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Laboratory for Atmospheric and Space Physics

Elevated Stratopause Events

An elevated stratopause (ES) is characterized by the polar winter stratopause reforming at high altitudes near 80 km, nearly 30 km above normal. ES events occur following prolonged stratospheric disturbances due to the anomalous filtering of gravity waves (GWs) by large-scale planetary waves. GWs with westerly phase speeds propagate up to mesospheric altitudes where they break and result in enhanced polar descent. Understanding the descent-driven ES is of interest in our group because increased descent of mesospheric NOx impacts stratospheric ozone chemistry.

The figure below shows timeseries of Arctic winter temperature at 75° N vs. altitude for 12 winter seasons (2002-2003 to 2013-2014). The polar winter stratopause is typically at ~55 km altitude. Recent ES events observed by satellite instruments occurred in 2004, 2006, 2009, 2010, 2012, and 2013. During these years poleward of ~70° N, the stratopause reforms near 80 km. Click on the image for full size view.