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

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 similar to 5 hPa and dropping to 0 at similar to 50 and similar to 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.