Editorial Type:
Article
Article Type:
Research Article

Large-Eddy Simulation of Moist Convection during a Cold Air Outbreak over the Gulf Stream

Eric D. Skyllingstad College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon

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James B. Edson Department of Marine Sciences, University of Connecticut, Groton, Connecticut

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Print Publication:
01 May 2009
DOI:
https://doi.org/10.1175/2008JAS2755.1
Page(s):
1274–1293
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Abstract

Cold air outflow over the Gulf Stream is modeled using a cloud-resolving large-eddy simulation model with three classes of precipitation. Simulations are conducted in a quasi-Lagrangian framework using an idealized sounding and uniform geostrophic winds based on observations taken on 20 February 2007 as part of the World Climate Research Program Climate Variability and Predictability (CLIVAR) Mode Water Dynamics Experiment (CLIMODE) project. Two cases are considered, one with an increasing sea surface temperature (SST) representing the crossing of the Gulf Stream front, and a second case with constant SST.

Cloud systems develop in the model with strong convective plumes that spread into regions of stratus clouds at the top of the boundary layer. Simulated boundary layer growth is forced by a combination of evaporative cooling at the cloud top, upward radiative flux, and mechanical entrainment of the overlying warmer and drier air. Constant growth of the boundary layer acts to maintain a near-constant water vapor level in the boundary layer, promoting high latent and sensible heat fluxes. Frictional surface drag is distributed throughout the boundary layer by convection, causing increased shear at the cloud top, qualitatively agreeing with observed sounding profiles. Overall, the frontal case develops stronger precipitation and turbulence in comparison with the constant SST case. A near-uniform stratocumulus layer and stronger radiative cooling are produced in the constant SST case, whereas the frontal case generates open cumuliform clouds with reduced cloud coverage. Cloud evolution in the frontal case is similar to the transition from stratocumulus to shallow cumulus observed in the subtropics, as cumuliform clouds enhance cloud-top entrainment and evaporation of stratus clouds.

Corresponding author address: Eric Skyllingstad, COAS, 104 COAS Admin. Bldg., Oregon State University, Corvallis, OR 97331. Email: skylling@coas.oregonstate.edu

Abstract

Cold air outflow over the Gulf Stream is modeled using a cloud-resolving large-eddy simulation model with three classes of precipitation. Simulations are conducted in a quasi-Lagrangian framework using an idealized sounding and uniform geostrophic winds based on observations taken on 20 February 2007 as part of the World Climate Research Program Climate Variability and Predictability (CLIVAR) Mode Water Dynamics Experiment (CLIMODE) project. Two cases are considered, one with an increasing sea surface temperature (SST) representing the crossing of the Gulf Stream front, and a second case with constant SST.

Cloud systems develop in the model with strong convective plumes that spread into regions of stratus clouds at the top of the boundary layer. Simulated boundary layer growth is forced by a combination of evaporative cooling at the cloud top, upward radiative flux, and mechanical entrainment of the overlying warmer and drier air. Constant growth of the boundary layer acts to maintain a near-constant water vapor level in the boundary layer, promoting high latent and sensible heat fluxes. Frictional surface drag is distributed throughout the boundary layer by convection, causing increased shear at the cloud top, qualitatively agreeing with observed sounding profiles. Overall, the frontal case develops stronger precipitation and turbulence in comparison with the constant SST case. A near-uniform stratocumulus layer and stronger radiative cooling are produced in the constant SST case, whereas the frontal case generates open cumuliform clouds with reduced cloud coverage. Cloud evolution in the frontal case is similar to the transition from stratocumulus to shallow cumulus observed in the subtropics, as cumuliform clouds enhance cloud-top entrainment and evaporation of stratus clouds.

