An examination of chemistry and transport processes in the tropical lower stratosphere using observations of long‐lived and short‐lived compounds obtained during STRAT and POLARIS

Flocke, Frank; Herman, R. L.; Salawitch, R. J.; Atlas, Elliot L.; Webster, C. R.; Schauffler, S.; Lueb, R.; May, R. D.; Moyer, E. J.; Rosenlof, Karen H.; Scott, David C.; Blake, D. R.; Bui, T. P.

doi:10.1029/1999jd900504

Cited by 65 publications

(63 citation statements)

References 66 publications

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“…SOLVE mission samples (January-March 2000, 29 -79°N, 11-20 km) were collected as whole air samples (WAS) (41). CO 2 was then isolated from the Ϸ5-L STP of air by a combination of liquid N 2 and ethanol-dry ice traps, then separated into aliquots of 12-18 mol of CO2 each and sealed into glass ampoules.…”

Section: Methodsmentioning

confidence: 99%

Large and unexpected enrichment in stratospheric ¹⁶ O ¹³ C ¹⁸ O and its meridional variation

Yeung¹,

Affek

Hoag³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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The stratospheric CO 2 oxygen isotope budget is thought to be governed primarily by the O( 1 D)+CO 2 isotope exchange reaction. However, there is increasing evidence that other important physical processes may be occurring that standard isotopic tools have been unable to identify. Measuring the distribution of the exceedingly rare CO 2 isotopologue 16 O 13 C 18 O, in concert with 18 O and 17 O abundances, provides sensitivities to these additional processes and, thus, is a valuable test of current models. We identify a large and unexpected meridional variation in stratospheric 16 O 13 C 18 O, observed as proportions in the polar vortex that are higher than in any naturally derived CO 2 sample to date. We show, through photochemical experiments, that lower 16 O 13 C 18 O proportions observed in the midlatitudes are determined primarily by the O( 1 D)+CO 2 isotope exchange reaction, which promotes a stochastic isotopologue distribution. In contrast, higher 16 O 13 C 18 O proportions in the polar vortex show correlations with long-lived stratospheric tracer and bulk isotope abundances opposite to those observed at midlatitudes and, thus, opposite to those easily explained by O( 1 D)+CO 2 . We believe the most plausible explanation for this meridional variation is either an unrecognized isotopic fractionation associated with the mesospheric photochemistry of CO 2 or temperature-dependent isotopic exchange on polar stratospheric clouds. Unraveling the ultimate source of stratospheric 16 O 13 C 18 O enrichments may impose additional isotopic constraints on biosphere–atmosphere carbon exchange, biosphere productivity, and their respective responses to climate change.

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Section: Methodsmentioning

confidence: 99%

Large and unexpected enrichment in stratospheric ¹⁶ O ¹³ C ¹⁸ O and its meridional variation

Yeung¹,

Affek

Hoag³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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“…Destruction of CO takes place via the reaction with OH forming CO 2 resulting in a lifetime of CO on the order of several months. If no additional CO from the troposphere is mixed into the stratosphere, a steady state volume mixing ratio of 8-15 ppbv establishes, which is the balance between photochemical production from CH 4 and the much faster CO oxidation via OH ( Flocke et al, 1999). High altitude measurements by the ER-2 in the tropics as well as in polar regions indicated almost constant CO-values of 12 ppbv Toon et al, 1999).…”

Section: Irreversibility Of Tstmentioning

confidence: 99%

Seasonality and extent of extratropical TST derived from in-situ CO measurements during SPURT

