Highly resolved observations of trace gases in the lowermost stratosphere and upper troposphere from the Spurt project: an overview

Engel, Andreas; Bönisch, Harald; Brunner, Dominik; Fischer, H.; Franke, Harald; Günther, G.; Gurk, C.; Hegglin, Michaela I.; Hoor, Peter; Königstedt, R.; Krebsbach, M.; Maser, R.; Parchatka, Uwe; Peter, Thomas; Schell, D.; Schiller, C.; Schmidt, Ulrich; Spelten, N.; Szabó, Tamás; Weers, U.; Wernli, Heini; Wetter, T.; Wirth, Volkmar

doi:10.5194/acp-6-283-2006

Cited by 92 publications

(85 citation statements)

References 54 publications

(57 reference statements)

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“…The error in mean age due to this simplification is less than half a month. CO 2 has a seasonal cycle in the troposphere which can propagate into the lower stratosphere (Andrews et al, 2001a, b;Hintsa et al, 1998;Bönisch et al, 2009;Engel et al, 2006a). Rosenlof et al (1997) found that the seasonal cycle in water vapour is observable up to potential temper- atures of about 450 K and termed this region the tropically controlled transition layer.…”

Section: Age Of Air From Aircorementioning

confidence: 99%

Mean age of stratospheric air derived from AirCore observations

et al. 2017

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Abstract. Mean age of stratospheric air can be derived from observations of sufficiently long-lived trace gases with approximately linear trends in the troposphere. Mean age can serve as a tracer to investigate stratospheric transport and long-term changes in the strength of the overturning BrewerDobson circulation of the stratosphere. For this purpose, a low-cost method is required in order to allow for regular observations up to altitudes of about 30 km. Despite the desired low costs, high precision and accuracy are required in order to determine mean age. We present balloonborne AirCore observations from two midlatitude sites: Timmins in Ontario/Canada and Lindenberg in Germany. During the Timmins campaign, five AirCores sampled air in parallel with a large stratospheric balloon and were analysed for CO 2 , CH 4 and partly CO. We show that there is good agreement between the different AirCores (better than 0.1 %), especially when vertical gradients are small. The measurements from Lindenberg were performed using small low-cost balloons and yielded very comparable results. We have used the observations to extend our long-term data set of mean age observations at Northern Hemisphere midlatitudes. The time series now covers more than 40 years and shows a small, statistically non-significant positive trend of 0.15 ± 0.18 years decade −1 . This trend is slightly smaller than the previous estimate of 0.24 ± 0.22 years decade −1 which was based on observations up to the year 2006. These observations are still in contrast to strong negative trends of mean age as derived from some model calculations.

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Section: Age Of Air From Aircorementioning

confidence: 99%

Mean age of stratospheric air derived from AirCore observations

et al. 2017

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“…A detailed description of the campaigns and the measurements is given by Engel et al (2006). The measurements during both projects were carried out in the extratropical UTLS between 30 • N and 80 • N latitude and below a level of 380 K potential temperature.…”

Section: Datamentioning

confidence: 99%

On the structural changes in the Brewer-Dobson circulation after 2000

et al. 2011

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Abstract. In this paper we present evidence that the observed increase in tropical upwelling after the year 2000 may be attributed to a change in the Brewer-Dobson circulation pattern. For this purpose, we use the concept of transit times derived from residual circulation trajectories and different in-situ measurements of ozone and nitrous dioxide. Observations from the Canadian midlatitude ozone profile record, probability density functions of in-situ N 2 O observations and a shift of the N 2 O-O 3 correlation slopes, taken together, indicate that the increased upwelling in the tropics after the year 2000 appears to have triggered an intensification of tracer transport from the tropics into the extratropics in the lower stratosphere below about 500 K. This finding is corroborated by the fact that transit times along the shallow branch of the residual circulation into the LMS have decreased for the same time period (1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003). On a longer time scale , the transit time of the shallow residual circulation branch show a steady decrease of about −1 month/decade over the last 30 yr, while the transit times of the deep branch remain unchanged. This highlights that changes in the upwelling across the tropical tropopause are not sufficient as an indicator for changes in the entire BrewerDobson circulation.

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“…There is a history of comparing models and measurements using such graphs (Hoor et al, 2002;Hsu et al, 2004;Engel et al, 2006;Pan et al, 2007;Strahan et al, 2007;Parrington et al, 2013;Gaudel et al, 2015). Often the goal is simply to define a linear correla- tion, but in many cases a line fit simply does not describe the heterogeneity (Köppe et al, 2009).…”

Section: Probability Distributions Of Species and Reactivitiesmentioning

confidence: 99%

“…There have been many aircraft missions designed to provide a wealth of in situ, high-resolution atmospheric chemistry data, including some with a nearly complete package of key species needed to calculate reactivities (Jacob et al, , 2017Engel et al, 2006;Pan et al, 2017). Unfortunately, many of these produced a biased, non-climatological sampling, for example, by chasing pollution plumes (Hsu et al, 2004) or by measuring only in clear skies (Nicely et al, 2016).…”

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confidence: 99%

Global atmospheric chemistry – which air matters

et al. 2017

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Abstract. An approach for analysis and modeling of global atmospheric chemistry is developed for application to measurements that provide a tropospheric climatology of those heterogeneously distributed, reactive species that control the loss of methane and the production and loss of ozone. We identify key species (e.g., O 3 , NO x , HNO 3 , HNO 4 , C 2 H 3 NO 5 , H 2 O, HOOH, CH 3 OOH, HCHO, CO, CH 4 , C 2 H 6 , acetaldehyde, acetone) and presume that they can be measured simultaneously in air parcels on the scale of a few km horizontally and a few tenths of a km vertically. As a first step, six global models have prepared such climatologies sampled at the modeled resolution for August with emphasis on the vast central Pacific Ocean basin. Objectives of this paper are to identify and characterize differences in model-generated reactivities as well as species covariances that could readily be discriminated with an unbiased climatology. A primary tool is comparison of multidimensional probability densities of key species weighted by the mass of such parcels or frequency of occurrence as well as by the reactivity of the parcels with respect to methane and ozone. The reactivity-weighted probabilities tell us which parcels matter in this case, and this method shows skill in differentiating among the models' chemistry. Testing 100 km scale models with 2 km measurements using these tools also addresses a core question about model resolution and whether fine-scale atmospheric structures matter to the overall ozone and methane budget. A new method enabling these six global chemistry-climate models to ingest an externally sourced climatology and then compute air parcel reactivity is demonstrated. Such an objective climatology containing these key species is anticipated from the NASA Atmospheric Tomography (ATom) aircraft mission (2015-2020), executing profiles over the Pacific and Atlantic Ocean basins. This modeling study addresses a core part of the design of ATom.

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Highly resolved observations of trace gases in the lowermost stratosphere and upper troposphere from the Spurt project: an overview

Cited by 92 publications

References 54 publications

Mean age of stratospheric air derived from AirCore observations

Mean age of stratospheric air derived from AirCore observations

On the structural changes in the Brewer-Dobson circulation after 2000

Global atmospheric chemistry – which air matters

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