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Recent Decline in Extratropical Lower Stratospheric Ozone Attributed to Circulation Changes
Author(s) -
Wargan Krzysztof,
Orbe Clara,
Pawson Steven,
Ziemke Jerald R.,
Oman Luke D.,
Olsen Mark A.,
Coy Lawrence,
Emma Knowland K.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl077406
Subject(s) - tropopause , extratropical cyclone , stratosphere , climatology , ozone layer , environmental science , ozone , atmospheric sciences , ozone depletion , radiosonde , meteorology , geology , geography
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°N and 60°N. A weaker but statistically significant trend of −1.17 ± 0.33 DU/decade exists between 50°S and 20°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°S–20°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.