The strength of the meridional overturning circulation of the stratosphere

Linz, Marianna; Plumb, R. Alan; Gerber, Edwin P.; Haenel, Florian; Stiller, G. P.; Kinnison, Douglas E.; Ming, Alison; Neu, J. L.

doi:10.1038/ngeo3013

Cited by 42 publications

(58 citation statements)

References 49 publications

(60 reference statements)

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“…However, the difference between the CO 2 and SF 6 ages obtained in this study is so large that the "polar vortex mixing" effect is not a major factor. Linz et al (2017) compared the MIPAS SF 6 age with the N 2 O age calculated from the N 2 O data from the Global OZone Chemistry And Related trace gas Data records for the Stratosphere (GOZCARDS) and showed that the MIPAS SF 6 age is larger than the N 2 O age in the tropics. The CO 2 and SF 6 ages observed in this study are consistent with the N 2 O age rather than the MIPAS SF 6 age, although the observation period is different.…”

Section: Difference In the Co 2 And Sf 6 Agesmentioning

confidence: 99%

“…From an analysis of the ERA-Interim dataset, Diallo et al (2012) also showed a negative trend over the 1989-2010 period in the lower stratosphere below 25 km. Linz et al (2017) discussed the strength of the meridional overturning circulation of the stratosphere by using satellite observation data of SF 6 and N 2 O and suggested that a mesospheric SF 6 loss is important for age estimation using SF 6 mole fraction in the upper layer.…”

Section: Introductionmentioning

confidence: 99%

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Age and gravitational separation of the stratospheric air over Indonesia

et al. 2018

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Abstract. The gravitational separation of major atmospheric components, in addition to the age of air, would provide additional useful information about stratospheric circulation. However, observations of the age of air and gravitational separation are still geographically sparse, especially in the tropics. In order to address this issue, air samples were collected over Biak, Indonesia in February 2015 using four large plastic balloons, each loaded with two compact cryogenic samplers. With a vertical resolution of better than 2 km, air samples from seven different altitudes were analyzed for CO 2 and SF 6 mole fractions, δ 15 N of N 2 , δ 18 O of O 2 , and δ(Ar/N 2 ) to examine the vertically dependent age and gravitational separation of air in the tropical tropopause layer (TTL) and the equatorial stratosphere. By comparing their measured mole fractions with aircraft observations in the upper tropical troposphere, we have found that CO 2 and SF 6 ages increase gradually with increasing altitude from the TTL to 22 km, and then rapidly from there up to 29 km. The CO 2 and SF 6 ages agree well with each other in the TTL and in the lower stratosphere, but show a significant difference above 24 km. The average values of δ 15 N of N 2 , δ 18 O of O 2 , and δ(Ar/N 2 ) all show a small but distinct upward decrease due to the gravitational separation effect. Simulations with a two-dimensional atmospheric transport model indicate that the gravitational separation effect decreases as tropical upwelling is enhanced. From the model calculations with enhanced eddy mixing, it is also found that the upward increase in air age is magnified by horizontal mixing. These model simulations also show that the gravitational separation effect remains relatively constant in the lower stratosphere. The results of this study strongly suggest that the gravitational separation, combined with the age of air, can be used to diagnose air transport processes in the stratosphere.

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Section: Difference In the Co 2 And Sf 6 Agesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Age and gravitational separation of the stratospheric air over Indonesia

et al. 2018

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“…Moreover, AoA determined from GOZCARDS N 2 O data is used (gray circles) (Andrews et al, 2001;Linz et al, 2017). The latitudinal AoA distribution is shown together with AoA from MIPAS SF 6 data (gray diamond symbols), with AoA from GOZCARDS N 2 O data (gray circle) and with in situ measurements of Andrews et al (2001) (black cross for CO 2 and black dot for SF 6 ).…”

Section: Tropical Upwellingmentioning

confidence: 99%

“…[a] in situ data we also use AoA calculated from the satellitebased GOZCARDS (Global OZone Chemistry And Related trace gas Data records for the Stratosphere, Froidevaux et al, 2015) N 2 O data, using the empirical relationship of N 2 O with AoA (see Andrews et al, 2001;Linz et al, 2017) (2001) were not reported with uncertainties. Moreover, AoA determined from GOZCARDS N 2 O data is used (gray circles) (Andrews et al, 2001;Linz et al, 2017).…”

