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NASA NTRS · 20180004621

Recent Decline in Extratropical Lower Stratospheric Ozone Attributed to Circulation Changes

Wargan, Krzysztof·Orbe, Clara·Pawson, Steven·Ziemke, Jerald R.·Oman, Luke D.·Olsen, Mark A.·Coy, Lawrence·Knowland, K. Emma
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Abstract

The 1998-2016 ozone trends in the lower stratosphere are examined using the Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2) and related National Aeronautics and Space Administration products. After removing biases resulting from step changes in the MERRA-2 ozone observations, a discernible negative trend of 1.67 +/- 0.54 Dobson units per decade (DU/decade) is found in the 10-km layer above the tropopause between 20 deg N and 60 deg N. A weaker but statistically significant trend of 1.17 +/- 0.33 DU/decade exists between 50 deg S and 20 deg S. In the Tropics, a positive trend is seen in a 5-km layer above the tropopause. Analysis of an idealized tracer in a model simulation constrained by MERRA-2 meteorological fields provides strong evidence that these trends are driven by enhanced isentropic transport between the tropical (20 deg S-20 deg N) and extratropical lower stratosphere in the past two decades. This is the first time that a reanalysis data set has been used to detect and attribute trends in lower stratospheric ozone.

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Wargan, Krzysztof, Orbe, Clara, Pawson, Steven, Ziemke, Jerald R., Oman, Luke D., Olsen, Mark A., Coy, Lawrence, Knowland, K. Emma. 2018-05-14. Recent Decline in Extratropical Lower Stratospheric Ozone Attributed to Circulation Changes. https://ntrs.nasa.gov/citations/20180004621

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