Transport of Trace Constituents in the Stratosphere

Mahlman, J. D.; Andrews, D. G.; Hartmann, Dennis L.; Matsuno, Taisuke; MURGATROYD, RJ

doi:10.1007/978-94-009-6390-0_21

Cited by 39 publications

(5 citation statements)

References 113 publications

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“…The data from the 1988 and 1989 and (3) a vertical displacement of some 10 km. A proper analysis of the contributions of these processes is beyond the scope of this paper, but the problem is an important issue for the interpretation of measurements of stratospheric composition [Andrews et al, 1987;Mahlman et al, 1984].…”

Section: Resultsmentioning

confidence: 99%

In situ measurement of water vapor in the stratosphere with a cryogenically cooled Lyman‐alpha hygrometer

Schwab¹,

Weinstock²,

Nee³

et al. 1990

J. Geophys. Res.

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In situ measurements of water vapor in the stratosphere with a new instrument are reported.The instrument has been designed to observe daytime water vapor from a multi-instrument balloon gondola that simultaneously measures free radicals such as OH, HOz, and Oa in the stratosphere up to 40 km. Lyman-alpha photofragment fluorescence is used to measure water molecules in a flowing sample of ambient air. Outgassing from the interior walls of the instrument is avoided by cooling the walls with liquid nitrogen to a temperature near or below the dewpoint of the environment and by drawing air through the instrument with a fan. A brief description of the instrument is given, followed by the results of the first four balloon flights. Because frost formation in the scattering chamber resulted in a large and variable background, the data from July 15, 1987, have a relatively modest signal-to-noise ratio. The measured mixing ratio for this flight varies from 3.0-5.5 ppmv over the altitude range of 17-34 kin. Adjustments in the cooling protocol for the flights of July 6, 1988, July 28, and August 25, 1989, result in a much higher signal-to-noise ratio. Profiles from these three flights are similar to, but somewhat higher, than the 1987' profile. The July 1988 and August 1989 profiles exhibit the highest mixing ratios, reaching peak values of about 6.5 ppmv near 35 kin. Implications of these four measurements are discussed, as are the issues of short-and long-term variability of stratospheric water vapor. to a secular trend of increasing water in the stratosphere [Ehhalt, 1986; Blake and Rowland, 1988]. The role of water vapor in the stratosphere takes on added significance in light of the dramatic ozone depletion over Antarctica and the severely perturbed chemical environment of the polar vortex regions [Anderson et al., 1989; Brune et al., 1990; Salawitch et al., 1990]. In particular, the formation of polar stratospherlc clouds depends upon the water vapor mixing ratio as well as the temperature. Water vapor concentration and trends should be reflected in the frequency, extent, and duration of PSCs and, by extension, in the perturbed nitrogen and chlorine chemistry observed in the polar stratosphere during the winter-spring transition. The generally accepted morphology of stratospheric water is based on the LIMS measurements from the NIMBUS 7 satellite [Russell et al., 1984; Remsberg et al., 1984], but typically little regard is given to the trend in water when these measurements are cited and used. While the LIMS H20 data have been subject to careful analysis and validated by a number of in situ profile measurements, it is extremely difficult to assess impartially the accuracy of satellite profile measurements. In the case of ozone measurements, there has been an ongoing systematic difference between in situ and satellite profile measurements [Hilsenrath et al., 1986; Robbins, 1987]. In particular, it should be stressed that satellite measurements are remote measurements, and yield water vapor mixing ratios only after exten...

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Section: Resultsmentioning

confidence: 99%

In situ measurement of water vapor in the stratosphere with a cryogenically cooled Lyman‐alpha hygrometer

Schwab¹,

Weinstock²,

Nee³

et al. 1990

J. Geophys. Res.

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“…Indeed, they suggest that in the winter lower stratosphere this contribution, which is caused by anomalous diabatic heating and cooling directly associated with the eddies, is numerically comparable to that from the mean circulation itself. Correspondingly, there may also be a dispersive effect of the eddies across, as well as along, isentropic surfaces [Mahlman et al, 1984]. Evidence from model simulations suggests that such dispersion has an effective vertical diffusion coefficient K z of no greater than a few times 10-• m 2 s-• [Plumb and Mahlman, 1987].…”

