Abstract
Abstract. The Microwave Ozone Profiling Instrument (MOPI1) has provided ozone (O3) profiles for the Network for the Detection of Atmospheric Composition Change (NDACC) at Lauder, New Zealand (45.0° S, 169.7° E), since 1992. We present the entire 22-year data set and compare with satellite O3 observations. We study in detail two particularly interesting variations in O3. The first is a large positive O3 anomaly that occurs in the mid-stratosphere (~ 10–30 hPa) in June 2001, which is caused by an anticyclonic circulation that persists for several weeks over Lauder. This O3 anomaly is associated with the most equatorward June average tracer equivalent latitude (TrEL) over the 36-year period (1979–2014) for which the Modern Era Retrospective-Analysis for Research and Applications (MERRA) reanalysis is available. A second, longer-lived feature, is a positive O3 anomaly in the mid-stratosphere (~ 10 hPa) from mid-2009 until mid-2013. Coincident measurements from the Aura Microwave Limb Sounder (MLS) show that these high O3 mixing ratios are well correlated with high nitrous oxide (N2O) mixing ratios. This correlation suggests that the high O3 over this 4-year period is driven by unusual dynamics. The beginning of the high O3 and high N2O period at Lauder (and throughout this latitude band) occurs nearly simultaneously with a sharp decrease in O3 and N2O at the equator, and the period ends nearly simultaneously with a sharp increase in O3 and N2O at the equator.
Highlights
Observations of total column ozone (O3) show that, over most of the globe, O3 loss has leveled off since ∼ 2000, and O3 has even begun to increase
Nedoluha et al.: Stratospheric ozone anomalies over Lauder ined the period 1997–2011, showing a general increase in O3 from Stratospheric Aerosol and Gas Experiment (SAGE) and Global Ozone Monitoring by Occultation of Stars (GOMOS) measurements, but a statistically significant decrease near 30 km in the tropics
Nedoluha et al (2015) showed that from 2004 to 2013, Aura Microwave Limb Sounder (MLS) measurements showed a strong decrease in mid-stratospheric O3 in the tropics
Summary
Observations of total column ozone (O3) show that, over most of the globe, O3 loss has leveled off since ∼ 2000, and O3 has even begun to increase. Kyrölä et al (2013), using measurements from the Stratospheric Aerosol and Gas Experiment (SAGE) from 1984 to 1997, show a general decrease in O3 that is statistically significant over much of the stratosphere and is large in the mid-latitude upper stratosphere. Nedoluha et al.: Stratospheric ozone anomalies over Lauder ined the period 1997–2011, showing a general increase in O3 from SAGE and Global Ozone Monitoring by Occultation of Stars (GOMOS) measurements, but a statistically significant decrease near 30 km in the tropics. Eckert et al (2014), using Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) data from 2002 to 2012, showed a general increase in O3 in most regions, especially in the Southern Hemisphere mid-latitudes near ∼ 20 hPa, but found statistically significant negative trends in the tropics from ∼ 25 hPa to 5 hPa. Nedoluha et al (2015) showed that from 2004 to 2013, Aura Microwave Limb Sounder (MLS) measurements showed a strong decrease in mid-stratospheric O3 in the tropics.
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