1. Transport of CO and O 3 into the UTLS Region Dave MacKenzie University of Toronto

2. CO/O 3 correlations: Assessing transport of tropospheric pollution to the lowermost stratosphere High CO (flat) indicates tropospheric air; high O 3 (steep) is stratospheric Points in between indicate a region of mixing between the troposphere and stratosphere Slope of mixing points indicates various reservoirs Figure adapted from Hoor et al., 2002 High CO (flat) indicates tropospheric air; high O 3 (steep) is stratospheric Points in between indicate a region of mixing between the troposphere and stratosphere Slope of mixing points indicates various reservoirs Figure adapted from Hoor et al., 2002 Stratosphere Troposphere

3. GEOS-Chem CO/O 3 Correlations: Lat=35N-75N, Lon=15E-25W Compactness of correlation varies with season Large scatter in Spring, indicating deep mixed layer in UTLS in GEOS-Chem Increased compactness through fall Compactness of correlation varies with season Large scatter in Spring, indicating deep mixed layer in UTLS in GEOS-Chem Increased compactness through fall CO [ppbv] O 3 [ppbv] Dec. 2002 O 3 [ppbv] CO [ppbv] Sept. 2002 CO [ppbv] O 3 [ppbv] March 2002 CO [ppbv] O 3 [ppbv] June 2002 Stratospheric air (CO < 50 ppb) Tropospheric air (O3 < 100 ppb) Mixed layer

4. CO/O 3 correlations: Comparison with aircraft data from SPURT  Too much CO/O 3 in the lower stratosphere in GEOS-Chem, relative to SPURT  Mixing in spring is excessive compared to SPURT  Too much CO/O 3 in the lower stratosphere in GEOS-Chem, relative to SPURT  Mixing in spring is excessive compared to SPURT O 3 Concentration [ppbv] CO Concentration [ppbv] O 3 Concentration [ppbv] Winter 2003 Summer 2003 CO Concentration [ppbv] O 3 Concentration [ppbv] Spring 2003 CO Concentration [ppbv] O 3 Concentration [ppbv] Fall 2002 Stratospheric air (CO < 50 ppb) Tropospheric air (O3 < 100 ppb) Mixed layer [SPURT data courtesy of Michaela Hegglin]

5. Mixing Layer Depths (distribution of mixing layer points with respect to the tropopause) GEOS-Chem fields for Lat=35N-75N, Lon=15E-25W Center and width of mixing layer varies with season Compactness yields narrow mixing layer Mixing layer is too thick in spring (7-10 km) in GEOS-Chem Center and width of mixing layer varies with season Compactness yields narrow mixing layer Mixing layer is too thick in spring (7-10 km) in GEOS-Chem Altitude - Tropopause Height [km] Number of Data Altitude - Tropopause Height [km] Number of Data Altitude - Tropopause Height [km] Number of Data Dec. 2002Sept. 2002 June 2002 Altitude - Tropopause Height [km] Number of Data March 2002

6. Vertical distribution of GEOS-Chem CO & O 3 plotted relative to the tropopause Profiles: Lat=35N-75N, Lon=15E-25W Strong concentration gradient near the tropopause for both tracers, as expected High CO (red) values in spring above tropopause; high O 3 (black) values in spring in troposphere Strong concentration gradient near the tropopause for both tracers, as expected High CO (red) values in spring above tropopause; high O 3 (black) values in spring in troposphere Concentration [ppbv] RALT [km] Sept. 2002 Concentration [ppbv] RALT [km] Dec. 2002 Concentration [ppbv] RALT [km] Marc 2002 Concentration [ppbv] RALT [km] June 2002 High CO in stratosphere in spring, which is absent in other seasons High O3 in troposphere in spring, which is absent in other seasons

7. Regional Contributions to CO in the lower stratosphere in spring Model fields for Lat=35N-75N, Lon=15E-25W Tagged CO simulation shows high CO in lower stratosphere from Europe, Asia and North America CO Concentration [ppbv] RALT [km] North America CO Concentration [ppbv] RALT [km] North Africa CO Concentration [ppbv] RALT [km] Asia CO Concentration [ppbv] RALT [km] Europe Profiles plotted relative to the altitude of the tropopause

8. Comparison of CO/O 3 correlations in GMI and GEOS-Chem Although the stratospheric and tropospheric end points are the same in GMI and GEOS-Chem (with LINOZ), there is more mixing in GEOS-Chem in all seasons compared to GMI GEOS-Chem (with SYNOZ and LINOZ) has significant mixing in spring Although the stratospheric and tropospheric end points are the same in GMI and GEOS-Chem (with LINOZ), there is more mixing in GEOS-Chem in all seasons compared to GMI GEOS-Chem (with SYNOZ and LINOZ) has significant mixing in spring MarchJune Sept.Dec.

9. CO/O 3 Correlations and Mixing Layer depth: GMI (with GEOS-4) and GEOS-Chem (with GEOS-5) CO [ppbv] O 3 [ppbv] Europe, March 2006 Altitude - Tropopause Height [km] Number of Data March 2006Europe Lat=36N-76N, Lon=0-25E  GEOS-Chem with GEOS-5 has more scatter and a wider mixing layer (1km bins) than GMI with GEOS-4  Other months show similar agreement with consistently wider mixing layers in GEOS-Chem with GEOS-5