Details
| Original language | English |
|---|---|
| Pages (from-to) | 45-65 |
| Number of pages | 21 |
| Journal | Boundary-Layer Meteorology |
| Volume | 84 |
| Issue number | 1 |
| Publication status | Published - Jul 1997 |
Abstract
The development of the boundary layer during a cold air outbreak in the Fram Strait is documented by aircraft measurements. The convection was organised into roll vortices with aspect ratios increasing from 2.9 near the ice edge to more than 6 at 100 km further downstream. This increase coincides with an increase 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 km downstream over open water where the satellite picture still shows cloud streets. The increase is mainly due to the deepening of the boundary layer. The turbulent vertical sensible and latent heat fluxes near the surface amount to 400 W m-2 within a 300 km off-ice zone. 25% of the upward heat flux in the subcloud layer is carried out by organised roll motions. Experiments with a 2-dimensional non-hydrostatic model show a similar roll aspect ratio in the first 50 km, but further downstream where condensational heating is more important the modelled roll wavelengths are distinctly smaller than the observed ones.
Keywords
- Boundary-Layer development, Cold air outbreak, Vortex rolls
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Atmospheric Science
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In: Boundary-Layer Meteorology, Vol. 84, No. 1, 07.1997, p. 45-65.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Roll vortices and boundary-layer development during a cold air outbreak
AU - Hartmann, Jörg
AU - Kottmeier, Christoph
AU - Raasch, Siegfried
PY - 1997/7
Y1 - 1997/7
N2 - The development of the boundary layer during a cold air outbreak in the Fram Strait is documented by aircraft measurements. The convection was organised into roll vortices with aspect ratios increasing from 2.9 near the ice edge to more than 6 at 100 km further downstream. This increase coincides with an increase 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 km downstream over open water where the satellite picture still shows cloud streets. The increase is mainly due to the deepening of the boundary layer. The turbulent vertical sensible and latent heat fluxes near the surface amount to 400 W m-2 within a 300 km off-ice zone. 25% of the upward heat flux in the subcloud layer is carried out by organised roll motions. Experiments with a 2-dimensional non-hydrostatic model show a similar roll aspect ratio in the first 50 km, but further downstream where condensational heating is more important the modelled roll wavelengths are distinctly smaller than the observed ones.
AB - The development of the boundary layer during a cold air outbreak in the Fram Strait is documented by aircraft measurements. The convection was organised into roll vortices with aspect ratios increasing from 2.9 near the ice edge to more than 6 at 100 km further downstream. This increase coincides with an increase 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 km downstream over open water where the satellite picture still shows cloud streets. The increase is mainly due to the deepening of the boundary layer. The turbulent vertical sensible and latent heat fluxes near the surface amount to 400 W m-2 within a 300 km off-ice zone. 25% of the upward heat flux in the subcloud layer is carried out by organised roll motions. Experiments with a 2-dimensional non-hydrostatic model show a similar roll aspect ratio in the first 50 km, but further downstream where condensational heating is more important the modelled roll wavelengths are distinctly smaller than the observed ones.
KW - Boundary-Layer development
KW - Cold air outbreak
KW - Vortex rolls
UR - http://www.scopus.com/inward/record.url?scp=0031391194&partnerID=8YFLogxK
U2 - 10.1023/A:1000392931768
DO - 10.1023/A:1000392931768
M3 - Article
AN - SCOPUS:0031391194
VL - 84
SP - 45
EP - 65
JO - Boundary-Layer Meteorology
JF - Boundary-Layer Meteorology
SN - 0006-8314
IS - 1
ER -