Role of the quasi‐biennial oscillation in the transport of aerosols from the tropical stratospheric reservoir to midlatitudes

Choi, Wookap; Grant, William B.; Park, Jae H.; Lee, Kwang‐Mog; Lee, Hyun-Ahn; Russell, James M.

doi:10.1029/97jd03118

Cited by 30 publications

(37 citation statements)

References 29 publications

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“…The evolution of the Junge layer has been extensively studied from satellite measurements (Hitchman et al, 1994;Trepte et al, 1994) and the existence of a tropical stratospheric reservoir has been suggested (Grant et al, 1996); the role of the quasi-biennial oscillation in transport to mid-latitudes has been discussed (Choi et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Evidence of transport, sedimentation and coagulation mechanisms in the relaxation of post-volcanic stratospheric aerosols

2001

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Abstract. Spatio-temporal distributions of stratospheric aerosols, measured by the ORA instrument from August 1992 until May 1993, are presented in the latitude range (40• S-40• N). Particle total number density, mode radius and distribution width are derived and interpreted. The respective roles of advection, sedimentation and coagulation are discussed. We also identify clear transport/sedimentation patterns and we show the enhancement of coagulation in stagnation regions. Efficient transport of aerosol particles up to 50 km is suggested.

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Section: Introductionmentioning

confidence: 99%

Evidence of transport, sedimentation and coagulation mechanisms in the relaxation of post-volcanic stratospheric aerosols

2001

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“…limited number of studies (Choi et al, 1998(Choi et al, , 2002Barnes and Hofmann, 2001). Since these studies do not show QBO signatures in other aerosol quantities than the retrieved extinction coefficients or the aerosol backscatter, in this study we also infer QBO signatures from climatologies of the aerosol surface area density inferred from SAGE II retrieved extinction coefficients, in order to establish a direct comparison between our modelled aerosol properties and observations.…”

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confidence: 99%

“…A respective model goes back to the works of Plumb and Bell (1982); for TSR aerosol it was first reported by Trepte and Hitchman (1992) based on aerosol extinction measurements from SAGE I and II instruments in the periods 1979-1981 and 1984-1991, when the volcanic aerosol load of the stratosphere was relatively low. Underlying mechanisms were later examined in detail by Choi et al (1998) and Choi et al (2002) from HALOE observations of aerosol extinction, ozone and other trace gases.…”

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confidence: 99%

Quasi-biennial oscillation of the tropical stratospheric aerosol layer

et al. 2015

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Abstract. This study describes how aerosol in an aerosolcoupled climate model of the middle atmosphere is influenced by the quasi-biennial oscillation (QBO) during times when the stratosphere is largely unperturbed by volcanic material. In accordance with satellite observations, the vertical extent of the stratospheric aerosol layer in the tropics is modulated by the QBO by up to 6 km, or ∼ 35 % of its mean vertical extent between 100-7 hPa (about 16-33 km). Its largest vertical extent lags behind the occurrence of strongest QBO westerlies. The largest reduction lags behind maximum QBO easterlies. Strongest QBO signals in the aerosol surface area (30 %) and number densities (up to 100 % e.g. in the Aitken mode) are found in regions where aerosol evaporates, that is above the 10 hPa pressure level (∼ 31 km). Positive modulations are found in the QBO easterly shear, negative modulations in the westerly shear. Below 10 hPa, in regions where the aerosol mixing ratio is largest (50-20 hPa, or ∼ 20-26 km), in most of the analysed parameters only moderate statistically significant QBO signatures (< 10 %) have been found.QBO signatures in the model prognostic aerosol mixing ratio are significant at the 95 % confidence level throughout the tropical stratosphere where modelled mixing ratios exceed 0.1 ppbm. In some regions of the tropical lower stratosphere the QBO signatures in other analysed parameters are partly not statistically significant. Peak-to-peak amplitudes of the QBO signature in the prognostic mixing ratios are up to twice as large as seasonal variations in the region where aerosols evaporate and between 70-30 hPa. Between the tropical tropopause and 70 hPa the QBO signature is relatively weak and seasonal variations dominate the variability of the simulated Junge layer. QBO effects on the upper lid of the tropical aerosol layer turn the quasi-static balance between processes maintaining the layer's vertical extent into a cyclic balance when considering this dominant mode of atmospheric variability. Global aerosol-interactive models without a QBO are only able to simulate the quasistatic balance state. To assess the global impact of stratospheric aerosols on climate processes, those partly nonlinear relationships between the QBO and stratospheric aerosols have to be taken into account.

