QBO signal found at the extratropical surface through northern annular modes

Coughlin, K.; Tung, K. K.

doi:10.1029/2001gl013565

Cited by 56 publications

(40 citation statements)

References 23 publications

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“…As discussed in another paper in this volume (Kodera 2001) and in Shindell et al (2001), volcanic aerosols and polar stratospheric ozone losses also seem to impact tropospheric circulations. The QBO by itself appears to affect tropospheric northern annular modes (Coughlin and Tung 2001). All these forcings seem to involve the same process-alteration in temperature gradients and zonal wind in the upper troposphere and stratosphere, affecting tropospheric wave propagation and tropospheric angular momentum transport.…”

Section: Introductionmentioning

confidence: 99%

2 * CO2 and Solar Variability Influences on the Troposphere Through Wave-Mean Flow Interactions.

Rind

Lonergan

Balachandran

et al. 2002

Journal of the Meteorological Society of Japan

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A variety of climate forcings are now thought to be able to influence planetary wave dynamics in the troposphere by affecting the propagation of planetary waves out of the troposphere. However, this propagation pattern is sensitive to the details of the corresponding zonal wind changes. Here we discuss two forcing mechanisms that alter zonal winds and subsequent tropospheric responses: changes in atmospheric CO 2 concentrations, and solar forcing in conjunction with the QBO. Increased atmospheric CO 2 concentrations can be shown to influence planetary wave refraction so as to produce an intensified residual circulation in the subtropical lower stratosphere (which increases transport of tropospheric species into the stratosphere). In our GCM experiments, the low latitude response appears qualitatively robust over a wide range of tropical warming magnitudes, although the quantitative circulation change depends upon the degree of tropical warming as influenced by convection and cloud cover changes; it varies by a factor of three with a factor of three change in tropical warming. At higher latitudes, this equatorward planetary wave refraction has been associated with an increase in the high phase of the Arctic Oscillation. In the model experiments, the extratropical response depends upon the magnitude of both low and high latitude warming in the troposphere; with SST and sea ice changes that result in a weaker Hadley Cell and greater high latitude warming, the Arctic Oscillation phase change may be negative.The QBO alters the latitudinal gradient of the zonal wind in the stratosphere, and solar heating, in association with ozone response, alters the vertical gradient of the zonal wind. Both gradients affect the refractive properties of planetary waves uniquely for each individual combination of tropical east/west winds and solar maximum/minimum activity. In the model, when we consider solar maximum compared to solar minimum conditions, the east (west) phase of the QBO results in a relative high (low) phase of the Arctic Oscillation with corresponding temperature changes. Observed and modeled surface air temperature variations calculated between the solar cycle extremes in the different QBO phases are similar in magnitude to those derived from regression of monthly data on the AO, both being on the order of observed interannual variations.

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Section: Introductionmentioning

confidence: 99%

2 * CO2 and Solar Variability Influences on the Troposphere Through Wave-Mean Flow Interactions.

Rind

Lonergan

Balachandran

et al. 2002

Journal of the Meteorological Society of Japan

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“…Collimore et al 1998, 2003, Giorgetta et al 1999Baldwin et al 2001). Also high latitude changes of the stratospheric polar vortex are thought to impact mid and high latitude tropospheric weather and climate, for example through changes in the North Atlantic Oscillation and position of the jet stream (Thompson and Wallace 2000;Coughlin and Tung 2001;Baldwin et al 2003;Dall'Amico and Egger 2007). Stenchikov et al (2004Stenchikov et al ( , 2006 have shown that inclusion of the equatorial QBO influences the high latitude volcanic response in the stratosphere and also at the surface.…”

Section: Introductionmentioning

confidence: 99%

Stratospheric temperature trends: impact of ozone variability and the QBO

et al. 2009

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In most climate simulations used by the Intergovernmental Panel on Climate Change 2007 fourth assessment report, stratospheric processes are only poorly represented. For example, climatological or simple specifications of time-varying ozone concentrations are imposed and the quasi-biennial oscillation (QBO) of equatorial stratospheric zonal wind is absent. Here we investigate the impact of an improved stratospheric representation using two sets of perturbed simulations with the Hadley Centre coupled ocean atmosphere model HadGEM1 with natural and anthropogenic forcings for the 1979-2003 period. In the first set of simulations, the usual zonal mean ozone climatology with superimposed trends is replaced with a time series of observed zonal mean ozone distributions that includes interannual variability associated with the solar cycle, QBO and volcanic eruptions. In addition to this, the second set of perturbed simulations includes a scheme in which the stratospheric zonal wind in the tropics is relaxed to appropriate zonal mean values obtained from the ERA-40 re-analysis, thus forcing a QBO. Both of these changes are applied strictly to the stratosphere only. The improved ozone field results in an improved simulation of the stepwise temperature transitions observed in the lower stratosphere in the aftermath of the two major recent volcanic eruptions. The contribution of the solar cycle signal in the ozone field to this improved representation of the stepwise cooling is discussed. The improved ozone field and also the QBO result in an improved simulation of observed trends, both globally and at tropical latitudes. The Eulerian upwelling in the lower stratosphere in the equatorial region is enhanced by the improved ozone field and is affected by the QBO relaxation, yet neither induces a significant change in the upwelling trend.

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“…It is therefore to be distinguished from the direct continuation of the stratospheric QBO into the (mainly midlatitude) troposphere, as reported by e.g. Coughlin and Tung (2001), Crooks and Gray (2005) and Garfinkel and Hartmann (2011). In addition, the Indian and West Pacific monsoon indices are themselves mutually coherent on quasi-biennial time-scales (section 3.4) and at least partly coherent with other tropical climate indices, such as those for West African rainfall, which also feature in schemes for seasonal forecasting e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Other evidence has suggested the direct penetration of the stratospheric QBO into the lower atmosphere, as manifest e.g. in variations of midlatitude surface pressure and zonal winds (Coughlin and Tung, 2001;Crooks and Gray, 2005;Garfinkel and Hartmann, 2011). The stratospheric QBO has thus been associated with cyclic variations in hurricane activity in the Atlantic, for example, such that QBO indices are commonly used as a component in the seasonal forecasting of tropical cyclones (Gray, 1984a,b).…”

Section: Introductionmentioning

confidence: 99%