Global carbonyl sulfide (OCS) measured by MIPAS/Envisat during 2002–2012

Glatthor, N.; Höpfner, Michael; Leyser, Adrian; Stiller, G. P.; Clarmann, T. von; Grabowski, U.; Kellmann, S.; Linden, A.; Sinnhuber, Björn-Martin; Krysztofiak, Gisèle; Walker, Kaley A.

doi:10.5194/acp-17-2631-2017

Cited by 38 publications

(60 citation statements)

References 71 publications

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“…Similar hemispheric asymmetries of trends of stratospheric trace species have been derived from other observational data sets by various groups, corroborating the results from the MIPAS AoA analysis, e.g. for ozone (Eckert et al, 2014;Gebhardt et al, 2014;Nedoluha et al, 2015a, b;Pawson et al, 2014), hydrogen fluoride (Harrison et al, 2016), hydrogen chloride (Mahieu et al, 2014), (H)CFCs (Chirkov et al, 2016;Kellmann et al, 2012), nitrous oxide (Nedoluha et al, 2015a), and carbonyl sulfide (Glatthor et al, 2017). Ploeger et al (2015b) performed an analysis of the time series of AoA as derived from the MIPAS SF 6 observations and the AoA derived from a Chemical Lagrangian Model of the Stratosphere (CLaMS) model run with a clock tracer G. P. Stiller et al: Shift of subtropical transport barriers included.…”

Section: Introductionsupporting

confidence: 86%

Shift of subtropical transport barriers explains observed hemispheric asymmetry of decadal trends of age of air

Stiller

Fierli

Ploeger³

et al. 2017

Atmos. Chem. Phys.

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Abstract. In response to global warming, the BrewerDobson circulation in the stratosphere is expected to accelerate and the mean transport time of air along this circulation to decrease. This would imply a negative stratospheric age of air trend, i.e. an air parcel would need less time to travel from the tropopause to any point in the stratosphere. Age of air as inferred from tracer observations, however, shows zero to positive trends in the northern mid-latitude stratosphere and zonally asymmetric patterns. Using satellite observations and model calculations we show that the observed latitudinal and vertical patterns of the decadal changes of age of air in the lower to middle stratosphere during the period 2002-2012 are predominantly caused by a southward shift of the circulation pattern by about 5 • . After correction for this shift, the observations reveal a hemispherically almost symmetric decrease of age of air in the lower to middle stratosphere up to 800 K of up to −0.25 years over the 2002-2012 period with strongest decrease in the northern tropics. This net change is consistent with long-term trends from model predictions.

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Section: Introductionsupporting

confidence: 86%

Shift of subtropical transport barriers explains observed hemispheric asymmetry of decadal trends of age of air

Stiller

Fierli

Ploeger³

et al. 2017

Atmos. Chem. Phys.

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“…From MI-PAS several data sets of trace gas species that are relevant for studying the stratospheric sulfur loading are available. These are volume mixing ratios (VMRs) of OCS (Glatthor et al, , 2017 and SO 2 . Here, we present a new data set of sulfate aerosol volume densities (AVDs) retrieved from MIPAS measurements and corresponding H 2 SO 4 volume mixing ratios.…”

Section: Introductionmentioning

confidence: 99%

MIPAS observations of volcanic sulfate aerosol and sulfur dioxide in the stratosphere

et al. 2018

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Abstract. Volcanic eruptions can increase the stratospheric sulfur loading by orders of magnitude above the background level and are the most important source of variability in stratospheric sulfur. We present a set of vertical profiles of sulfate aerosol volume densities and derived liquidphase H 2 SO 4 (sulfuric acid) mole fractions for 2005-2012, retrieved from infrared limb emission measurements performed with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board of the Environmental Satellite (Envisat). Relative to balloon-borne in situ measurements of aerosol at Laramie, Wyoming, the MIPAS aerosol data have a positive bias that has been corrected, based on the observed differences to the in situ data. We investigate the production of stratospheric sulfate aerosol from volcanically emitted SO 2 for two case studies: the eruptions of Kasatochi in 2008 and Sarychev in 2009, which both occurred in the Northern Hemisphere midlatitudes during boreal summer. With the help of chemical transport model (CTM) simulations for the two volcanic eruptions we show that the MIPAS sulfate aerosol and SO 2 data are qualitatively and quantitatively consistent with each other. Further, we demonstrate that the lifetime of SO 2 is explained well by its oxidation by hydroxyl radicals (OH). While the sedimentation of sulfate aerosol plays a role, we find that the long-term decay of stratospheric sulfur after these volcanic eruptions in midlatitudes is mainly controlled by transport via the BrewerDobson circulation. Sulfur emitted by the two midlatitude volcanoes resides mostly north of 30 • N at altitudes of ∼ 10-16 km, while at higher altitudes (∼ 18-22 km) part of the volcanic sulfur is transported towards the Equator where it is lifted into the stratospheric "overworld" and can further be transported into both hemispheres.

