Boundary-Layer Meteorology

, Volume 84, Issue 1, pp 45–65

Roll Vortices and Boundary-Layer Development during a Cold Air Outbreak

  • Jörg Hartmann
  • Christoph Kottmeier
  • Siegfried Raasch
Article

Abstract

The development of the boundary layer during a cold air outbreak in the FramStrait is documented by aircraft measurements. The convection was organisedinto roll vortices with aspect ratios increasing from 2.9 near the ice edgeto more than 6 at 100 km further downstream. This increase coincides with anincrease of the latent heat release in the cloud layer. The stability parameter-zi/L varies from about zero at the ice edge to 30 at a distance of 200 kmdownstream over open water where the satellite picture still shows cloudstreets. The increase is mainly due to the deepening of the boundary layer.The turbulent vertical sensible and latent heat fluxes near the surface amountto 400 W m-2 within a 300 km off-ice zone. 25% of the upward heat fluxin the subcloud layer is carried out by organised roll motions. Experimentswith a 2-dimensional non-hydrostatic model show a similar roll aspect ratio inthe first 50 km, but further downstream where condensational heating is moreimportant the modelled roll wavelengths are distinctly smaller than the observedones.

Boundary-Layer development Vortex rolls Cold air outbreak 

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References

  1. Brümmer, B., Rump, B., and Kruspe, G.: 1992, 'A Cold Air Outbreak near Spitsbergen in Springtime-Boundary-Layer Modification and Cloud Development', Boundary-Layer Meteorol. 61, 13–46.Google Scholar
  2. Brümmer, B., Bakan, S., and Hinzpeter, H.: 1985, 'Kontur: Observations of Cloud Streets and Open Cellular Structures', Dyn. Atmos. Oceans 9, 281–296.Google Scholar
  3. Charnock, H.: 1955, 'Wind Stress on a Water Surface', Quart. J. Roy. Meteorol. Soc. 81, 639–640.Google Scholar
  4. Chlond, A.: 1987, 'ANumerical Study of HorizontalRollVortices in Neutral and Unstable Atmospheric Boundary Layers', Beitr. Phys. Atmosph. 60, 144–169.Google Scholar
  5. Chlond, A.: 1988, 'Numerical and Analytical Studies of Diabatic Heating Effect upon Flatness of Boundary Layer Rolls', Beitr. Phys. Atmosph. 61, 312–329.Google Scholar
  6. Deardorff, J.W.: 1972, 'Numerical Investigation ofNeutral andUnstable Planetary Boundary Layers', J. Atmos. Sci. 29, 91–115.Google Scholar
  7. Etling, D. and Brown, R. A.: 1993, 'Roll Vortices in the Planetary Boundary Layer: A Review', Boundary-Layer Meteorol. 65, 215–248.Google Scholar
  8. Etling, D.: 1971, 'The Stability of an Ekman Boundary Flow as Influenced by Thermal Stratification', Beitr. Phys. Atmosph. 44, 168–186.Google Scholar
  9. Garratt, J. R.: 1977, 'Review of Drag Coefficients over Oceans and Continents', Mon. Wea. Rev. 105, 915–929.Google Scholar
  10. Grossmann, R. L.: 1982, 'An Analysis of vertical velocity spectra obtained in the BOMEX Fair-Weather, Tradewind Boundary Layer', Boundary-Layer Meteorol. 23, 323–357.Google Scholar
  11. Hartmann, J., Kottmeier, C., and Wamser, C.: 1992, 'Radiation and Eddy Flux Experiment 1991', Reports on Polar Research 105, Alfred Wegener Institut for Polar and Marine Research, 72 pp.Google Scholar
  12. Hein, P. F. and Brown, R. A.: 1988, 'Observations of Longitudinal Roll Vortices during Arctic Cold Air Outbreaks over open Water', Boundary-Layer Meteorol. 45, 177–199.Google Scholar
  13. Kottmeier, C.: 1993, 'User Handbook Polar Aircraft', Alfred Wegener Institut for Polar and Marine Research, 46 pp.Google Scholar
  14. Krishnamurti, R.: 1975, 'On Cellular Cloud Patterns. Parts 1-3', J. Atmos. Sci. 32, 1355–1383.Google Scholar
  15. Kuettner, J. P.: 1971, 'Cloud Bands in the Atmosphere', Tellus 23, 404–425.Google Scholar
  16. LeMone, M.: 1973, 'The Structure and Dynamics of Horizontal Roll Vortices in the Planetary Boundary Layer', J. Atmos. Sci. 30, 1077–1091.Google Scholar
  17. LeMone,M.: 1976, 'Modulation of Turbulence Energy by LongitudinalRolls in an UnstableBoundary Layer', J. Atmos. Sci. 33, 1308–1320.Google Scholar
  18. Lilly, D. K.: 1966, 'On the Instability of Ekman Boundary Flow', J. Atmos. Sci. 23, 481–494.Google Scholar
  19. Miura, Y.: 1986, 'Aspect Ratios of Longitudinal Rolls and Convection Cells Observed during Cold Air Outbreaks', J. Atmos. Sci. 43, 26–39.Google Scholar
  20. Müller, G. and Chlond, A.: 1996, 'Three-Dimensional Numerical Study of Cell Broadening during Cold-Air Outbreaks', Boundary-Layer Meteorol. 81, 289–323.Google Scholar
  21. Raasch, S.: 1990, 'Numerical Simulation of the Development of the Convective Boundary Layer During a Cold Air Outbreak', Boundary-Layer Meteorol. 52, 349–375.Google Scholar
  22. Raasch, S.: 1991, 'Two Numerical Case Studies of Horizontal Roll Vortices in Near Neutral Inversion Capped Planetary Boundary Layers', Beitr. Phys. Atmosph. 63, 205–222.Google Scholar
  23. Smith, S.D.: 1988, 'Coefficients for Sea Surface Wind Stress, Heat Flux, and Wind Profiles as a Function of Wind Speed and Temperature', J. Geophys. Res. 93, C 12, 15467–15472.Google Scholar
  24. Stull, R.B.: 1976, 'The Energetics of Entrainment Across a Density Interface', J. Atmos. Sci. 33, 1260–1267.Google Scholar
  25. Sykes, R. I., Lewellen, W. S., and Henn, D. S.: 1988, 'A Numerical Study of the Development of Cloud-Street Spacing', J. Atmos. Sci. 45, 2556–2569.Google Scholar

Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

  • Jörg Hartmann
    • 1
  • Christoph Kottmeier
    • 1
    • 2
  • Siegfried Raasch
    • 3
  1. 1.Alfred-Wegener-Institut für Polar- und MeeresforschungBremerhavenGermany
  2. 2.Faehbereich PhysikUniversität BremenBremenGermany
  3. 3.Insitut für Meteorologie und Klimatologie der Universität HannoverHannoverGermany

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