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Enhanced Tropospheric Ozone and the Arabian Anti-Cyclone (or the “Middle east ozone maximum?”) John Worden 1 , Jane Liu 2, Dylan Jones 2 , Kevin Bowman 1 , Helen Worden 3 , Ming Luo 1 , and JPL/TES team 1 1 JPL / Caltech 2 U. of Toronto 3 NCAR. Background on Middle East Ozone Maximum. - PowerPoint PPT Presentation
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Enhanced Tropospheric Ozone and the Arabian Anti-Cyclone (or the “Middle east ozone maximum?”)
John Worden1, Jane Liu2, Dylan Jones2, Kevin Bowman1, Helen Worden3, Ming Luo1, and JPL/TES team1
1 JPL / Caltech
2 U. of Toronto
3 NCAR
Background on Middle East Ozone Maximum
The GEOS-CHEM model predicts that ozone amounts in the upper troposphere during the summer are highest over the middle east relative to the rest of the globe.
Enhanced ozone due to summer time Arabian anti-cyclone which gathers ozone and ozone pre-cursors. Subsidence of Ozone also plays a role
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H. Worden et al. In Preperation
Enhanced Ozone Over Middle East Significant Green House Gas
Li et al., 2001
Monthly Mean O3 in GEOS-CHEM at ~350 hPa, ~8 km May 2005 June 2005 July 2005
Aug 2005 Sept 2005 Oct 2005
The ozone maximum is confined to a narrow altitude layer in the upper troposphere, where TES is most sensitive Ozone accumulation is seasonal, peaking during June-August
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What do satellite observations show?
SAGE II UV/visible solar occultation ozone at 7km (July 1985-1994)
TES Ozone 460 hPa July 2006
High ozone over NE Africa and Mediterranean and some enhanced ozone over middle east
Also high ozone over Central Asia and E. China
Kar et al., 2002
As with GEOS-CHEM….. TES Observations show this feature is seasonal with a peak in July
June July 2006 August
And is persistent year to year
July 2007
Upper Tropospheric Ozone in NE Africa and S.W. Russia is about 95 - 110 PPB as compared to 65-85 PPB at other longitudes
TES observations sensitive to these regions 0.5 < DOFS < 0.7 in Upper Troposphere Random Error < 5 PPB
Observed ozone spatial variations are statistically significant
Ozone spatial variations not due too a priori bias
TES Estimate TES estimate w/ fixed constraint vector
Ozone variations have low bias error in regions of interest
bias differences larger at higher latitudes where sensitivity is low
Conclusions• TES observes summertime enhanced upper tropospheric ozone over
NE Africa, the Mediterranean, and Central Asia.
• TES ozone observations are consistent with SAGE data and the observed spatial variability is statistically significant
• Spatial distribution of TES observed ozone is different from the GEOS-CHEM model in that ozone does not peak over the Middle East
• However, …the seasonality of the distribution and lack of ozone pre-cursors under regions of enhanced ozone suggests the Arabian anti-cyclone is driving the observed ozone spatial distribution (more on this from Dylan!)