How sharp is the tropopause at midlatitudes?

Birner, Thomas; Dörnbrack, Andreas; Schumann, U.

doi:10.1029/2002gl015142

Cited by 171 publications

(271 citation statements)

References 18 publications

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“…In order to clearly separate tropospheric and stratospheric air we transform the data to a tropopause-based vertical coordinate, chosen as the distance to the local tropopause in potential temperature before calculating all averages (for using this method in a different context, see, e.g., Birner et al, 2002;Hoor et al, 2004). The distributions in the monsoon region change substantially when viewed in tropopausebased coordinates along a surface at 10 K above the local tropopause (Fig.…”

Section: Resultsmentioning

confidence: 99%

Quantifying pollution transport from the Asian monsoon anticyclone into the lower stratosphere

et al. 2017

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Abstract. Pollution transport from the surface to the stratosphere within the Asian monsoon circulation may cause harmful effects on stratospheric chemistry and climate. Here, we investigate air mass transport from the monsoon anticyclone into the stratosphere using a Lagrangian chemistry transport model. We show how two main transport pathways from the anticyclone emerge: (i) into the tropical stratosphere (tropical pipe), and (ii) into the Northern Hemisphere (NH) extratropical lower stratosphere. Maximum anticyclone air mass fractions reach around 5 % in the tropical pipe and 15 % in the extratropical lowermost stratosphere over the course of a year. The anticyclone air mass fraction correlates well with satellite hydrogen cyanide (HCN) and carbon monoxide (CO) observations, confirming that pollution is transported deep into the tropical stratosphere from the Asian monsoon anticyclone. Cross-tropopause transport occurs in a vertical chimney, but with the pollutants transported quasihorizontally along isentropes above the tropopause into the tropics and NH.

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Section: Resultsmentioning

confidence: 99%

Quantifying pollution transport from the Asian monsoon anticyclone into the lower stratosphere

et al. 2017

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“…Vertical transport through the tropopause is inhibited by a strong gradient in static stability (cf. Birner, 2002;Pan et al, 2004), whereas quasi-horizontal transport along isentropes near the tropopause is inhibited by a strong meridional PV gradient (cf. Birner, 2006).…”

Section: Discussionmentioning

confidence: 99%

“…Pan et al, 2004). A tropopause based climatology of high-resolution radiosonde data by Birner et al (2002) revealed that static stability exhibits a distinct maximum just above the extratropical tropopause, a feature not reproduced in ECMWF data which are used in the here presented study. However, the existence of the maximum in static stability and the coincident gradient in the tracer observations highlight the role of the tropopause to act as a transport barrier.…”

Section: Median Tracer Distributions In (φ E ) Coordinatesmentioning

confidence: 99%

Measurements of NO, NOy, N2O, and O3 during SPURT: implications for transport and chemistry in the lowermost stratosphere

et al. 2006

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Abstract. We present measurements of NO, NO y , O 3 , and N 2 O within the lowermost stratosphere (LMS) over Europe obtained during the SPURT project. The measurements cover all seasons between November 2001 and July 2003. They span a broad band of latitudes from 30 • N to 75 • N and a potential temperature range from 290 to 380 K. The measurements represent a comprehensive data set of these tracers and reveal atmospheric transport processes that influence tracer distributions in the LMS. Median mixing ratios of stratospheric tracers in equivalent latitude-potential temperature coordinates show a clear seasonal cycle related to the Brewer-Dobson circulation, with highest values in spring and lowest values in autumn. Vertical tracer profiles show strong gradients at the extratropical tropopause, suggesting that vertical (cross-isentropic) mixing is reduced above the tropopause. Pronounced meridional gradients in the tracer mixing ratios are found on potential temperature surfaces in the LMS. This suggests strongly reduced mixing along isentropes. Concurrent large gradients in static stability in the vertical direction, and of PV in the meridional direction, suggest the presence of a mixing barrier. Seasonal cycles were found in the correlation slopes O 3 / N 2 O and NO y / N 2 O well above the tropopause. Absolute slope values are smallest in spring indicating chemically aged stratospheric air originating from high altitudes and latitudes. Larger values were measured in summer and autumn suggesting that a substantial fraction of air takes a "short-cut" from the tropical tropopause region into the extratropical LMS. The seasonal change in the composition of the LMS has direct implications for the ozone chemistry in this reCorrespondence to: M. I. Hegglin (michaela@atmosp.physics.utoronto.ca) gion. Comparisons of measured NO with the critical NO value at which net ozone production changes from negative to positive, imply ozone production up to 20 K above the local tropopause in spring, up to 30 K in summer, and up to 40 K in autumn. Above these heights, and in winter, net ozone production is negative.

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“…Most of the contrails form in the upper troposphere or lower stratosphere where strong winds, shear and stratification prevail (Birner et al, 2002;Houchi et al, 2010;Manney et al, 2011). Shear production of turbulence is driven by total shear S T , while plume distortion follows the vertical shear S of the plume-normal velocity,…”

Section: The Turbulence Modelmentioning

confidence: 99%

A contrail cirrus prediction model

2012

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Abstract.A new model to simulate and predict the properties of a large ensemble of contrails as a function of given air traffic and meteorology is described. The model is designed for approximate prediction of contrail cirrus cover and analysis of contrail climate impact, e.g. within aviation system optimization processes. The model simulates the full contrail life-cycle. Contrail segments form between waypoints of individual aircraft tracks in sufficiently cold and humid air masses. The initial contrail properties depend on the aircraft. The advection and evolution of the contrails is followed with a Lagrangian Gaussian plume model. Mixing and bulk cloud processes are treated quasi analytically or with an effective numerical scheme. Contrails disappear when the bulk ice content is sublimating or precipitating. The model has been implemented in a "Contrail Cirrus Prediction Tool" (CoCiP). This paper describes the model assumptions, the equations for individual contrails, and the analysis-method for contrailcirrus cover derived from the optical depth of the ensemble of contrails and background cirrus. The model has been applied for a case study and compared to the results of other models and in-situ contrail measurements. The simple model reproduces a considerable part of observed contrail properties. Mid-aged contrails provide the largest contributions to the product of optical depth and contrail width, important for climate impact.

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How sharp is the tropopause at midlatitudes?

Cited by 171 publications

References 18 publications

Quantifying pollution transport from the Asian monsoon anticyclone into the lower stratosphere

Quantifying pollution transport from the Asian monsoon anticyclone into the lower stratosphere

Measurements of NO, NO<sub>y</sub>, N<sub>2</sub>O, and O<sub>3</sub> during SPURT: implications for transport and chemistry in the lowermost stratosphere

A contrail cirrus prediction model

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How sharp is the tropopause at midlatitudes?

Cited by 171 publications

References 18 publications

Quantifying pollution transport from the Asian monsoon anticyclone into the lower stratosphere

Quantifying pollution transport from the Asian monsoon anticyclone into the lower stratosphere

Measurements of NO, NO&lt;sub&gt;y&lt;/sub&gt;, N&lt;sub&gt;2&lt;/sub&gt;O, and O&lt;sub&gt;3&lt;/sub&gt; during SPURT: implications for transport and chemistry in the lowermost stratosphere

A contrail cirrus prediction model

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Measurements of NO, NO<sub>y</sub>, N<sub>2</sub>O, and O<sub>3</sub> during SPURT: implications for transport and chemistry in the lowermost stratosphere