Effective diffusivity as a diagnostic of atmospheric transport: 2. Troposphere and lower stratosphere

Haynes, P. H.; Shuckburgh, Emily

doi:10.1029/2000jd900092

Cited by 225 publications

(368 citation statements)

References 24 publications

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“…Indeed, using contour advection, Kowol-Santen [1998] found that the PV contours at the tropopause grow much slower than the PV contours both in the troposphere and in the stratosphere. This is in agreement with Haynes and Shuckburgh [2000], who applied a diagnostic introduced by Nakamura [1996]. They even proposed that the minimum in effective diffusivity at the tropopause level can be used for an alternative definition of the tropopause.…”

Section: Ste In the Extratropicssupporting

confidence: 85%

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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Section: Ste In the Extratropicssupporting

confidence: 85%

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

et al. 2003

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“…2). The general aspects are consistent with the effective diffusivity derived from passive tracer calculations (Haynes and Schuckburgh 2000). Kyy is substantial in the winter hemisphere at mid-latitudes, particularly outside the polar vortex in the stratosphere, and is also remarkable in the mid-latitudes troposphere with relation to the breaking of the baroclinic waves.…”

Section: Space-time Distribution Of Kyysupporting

confidence: 85%

Isentropic Diffusion Coefficient Derived from Chemical Constituent Data

Miyazaki

Iwasaki

2009

SOLA

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The isentropic diffusion coefficient (Kyy) characterizes large-scale atmospheric mixing processes. Chemical constituents allow us to directly estimate Kyy from observational data sets. This study investigates general aspects of the mixing processes from a systematic survey of the common features and constituent dependency of Kyy . Analysis with chemical constituent data obtained from a global chemical transport model demonstrates that long-lived species whose chemical lifetimes ( ) are several years long have very common seasonal and latitudinal variations of Kyy, which is considered to represent actual atmospheric mixing. Kyy, estimated from chemical species with shorter than several weeks, becomes considerably greater than that from long-lived species and indicates the significance of nonlinear effects. Meridional transport analysis also investigates that shorter results in greater spatial constituent variations and larger contributions of the eddy compared to the mean motions in the constituent transport flux. IntroductionLarge-scale isentropic eddy mixing plays an important role in determining constituent distribution (e.g., Plumb 2007). Isentropic mixing due to planetary wave breaking causes significant mixing in the stratospheric "surf zone" (McIntyre and Palmer 1984), while synopticscale disturbance, caused by baroclinic waves, disperses air along isentropes in the extratropical troposphere (e.g., Kida 1980). These mixings increase the constituent gradients over isentropic surfaces at the edge of the mixing region, but decrease them within the mixing region (e.g., Juckes and McIntyre 1987;Miyazaki and Iwasaki 2008).The eddy diffusion coefficient has been widely used to characterize mixing processes. The adiabatic component of the eddy diffusion coefficient, Kyy, reflects wave motions of the atmosphere since the eddy transport is almost parallel to the isentropic surface, particularly in the stratosphere. Kyy has also been used to parameterize the Rossby wave mixing in two-dimensional chemical transport models (CTMs, e.g., Garcia and Solomon 1983). Kyy is generally diagnosed using the potential vorticity (PV) flux (Newman et al. 1988) since the PV acts as a conservative passive tracer for adiabatic and frictionless flow. Magnitude of the diffusion coefficient also can be measured by ideal passive tracer calculations. However, it is difficult to directly estimate the PV flux from any observation, and calculations of the PV flux or an ideal passive tracer can suffer from numerical error. Instead of using the PV flux or the ideal passive tracer, some studies have used the distributions of specific long-lived species such as N2O and CH4 to investigate atmospheric transport and mixing processes (e.g., Lingenfelser and Grose 2002). Although long-lived species allow us to directly estimate Kyy from observational data sets, the sensitivity of Kyy to chemical species has not been clearly understood.In this study, we investigate the common features and constituent dependency of Kyy to facilitate understandin...

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“…Transport processes in the troposphere play a key role for the distribution of water vapor. In the vicinity of the tropopause and in particular across the subtropical jet stream, large gradients of water vapor exist due to the barrier effects of the tropopause (Haynes and Shuckburgh, 2000; Pan et al, 2004;Flentje et al, 2007;Kunz et al, 2011b). In the tropics, the low temperatures at the tropopause lead to strong freeze-drying (Jensen and Pfister, 2004;Fueglistaler et al, 2009;Schiller et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Comparison of Fast In situ Stratospheric Hygrometer (FISH) measurements of water vapor in the upper troposphere and lower stratosphere (UTLS) with ECMWF (re)analysis data

Kunz

Spelten²,

Konopka³

et al. 2014

Atmos. Chem. Phys.

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Abstract. An evaluation of water vapor in the upper troposphere and lower stratosphere (UTLS) of the ERA-Interim, the global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), is presented. Water vapor measurements are derived from the Fast In situ Stratospheric Hygrometer (FISH) during a large set of airborne measurement campaigns from 2001 to 2011 in the tropics, midlatitudes and polar regions, covering isentropic layers from 300 to 400 K (5-18 km).The comparison shows around 87 % of the reanalysis data are within a factor of 2 of the FISH water vapor measurements and around 30 % have a nearly perfect agreement with an over-and underestimation lower than 10 %. Nevertheless, strong over-and underestimations can occur both in the UT and LS, in particularly in the extratropical LS and in the tropical UT, where severe over-and underestimations up to 10 times can occur.The analysis data from the evolving ECMWF operational system is also evaluated, and the FISH measurements are divided into time periods representing different cycles of the Integrated Forecast System (IFS). The agreement with FISH improves over the time, in particular when comparing water vapor fields for time periods before 2004 and after 2010. It appears that influences of tropical tropospheric and extratropical UTLS processes, e.g., convective and quasiisentropic exchange processes, are particularly challenging for the simulation of the UTLS water vapor distribution. Both the reanalysis and operational analysis data show the tendency of an overestimation of low water vapor mixing ratio ( 10 ppmv) in the LS and underestimation of high water vapor mixing ratio ( 300 ppmv) in the UT.

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Effective diffusivity as a diagnostic of atmospheric transport: 2. Troposphere and lower stratosphere

Cited by 225 publications

References 24 publications

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

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

Isentropic Diffusion Coefficient Derived from Chemical Constituent Data

Comparison of Fast In situ Stratospheric Hygrometer (FISH) measurements of water vapor in the upper troposphere and lower stratosphere (UTLS) with ECMWF (re)analysis data

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