Long-term climatology of air mass transport through the Tropical Tropopause Layer (TTL) during NH winter

Krüger, Kirstin; Tegtmeier, Susann; Rex, Markus

doi:10.5194/acp-8-813-2008

Cited by 53 publications

(46 citation statements)

References 37 publications

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“…The difference in the distribution of the position of minimum saturation mixing ratios between kinematic and diabatic ERA-Interim trajectories induces only minor differences in model predicted entry mixing ratios (see also Liu et al, 2010). In agreement with previous work (Krüger et al, 2008) we find that the patterns of distribution of minimum saturation mixing ratio of TST-trajectories (Bonazzola and Haynes, 2004;Kremser et al, 2009) are a robust feature of TST.…”

Section: The Difference Between Water Vapour and Ozone As Transport Tsupporting

confidence: 90%

Insight from ozone and water vapour on transport in the tropical tropopause layer (TTL)

et al. 2011

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Abstract. We explore the potential of ozone observations to constrain transport processes in the tropical tropopause layer (TTL), and contrast it with insights that can be obtained from water vapour. Global fields from Halogen Occultation Experiment (HALOE) and in-situ observations are predicted using a backtrajectory approach that captures advection, instantaneous freeze-drying and photolytical ozone production. Two different representations of transport (kinematic and diabatic 3-month backtrajectories based on ERAInterim data) are used to evaluate the sensitivity to differences in transport. Results show that mean profiles and seasonality of both tracers can be reasonably reconstructed. Water vapour predictions are similar for both transport representations, but predictions for ozone are systematically higher for kinematic transport. Compared to global HALOE observations, the diabatic model prediction underestimates the vertical ozone gradient. Comparison of the kinematic prediction with observations obtained during the tropical SCOUT-O3 campaign shows a large high bias above 390 K potential temperature. We show that ozone predictions and vertical dispersion of the trajectories are highly correlated, rendering ozone an interesting tracer for aspects of transport to which water vapour is not sensitive. We show that dispersion and mean upwelling have similar effects on ozone profiles, with slower upwelling and larger dispersion both leading to higher ozone concentrations. Analyses of tropical upwelling basedCorrespondence to: F. Ploeger (f.ploeger@fz-juelich.de) on mean transport characteristics, and model validation have to take into account this ambiguity between tropical ozone production and in-mixing from the stratosphere. In turn, ozone provides constraints on transport in the TTL and lower stratosphere that cannot be obtained from water vapour.

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Section: The Difference Between Water Vapour and Ozone As Transport Tsupporting

confidence: 90%

Insight from ozone and water vapour on transport in the tropical tropopause layer (TTL)

et al. 2011

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“…Any later breakdown of species can only change the stratospheric balance between species but not the total budgets of e.g., halogens or sulfur. It has been shown that most air masses reach their LCP above the West Pacific (Fueglistaler et al, 2004;Bonazzola and Haynes, 2004;Krüger et al, 2008) and we will show here that the source region in the boundary layer and the transit region in the troposphere are also situated in the same region.…”

Section: Introductionsupporting

confidence: 54%

A tropical West Pacific OH minimum and implications for stratospheric composition

et al. 2014

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Abstract. Most of the short-lived biogenic and anthropogenic chemical species that are emitted into the atmosphere break down efficiently by reaction with OH and do not reach the stratosphere. Here we show the existence of a pronounced minimum in the tropospheric column of ozone over the West Pacific, the main source region for stratospheric air, and suggest a corresponding minimum of the tropospheric column of OH. This has the potential to amplify the impact of surface emissions on the stratospheric composition compared to the impact when assuming globally uniform OH conditions. Specifically, the role of emissions of biogenic halogenated species for the stratospheric halogen budget and the role of increasing emissions of SO 2 in Southeast Asia or from minor volcanic eruptions for the increasing stratospheric aerosol loading need to be reassessed in light of these findings. This is also important since climate change will further modify OH abundances and emissions of halogenated species. Our study is based on ozone sonde measurements carried out during the TransBrom cruise with the RV Sonne roughly along 140-150 • E in October 2009 and corroborating ozone and OH measurements from satellites, aircraft campaigns and FTIR instruments. Model calculations with the GEOS-Chem Chemistry and Transport Model (CTM) and the ATLAS CTM are used to simulate the tropospheric OH distribution over the West Pacific and the transport pathways to the stratosphere. The potential effect of the OH minimum on species transported into the stratosphere is shown via modeling the transport and chemistry of CH 2 Br 2 and SO 2 .

