Stratospheric transport from the tropics to middle latitudes by planetary-wave mixing

Randel, William J.; Gille, J. C.; Roche, A. E.; Kumer, J. B.; Mergenthaler, J. L.; Waters, J. W.; Fishbein, Evan; Lahoz, W. A.

doi:10.1038/365533a0

Cited by 143 publications

(97 citation statements)

References 22 publications

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“…1 and 4 show the interaction between the annual variations in the BDC and the QBO acting on the ozone and temperature concentrations. The BDC upwelling is stronger during the Northern Hemisphere winter due to stratospheric wave driving (Haynes et al, 1991;Waugh, 1993;Randel et al, 1993;Schoeberl et al, 2008). In the case where the QBO and the BDC are in phase, the QBO signal appears to descend to the tropopause, as positive ozone anomalies of both systems merge, as previously noted by Gray and Dunkerton (1990).…”

Section: Annual Cycles In Ozone and Temperaturementioning

confidence: 60%

The Quasi-biennial Oscillation and annual variations in tropical ozone from SHADOZ and HALOE

Witte,

Schoeberl,

Douglass

et al. 2008

Atmos. Chem. Phys.

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Abstract. We examine the tropical ozone mixing ratio perturbation fields generated from a monthly ozone climatology using 1998 to 2006 ozonesonde data from the Southern Hemisphere Additional Ozonesondes (SHADOZ) network and the 13-year satellite record from 1993 to 2005 obtained from the Halogen Occultation Experiment (HALOE). The long time series and high vertical resolution of the ozone and temperature profiles from the SHADOZ sondes coupled with good tropical coverage north and south of the equator gives a detailed picture of the ozone structure in the lowermost stratosphere down through the tropopause where the picture obtained from HALOE measurements is blurred by coarse vertical resolution. Ozone perturbations respond to annual variations in the Brewer-Dobson Circulation (BDC) in the region just above the cold-point tropopause to around 20 km. Annual cycles in ozone and temperature are well correlated. Above 20 km, ozone and temperature perturbations are dominated by the Quasi-biennial Oscillation (QBO). Both satellite and sonde records show good agreement between positive and negative ozone mixing ratio anomalies and alternating QBO westerly and easterly wind shears from the Singapore rawinsondes with a mean periodicity of 26 months for SHADOZ and 25 months for HALOE. There is a temporal offset of one to three months with the QBO wind shear ahead of the ozone anomaly field. The meridional length scales for the annual cycle and the QBO, obtained using the temperature anomalies and wind shears in the thermal wind equation, compare well with theoretical calculations.

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Section: Annual Cycles In Ozone and Temperaturementioning

confidence: 60%

The Quasi-biennial Oscillation and annual variations in tropical ozone from SHADOZ and HALOE

Witte,

Schoeberl,

Douglass

et al. 2008

Atmos. Chem. Phys.

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“…The distribution can reveal the structure of the general circulation of the middle atmosphere. The apparent seasonal and meridional variations of the N20 mixing ratio are well illustrated by Jones and Pyle [1984], who analyzed N20 monthly mean measurements from the Nimbus 7 stratospheric and me- [Polvani et al, 1995], but the incorporation of tropical air into midlatitudes during wave activity associated with stratospheric warming events, which was discussed in section 3, has been noted in the trace gas observations [Randel et al, 1993] An important characteristic of the mean distribution, which is seen in both the model and the observations, is its asymmetry about the equator. The maximum of the mixing ratio at each level has a latitudinal tilt with height from the lower to the upper stratosphere.…”

Section: Climatological Distribution Of Nzomentioning

confidence: 84%

N₂O transport in a three‐dimensional model driven by U. K. Meteorological Office winds

Lou¹,

Alyea²,

Cunnold³

et al. 1997

J. Geophys. Res.

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Abstract. A three-dimensional spectral chemical transport model truncated at T21 is employed to simulate N20 transport. The wind and vertical motion fields are taken from the U.K. Meteorological Office four-dimensional assimilation data set. UARS cryogenic limb array etalon spectrometer (CLAES) N20 measurements are used to initialize the model in late August 1992. Model results are shown to simulate the CLAES measurements quite well over the first few months: N20 variability is similar at extratropical latitudes in the southern hemisphere over the period September 2-17, 1992, at 4.6 and 10 mbar, and there is good agreement in the synoptic maps of minor warmings during this period. Prior to a large warming event on September 30, minor stratospheric warmings are shown to produce negligible changes in the vortex below 4.6 mbar, but considerable mixing of air from the vortex edge and subtropical air is indicated. This results in a steepening of the N20 gradient at the vortex edge. During a warming event when the vortex center moves away from the pole, downward transport by the residual circulation can be large. This is offset by eddy transport effects, but these terms reverse during the recovery from the warming. From September 2 to 17, there is evidence of continuous mixing at midlatitudes at 4.6 mbar in contrast to more discontinuous, warmingassociated mixing at 10 mbar. The breakup of the vortex is initiated by the September 30 warming, and a warming on October 13 has a strong influence on the breakup. The breakup propagates downward. The climatological distribution of N20 in the tropics follows the seasonal variation of the solar radiation with a maximum, which is determined by the strength of the upward residual motion, shifting towards the summer hemisphere by 10ø-15 ø latitude. The surf zone in both the model and the observations at the middle latitudes is well defined, but the gradients of N20 at the edge of the tropics and at the edge of the vortex are smaller in the model than in the observations. This is probably being caused by excessive mixing in the model.