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“…The annual cycle induces the asymmetric distributions of tracers in Northern and Southern Hemisphere [11] . The antisymmetric structure of methane QBO may have some relationship to the anomalous annual cycle.…”

Section: Analysis Resultsmentioning

confidence: 99%

“…The residual circulations related to the QBO induce the exchanges between tropics and subtropics, and between tropical upper and lower layers. Since the QBO has characteristics of equatorial symmetry [9,10] , its meridional transport is nearly symmetry with respect to the equator [11] . As a result, tracers' anomalies also distribute symmetrically.…”

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confidence: 99%

Antisymmetric transport of middle stratospheric methane with respect to the equator

2006

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Halogen Occultation Experiment (HALOE) data are used to study the quasi-biennial variability of CH 4 mixing ratio in the middle stratosphere. The results of EOF analysis indicate that quasi-biennial period is principal for the interannual variability of methane. Antisymmetry with respect to the equator is significant for the methane QBO by explaining 59.3% variance, while the symmetric component only explains about 30%. The antisymmetry is more significant in 10°-20° latitude than between 10ºS and 10ºN. Analyses of the vertical motions show that anomalies of annual cycle play an important role in the antisymmetric distributions. Whereas, the zonal wind QBO is still the most important dynamical effect for the interannual variability of CH 4 between 10°S-10°N.As one of the important green-house gases, methane in the stratosphere affects the stratospheric processes of radiation, dynamics and chemistry, even the tropospheric circulation through interactions between the stratosphere and the troposphere.To a great degree, methane sources and sinks determine their distribution in the stratosphere. Furthermore, some effects on methane sources or sinks will change the distribution. Wang [1] pointed out that methane emission from rice field and wetlands can be 1-3 times higher under elevated CO 2 condition than that in the ambient CO 2 condition (about 40% of CH4 is released from rice paddies and natural wetlands within the total world CH 4 budget). Zhang and Wang [2] used a two-dimensional global chemical model to investigate the cause of a dramatic decrease in the growth rate of CH 4 in 1992, and the results show that the decrease of CO emissions is a main cause accounting for about 27% except for the influences of CH 4 sources. Considine et al. [3] used the Goddard Space Flight Center interactive two-dimensional model to evaluate the effects of the Mount Pinatubo volcanic aerosol cloud on subsequent trends in upper stratospheric CH 4 and H 2 O. The simulated negative upper stratospheric trend of CH 4 between 1992 and 1997 is in better agreement with observations than a nonvolcanic simulation, but is still substantially weaker than the observations in the upper stratosphere by the Halogen Occultation Experiment (HALOE) between 1992 and 1997. Those comparisons suggest that the aerosol from the Mount Pinatubo eruption could have contributed to the observed changes in CH 4 following the eruption, but was probably not the sole driver of the observed changes.Dynamical processes also control the CH 4 distributions in the stratosphere. Nedoluha et al. [4] found a decreases in the middle-upper stratospheric CH 4 between 1991 and 1997 when they had analyzed the HALOE methane data, and the simulation results by a two-dimensional model show that the decreases of tropical ascending flow would cause the CH 4 decreases. Zhang et al. [5] used a SOCRATES model (interactive chemical, dynamical and radiative two-dimensional model) to study the impact of the zonal wind QBO on the distribution of the stratospheric tracer gases, and the resu...

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Role of the quasi‐biennial oscillation in the transport of aerosols from the tropical stratospheric reservoir to midlatitudes

Cited by 30 publications

References 29 publications

Evidence of transport, sedimentation and coagulation mechanisms in the relaxation of post-volcanic stratospheric aerosols

Evidence of transport, sedimentation and coagulation mechanisms in the relaxation of post-volcanic stratospheric aerosols

Quasi-biennial oscillation of the tropical stratospheric aerosol layer

Antisymmetric transport of middle stratospheric methane with respect to the equator

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