German contribution to the international acsys project
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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

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German Contribution to the international ACSYS Project

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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

[email protected]

http: www.meteo.uni-bonn.de

A project funded by the Federal Ministry of Education and Research


The katabatic wind system (KWS)

Wintertime near-surface wind Antarctica

RACMO simulations

55 km resolution

1980-1993

winter months JJA

Van Lipzig (2003)

Sample=2

Orography contour interval 1000 m


(Klein, 2000)

Wintertime near-surface wind Greenland

NORLAM simulations

25 km resolution

10m wind Jan 1990

Heinemann and Klein (2002)

Constancy

0.8-0.9

>0.9

Sample=4

Orography contour interval 500 m


Katabatic wind dynamics

Integrated katabatic wind layer (Ball, 1956):

Pressure gradient (2D):

Pressure gradient (1D):

=- zs/x


Monthly means January 1990

10-4 ms-2

Synoptic forcing FS

10-4 ms-2

Topographic forcing FT


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


Topographic forcing FT

10-4 ms-2


Comparison NORLAM/aircraft


Tasiilaq

Katabatic wind and boundary layer front experiment around Greenland

April+May 1997

KABEG


Polar 2 (AWI)

Meteopod 120 Hz

A3

A4

100 km


KABEG Case study22 April 1997

Heinemann (2002)


Profiles of turbulent fluxes

Evaporation 1 W/m2.10 mm/a


Regimes of the katabatic wind system


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


Scaling regions KABEG

L* from A4 data


Local scaling for KABEG data

Cabauw data, Nieuwstadt (1984)

Data collected within 18 months

Variances

(about 250 data points, 6 flights)

Heinemann (2004)

KABEG


German Contribution to the international ACSYS Project

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 model:2-12 km resolution

12h forecast

6h forecast

CI concentration

15 m wind 12h forecast

12 km nested and coupled run

m/s


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