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1.
A Chemical Characterization of North American Pollution Plumes over Europe
2.A 15-Year Climatology of Global
Warm Conveyor Belt (WCB) Transport
A. Stohl1, H. Huntrieser2, O. Cooper3, S. Eckhardt1, C. Forster1,P. James1, J. Heland2, H. Mannstein2, H. Schlager2, B. Rappenglück4, W.
Junkermann4, F. Arnold5, H. Aufmhoff5, S. Wilhelm5
1 Technical University of Munich, Germany 2 DLR, Oberpfaffenhofen, Germany
3 NOAA Aeronomy Laboratory, Boulder, USA 4 Research Center Karlsruhe, Germany
5 Max-Planck Institute for Nuclear Physics, Heidelberg, Germany
Part 1:Aircraft measurements during CONTRACE
Stohl et al., submitted to J. Geophys. Res.
Aim of the first campaign in November 2001:
To study the role of WCBs for intercontinental pollution transport
Due to successful model forecasts, 3 North American plumes were encountered
3 cases were quite similar, only 1 case presented here
Tracer simulations using FLEXPART
FLEXPART is a Lagrangian particle dispersion modelno chemistry, only transport
3 carbon monoxide emission tracers (EDGAR)AsiaEuropeNorth America
Stratospheric ozone tracer
Transport of North American CO tracer
13 November 2001: Accumulation of pollution in high-pressuresystem over North America
FLEXPART total column of CO tracer GOES-East IR satellite image
Transport of North American CO tracer
15 November 2001: A low forms and opens an export pathwayto the east in its warm sector: transport over high-emission regions
FLEXPART total column of CO tracer GOES-East IR satellite image
Transport of North American CO tracer
17 November 2001: Cold front pushes pollution to the AtlanticTracer plume and clouds are aligned in WCBLifting to free troposphere
FLEXPART total column of CO tracer GOES-East IR satellite image
Transport of North American CO tracer
18 November 2001: Pollution plume in the WCB outflowin the upper troposphere
FLEXPART total column of CO tracer METEOSAT + GOES-East
5-day trajectoriesthat ascend more than5000 m during last 4 days
Transport of North American CO tracer
19 November 2001: Pollution plume arrives over Europe
FLEXPART total column of CO tracer METEOSAT + GOES-East
Falcon flight track
Meridional section through North America CO tracer along the flight track
Northbound flight Southbound flight Munich to Stockholm Stockhom to Munich
Model tracers interpolated to the flight track
Stratospheric O3 tracer+ measured O3+ measured humidity+altitude (black)
Asia CO tracer+ measured NOy (black)+measured NO
Europe CO tracer+ measured CO2 (black)
North America CO tracer+ measured CO (black)
Backward reconstruction of North American CO and NOy along flight track
• About 600 individual FLEXPART simulations• every 200 m vertically• every 0.1° along the track
• Advect unit mixing ratio backwards from aircraft position and calculate „residence times“ on a grid
• Multiply with emissions from EDGAR and obtain concentration at flight track
North American CO and NOy along flight trackfrom 600 backward simulations
EDGAR NOx
+ measured NOy (black)+ measured NO
EDGAR CO+ measured CO (black)+ aircraft altitude
FLEXPART backward simulation for peak at 11:53 UTC27 second interval
Residence time in wholeatmospheric column
Residence time in footprint
Conclusions from Part 1
• WCB transport is the key mechanism for fast intercontinental pollution transport
• Many chemical species were enhanced in the observed plumes• CO• CO2
• NOy (but 90% were removed due to washout)• Ozone (even in November!)• Acetone• SO2
• Numerous hydrocarbons
• Lagrangian backward modeling allows quantitative determination of source contribution and resolves very small-scale features
Don´t use „cheap“ trajectories to interpret „expensive“ aircraft measurements!Stohl, A., S. Eckhardt, C. Forster, P. James,
N. Spichtinger, and P. Seibert (2002):
A replacement for simple back trajectory calculations in the
interpretation of atmospheric trace substance measurements.
Atmos. Environ. 36, 4635-4648 (October issue)
Part 2:A 15-Year WCB Climatology
Eckhardt et al., in preparation for J. Climate
Basis:• 360 million 6-day trajectories
starting daily on a 1° x 1° global grid
• ECMWF ERA-15 re-analysis data
• WCB diagnosis by identifying trajectories that– ascend strongly and– travel northeastward during the first 48 hours
Frequency of WCB inflow:
Strong contrasts between Northern and Southern Hemisphere:NH: maxima downwind of North America and Asia, winter maximumSH: less zonal variability, spring maximum
Climate variability and intercontinental transportExample: Influence of the North Atlantic Oscillation on WCBs
NAO + NAO –
At day 0
At day 2
http://www.forst.tu-muenchen.de/EXT/LST/METEO/stohl/