arctic ozone loss 2011 john pyle scientific assessment panel national centre for atmospheric...
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Arctic ozone loss 2011
John Pyle
Scientific Assessment PanelNational Centre for Atmospheric Science, UK
&
Centre for Atmospheric Science
Department of Chemistry
University of Cambridge
With thanks to Paul Newman, Martyn Chipperfield, Gloria Manney Michelle Santee and Markus Rex
Side event to 23rd MOP / 9th COP, Bali
23 November 2011
Overview
Polar ozone loss depends on temperature and inorganic halogen concentrations in lower stratosphere (depends on MP)
Assessments in 1990s recognised
that could have severe Arctic ozone depletion in very cold Arctic winters
Very large ozone depletions previously reported in , e.g., 95/96, 96/97, 99/00, 04/05, 07/08
Low temperatures into spring are key ingredient for large ozone loss
Arctic 2011 Overview
Stratospheric minimum temperatures in 2010/2011 were unusually low/long lasting
Severe ozone loss (>80%), over a significant depth of atmosphere occurred.
Some records established – but consistent with our chemical understanding
But what is driving the low temperatures (natural variability vs GHG, say)?
Record Arctic Ozone Loss – 2010/11
Vortex Average Loss at 20km TOMCAT/SLIMCAT CTM
Courtesy Martyn Chipperfieldwww.see.leeds.ac.uk/slimcat
Over -85% loss in vortex
Cold
Arctic Ozone Loss: SLIMCAT Results
Arctic ozone loss is initially limited by the availability of sunlight in early winter and curtailed by the breakdown on the vortex in mid winter. Year-to-year variations of polar Arctic O3 loss due to different meteorological conditions.Record Arctic polar ozone loss for 2010/11 (local maximum ozone loss is ~95% at 465K by 29 March 2011). Partial column ozone loss is ~175 DU.Courtesy Chipperfield,www.see.leeds.ac.uk/slimcat
Updated from Feng et al. (GRL, 2007)
High levels of Activated Chlorine observed in Arctic in March 2011
Adapted from Figure 2 of Manney et al. (2011) - Aura MLS 2005-2010 ClO.
Arctic ClO in 2011 was outside the range of the 2005-2010 winter observations, and comparable to Antarctic ClO.
As a result of the high Cl levels, there were large ozone losses
Adapted from Figure 2 of Manney et al. (2011) Aura MLS 2005-2010 Ozone.
Arctic Ozone in 2011 was outside the range of the 2005-2010 winter observations, and almost as low as Antarctic ozone.
Overview
Stratospheric minimum temperatures in 2010/2011 were unusually low/long lasting
Severe ozone loss (>80%), over a significant depth of atmosphere occurred.
Some records established – but consistent with our chemical understanding
But what is driving the low temperatures (natural variability vs GHG, say)?