR MM5 modeling system. Part I: Model description and implementation, Mon. Weather Rev., 129, 569–585, 2001. Collins, W. D., Rasch, P. J., Boville, B. A., Hack, J. J., Mccaa, J. R., Williamson, D. L., and Briegleb, B. P.: Description of the NCAR Community Atmosphere Model (CAM 3.0), NCAR Technical Note, NCAR/TN-464+STR, 226~pp., 2004. Curry, J. A., Ebert, E. E., and Herman, G. F.: Mean and turbulence structure of the summertime Arctic cloudy boundary layer, Q. J. Roy. Meteor. Soc., 114, 715–746, 1988. Curry, J. A., Randall, D., Rossow, W. B., and Schramm, J. L.: Overview of arctic cloud and radiation characteristics, J. Climate, 9, 1731–1764, 1996. Curry, J. A., Hobbs,~P. V., King,~M. D., Randall,~D. A., Minnis,~P., Isaac,~G. A., Pinto,~J. O., Uttal,~T., Bucholtz,~A., Cripe,~D. G., Gerber,~H., Fairall,~C. W., Garrett,~T. J., Hudson, J., Intrieri,~J. M., Jakob,~C., Jensen,~T., Lawson,~P., Marcotte,~D., Nguyen,~L., Pilewskie, P., Rangno,~A., Rogers, D. C., Strawbridge,~K. B., Valero,~F. P. J., Williams, A. G., and Wylie, D.: FIRE Arctic Clouds Experiment, B. Am. Meteorol. Soc., 81, 5–30, 2000. Deardorff, J. W.: Prediction of convective mixed-layer entrainment for realistic capping inversion structure, J. Atmos. Sci., 36, 424–436, 1979. Deardorff, J. W.: Cloud top entrainment instability, J. Atmos. Sci., 37, 131–147, 1980. Dyer, A. J. and Hicks, B. B.: Flux-gradient relationships in the constant flux layer, Q. J. Roy. Meteor. Soc., 96, 715–721, 1970. Fridlind, A. M., van Diedenhoven, B., Ackerman, A. S., Avramov, A., Mrowiec, A., Morrison, H., Zuidema, P., and Shupe, M. D.: A FIRE-ACE/SHEBA case study of mixed-phase Arctic boundary-layer clouds: Entrainment rate limitations on rapid primary ice nucleation processes, J. Atmos. Sci., accepted, doi:10.1175/JAS-D-11-052.1, 2011. Garratt, J. R.: The Atmospheric Boundary Layer, Cambridge University Press, UK, 316~pp., 1992. Harrington, J., Reisin, T., Cotton, W. R., and Kreidenweis, S. M.: Exploratory cloud resolving simulations of boundary layer Arctic stratus: Part II: Transition-season clouds, Atmos. Res., 51, 45–75, http://dx.doi.org/10.1016/S0169-8095(98)00098-2doi:10.1016/S0169-8095(98)00098-2, 1999. Hong, S.-Y., Noh, Y., and Dudhia, J.: A new vertical diffusion package with an explicit treatment of entrainment processes, Mon. Weather Rev., 134, 2318–2341, 2006. Jiang, H. J., Feingold, G., Cotton, W. R., and Duynkerke, P. G.: Large-eddy simulations of entrainment of cloud condensation nuclei into the Arctic boundary layer: May 18, 1998, FIRE/SHEBA case study,. J. Geophys. Res., 106, 15113–-15122, 2001. Klein, S. A., McCoy, R., Morrison, H., Ackerman, A., Avramov, A., de Boer, G., Chen, M., Cole, J., DelGenio, A. D., Falk, M., Foster, M., Fridlind, A., Golaz, J.-C., Hashino, T., Harrington, J., Hoose, C., Khairoutdinov, M., Larson, V., Liu, X., Luo, Y., McFarquhar, G., Menon, S., Neggers, R., Park, S., von Salzen, K., Schmidt, J. M., Sednev, I., Shipway, B., Shupe, M., Spangenberg, D., Sud, Y., Turner, D., Veron, D., Walker, G., Wang, Z., Wolf, A., Xie, S., Xu, K.