Section: Of Exchange: Application To the Real Atmospherementioning

confidence: 99%

Stratosphere‐troposphere exchange

Holton¹,

Haynes²,

McIntyre³

et al. 1995

Reviews of Geophysics

2,430

2,200

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In the past, studies of stratosphere-tropo-sphere exchange of mass and chemical species have mainly emphasized the synoptic-and small-scale mechanisms of exchange. This review, however, includes also the global-scale aspects of exchange, such as the transport across an isentropic surface (potential temperature about 380 K) that in the tropics lies just above the tropopause, near the 100-hPa pressure level. Such a surface divides the stratosphere into an "over-world" and an extratropical "lowermost strato-sphere" that for transport purposes need to be sharply distinguished. This approach places stratosphere-tro-posphere exchange in the framework of the general circulation and helps to clarify the roles of the different mechanisms involved and the interplay between large and small scales. The role of waves and eddies in the extratropical overworld is emphasized. There, wave-induced forces drive a kind of global-scale extratropi-cal "fluid-dynamical suction pump," which withdraws air upward and poleward from the tropical lower stratosphere and pushes it poleward and downward into the extratropical troposphere. The resulting global scale circulation drives the stratosphere away from radiative equilibrium conditions. Wave-induced forces may be considered to exert a nonlocal control, mainly downward in the extratropics but reaching laterally into the tropics, over the transport of mass across lower stratospheric isentropic surfaces. This mass transport is for many purposes a useful measure of global-scale stratosphere-troposphere exchange, especially on seasonal or longer timescales. Because the strongest wave-induced forces occur in the northern hemisphere winter season, the exchange rate is also a maximum at that season. The global exchange rate is not determined by details of near-tropopause phenomena such as penetrative cumulus convection or small-scale mixing associated with upper level fronts and cyclones. These smaller-scale processes must be considered , however, in order to understand the finer details of exchange. Moist convection appears to play an important role in the tropics in accounting for the extreme dehydration of air entering the stratosphere. Stratospheric air finds its way back into the tropo-sphere through a vast variety of irreversible eddy exchange phenomena, including tropopause folding and the formation of so-called tropical upper tropo-spheric troughs and consequent irreversible exchange. General circulation models are able to simulate the mean global-scale mass exchange and its seasonal cycle but are not able to properly resolve the tropical dehydration process. Two-dimensional (height-latitude) models commonly used for assessment of human impact on the ozone layer include representation of stratosphere-troposphere exchange that is adequate to allow reasonable simulation of photochemical processes occurring in the overworld. However, for assessing changes in the lowermost stratosphere, the strong longitudinal asymmetries in stratosphere-troposphere exchange render current two-dimensional m...

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“…the zonal mean wind, 0* and ½* are the meridional and vertical components of the residual circulation, f is the Coriolis parameter, a is the radius of the Earth, 0 is the latitude angle, and • is the zonal mean potential vorticity. The strength of the diabatic circulation depends on the internal friction and the eddy diffusion, as these processes provide the meridional coupling necessary to maintain a meridional circulation [cf Mahlman et al, 1984]…”

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confidence: 99%

Response of an interactive two‐dimensional model to ozone changes: An estimate of the radiative dynamical feedback effect

Schneider

Ko²

1990

J. Geophys. Res.

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The response of an interactive two‐dimensional model of the stratosphere to increased chemical removal of ozone is studied. A simplified ozone chemistry model was used. The radiative dynamical feedback in the model leads to a recovery of about one third of the calculated ozone decrease at high altitudes, and to about one sixth of the predicted losses in the column densities at high latitudes when compared with predictions by a model with fixed temperature and circulation. The model response is analyzed with the aid of stationary linear models for the diabatic circulation. A simple interpretation of the adjustment of dynamical quantities is obtained by comparing the global mean and the differential solar heating rates derived from perturbed and unperturbed ozone distributions. The feedback effect can be qualitatively described as (1) an adjustment of the global mean temperature in response to global mean solar heating changes and (2) an approximately linear response in all other dynamical variables, proportional to the change in the differential heating. The exact magnitude of the feedback effect on ozone in our model is a function of the simplified treatment of the photochemistry; however, we believe that the structure of the ozone changes and the interpretation of the dynamical response is independent of the details of the chemistry. Our model results further show an increase in the predicted high‐latitude ozone depletion with decreasing eddy diffusion in the model stratosphere. This effect can be explained by the reduction of advective and diffusive horizontal transport from the tropics to the polar region in the lower stratosphere with decreasing eddy diffusion.

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Transport of Trace Constituents in the Stratosphere

Cited by 39 publications

References 113 publications

In situ measurement of water vapor in the stratosphere with a cryogenically cooled Lyman‐alpha hygrometer

In situ measurement of water vapor in the stratosphere with a cryogenically cooled Lyman‐alpha hygrometer

Stratosphere‐troposphere exchange

Response of an interactive two‐dimensional model to ozone changes: An estimate of the radiative dynamical feedback effect

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