The mesoscale structure of a mature polar low Airborne measurements and numerical simulations Andreas Dörnbrack 1 , Johannes Wagner 2 , Alexander Gohm 2 and Andreas Schäfler 1 (1) Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft und Raumfahrt (DLR), Oberpfaffenhofen, Germany Folie 1 EGU Session AS1.1: Dynamical Meteorology, Vienna 8 April 2011 (2) Institute of Meteorology and Geophysics, University of Innsbruck, Innrain 52, A-6020 Innsbruck, Austria in cooperation with the Norwegian IPY-THORPEX project lead by J. E. Kristjánsson and the Norwegian Met Service
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The mesoscale structure of a mature polar lowAirborne measurements and numerical simulations
Andreas Dörnbrack1, Johannes Wagner2, Alexander Gohm2 and Andreas Schäfler1
(1) Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft und Raumfahrt (DLR), Oberpfaffenhofen, Germany
Folie 1EGU Session AS1.1: Dynamical Meteorology, Vienna 8 April 2011
(2) Institute of Meteorology and Geophysics, University of Innsbruck, Innrain 52, A-6020 Innsbruck, Austria
in cooperation with the Norwegian IPY-THORPEX project lead by J. E. Kristjánsson and the Norwegian Met Service
Table of Contents
1 Objectives
2 Model Description
3 Synoptic Situation
Folie 2EGU Session AS1.1: Dynamical Meteorology, Vienna 8 April 2011
3 Synoptic Situation
4 Comparison Model-Observations
5 Polar Low Core Structure
6 Conclusions
Campaign: IPY THORPEX 2008
● IPY: International Polar Year (March 2007 to 2009)
● THORPEX: The Observing System Research and
Predictability Experiment
● Airborne in)situ and remote)sensing observations
Folie 3EGU Session AS1.1: Dynamical Meteorology, Vienna 8 April 2011
● Airborne in)situ and remote)sensing observations
over
the Norwegian and Barents Seas
Focus on Arctic fronts, polar lows and terrain)inducedflow disturbances
Objective: Improved forecasting of adverse weather in theArctic region – present and future
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Monthly mean SST for March (2006-2010)
Andøya
Vilhelm Bjerknes on the quay at Bergen (R. Groven, 1983)
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"The northernmost part of Norway in winter is one of the stormiest locations on Earth, and the
terrible accidents that occur from time to time, when large parts of the fishing fleet with crew
and tools are lost, are only too well known. A look at the climatological conditions show [that]
the reason for the frequency of the storms [is that] the mean temperature in January by the
outermost Lofoten islands is 27 degrees Celsius higher than the mean for the same latitude
around the globe. This is the effect of the warm waters of the Gulf Stream. At the same time a
Siberian winter cold reigns on the Finnmark plateau. Nature has, in other words, put an
immense steam kettle side by side with an immense condenser. This steam engine must always
work, and that is what it does, with great, irregular strokes." (1904)
Vilhelm Bjerknes on the quay at Bergen (R. Groven, 1983)
Folie 6EGU Session AS1.1: Dynamical Meteorology, Vienna 8 April 2011
NOAA IR - 4 March 2008
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rel. difference to drops ~ 3.8 %
∆x ~ 5 km, ∆z ~ 350 m
Horizontal Wind Speed (ms-1)
data available ~53 % of flight time
rel. difference to drops ~ 3.5 %
∆x ~ 7 km, ∆z ~ 100 m
Backscatter Ratio
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Water Vapor Mixing Ratio (g kg-1)
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Water Vapor Mixing Ratio (g kg-1)
WRF CTRL Simulation
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Contour lines: Equivalent Potential Temperature (K)
Horizontal Wind (ms-1)
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Horizontal Wind (ms-1)
WRF CTRL Simulation
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Structure of the polar low core
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Structure of the polar low core
- backward trajectories
- radial wind profile at extended section
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3 March 2008 16 UTC
Trajectories: subsidence of 500 m/10 h
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z = 3000 mz = 3500 m
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simulated (observed)
D9
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axi-symmetric model (Gray, 1998)
observed/simulated D9
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axi-symmetric model (Gray, 1998)
Conclusions
• LIDAR suitable instrumentation to characterize the
H2O, wind and aerosol particle structure above and around Polar Lows (PL), in intrusions and in the PL core
• careful selection of model parameters necessary to obtainreliable simulations to quantify hypotheses and theories) WRF and ECMWF IFS runs capture the formation of a PL
) Model Verification has been done with different types of
Folie 58EGU Session AS1.1: Dynamical Meteorology, Vienna 8 April 2011
) Model Verification has been done with different types ofobservational data
) dignificant dependence of simulation results on initialisationtime
) use of new high resolution SST/SEAICE data set) usage of ECMWF model)level data brings great improvementscompared to pressure)level data (not shown)
• verification of radial wind structure in the polar low core
Thank you for your attention!
Folie 59EGU Session AS1.1: Dynamical Meteorology, Vienna 8 April 2011