-M., Yang, G., and Zhang, G.: Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. I: Single-layer cloud, Q. J. Roy. Meteor. Soc., 135, 979–1002, 2009. McFarquhar, G. M., Ghan, S., Verlinde, J., Korolev, A., Strapp, J. W., Schmid, B., Tomlinson, J. M., Wolde, M., Brooks, S. D., Cziczo, D., Dubey, M. K., Fan, J., Flynn, C., Gultepe, I., Hubbe, J., Gilles, M. K., Laskin, A., Lawson, P., Leaitch, W. R., Liu, P., Liu, X., Lubin, D., Mazzoleni, C., Macdonald, A.-M., Moffet, R. C., Morrison, H., Ovchinnikov, M., Shupe, M. D., Turner, D. D., Xie, S., Zelenyuk, A., Bae, K., Freer, M., and Glen, A.: Indirect and Semi-Direct Aerosol Campaign (ISDAC): The Impact of Arctic Aerosols on Clouds, B. Am. Meteorol. Soc., 92, 183–201, http://dx.doi.org/10.1175/2010BAMS2935.1doi:10.1175/2010BAMS2935.1, 2011. Morrison, H. and Pinto, J. O.: Mesoscale modeling of springtime Arctic mixed-phase stratiform clouds using a new two-moment bulk microphysics scheme, J. Atmos. Sci., 62, 3683–3704, 2005. Morrison, H. and Pinto, J. O.: Intercomparison of bulk cloud microphysics schemes in mesoscale simulations of springtime Arctic mixed-phase stratiform clouds, Mon. Weather Rev., 134, 1880–1900, 2006. Morrison, H., Pinto, J. O., Curry, J. A., and McFarquhar, G. M.: Sensitivity of modeled arctic mixed-phase stratocumulus to cloud condensation and ice nuclei over regionally varying surface conditions, J. Geophys. Res., 113, D05203, http://dx.doi.org/10.1029/2007JD008729doi:10.1029/2007JD008729, 2008. Morrison, H., Thompson, G., and Tatarskii, V.: Impact of Cloud Microphysics on the Development of Trailing Stratiform Precipitation in a Simulated Squall Line: Comparison of One- and Two-Moment Schemes, Mon. Weather Rev., 137, 991–1007, http://dx.doi.org/10.1175/2008MWR2556.1doi:10.1175/2008MWR2556.1, 2009. Morrison, H., Zuidema, P., Ackerman, A. S., Avramov, A., de Boer, G., Fan, J., Fridlind, A. M., Hashino, T., Harrington, J. Y., Luo, Y., Mikhail Ovchinnikov, M., and Shipway, B.: Intercomparison of cloud model simulations of Arctic mixed-phase boundary layer clouds observed during SHEBA, J. Adv. Mod. Earth Systems, 3, M06003, http://www.agu.org/journals/ms/, 2011. Nicholls, S.: The dynamics of stratocumulus: Aircraft observations and comparisons with a mixed layer model, Q. J. Roy. Meteor. Soc., 110, 783–820, 1984. Norris, J. R.: Low cloud type over the ocean from surface observations. Part I: Relationship to surface meteorology and the vertical distribution of temperature and moisture, J. Climate, 11, 369–382, 1998. Paulson, C. A.: The mathematical representation of wind speed and temperature profiles in the unstable atmospheric surface layer, J. Appl. Meteor., 9, 857–861, 1970. Pinto, J. O.: Autumnal mixed-phase cloudy boundary layers in the Arctic, J. Atmos. Sci., 55, 2016–2038. http://dx.doi.org/10.1175/1520-0469(1998)055<2016:AMPCBL>2.0.CO;2doi:10.1175/1520-0469(1998)055<2016:AMPCBL>2.0.CO;2, 1998. Prenni, A. J., Harrington, J. Y., Tjernström, M., DeMott, P. J., Avramov, A., Long, C. N., Kreidenweis, S. M., Olsson, P. Q., and Verlinde, J.: Can ice-nucleating aerosols affect Arctic seasonal climate?, B. Am. Meteorol. Soc., 88, 541–550, 2007. Randall, D. A.: Conditional instability of the first kind upside-down, J. Atmos. Sci., 37, 125–130, 1980. Sedlar, J. and Tjernström, M.:~ Stratiform cloud-inversion characterization during the Arctic melt season, Bound.