Articles | Volume 16, issue 24
Research article
15 Dec 2016
Research article |  | 15 Dec 2016

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

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

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.

Short summary
We find monthly, mid-latitude temperature changes above 40 km are related to ozone and temperature variations throughout the middle atmosphere. We develop an index to represent this atmospheric variability. In statistical analysis, the index can account for up to 60 % of variability in tropical temperature and ozone above 27 km. The uncertainties can be reduced by up to 35 % and 20 % in temperature and ozone, respectively. This index is an important tool to quantify current and future ozone recovery.
Final-revised paper