larger chemical ozone loss in 2004/2005 arctic winter/spring wuhu feng and martyn chipperfield...
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Larger Chemical Ozone Loss in 2004/2005 Arctic Winter/Spring
Wuhu Feng and Martyn ChipperfieldSchool of Earth and Environment, University of Leeds
Acknowledgments
R. Salawitch, P. von der Gathen, H. Kuhlman et al
• Temperatures• Modelled fields of ClOx, NOy, H2O etc.• Modelled O3 loss• Comparison with previous years• Comparison with ASUR data
Temperatures 04/05 v 99/00
Minimum Temperature – Cold winters since 95/96
SLIMCAT/TOMCAT 3D CTM• Off-line 3D chemical transport model
• Extends to surface using hybrid - levels (SLIMCAT version).
• Horizontal winds and temperatures from ECMWF analyses.
• Vertical motion from diagnosed heating rates.
• Chemistry: ‘Full’ stratospheric chemistry scheme (41 species, 160 reactions) with heterogeneous chemistry on liquid/solid aerosols/PSCs and an equilibrium (NAT rock) denitrification scheme.
• Near real time run: 2.8o x 2.8o x 24 levels (0-60 km)
• Web page with results:
http://www.env.leeds.ac.uk/slimcat
What has changed in model to improve polar O3?
A lot! Key points for polar O3 are probably:
• Updated kinetics (JPL 2002) + faster JCl2O2 (Burkholder et al extended to 450 nm).
• NAT-based denitrification scheme.• Minimum aerosol (H2SO4) loading.
• Better vertical transport (more Cly in lower stratosphere) and no lower boundary near tropopause.
• ECMWF analyses (ERA40 + operational).
• Source gas scenarios: + 100pptv short-lived organic Cl, + shift in long-lived organic loading to shorter lived species.
SLIMCAT 3D CTM – Arctic winters since 1994/95
SLIMCAT 3D CTM – Modelled dehydration
O3 at Ny Alesund
SLIMCAT ClOx and NOy at Ny Alesund
SLIMCAT v ASUR Data
31/1/2005 5/2/2005
HCl HCl
ClO
N2O
ClO
N2O
Recent results (3/3/2000)
Conclusions
• (Updated) SLIMCAT model does a good job in simulation of polar ozone + related species for 2004/05 Arctic winter.
• ‘Largest modelled Arctic ozone loss so far’ for this time of year.
• Strongest modelled chlorine activation and much more descent than previous years
• Model captures the dehydration as measured on January 26 at (~67N, 27E)
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