Properties of the Arctic tropopause

HIGHWOOD, EJ; HOSKINS, BJ; BERRISFORD, P

doi:10.1256/smsqj.56514

Cited by 26 publications

(21 citation statements)

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“…However, this is primarily a reflection of the frequently low and variable polar tropopause, which is sometimes even poorly defined [Highwood et al, 2000;Zängl and Hoinka, 2001]. When looking at the PV > 4 tracer, which excludes air sourced in the whole TPR, deep STT in the lowest 3km of the troposphere is seen to be concentrated in midlatitudes and subtropics, even on very short timescales.…”

Section: Stratosphere-to-troposphere Transportmentioning

confidence: 99%

A 15‐year climatology of stratosphere–troposphere exchange with a Lagrangian particle dispersion model 2. Mean climate and seasonal variability

et al. 2003

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[1] A comprehensive climatology of stratosphere-troposphere exchange (STE), based on 15 years of ECMWF global atmospheric reanalysis data for the period 1979-1993, has been carried out with a specially tuned version of the Lagrangian particle dispersion model, FLEXPART. The typical amplitudes, timescales, seasonality, and spatial variability of STE revealed in the climatology are described. Mean distributions of STE air masses of various ages relate to aspects of the global circulation, while anomaly patterns, such as the North Atlantic Oscillation (NAO) and El Niño, influence STE variability. Characteristic differences are seen between shallow STE flows remaining within the tropopause region (TPR) and deep STE transports, which include cases of stratospheric air reaching the lower troposphere. Unlike for shallow STE events, such deep intrusions show a distinct winter maximum. This subsequently impacts on the seasonal cycle of stratospheric ozone in the troposphere, which thus depends on altitude but also on the decay timescale of ozone. A much broader view of STE than has previously been possible is enabled. The inherent scope of STE is far wider than a discussion of cross-tropopause fluxes alone. Indeed, more than 90% of all cross-tropopause flows return within 6 hours. It is thus crucial to distinguish between short-term STE, during which air parcels rapidly recross the tropopause, and deep and/or long-term STE, in which air parcels have subsequently long residence times away from their source.

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Section: Stratosphere-to-troposphere Transportmentioning

confidence: 99%

A 15‐year climatology of stratosphere–troposphere exchange with a Lagrangian particle dispersion model 2. Mean climate and seasonal variability

et al. 2003

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“…However, substantial difficulties remain in determining the height of the tropopause, particularly at polar latitudes [Highwood et al, 2000;Zängl and Hoinka, 2001]. A certain degree of subjectivity as to which definition is used remains, and the associated sensitivity can be substantial in cases when the tropopause is less sharp than normal [Wirth, 2000;Zängl and Hoinka, 2001].…”

Section: Tropopausementioning

confidence: 99%

“…However, the stratospheric cooling resulting from stratospheric O 3 losses also reduces the vertical stability of the upper troposphere/ lower stratosphere (UTLS) system [Rind and Lonergan, 1995]. Highwood et al [2000] related an observed increase in Arctic tropopause heights to stratospheric cooling.…”

Section: Tropopausementioning

confidence: 99%

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Stratosphere‐troposphere exchange: A review, and what we have learned from STACCATO

et al. 2003

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[1] This paper provides a review of stratosphere-troposphere exchange (STE), with a focus on processes in the extratropics. It also addresses the relevance of STE for tropospheric chemistry, particularly its influence on the oxidative capacity of the troposphere. After summarizing the current state of knowledge, the objectives of the project Influence of Stratosphere-Troposphere Exchange in a Changing Climate on Atmospheric Transport and Oxidation Capacity (STACCATO), recently funded by the European Union, are outlined. Several papers in this Journal of Geophysical ResearchAtmospheres special section present the results of this project, of which this paper gives an overview. STACCATO developed a new concept of STE in the extratropics, explored the capacities of different types of methods and models to diagnose STE, and identified their various strengths and shortcomings. Extensive measurements were made in central Europe, including the first monitoring over an extended period of time of beryllium-10 ( 10 Be), to provide a suitable database for case studies of stratospheric intrusions and for model validation. Photochemical models were used to examine the impact of STE on tropospheric ozone and the oxidizing capacity of the troposphere. Studies of the present interannual variability of STE and projections into the future were made using reanalysis data and climate models.

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“…According to several studies (e.g. Cai and Ren, 2007;Ambaum and Hoskins, 2002;Highwood et al, 2000), the high-latitude tropopause tends to rise during the positive phase of the AO. Therefore, the response of the tropopause to the AO is of the wrong sign to explain increases in UTWV during the negative phase of the AO.…”

Section: Proposed Mechanismsmentioning

confidence: 98%

Upper tropospheric water vapour variability at high latitudes – Part 1: Influence of the annular modes

et al. 2016

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Abstract. Seasonal and monthly zonal medians of water vapour in the upper troposphere and lower stratosphere (UTLS) are calculated for both Atmospheric Chemistry Experiment (ACE) instruments for the northern and southern high-latitude regions (60-90 • N and 60-90 • S). Chosen for the purpose of observing high-latitude processes, the ACE orbit provides sampling of both regions in 8 of 12 months of the year, with coverage in all seasons. The ACE water vapour sensors, namely MAESTRO (Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) and the Fourier Transform Spectrometer (ACE-FTS) are currently the only satellite instruments that can probe from the lower stratosphere down to the midtroposphere to study the vertical profile of the response of UTLS water vapour to the annular modes.The Arctic oscillation (AO), also known as the northern annular mode (NAM), explains 64 % (r = −0.80) of the monthly variability in water vapour at northern high latitudes observed by ACE-MAESTRO between 5 and 7 km using only winter months (January to March, 2004March, -2013. Using a seasonal time step and all seasons, 45 % of the variability is explained by the AO at 6.5 ± 0.5 km, similar to the 46 % value obtained for southern high latitudes at 7.5 ± 0.5 km explained by the Antarctic oscillation or southern annular mode (SAM). A large negative AO event in March 2013 produced the largest relative water vapour anomaly at 5.5 km (+70 %) over the ACE record. A similarly large event in the 2010 boreal winter, which was the largest negative AO event in the record , led to > 50 % increases in water vapour observed by MAESTRO and ACE-FTS at 7.5 km.

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Properties of the Arctic tropopause

Cited by 26 publications

References 0 publications

A 15‐year climatology of stratosphere–troposphere exchange with a Lagrangian particle dispersion model 2. Mean climate and seasonal variability

A 15‐year climatology of stratosphere–troposphere exchange with a Lagrangian particle dispersion model 2. Mean climate and seasonal variability

Stratosphere‐troposphere exchange: A review, and what we have learned from STACCATO

Upper tropospheric water vapour variability at high latitudes – Part 1: Influence of the annular modes

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