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.
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References
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.
Brümmer, B., Bakan, S., and Hinzpeter, H.: 1985, 'Kontur: Observations of Cloud Streets and Open Cellular Structures', Dyn. Atmos. Oceans 9, 281–296.
Charnock, H.: 1955, 'Wind Stress on a Water Surface', Quart. J. Roy. Meteorol. Soc. 81, 639–640.
Chlond, A.: 1987, 'ANumerical Study of HorizontalRollVortices in Neutral and Unstable Atmospheric Boundary Layers', Beitr. Phys. Atmosph. 60, 144–169.
Chlond, A.: 1988, 'Numerical and Analytical Studies of Diabatic Heating Effect upon Flatness of Boundary Layer Rolls', Beitr. Phys. Atmosph. 61, 312–329.
Deardorff, J.W.: 1972, 'Numerical Investigation ofNeutral andUnstable Planetary Boundary Layers', J. Atmos. Sci. 29, 91–115.
Etling, D. and Brown, R. A.: 1993, 'Roll Vortices in the Planetary Boundary Layer: A Review', Boundary-Layer Meteorol. 65, 215–248.
Etling, D.: 1971, 'The Stability of an Ekman Boundary Flow as Influenced by Thermal Stratification', Beitr. Phys. Atmosph. 44, 168–186.
Garratt, J. R.: 1977, 'Review of Drag Coefficients over Oceans and Continents', Mon. Wea. Rev. 105, 915–929.
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.
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.
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.
Kottmeier, C.: 1993, 'User Handbook Polar Aircraft', Alfred Wegener Institut for Polar and Marine Research, 46 pp.
Krishnamurti, R.: 1975, 'On Cellular Cloud Patterns. Parts 1-3', J. Atmos. Sci. 32, 1355–1383.
Kuettner, J. P.: 1971, 'Cloud Bands in the Atmosphere', Tellus 23, 404–425.
LeMone, M.: 1973, 'The Structure and Dynamics of Horizontal Roll Vortices in the Planetary Boundary Layer', J. Atmos. Sci. 30, 1077–1091.
LeMone,M.: 1976, 'Modulation of Turbulence Energy by LongitudinalRolls in an UnstableBoundary Layer', J. Atmos. Sci. 33, 1308–1320.
Lilly, D. K.: 1966, 'On the Instability of Ekman Boundary Flow', J. Atmos. Sci. 23, 481–494.
Miura, Y.: 1986, 'Aspect Ratios of Longitudinal Rolls and Convection Cells Observed during Cold Air Outbreaks', J. Atmos. Sci. 43, 26–39.
Müller, G. and Chlond, A.: 1996, 'Three-Dimensional Numerical Study of Cell Broadening during Cold-Air Outbreaks', Boundary-Layer Meteorol. 81, 289–323.
Raasch, S.: 1990, 'Numerical Simulation of the Development of the Convective Boundary Layer During a Cold Air Outbreak', Boundary-Layer Meteorol. 52, 349–375.
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.
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.
Stull, R.B.: 1976, 'The Energetics of Entrainment Across a Density Interface', J. Atmos. Sci. 33, 1260–1267.
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.
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Hartmann, J., Kottmeier, C. & Raasch, S. Roll Vortices and Boundary-Layer Development during a Cold Air Outbreak. Boundary-Layer Meteorology 84, 45–65 (1997). https://doi.org/10.1023/A:1000392931768
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DOI: https://doi.org/10.1023/A:1000392931768