Trend analysis of upper stratospheric Umkehr ozone data for evidence of turnaround

Recent upper stratospheric (∼35–45 km) Umkehr ozone data from three high‐quality stations have been examined, with residual and change‐in‐trend analyses performed. These data show a consistent feature of mildly positive tendency in values for the recent several years. Trend analyses of these data yield significant positive change‐in‐trend estimates of about 0.75% per year since 1996 relative to negative trends of about −0.55% per year existing prior to 1996, leading to a (nonsignificant) estimate of about 0.2% per year positive trend for the recent 5‐year period since the 1996 change‐in‐trend date.