Corresponding author address: Eric Skyllingstad, COAS, 104 COAS Admin. Bldg., Oregon State University, Corvallis, OR 97331. Email: skylling@coas.oregonstate.edu

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  • Abel, S. J., and B. J. Shipway, 2007: A comparison of cloud-resolving model simulations of trade wind cumulus with aircraft observations taken during RICO. Quart. J. Roy. Meteor. Soc., 133 , 781–794.

    • Search Google Scholar
    • Export Citation

  • Alexander, M. J., J. R. Holton, and D. R. Durran, 1995: The gravity wave response above deep convection in a squall line simulation. J. Atmos. Sci., 52 , 2212–2226.

    • Search Google Scholar
    • Export Citation

  • Bretherton, C. S., and M. C. Wyant, 1997: Moisture transport, lower-tropospheric stability, and decoupling of cloud-topped boundary layers. J. Atmos. Sci., 54 , 148–167.

    • Search Google Scholar
    • Export Citation

  • Chelton, D. B., and Coauthors, 2001: Observations of coupling between surface wind stress and sea surface temperature in the eastern tropical Pacific. J. Climate, 14 , 1479–1498.

    • Search Google Scholar
    • Export Citation

  • Chelton, D. B., M. G. Schlax, M. H. Freilich, and R. F. Milliff, 2004: Satellite measurements reveal persistent small-scale features in ocean winds. Science, 303 , 978–983.

    • Search Google Scholar
    • Export Citation

  • Collela, P., 1990: Multidimensional upwind methods for hyperbolic conservation laws. J. Comput. Phys., 87 , 171–200.

  • Deardorff, J. W., 1980: Stratocumulus-capped mixed layers derived from a three-dimensional model. Bound.-Layer Meteor., 18 , 495–527.

    • Search Google Scholar
    • Export Citation

  • de Szoeke, S. P., and C. S. Bretherton, 2004: Quasi-Lagrangian large eddy simulations of cross equatorial flow in the east Pacific atmospheric boundary layer. J. Atmos. Sci., 61 , 1837–1858.

    • Search Google Scholar
    • Export Citation

  • Dewar, W. K., R. M. Samelson, and G. K. Vallis, 2005: The ventilated pool: A model of subtropical mode water. J. Phys. Oceanogr., 35 , 137–150.

    • Search Google Scholar
    • Export Citation

  • Ducros, F., P. Comte, and M. Lesieur, 1996: Large-eddy simulation of transition to turbulence in a boundary layer developing spatially over a flat plate. J. Fluid Mech., 326 , 1–36.

    • Search Google Scholar
    • Export Citation

  • Durran, D. R., and J. B. Klemp, 1983: A compressible model for the simulation of moist mountain waves. Mon. Wea. Rev., 111 , 2341–2361.

    • Search Google Scholar
    • Export Citation

  • Fairall, C. W., E. F. Bradley, D. P. Rogers, J. B. Edson, and G. S. Young, 1996: Bulk parameterization of air–sea fluxes for Tropical Ocean–Global Atmosphere Coupled Ocean–Atmosphere Response Experiment. J. Geophys. Res., 101 , 3747–3764.

    • Search Google Scholar
    • Export Citation

  • Fedorovich, E., R. Conzemius, and D. Mironov, 2004: Convective entrainment into a shear-free, linearly stratified atmosphere: Bulk models reevaluated through large eddy simulations. J. Atmos. Sci., 61 , 281–295.

    • Search Google Scholar
    • Export Citation

  • Grossman, R. L., and A. K. Betts, 1990: Air–sea interaction during an extreme cold air outbreak from the eastern coast of the United States. Mon. Wea. Rev., 118 , 324–342.

    • Search Google Scholar
    • Export Citation

  • Gryschka, M., and S. Raasch, 2005: Roll convection during a cold air outbreak: A large eddy simulation with stationary model domain. Geophys. Res. Lett., 32 , L14805. doi:10.1029/2005GL022872.

    • Search Google Scholar
    • Export Citation

  • Hartmann, J., C. Kottmeier, and S. Raasch, 1997: Roll vortices and boundary-layer development during a cold air outbreak. Bound.-Layer Meteor., 84 , 45–65.

