Effects of fluid‐dynamical stirring and mixing on the deactivation of stratospheric chlorine

Tan, David; Haynes, P. H.; MacKenzie, A. R.; Pyle, J. A.

doi:10.1029/97jd02495

Cited by 63 publications

(96 citation statements)

References 55 publications

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“…These values are consistent with the eddy diffusion values that have been used for global zonal-mean 2-D chemical transport models (Newman et al 1986;Plumb and Mahlman 1987;Yang et al 1990;Haynes and Shuckburgh 2000). The values are also close to 2:59 Â 10 5 m 2 s À1 , the effective horizontal diffusivity that gives a diffusion-limited horizontal scale length of 300 km (Tan et al 1998). However, the values are much larger than 10 3 m 2 s À1 , an effective horizontal diffusivity in the lower stratosphere estimated by aircraft observations of chemical mixing (Waugh et al 1997).…”

Section: Discussionsupporting

confidence: 86%

Low-N2O Air Masses after the Breakdown of the Arctic Polar Vortex in 1997 Simulated by the CCSR/NIES Nudging CTM.

Akiyoshi

Sugata

Sugita

et al. 2002

Journal of the Meteorological Society of Japan

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Low-concentration N 2 O regions in high latitudes of the lower stratosphere were observed by the Improved Limb Atmospheric Spectrometer (ILAS) for one and half months after the Arctic vortex breakdown in May 1997. A new Chemical Transport Model (CTM), referred to as the CCSR/NIES nudging CTM, has been developed, and used to simulate these low-N 2 O air masses. The simulation shows that one of the air masses had a horizontal scale of 1,000-1,500 km, and remained at high latitudes for 1.5-2.5 months after the polar vortex breakdown. The simulation also shows that the contrast between the N 2 O concentration of the low-N 2 O air mass and that of the ambient air was diminished when the air mass was stretched, which had a considerable influence on the duration of the air mass. From the duration, and the horizontal scale simulated by the CTM, an estimate was made of the horizontal eddy diffusivity after the polar vortex breakdown.

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Section: Discussionsupporting

confidence: 86%

Low-N2O Air Masses after the Breakdown of the Arctic Polar Vortex in 1997 Simulated by the CCSR/NIES Nudging CTM.

Akiyoshi

Sugata

Sugita

et al. 2002

Journal of the Meteorological Society of Japan

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“…If the composition of two air masses is very different, some chemical reactions could occur only at the interface between them. Examples include chlorine activation at the edge of the Antarctic stratospheric polar vortex [Prather and Jaffe, 1990;Edouard et al, 1996;Tan et al, 1998] and OH chemistry near the tropopause [Esler et al, 2001]. However, signatures of special interfacial chemistry were not observed in the case discussed in this paper and thus all significant chemistry is assumed to occur within air masses (since the volume of the interfacial regions is very small).…”

Section: Introductionmentioning

confidence: 84%

Estimating photochemically produced ozone throughout a domain using flight data and a Lagrangian model

et al. 2003

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[1] Can airborne observations from infrequent flights be used to infer the budget of ozone in the upper troposphere with any degree of certainty or representativeness? Fluctuations in ozone mixing ratio observed along flights are dominated by flying between air masses with distinct origins, rather than the recent chemical transformation that has occurred within those air masses. Reverse domain filling trajectories arriving on a high-resolution three-dimensional grid (RDF3D) can simulate air mass structure accurately by coloring arrival grid points with specific humidity (q) from the origin of each trajectory. Typical displacement errors in tracer filaments are only about 30 km, but the associated phase errors greatly reduce the correlations between airborne observations of long-lived chemicals and their model simulations. However, the comparison can be vastly improved if equivalent potential temperature (q e ) and specific humidity are used as coordinates to label air masses. Both properties are approximately conserved following unsaturated air and serve as good markers of air masses even if the air is saturated or mixing takes place. Ozone simulations from a Lagrangian model are evaluated against observations in thermodynamic coordinates, factoring out many of the transport phase errors. The proportion of the atmosphere occupied by different chemical air masses is estimated by using RDF3D trajectories to simulate the distributions of q and q e and then assuming that chemical composition is homogeneous within air masses, each with characteristic (q, q e ). Mass density in thermodynamic coordinates is used to weight the modeled ozone transformation and error in concentration (calculated along flight tracks) to estimate photochemically produced ozone throughout a volume encompassing the flights.

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“…Breaking of planetary waves is characterized by rapid and irreversible deformation of material contours. The contours form tongues that become longer and thinner with time, more and more fine-scaled, until the material is diffused into its surroundings (Tan et al, 1998). The "surf-zone" is bounded on its equatorward edge by a barrier to mixing with tropical air.…”

Section: Introductionmentioning

confidence: 99%

Trends and variability in stratospheric mixing: 1979–2005

Garny¹,

Bodeker

Dameris³

2007

Atmos. Chem. Phys.

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Abstract. Changes in climate are likely to drive changes in stratospheric mixing with associated implications for changes in transport of ozone from tropical source regions to higher latitudes, transport of water vapour and source gas degradation products from the tropical tropopause layer into the mid-latitude lower stratosphere, and changes in the meridional distribution of long-lived trace gases. To diagnose long-term changes in stratospheric mixing, global monthly fields of Lyapunov exponents were calculated on the 450 K, 550 K, and 650 K isentropic surfaces by applying a trajectory model to wind fields from NCEP/NCAR reanalyses over the period 1979 to 2005. Potential underlying geophysical drivers of trends and variability in these mixing fields were investigated by applying a least squares regression model, which included basis functions for a mean annual cycle, seasonally dependent linear trends, the quasibiennial oscillation (QBO), the solar cycle, and the El Niño Southern Oscillation (ENSO), to zonal mean time series of the Lyapunov exponents.Long-term positive trends in mixing are apparent over southern middle to high latitudes at 450 K through most of the year, while negative trends over southern high latitudes are apparent at 650 K from May to August. Wintertime negative trends in mixing over northern mid-latitudes are apparent at 550 K and 650 K. Over low latitudes, within 40 • of the equator, the QBO exerts a strong influence on mixing at all three analysis levels. This QBO influence is strongly modulated by the annual cycle and shows a phase shift across the subtropical mixing barrier. Solar cycle and ENSO influences on mixing are generally not significant. The diagnosed long-term changes in mixing should aid the interpretation of trends in stratospheric trace gases.

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Effects of fluid‐dynamical stirring and mixing on the deactivation of stratospheric chlorine

Cited by 63 publications

References 55 publications

Low-N2O Air Masses after the Breakdown of the Arctic Polar Vortex in 1997 Simulated by the CCSR/NIES Nudging CTM.

Low-N2O Air Masses after the Breakdown of the Arctic Polar Vortex in 1997 Simulated by the CCSR/NIES Nudging CTM.

Estimating photochemically produced ozone throughout a domain using flight data and a Lagrangian model

Trends and variability in stratospheric mixing: 1979–2005

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