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Transport of CO and O 3 into the UTLS Region. University of Toronto. Dave MacKenzie. CO/O 3 correlations: Assessing transport of tropospheric pollution to the lowermost stratosphere. Stratosphere. High CO (flat) indicates tropospheric air; high O 3 (steep) is stratospheric
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Transport of CO and O3 into the UTLS Region University of Toronto Dave MacKenzie
CO/O3 correlations:Assessing transport of tropospheric pollution to the lowermost stratosphere Stratosphere • High CO (flat) indicates tropospheric air; high O3 (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 Troposphere
GEOS-Chem CO/O3 Correlations: Lat=35N-75N, Lon=15E-25W Stratospheric air (CO < 50 ppb) • Compactness of correlation varies with season • Large scatter in Spring, indicating deep mixed layer in UTLS in GEOS-Chem • Increased compactness through fall March 2002 June 2002 Mixed layer Tropospheric air (O3 < 100 ppb) O3 [ppbv] O3 [ppbv] CO [ppbv] CO [ppbv] Sept. 2002 Dec. 2002 O3 [ppbv] O3 [ppbv] CO [ppbv] CO [ppbv]
CO/O3 correlations: Comparison with aircraft data from SPURT Stratospheric air (CO < 50 ppb) [SPURT data courtesy of Michaela Hegglin] • Too much CO/O3 in the lower stratosphere in GEOS-Chem, relative to SPURT • Mixing in spring is excessive compared to SPURT Spring 2003 Summer 2003 Mixed layer Tropospheric air (O3 < 100 ppb) O3 Concentration [ppbv] O3 Concentration [ppbv] CO Concentration [ppbv] CO Concentration [ppbv] Fall 2002 Winter 2003 O3 Concentration [ppbv] O3 Concentration [ppbv] CO Concentration [ppbv] CO Concentration [ppbv]
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 March 2002 June 2002 Number of Data Number of Data Altitude - Tropopause Height [km] Altitude - Tropopause Height [km] Sept. 2002 Dec. 2002 Number of Data Number of Data Altitude - Tropopause Height [km] Altitude - Tropopause Height [km]
Vertical distribution of GEOS-Chem CO & O3 plotted relative to the tropopauseProfiles: Lat=35N-75N, Lon=15E-25W High CO in stratosphere in spring, which is absent in other seasons • Strong concentration gradient near the tropopause for both tracers, as expected • High CO (red) values in spring above tropopause; high O3 (black) values in spring in troposphere Marc 2002 June 2002 RALT [km] RALT [km] Concentration [ppbv] Concentration [ppbv] High O3 in troposphere in spring, which is absent in other seasons Sept. 2002 Dec. 2002 RALT [km] RALT [km] Concentration [ppbv] Concentration [ppbv]
Regional Contributions to CO in the lower stratosphere in springModel fields for Lat=35N-75N, Lon=15E-25W Profiles plotted relative to the altitude of the tropopause • Tagged CO simulation shows high CO in lower stratosphere from Europe, Asia and North America Asia Europe RALT [km] RALT [km] CO Concentration [ppbv] CO Concentration [ppbv] North America North Africa RALT [km] RALT [km] CO Concentration [ppbv] CO Concentration [ppbv]
Comparison of CO/O3 correlations in GMI and GEOS-Chem March June • 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 Sept. Dec.
CO/O3 Correlations and Mixing Layer depth: GMI (with GEOS-4) and GEOS-Chem (with GEOS-5) Europe, March 2006 Lat=36N-76N, Lon=0-25E O3 [ppbv] • 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 CO [ppbv] Europe March 2006 Number of Data Altitude - Tropopause Height [km]