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“…Observational evidence of narrow tongues of tropical air transported into mid-latitudes in the middle stratosphere was shown with low resolution satellite measurements (Leovy et al, 1985;Randel et al, 1993;Manney et al, 1993;Trepte et al, 1993). Rossby wave breaking events at the edge of the tropics and a shift of the polar vortex towards lower latitudes seem to be linked with tropical air extrusions into midlatitudes (Chen et al, 1994;Waugh, 1996).…”

Section: Introductionmentioning

confidence: 93%

Climatological features of stratospheric streamers in the FUB-CMAM with increased horizontal resolution

Krüger

Langematz²,

Grenfell³

et al. 2005

Atmos. Chem. Phys.

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Abstract. The purpose of this study is to investigate horizontal transport processes in the winter stratosphere using data with a resolution relevant for chemistry and climate modeling. For this reason the Freie Universität Berlin Climate Middle Atmosphere Model (FUB-CMAM) with its model top at 83 km altitude, increased horizontal resolution T42 and the semi-Lagrangian transport scheme for advecting passive tracers is used.A new approach of this paper is the classification of specific transport phenomena within the stratosphere into tropical-subtropical streamers (e.g. Offermann et al., 1999) and polar vortex extrusions hereafter called polar vortex streamers. To investigate the role played by these largescale structures on the inter-annual and seasonal variability of transport processes in northern mid-latitudes, the global occurrence of such streamers was calculated based on a 10-year model climatology, concentrating on the existence of the Arctic polar vortex. For the identification and counting of streamers, the new method of zonal anomaly was chosen. The analysis of the months October-May yielded a maximum occurrence of tropical-subtropical streamers during Arctic winter and spring in the middle and upper stratosphere. Synoptic maps revealed highest intensities in the subtropics over East Asia with a secondary maximum over the Atlantic in the northern hemisphere. Furthermore, tropicalsubtropical streamers exhibited a higher occurrence than polar vortex streamers, indicating that the subtropical barrier is more permeable than the polar vortex barrier (edge) in the model, which is in good correspondence with observations (e.g. Plumb, 2002;Neu et al., 2003). Interesting for the total ozone decrease in mid-latitudes is the consideration of the lower stratosphere for tropical-subtropical streamers and the stratosphere above ∼20 km altitude for polar vortex streamers, where strongest ozone depletion is observed at polar latCorrespondence to: K. Krüger (kkrueger@awi-potsdam.de) itudes (WMO, 2003). In the lower stratosphere the FUB-CMAM simulated a climatological maximum of 10% occurrence of tropical-subtropical streamers over East-Asia/West Pacific and the Atlantic during early-and mid-winter.The results of this paper demonstrate that stratospheric streamers e.g. large-scale, tongue-like structures transporting tropical-subtropical and polar vortex air masses into midlatitudes occur frequently during Arctic winter. They can therefore play a significant role on the strength and variability of the observed total ozone decrease at mid-latitudes and should not be neglected in future climate change studies.

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Stratospheric transport from the tropics to middle latitudes by planetary-wave mixing

Cited by 143 publications

References 22 publications

The Quasi-biennial Oscillation and annual variations in tropical ozone from SHADOZ and HALOE

The Quasi-biennial Oscillation and annual variations in tropical ozone from SHADOZ and HALOE

N₂O transport in a three‐dimensional model driven by U. K. Meteorological Office winds

Climatological features of stratospheric streamers in the FUB-CMAM with increased horizontal resolution

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Stratospheric transport from the tropics to middle latitudes by planetary-wave mixing

Cited by 143 publications

References 22 publications

The Quasi-biennial Oscillation and annual variations in tropical ozone from SHADOZ and HALOE

The Quasi-biennial Oscillation and annual variations in tropical ozone from SHADOZ and HALOE

N2O transport in a three‐dimensional model driven by U. K. Meteorological Office winds

Climatological features of stratospheric streamers in the FUB-CMAM with increased horizontal resolution

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N₂O transport in a three‐dimensional model driven by U. K. Meteorological Office winds