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

Ball, William T.; Kuchař, Aleš; Rozanov, Eugene V.; Staehelin, Johannes; Tummon, Fiona; Smith, Anne K.; Sukhodolov, Timofei; Stenke, Andrea; Revell, Laura; Coulon, Ancelin; Schmutz, Werner; Peter, Thomas

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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Ball, William T. / Kuchař, Aleš / Rozanov, Eugene V. / et al: An upper-branch Brewer–Dobson circulation index for attribution of stratospheric variability and improved ozone and temperature trend analysis. 2016. Copernicus Publications.

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Rechteinhaber: William T. Ball et al.

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