-Lay. Meteorol., 132, 455–474, 2009. Sedlar, J., Shupe, M. D., and Tjernström, M.: On the relationship between thermodynamic structure and cloud top, and its climate significance in the Arctic, J. Climate, under review, 2011. Shupe, M. D.: A ground-based multiple remote-sensor cloud phase classifier, Geophys. Res. Lett., 34, L2209, http://dx.doi.org/10.1029/2007GL031008doi:10.1029/2007GL031008, 2007. Shupe, M. D.: Clouds at Arctic Atmospheric Observatories, Part II: Thermodynamic phase characteristicsm, J. Appl. Meteor. Clim., 50, 645–661, 2011. Shupe, M. D., Matrosov, S. Y., and Uttal, T.: Arctic mixed-phase cloud properties derived from surface-based sensors at SHEBA, J. Atmos. Sci., 63, 697–711, 2006. Shupe, M. D., Kollias, P., Poellot, M., and Eloranta, E.: On deriving vertical air motions from cloud radar Doppler spectra, J. Atmos. Ocean. Tech., 25, 547–557, 2008a. Shupe, M. D., Kollias, P., Persson, P. O. G., and McFarquhar, G. M.: Vertical motions in Arctic mixed-phase stratiform clouds. J. Atmos. Sci., 65, 1304–1322, 2008b. Solomon, A., Morrison, H., Persson, O., Shupe, M., and Bao, J.-W.: Investigations of microphysical parameterizations of snow and ice in Arctic clouds during M-PACE through model-observations comparison, Mon. Weather Rev., 137, 3110–3128, 2009. Skamarock, W. C., Klemp, J. B., Dudhia, J., Gill, D. O., Barker, D. M., Duda, M. G., Huang, X.-Y., Wang, W., and Powers, J. G.: A description of the Advanced Research WRF version 3. NCAR Tech. Note NCAR/TN-475+STR, 113~pp., 2008. Stevens, B., Cotton, W. R., Feingold, G., and Moeng, C.-H.: Large-eddy simulations of strongly precipitating, shallow, stratocumulus-topped boundary layers, J. Atmos. Sci., 55, 3616–3638, 1998. Tjernström, M., Leck, C., Persson, P. O. G., Jensen, M. L., Oncley, S. P., and Targino, A.:~ The summertime Arctic atmosphere:~ meteorological measurements during the Arctic Ocean Experiment 2001, B. Am. Meteorol. Soc., 85, 1305–1321, 2004. Turner, D. D., Clough, S. A., Liljegren, J. C., Clothiaux, E. E., Cady-Pereira, K., and Gaustad, K. L.: Retrieving precipitable water vapor and liquid water path from Atmospheric Radiation Measurement (ARM) program's microwave radiometers, IEEE T. Geosci. Remote, 45, 3680–3690, 2007. Webb, E. K.: Profile relationships: The log-linear range, and extension to strong stability, Q. J. Roy. Meteor. Soc., 96, 67–90, 1970. Wood, R. and Bretherton, C. S.: Boundary layer depth, entrainment, and decoupling in the cloud-capped subtropical and tropical marine boundary layer, J. Climate, 17, 3576–3588, 2004. Wyant, M. C., Bretherton, C. S., Rand, H. A., and Stevens, D. E.: Numerical simulations and a conceptual model of the stratocumulus to trade cumulus transition, J. Atmos. Sci., 54, 168–192, 1997. Zhang, D.-L. and Anthes, R. A.: A high-resolution model of the planetary boundary layer–sensitivity tests and comparisons with SESAME–79 data, J. Appl. Meteor., 21, 1594–1609, 1982. Zhu, P., Albrecht, B. A., Ghate, V. P., and Zhu, Z.: Multiple-scale simulations of stratocumulus clouds, J. Geophys. Res., 115, D23201, http://dx.doi.org/10.1029/2010JD014400doi:10.1029/2010JD014400, 2010.