German Contribution to the international ACSYS Project

1
German Contribution to the international ACSYS
Project
The ACSYS Decade and Beyond 11-14 November
2003, St. Petersburg, Russia
Observations, simulations and scale interactions
of the stable boundary layer over polar ice
sheets Günther Heinemann Meteorological
Institute University of Bonn, Germany gheinemann_at_
uni-bonn.de http www.meteo.uni-bonn.de
A project funded by the Federal Ministry of
Education and Research
2
The katabatic wind system (KWS)
Wintertime near-surface wind Antarctica
RACMO simulations 55 km resolution 1980-1993
winter months JJA Van Lipzig (2003)
Sample2
Orography contour interval 1000 m
3
Wintertime near-surface wind Greenland
NORLAM simulations 25 km resolution 10m wind Jan
1990 Heinemann and Klein (2002)
Constancy 0.8-0.9 gt0.9
Sample4
Orography contour interval 500 m
4
Katabatic wind dynamics
Integrated katabatic wind layer (Ball, 1956)
Pressure gradient (2D)
Pressure gradient (1D)
?- ?zs/?x
5
Monthly means January 1990
10-4 ms-2
Synoptic forcing FS
10-4 ms-2
Topographic forcing FT
6
Case study 22 April 1997
NORLAM 22 April 06 UTC (30h)
NORLAM 22 April 06 UTC (30h)
10-4 ms-2
10m wind
Topographic forcing FT
7
Topographic forcing FT
10-4 ms-2
8
Comparison NORLAM/aircraft
9
Katabatic wind and boundary layer front
experiment around Greenland AprilMay 1997
KABEG
10
(No Transcript)
11
KABEG Case study22 April 1997
Heinemann (2002)
12
Profiles of turbulent fluxes
13
Regimes of the katabatic wind system
14
Stable boundary layer (SBL) Similarity
Surface layer (SL) scalingMonin-Obukhov (MO)
similarity theory (MOST) (Monin and Obukhov, 1956)
- Stationarity - Horizontal homogeneity - No
radiation flux divergence
Local scaling concept for the SBLNieuwstadt
(1984), Holtslag and Nieuwstadt (1986)

• - Stationarity
• - Horizontal homogeneity
• No TKE flux divergence

15
Scaling regions KABEG
L from A4 data
16
Local scaling for KABEG data
Variances (about 250 data points, 6 flights)
Heinemann (2004)
KABEG
17
Outlook German ACSYS Project Phase II
(2002-2005)Katabatic wind and polynia interaction
? Prognostic two-class sea ice model frazil ice
(FI) and consolidated ice (CI) Flato and Hibler
(1992), Shinohara (1990), Semtner (1976), Gallée
(1997)
22h forecast
? Non-hydrostatic atmospheric model2-12 km
resolution
12h forecast
6h forecast
CI concentration
15 m wind 12h forecast
12 km nested and coupled run
m/s