A mid-latitude stratosphere dynamical index for attribution of stratospheric variability and improved ozone and temperature trend analysis

Abstract

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 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 40 % of the total variability of temperature and ozone and a doubling of the total coefficient of determination in the equatorial stratosphere above 20 hPa. Further, the uncertainty on all multiple-linear regression coefficients can be reduced by up to 45 % and 25 % in temperature and ozone, respectively, and so this index is an important tool for quantifying current and future ozone recovery.