et al. 2004

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Abstract. We present airborne in-situ trace gas measurements which were performed on eight campaigns between November 2001 and July 2003 during the SPURT-project (SPURenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region). The measurements on a quasi regular basis allowed an overview of the seasonal variations of the trace gas distribution in the tropopause region over Europe from 35 • -75 • N to investigate the influence of transport and mixing across the extratropical tropopause on the lowermost stratosphere.From the correlation of CO and O 3 irreversible mixing of tropospheric air into the lowermost stratosphere is identified. The CO distribution indicates that transport and subsequent mixing of tropospheric air across the extratropical tropopause predominantly affects a layer, which closely follows the shape of the local tropopause. In addition, the seasonal cycle of CO 2 illustrates the strong coupling of that layer to the extratropical troposphere. Both, horizontal gradients of CO on isentropes as well as the CO-O 3 -distribution in the lowermost stratosphere reveal that the influence of quasihorizontal transport and subsequent mixing weakens with distance from the local tropopause. The mixing layer extends to about 25 K in potential temperature above the local tropopause exhibiting only a weak seasonality.However, at large distances from the tropopause a significant influence of tropospheric air is still evident. The relation between N 2 O and CO 2 indicates that a significant contribution of air originating from the tropical tropopause contributes to the background air in the extratropical lowermost stratosphere.

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“…Starting 18 March, 800-ml canisters were also filled with the same sampling system and analyzed later at the United States Forest Service (USFS) Fire Sciences Laboratory by GC/FID/RGD for CO 2 , CO, CH 4 , H 2 , and several C 2 -C 3 hydrocarbons. Details of the canister analysis are given by Weinheimer et al (1998), Flocke et al (1999), and Hao et al (1996). GC with mass-selective detection (MSD) measurements of higher molecular weight hydrocarbons and halocarbons will be reported elsewhere.…”

Section: Whole Air Sampling (Was)mentioning

confidence: 99%

Emissions from forest fires near Mexico City

et al. 2007

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Abstract. The emissions of NO x (defined as NO (nitric oxide) + NO 2 (nitrogen dioxide)) and hydrogen cyanide (HCN), per unit amount of fuel burned, from fires in the pine forests that dominate the mountains surrounding Mexico City (MC) are about 2 times higher than normally observed for forest burning. The ammonia (NH 3 ) emissions are about average for forest burning. The upper limit for the mass ratio of NO x to volatile organic compounds (VOC) for these MC-area mountain fires was ∼0.38, which is similar to the NO x /VOC ratio in the MC urban area emissions inventory of 0.34, but much larger than the NO x /VOC ratio for tropical forest fires in Brazil (∼0.068). The nitrogen enrichment in the fire emissions may be due to deposition of nitrogencontaining pollutants in the outflow from the MC urban area. This effect may occur worldwide wherever biomass burning coexists with large urban areas (e.g. the tropics, southeastern US, Los Angeles Basin). The molar emission ratio of HCN to carbon monoxide (CO) for the mountain fires was 0.012±0.007, which is 2-9 times higher than widely used literature values for biomass burning. The ambient molar ratio HCN/CO in the MC-area outflow is about 0.003±0.0003.

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An examination of chemistry and transport processes in the tropical lower stratosphere using observations of long‐lived and short‐lived compounds obtained during STRAT and POLARIS

Cited by 65 publications

References 66 publications

Large and unexpected enrichment in stratospheric ¹⁶ O ¹³ C ¹⁸ O and its meridional variation

Large and unexpected enrichment in stratospheric ¹⁶ O ¹³ C ¹⁸ O and its meridional variation

Seasonality and extent of extratropical TST derived from in-situ CO measurements during SPURT

Emissions from forest fires near Mexico City

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An examination of chemistry and transport processes in the tropical lower stratosphere using observations of long‐lived and short‐lived compounds obtained during STRAT and POLARIS

Cited by 65 publications

References 66 publications

Large and unexpected enrichment in stratospheric 16 O 13 C 18 O and its meridional variation

Large and unexpected enrichment in stratospheric 16 O 13 C 18 O and its meridional variation

Seasonality and extent of extratropical TST derived from in-situ CO measurements during SPURT

Emissions from forest fires near Mexico City

Contact Info

Product

Resources

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Large and unexpected enrichment in stratospheric ¹⁶ O ¹³ C ¹⁸ O and its meridional variation

Large and unexpected enrichment in stratospheric ¹⁶ O ¹³ C ¹⁸ O and its meridional variation