Variability of the polar night jet in the northern and southern hemispheres

Kuroda, Yoji; Kodera, Kunihiko

doi:10.1029/2001jd900226

Cited by 77 publications

(91 citation statements)

References 32 publications

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“…Reduced wave forcing can lead to decreasing/increasing or upwelling/downwelling motions in the equatorial or higher latitudes respectively (Kodera and Kuroda, 2002). The Brewer-Dobson circulation (BDC) is weaker during solar maxima (Kuroda and Kodera, 2001), although this appears to be sensitive to the state of the polar winter. Observational studies, together with model experiments (e.g.…”

Section: A Kuchar Et Al: Solar Cycle In Current Reanalysesmentioning

confidence: 99%

“…As was pointed out by Frame and Gray (2010), it is necessary to examine the solar signal in individual months because of a solar impact on polar-night jet oscillation (Kuroda and Kodera, 2001). For example, the amplitude of the lower stratospheric solar signal in the northern polar latitudes in February exceeds the annual response since the SC influence on vortex stability is most pronounced in February.…”

Section: Monthly Response (Merra)mentioning

confidence: 99%

“…Hemispheric asymmetry in the temperature response above the stratopause probably originates from the hemispheric differences, i.e. different wave activity (Kuroda and Kodera, 2001). These statistically significant and positive temperature anomalies across the subtropical stratopause begin to descend and move Figure 6.…”

Section: Monthly Response (Merra)mentioning

confidence: 99%

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The 11-year solar cycle in current reanalyses: a (non)linear attribution study of the middle atmosphere

et al. 2015

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Abstract. This study focusses on the variability of temperature, ozone and circulation characteristics in the stratosphere and lower mesosphere with regard to the influence of the 11-year solar cycle. It is based on attribution analysis using multiple nonlinear techniques (support vector regression, neural networks) besides the multiple linear regression approach. The analysis was applied to several current reanalysis data sets for the 1979-2013 period, including MERRA, ERA-Interim and JRA-55, with the aim to compare how these types of data resolve especially the doublepeaked solar response in temperature and ozone variables and the consequent changes induced by these anomalies. Equatorial temperature signals in the tropical stratosphere were found to be in qualitative agreement with previous attribution studies, although the agreement with observational results was incomplete, especially for JRA-55. The analysis also pointed to the solar signal in the ozone data sets (i.e. MERRA and ERA-Interim) not being consistent with the observed double-peaked ozone anomaly extracted from satellite measurements. The results obtained by linear regression were confirmed by the nonlinear approach through all data sets, suggesting that linear regression is a relevant tool to sufficiently resolve the solar signal in the middle atmosphere. The seasonal evolution of the solar response was also discussed in terms of dynamical causalities in the winter hemispheres. The hypothetical mechanism of a weaker BrewerDobson circulation at solar maxima was reviewed together with a discussion of polar vortex behaviour.

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Section: A Kuchar Et Al: Solar Cycle In Current Reanalysesmentioning

confidence: 99%

Section: Monthly Response (Merra)mentioning

confidence: 99%

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The 11-year solar cycle in current reanalyses: a (non)linear attribution study of the middle atmosphere

et al. 2015

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“…Figure 1 shows that in the case of the 4 largest ENSO events, the polar warming occurs first in the upper stratosphere (about 4 K for SSU and 8 K for ERA40, significant in December at 95%) and then descends to the lower stratosphere, characteristic of the polar night jet variability (Kuroda and Kodera, 2001). The warming is about 4 K between 50 and 100 hPa significant in January and February at 90% for SSU/MSU, and reaching 95% in ERA40.…”

Section: We 6 Wementioning

confidence: 99%

Northern winter stratospheric temperature and ozone responses to ENSO inferred from an ensemble of Chemistry Climate Models

et al. 2009

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Abstract. The connection between the El Niño Southern Oscillation (ENSO) and the Northern polar stratosphere has been established from observations and atmospheric modeling. Here a systematic inter-comparison of the sensitivity of the modeled stratosphere to ENSO in Chemistry Climate Models (CCMs) is reported. This work uses results from a number of the CCMs included in the 2006 ozone assessment. In the lower stratosphere, the mean of all model simulations reports a warming of the polar vortex during strong ENSO events in February-March, consistent with but smaller than the estimate from satellite observations and ERA40 reanalysis. The anomalous warming is associated with an anomalous dynamical increase of column ozone north of 70 • N that is accompanied by coherent column ozone decrease in the Correspondence to: C. Cagnazzo (chiara.cagnazzo@cmcc.it) Tropics, in agreement with that deduced from the NIWA column ozone database, implying an increased residual circulation in the mean of all model simulations during ENSO. The spread in the model responses is partly due to the large internal stratospheric variability and it is shown that it crucially depends on the representation of the tropospheric ENSO teleconnection in the models.

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“…7 and 8 in Shapiro et al (2013), and which could be related to high-latitude variability (e.g. Kuroda and Kodera, 2001;Hitchcock et al, 2013), may simply be considered as noise in MLR trend estimates (and other regressors) where it is not accounted for, which increases the uncertainty.…”

Section: Introductionmentioning

confidence: 99%

An upper-branch Brewer–Dobson circulation index for attribution of stratospheric variability and improved ozone and temperature trend analysis

Ball

Kuchař²,

Rozanov

et al. 2016

Atmos. Chem. Phys.

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Abstract. We find that wintertime temperature anomalies near 4 hPa and 50 • N/S are related, through dynamics, to anomalies in ozone and temperature, particularly in the tropical stratosphere but also throughout the upper stratosphere and mesosphere. These mid-latitude anomalies occur on timescales of up to a month, and are related to changes in wave forcing. A change in the meridional Brewer-Dobson circulation extends from the middle stratosphere into the mesosphere and forms a temperature-change quadrupole from Equator to pole. We develop a dynamical index based on detrended, deseasonalised mid-latitude temperature. When employed in multiple linear regression, this index can account for up to 60 % of the total variability of temperature, peaking at ∼ 5 hPa and dropping to 0 at ∼ 50 and ∼ 0.5 hPa, respectively, and increasing again into the mesosphere. Ozone similarly sees up to an additional 50 % of variability accounted for, with a slightly higher maximum and strong altitude dependence, with zero improvement found at 10 hPa. Further, the uncertainty on all equatorial multiple-linear regression coefficients can be reduced by up to 35 and 20 % in temperature and ozone, respectively, and so this index is an important tool for quantifying current and future ozone recovery.

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Variability of the polar night jet in the northern and southern hemispheres

Cited by 77 publications

References 32 publications

The 11-year solar cycle in current reanalyses: a (non)linear attribution study of the middle atmosphere

The 11-year solar cycle in current reanalyses: a (non)linear attribution study of the middle atmosphere

Northern winter stratospheric temperature and ozone responses to ENSO inferred from an ensemble of Chemistry Climate Models

An upper-branch Brewer–Dobson circulation index for attribution of stratospheric variability and improved ozone and temperature trend analysis

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