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Larger Chemical Ozone Loss in 2004/2005 Arctic Winter/Spring. Wuhu Feng and Martyn Chipperfield School of Earth and Environment, University of Leeds. Temperatures Modelled fields of ClO x , NOy, H 2 O etc. Modelled O 3 loss Comparison with previous years Comparison with ASUR data.
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Larger Chemical Ozone Loss in 2004/2005 Arctic Winter/Spring Wuhu Feng and Martyn Chipperfield School of Earth and Environment, University of Leeds • Temperatures • Modelled fields of ClOx, NOy, H2O etc. • Modelled O3 loss • Comparison with previous years • Comparison with ASUR data Acknowledgments R. Salawitch, P. von der Gathen, H. Kuhlman et al
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 v ASUR Data 31/1/2005 5/2/2005 HCl HCl ClO ClO N2O N2O
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)