    • Search Google Scholar
    • Export Citation

  • Hashizume, H., S-P. Xie, W. T. Liu, and K. Takeuchi, 2001: Local and remote response to tropical instability waves: A global view from space. J. Geophys. Res., 106 , 10173–10185.

    • Search Google Scholar
    • Export Citation

  • Jiang, H., and W. R. Cotton, 2000: Large-eddy simulation of shallow cumulus convection during BOMEX: Sensitivity to microphysics and radiation. J. Atmos. Sci., 57 , 582–594.

    • Search Google Scholar
    • Export Citation

  • Maesaka, T., G. W. K. Moore, Q. Liu, and K. Tsuboki, 2006: A simulation of a lake effect snowstorm with a cloud-resolving numerical model. Geophys. Res. Lett., 33 , L20813. doi:10.1029/2006GL026638.

    • Search Google Scholar
    • Export Citation

  • Marshall, J., and Coauthors, 2009: Observing the cycle of convection and restratification over the Gulf Stream system and the subtropical gyre of the North Atlantic Ocean: Preliminary results from the CLIMODE field campaign. Bull. Amer. Meteor. Soc., in press.

    • Search Google Scholar
    • Export Citation

  • Mlawer, E. J., S. J. Taubman, P. D. Brown, M. J. Iacono, and S. A. Clough, 1997: Radiative transfer for inhomogeneous atmosphere: RRTM, a validated correlated-k model for the longwave. J. Geophys. Res., 102 , (D14). 16663–16682.

    • Search Google Scholar
    • Export Citation

  • Moeng, C-H., 1986: Large-eddy simulation of a stratus-topped boundary layer. Part I: Structure and budgets. J. Atmos. Sci., 43 , 2886–2900.

    • Search Google Scholar
    • Export Citation

  • O’Neill, L. W., D. B. Chelton, and S. K. Esbensen, 2003: Observations of SST-induced perturbations of the wind stress field over the Southern Ocean on seasonal time scales. J. Climate, 16 , 2340–2354.

    • Search Google Scholar
    • Export Citation

  • Rao, G-S., and E. M. Agee, 1996: Large eddy simulation of turbulent flow in a marine convective boundary layer with snow. J. Atmos. Sci., 53 , 86–100.

    • Search Google Scholar
    • Export Citation

  • Reisner, J., R. M. Rasmussen, and R. T. Bruintjes, 1998: Explicit forecasting of supercooled liquid water in winter storms using the MM5 mesoscale model. Quart. J. Roy. Meteor. Soc., 124 , 1071–1107.

    • Search Google Scholar
    • Export Citation

  • Savic-Jovcic, V., and B. Stevens, 2008: The structure and mesoscale organization of precipitating stratocumulus. J. Atmos. Sci., 65 , 1587–1605.

    • Search Google Scholar
    • Export Citation

  • Schröter, M., S. Raasch, and H. Jansen, 2005: Cell broadening revisited: Results from high-resolution large-eddy simulations of cold air outbreaks. J. Atmos. Sci., 62 , 2023–2032.

    • Search Google Scholar
    • Export Citation

  • Siebesma, A. P., and Coauthors, 2003: A large eddy simulation intercomparison study of shallow cumulus convection. J. Atmos. Sci., 60 , 1201–1219.

    • Search Google Scholar
    • Export Citation

  • Skamarock, W. C., J. B. Klemp, J. Dudhia, D. O. Gill, D. M. Barker, W. Wang, and J. G. Powers, 2005: A description of the Advanced Research WRF version 2. NCAR Tech. Note NCAR/TN-468+STR, 100 pp.

    • Search Google Scholar
    • Export Citation

  • Skyllingstad, E. D., R. M. Samelson, L. Mahrt, and P. Barbour, 2005: A numerical modeling study of warm offshore flow over cool water. Mon. Wea. Rev., 133 , 345–361.