Section: Tropical Upwellingmentioning

confidence: 99%

Quantifying the effect of mixing on the mean age of air in CCMVal-2 and CCMI-1 models

et al. 2018

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Abstract. The stratospheric age of air (AoA) is a useful measure of the overall capabilities of a general circulation model (GCM) to simulate stratospheric transport. Previous studies have reported a large spread in the simulation of AoA by GCMs and coupled chemistry-climate models (CCMs). Compared to observational estimates, simulated AoA is mostly too low. Here we attempt to untangle the processes that lead to the AoA differences between the models and between models and observations. AoA is influenced by both mean transport by the residual circulation and two-way mixing; we quantify the effects of these processes using data from the CCM inter-comparison projects CCMVal-2 (Chemistry-Climate Model Validation Activity 2) and CCMI-1 (Chemistry-Climate Model Initiative, phase 1). Transport along the residual circulation is measured by the residual circulation transit time (RCTT). We interpret the difference between AoA and RCTT as additional aging by mixing. Aging by mixing thus includes mixing on both the resolved and subgrid scale. We find that the spread in AoA between the models is primarily caused by differences in the effects of mixing and only to some extent by differences in residual circulation strength. These effects Published by Copernicus Publications on behalf of the European Geosciences Union. are quantified by the mixing efficiency, a measure of the relative increase in AoA by mixing. The mixing efficiency varies strongly between the models from 0.24 to 1.02. We show that the mixing efficiency is not only controlled by horizontal mixing, but by vertical mixing and vertical diffusion as well. Possible causes for the differences in the models' mixing efficiencies are discussed. Differences in subgrid-scale mixing (including differences in advection schemes and model resolutions) likely contribute to the differences in mixing efficiency. However, differences in the relative contribution of resolved versus parameterized wave forcing do not appear to be related to differences in mixing efficiency or AoA.

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“…The difference in the estimated time lag between CO 2 and SF 6 was also reported by previous studies (e.g., Andrew et al 2001;Sugawara et al 2017), however, the cause is not yet understood well. The downward transport of the mesospheric air with low SF 6 mole fractions is suggested as one of possible candidates (e.g., Reddmann et al 2001;Linz et al 2017). …”

Section: Methodsmentioning

confidence: 99%

Vertical Profiles and Temporal Variations of Greenhouse Gases in the Stratosphere over Syowa Station, Antarctica

Goto

Morimoto

Aoki

et al. 2017

SOLA

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Stratospheric air sampling using balloon-borne cryogenic air samplers was conducted over Syowa Station, Antarctica in four austral summers between 1998 and 2013. The CH 4 and N 2 O mole fractions decreased with increasing altitude due to chemical reactions and photodissociation in the stratosphere, and a compact positive correlation between CH 4 and N 2 O was found in their vertical profiles. The vertical profiles of CO 2 and SF 6 mole fractions showed high values in the lower stratosphere, decreasing gradually with altitude, and then becoming almost constant at altitudes above 18 km. Stratospheric CO 2 and SF 6 above 18km over Antarctica increased secularly at the respective average rates of 1.82 ± 0.31 ppm yr −1 and 0.26 ± 0.01 ppt yr −1 during the study period. The CO 2 and SF 6 mole fractions increased in the Antarctic stratosphere, but were delayed 4.5 ± 0.5 and 5.6 ± 0.2 years, respectively, compared to the tropical troposphere. The secular increase in stratospheric CH 4 was also detected by classifying the measured mole fractions in terms of the N 2 O depletion in the stratosphere.

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The strength of the meridional overturning circulation of the stratosphere

Cited by 42 publications

References 49 publications

Age and gravitational separation of the stratospheric air over Indonesia

Age and gravitational separation of the stratospheric air over Indonesia

Quantifying the effect of mixing on the mean age of air in CCMVal-2 and CCMI-1 models

Vertical Profiles and Temporal Variations of Greenhouse Gases in the Stratosphere over Syowa Station, Antarctica

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