The impact of planetary waves on the latitudinal displacement of sudden stratospheric warmings

Matthias, Vivien; Hoffmann, Peter; Manson, A. H.; Meek, C. E.; Stober, Gunter; Brown, Peter; Rapp, Markus

doi:10.5194/angeo-31-1397-2013

Cited by 31 publications

(36 citation statements)

References 45 publications

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“…Further, the observed mean characteristics of the MLT dynamics agree reasonably well with the zonal-mean behavior as for instance discussed in Hoffmann et al (2010). In contrast, the winter season is mainly dominated by the presence of planetary waves, which disturb the propagation of GWs (see, e.g., Pancheva and Mitchell, 2004;Matthias et al, 2013). This additional influence of the planetary waves on the momentum balance is not considered by the SMF radar observations in this study.…”

Section: Mean Annual Variationsupporting

confidence: 83%

First experimental verification of summertime mesospheric momentum balance based on radar wind measurements at 69° N

2015

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Abstract. Gravity waves (GWs) greatly influence the background state of the middle atmosphere by imposing their momentum on the mean flow upon breaking and by thus driving, e.g., the upper mesospheric summer zonal wind reversal. In this situation momentum is conserved by a balance between the vertical divergence of GW momentum flux (the so-called GW drag) and the Coriolis acceleration of the mean meridional wind. In this study, we present first quantitative mean annual cycles of these two balancing quantities from the medium frequency Doppler radar at the polar site Saura (SMF radar, 69 • N, 16 • E). Three-year means for 2009 through 2011 clearly show that the observed zonal momentum balance between 70 and 100 km with contributions from GWs only is fulfilled during summer when GW activity is strongest and more stable than in winter. During winter, the balance between GW drag and Coriolis acceleration of the mean meridional wind is not existent, which is likely due to the additional contribution from planetary waves, which are not considered by the present investigation. The differences in the momentum balance between summer and winter conditions are additionally clarified by 3-month mean vertical profiles for summer

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Section: Mean Annual Variationsupporting

confidence: 83%

First experimental verification of summertime mesospheric momentum balance based on radar wind measurements at 69° N

2015

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Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

“…Matthias et al (2013) used observations as well as reanalysis data to study the latitudinal displacement of SSWs throughout the Northern Hemisphere middle atmosphere. Although in most cases disturbances related to SSWs are strongest over the polar region, these disturbances have been observed to shift to mid-latitudes, which has been linked to increased mid-latitude PW activity (Matthias et al, 2013). Fritz and Soules (1970) were the first to show, using satellite radiance observations, that SSWs are accompanied by a simultaneous cooling over the equatorial region as well as the summer hemisphere at stratospheric levels.…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

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Coupling in the middle atmosphere related to the 2013 major sudden stratospheric warming

et al. 2015

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Abstract. The previously reported observation of anomalous eastward gravity wave forcing at mesopause heights around the onset of the January 2013 major sudden stratospheric warming (SSW) over Trondheim, Norway (63 • N, 10 • E), is placed in a global perspective using Microwave Limb Sounder (MLS) temperature observations from the Aura satellite. It is shown that this anomalous forcing results in a clear cooling over Trondheim about 10 km below mesopause heights. Conversely, near the mesopause itself, where the gravity wave forcing was measured, observations with meteor radar, OH airglow and MLS show no distinct cooling. Polar cap zonal mean temperatures show a similar vertical profile. Longitudinal variability in the high northern-latitude mesosphere and lower thermosphere (MLT) is characterized by a quasi-stationary wave-1 structure, which reverses phase at altitudes below ∼ 0.1 hPa. This wave-1 develops prior to the SSW onset, and starts to propagate westward at the SSW onset. The latitudinal pole-to-pole temperature structure associated with the major SSW shows a warming (cooling) in the winter stratosphere (mesosphere) which extends to about 40 • N. In the stratosphere, a cooling extending over the equator and far into the summer hemisphere is observed, whereas in the mesosphere an equatorial warming is noted. In the Southern Hemisphere mesosphere, a warm anomaly overlaying a cold anomaly is present, which is shown to propagate downward in time. This observed structure is in accordance with the temperature perturbations predicted by the proposed interhemispheric coupling mechanism for cases of increased winter stratospheric planetary wave activity, of which major SSWs are an extreme case. These results provide observational evidence for the interhemispheric coupling mechanism, and for the wave-mean flow interaction believed to be responsible for the establishment of the anomalies in the summer hemisphere.

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“…Comparison of these results to the average behaviour of major SSWs show that both coupling processes are characterised by a wind weakening/reversal in the middle atmosphere (e.g. Limpasuvan et al, 2004;Matthias et al, 2013). However, while the hiccup seems to propagate upward, studies of Matthias et al (2012) show an ∼ 4 days earlier onset of the wind reversal in the mesosphere than in the stratosphere in composite analysis of major SSWs implying a downward propagation.…”

Section: Resultsmentioning

confidence: 82%

The Hiccup: a dynamical coupling process during the autumn transition in the Northern Hemisphere – similarities and differences to sudden stratospheric warmings

et al. 2015

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Abstract. Sudden stratospheric warmings (SSWs) are the most prominent vertical coupling process in the middle atmosphere, which occur during winter and are caused by the interaction of planetary waves (PWs) with the zonal mean flow. Vertical coupling has also been identified during the equinox transitions, and is similarly associated with PWs. We argue that there is a characteristic aspect of the autumn transition in northern high latitudes, which we call the "hiccup", and which acts like a "mini SSW", i.e. like a small minor warming. We study the average characteristics of the hiccup based on a superimposed epoch analysis using a nudged version of the Canadian Middle Atmosphere Model, representing 30 years of historical data. Hiccups can be identified in about half the years studied. The mesospheric zonal wind results are compared to radar observations over Andenes (69 • N, 16 • E) for the years 2000-2013. A comparison of the average characteristics of hiccups and SSWs shows both similarities and differences between the two vertical coupling processes.

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The impact of planetary waves on the latitudinal displacement of sudden stratospheric warmings

Cited by 31 publications

References 45 publications

First experimental verification of summertime mesospheric momentum balance based on radar wind measurements at 69° N

First experimental verification of summertime mesospheric momentum balance based on radar wind measurements at 69° N

Coupling in the middle atmosphere related to the 2013 major sudden stratospheric warming

The Hiccup: a dynamical coupling process during the autumn transition in the Northern Hemisphere – similarities and differences to sudden stratospheric warmings

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