    • Search Google Scholar
    • Export Citation

  • Skyllingstad, E. D., D. Vickers, L. Mahrt, and R. Samelson, 2007: Effects of mesoscale sea-surface temperature fronts on the marine boundary layer. Bound.-Layer Meteor., 123 , 219–237.

    • Search Google Scholar
    • Export Citation

  • Smolarkiewicz, P. K., and L. G. Margolin, 1994: Variational solver for elliptical problems in atmospheric flows. Appl. Math. Comput. Sci., 4 , 527–551.

    • Search Google Scholar
    • Export Citation

  • Song, Q., T. Hara, P. Cornillon, and C. A. Friehe, 2004: A comparison between observations and MM5 simulations of the marine atmospheric boundary layer across a temperature front. J. Atmos. Oceanic Technol., 21 , 170–178.

    • Search Google Scholar
    • Export Citation

  • Stevens, B., 2007: On the growth of layers of nonprecipitating cumulus convection. J. Atmos. Sci., 64 , 2916–2931.

  • Stevens, B., W. R. Cotton, G. Feingold, and C-H. Moeng, 1998: Large-eddy simulation of strongly precipitating, shallow, stratocumulus-topped boundary layers. J. Atmos. Sci., 55 , 3616–3638.

    • Search Google Scholar
    • Export Citation

  • Stevens, B., and Coauthors, 2001: Simulations of trade wind cumuli under a strong inversion. J. Atmos. Sci., 58 , 1870–1891.

  • Thompson, G., R. M. Rasmussen, and K. Manning, 2004: Explicit forecasts of winter precipitation using an improved bulk microphysics scheme. Part I: Description and sensitivity analysis. Mon. Wea. Rev., 132 , 519–542.

    • Search Google Scholar
    • Export Citation

  • Thompson, G., P. R. Field, R. M. Rasmussen, and W. D. Hall, 2008: Explicit forecasts of winter precipitation using an improved bulk microphysics scheme. Part II: Implementation of a new snow parameterization. Mon. Wea. Rev., 136 , 5095–5115.

    • Search Google Scholar
    • Export Citation

  • Tripoli, G. J., 2005: Numerical study of the 10 January 1998 lake-effect bands observed during Lake-ICE. J. Atmos. Sci., 62 , 3232–3249.

    • Search Google Scholar
    • Export Citation

  • Vickers, D., and L. Mahrt, 2006: Evaluation of the air–sea bulk formula and sea-surface temperature variability from observations. J. Geophys. Res., 111 , C05002. doi:10.1029/2005JC003323.

    • Search Google Scholar
    • Export Citation

  • Warner, T. T., M. N. Lakhtakia, J. D. Doyle, and R. A. Pearson, 1990: Marine atmospheric boundary layer circulations forced by Gulf Stream sea surface temperature gradients. Mon. Wea. Rev., 118 , 309–323.

    • Search Google Scholar
    • Export Citation

  • Wyant, M. C., C. S. Bretherton, H. A. Rand, and D. E. Stevens, 1997: Numerical simulations and a conceptual model of the subtropical marine stratocumulus to trade cumulus transition. J. Atmos. Sci., 54 , 168–192.

    • Search Google Scholar
    • Export Citation

  • Wyant, M. C., M. Khairoutdinov, and C. S. Bretherton, 2006: Climate sensitivity and cloud response of a GCM with a superparameterization. Geophys. Res. Lett., 33 , L06714. doi:10.1029/2005GL025464.

    • Search Google Scholar
    • Export Citation

  • Zurn-Birkhimer, S. M., E. M. Agee, and Z. Sorbjan, 2005: Convective structures in a cold air outbreak over Lake Michigan during Lake-ICE. J. Atmos. Sci., 62 , 2414–2432.

    • Search Google Scholar
    • Export Citation
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