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“…By assuming that this gap is significant, additional processes may come into the focus of stratospheric bromine research, i.e., the seasonality and possibly long-term trend of the bromine transported into the stratosphere (e.g., Levine et al, 2008;Krüger et al, 2008;Fueglistaler et al, 2009;Schofield et al, 2011;Ploeger et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…Here one may wonder whether (a) this result is significant, (b) some Br inorg y is actually removed by heterogeneous processes in the TTL (e.g., Aschmann et al, 2011;Aschmann and Sinnhuber, 2013), or (c) TTL Br y shows some seasonality analogous to the "tape recorder" for H 2 O (e.g., Levine et al, 2008;Krüger et al, 2008;Fueglistaler et al, 2009;Schofield et al, 2011;Ploeger et al, 2011).…”

Section: Uncertainties In Estimating the Inorganic Bromine Partitioningmentioning

confidence: 99%

Probing the subtropical lowermost stratosphere and the tropical upper troposphere and tropopause layer for inorganic bromine

et al. 2017

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Abstract. We report measurements of CH 4 (measured in situ by the Harvard University Picarro Cavity Ringdown Spectrometer (HUPCRS) and NOAA Unmanned Aircraft System Chromatograph for Atmospheric Trace Species (UCATS) instruments), O 3 (measured in situ by the NOAA dual-beam ultraviolet (UV) photometer), NO 2 , BrO (remotely detected by spectroscopic UV-visible (UV-vis) limb observations; see the companion paper of Stutz et al., 2016), and of some key brominated source gases in whole-air samples of the Global Hawk Whole Air Sampler (GWAS) instrument within the subtropical lowermost stratosphere (LS) and the tropical upper troposphere (UT) and tropopause layer (TTL). The measurements were performed within the framework of the NASA-ATTREX (National Aeronautics and Space Administration -Airborne Tropical Tropopause Experiment) project from aboard the Global Hawk (GH) during six deployments over the eastern Pacific in early 2013. These measurements are compared with TOMCAT/SLIMCAT (Toulouse Off-line Model of Chemistry And Transport/Single Layer Isentropic Model of Chemistry And Transport) 3-D model simulations, aiming at improvements of our understanding of the bromine budget and photochemistry in the LS, UT, and TTL.Changes in local O 3 (and NO 2 and BrO) due to transport processes are separated from photochemical processes in intercomparisons of measured and modeled CH 4 and O 3 . After excellent agreement is achieved among measured and simulated CH 4 and O 3 , measured and modeled [NO 2 ] are found to closely agree with ≤ 15 ppt in the TTL (which is the detection limit) and within a typical range of 70 to 170 ppt in the subtropical LS during the daytime. Measured [BrO] ranges between 3 and 9 ppt in the subtropical LS. In the TTL, [BrO] ] is found to increase from a mean of 2.63 ± 1.04 ppt for potential temperatures (θ ) in the range of 350-360 K to 5.11 ± 1.57 ppt for θ = 390 − 400 K, whereas in the subtropical LS (i.e., when [CH 4 ] ≤ 1790 ppb), it reaches 7.66 ± 2.95 ppt for θ in the range of 390-400 K. Finally, for the eastern Pacific (170-90 • W), the TOMCAT/SLIMCAT simulations indicate a net loss of ozone of −0.3 ppbv day −1 at the base of the TTL (θ = 355 K) and a net production of +1.8 ppbv day −1 in the upper part (θ = 383 K).

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Long-term climatology of air mass transport through the Tropical Tropopause Layer (TTL) during NH winter

Cited by 53 publications

References 37 publications

Insight from ozone and water vapour on transport in the tropical tropopause layer (TTL)

Insight from ozone and water vapour on transport in the tropical tropopause layer (TTL)

A tropical West Pacific OH minimum and implications for stratospheric composition

Probing the subtropical lowermost stratosphere and the tropical upper troposphere and tropopause layer for inorganic bromine

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