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“…Figure 4 visualizes how much denser the MIPAS sampling is, compared to that of ACE-FTS in the chosen latitudetime box. It should be noted that Glatthor et al (2017) found a systematic difference between OCS from MIPAS and ACE-FTS that is highest at 14 km altitude, with ACE-FTS measurements lower by 75 to 100 ppt. We also find the ACE-FTS mean value between 60°S and 90°S to be 115 ppt (28%) lower 15 than the mean value of MIPAS.…”

Section: Quantitative Evaluation Based On Mipas Observationsmentioning

confidence: 99%

“…To obtain the stratospheric burden for a particular region, respective columns are summed. et al, 2015;Glatthor et al, 2017). The retrieval uncertainty for a single OCS scan is estimated to be 10% between 10 and 15 km, 26% at 20 km and increasing up to 195% at 40 km altitude (Glatthor et al, 2015).…”

Section: Ace-fts Ocs Observationsmentioning

confidence: 99%

On sampling bias adjustment for sparsely observing satellite instruments for the example of carbonyl sulfide (OCS)

Kloss

Hobe

Höpfner

et al. 2018

Preprint

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Abstract. When computing climatological averages of atmospheric trace gas mixing ratios obtained from satellite-based measurements, sampling biases arise if data coverage is not uniform in space and time. Complete homogeneous spatio-temporal coverage is essentially impossible to achieve. Solar occultation measurements, by virtue of satellite orbits and the requirement of direct observation of the sun through the atmosphere, result in particularly sparse spatial coverage. In this study, a method is presented to adjust for such sampling biases when calculating climatological means. The method is demonstrated using carbonyl sulfide (OCS) measurements at 16 km altitude from the ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform 15 Spectrometer). At this altitude, OCS mixing ratios show a steep gradient between the poles and equator. ACE-FTS measurements, which are provided as vertically resolved profiles, and integrated stratospheric OCS columns are used in this study. The bias adjustment procedure requires no additional observations other than the satellite data product itself and is expected to be generally applicable when constructing climatologies of long-lived tracers from sparsely and heterogeneously sampled satellite data. In a first step of the adjustment procedure, a regression model is used to fit a 2-D surface to all available ACE-FTS OCS measurements as a function of day-of-year and latitude. The regression model fit is used to calculate an adjustment factor, 20 which is then used to adjust each measurement individually. The mean of the adjusted measurement points of a chosen spatio-temporal frame is then used as the bias-free climatological value. When applying the adjustment factor to seasonal averages in 30° zones, the maximum spatio-temporal sampling bias adjustment was 11 % for OCS mixing ratios at 16 km and 5 % for the stratospheric OCS column. The adjustments were validated against the much denser and more homogeneous OCS data product from the limb-sounding MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) instrument, and both the direction and sign of the adjustments were in agreement with the adjustment of the ACE-FTS data.

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Global carbonyl sulfide (OCS) measured by MIPAS/Envisat during 2002–2012

Cited by 38 publications

References 71 publications

Shift of subtropical transport barriers explains observed hemispheric asymmetry of decadal trends of age of air

Shift of subtropical transport barriers explains observed hemispheric asymmetry of decadal trends of age of air

MIPAS observations of volcanic sulfate aerosol and sulfur dioxide in the stratosphere

On sampling bias adjustment for sparsely observing satellite instruments for the example of carbonyl sulfide (OCS)

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