The decrease in mid-stratospheric tropical ozone since 1991

Nedoluha, Gerald E.; Siskind, D. E.; Lambert, A.; Boone, Christopher D.

doi:10.5194/acp-15-4215-2015

Cited by 23 publications

(43 citation statements)

References 32 publications

(36 reference statements)

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“…8 certainly does emphasize is that the anomalies over Lauder at 10 hPa during the period 2004-2014 are not, predominantly, driven by a decadal-scale global trend. Nedoluha et al (2015) showed that O 3 variations at the equator are very strongly positively correlated to variations in N 2 O. This relationship could best be understood as resulting from dynamical variations.…”

Section: Unusually High Mid-stratospheric O 3 From August 2009 Througmentioning

confidence: 99%

“…This relationship could best be understood as resulting from dynamical variations. Using a 2-D chemical transport model, Nedoluha et al (2015) showed that slower ascent resulted in more N 2 O being photodissociated and oxidized to produce NO x (while reducing N 2 O), and the increased NO x destroyed more ozone, resulting in a positive correlation between O 3 and N 2 O. Such a relationship has been previously deduced from changes in HALOE measurements of NO 2 at ∼ 10 hPa from 1993 to 1997, where the change in NO 2 was shown to be consistent with a decrease in upward transport (Nedoluha et al, 1998).…”

Section: Unusually High Mid-stratospheric O 3 From August 2009 Througmentioning

confidence: 99%

“…Eckert et al (2014), using Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) data from 2002 to 2012, also showed a general increase in O 3 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. Finally, Nedoluha et al (2015) showed that from 2004 to 2013, Aura Microwave Limb Sounder (MLS) measurements showed a strong decrease in mid-stratospheric O 3 in the tropics. Nedoluha et al (2015) also showed, based on changes in N 2 O measured by MLS and NO x measured by HALOE, that the decadal-scale changes in equatorial O 3 of the magnitude observed could best be understood as being caused by dynamical variations.…”

Section: Introductionmentioning

confidence: 99%

“…Finally, Nedoluha et al (2015) showed that from 2004 to 2013, Aura Microwave Limb Sounder (MLS) measurements showed a strong decrease in mid-stratospheric O 3 in the tropics. Nedoluha et al (2015) also showed, based on changes in N 2 O measured by MLS and NO x measured by HALOE, that the decadal-scale changes in equatorial O 3 of the magnitude observed could best be understood as being caused by dynamical variations. The goal of this paper is to better understand how variations in mid-stratospheric O 3 over Lauder are affected by large scale dynamical variations.…”

Section: Introductionmentioning

confidence: 99%

“…Nedoluha et al (2015) studied O 3 over the period 1991-2005, when Halogen Occultation Experiment (HALOE) measurements are available, and found a strong decrease in mid-stratospheric O 3 in the tropics over this period. Kyrölä et al (2013) Gebhardt et al (2014), showed a pattern similar to the 1997-2011 pattern reported by Kyrölä et al (2013) (i.e., a strong, statistically significant decrease in tropical O 3 in the 30-35 km region while most of the middle atmosphere shows a slight increase in O 3 ).…”

Section: Introductionmentioning

confidence: 99%

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Unusual stratospheric ozone anomalies observed in 22 years of measurements from Lauder, New Zealand

et al. 2015

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Abstract. The Microwave Ozone Profiling Instrument (MOPI1) has provided ozone (O 3 ) 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 O 3 observations. We study in detail two particularly interesting variations in O 3 . The first is a large positive O 3 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 O 3 anomaly is associated with the most equatorward June average tracer equivalent latitude (TrEL) over the 36-year period for which the Modern Era RetrospectiveAnalysis for Research and Applications (MERRA) reanalysis is available. A second, longer-lived feature, is a positive O 3 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 O 3 mixing ratios are well correlated with high nitrous oxide (N 2 O) mixing ratios. This correlation suggests that the high O 3 over this 4-year period is driven by unusual dynamics. The beginning of the high O 3 and high N 2 O period at Lauder (and throughout this latitude band) occurs nearly simultaneously with a sharp decrease in O 3 and N 2 O at the equator, and the period ends nearly simultaneously with a sharp increase in O 3 and N 2 O at the equator.

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Section: Unusually High Mid-stratospheric O 3 From August 2009 Througmentioning

confidence: 99%

Section: Unusually High Mid-stratospheric O 3 From August 2009 Througmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Unusual stratospheric ozone anomalies observed in 22 years of measurements from Lauder, New Zealand

et al. 2015

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Regional and seasonal stratospheric temperature trends in the last decade (2002–2014) from AMSU observations

et al. 2016

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Stratospheric temperature trends for the period 2002-2014 have been estimated using NOAA's Integrated Microwave Inter-calibration Approach (IMICA) version of advanced microwave sounding unit (AMSU) on AQUA satellite. In this period the stratosphere continued cooling over most of the globe with a rate ranging from −0.4 ± 0.3 to −0.5 ± 0.4 K/decade above 25 km. Considering specific latitude bands, trends are highly variable with height. In the tropical region, trends vary from −0.5 ± 0.3 K/decade for channel 12 (∼30 km) to −0.7 ± 0.3 K/decade for higher channels and present small seasonal variability in the intensity of cooling. In the polar regions and in the midlatitudes, trends for all channels are negative but not significant; uncertainties are large due to the high dynamical variability particularly in high latitudes. There is also large seasonal variability, with southern midlatitudes seasonal trends significant during summer (December, January, February) and autumn (March, April, May) above ∼25 km, with values ranging from −1.0 ± 0.5 to −0.6 ± 0.5 K/decade. Regional trends estimated with AMSU and long-term lidar measurements (over two decades) confirm stratospheric cooling in the northern midlatitudes and tropical regions. The effect of the length of the short series on trends was found to be small outside polar regions. It was found to be large in polar regions with about 1 K changes in trend depending on start dates of the time series.

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Variability of Stratospheric Reactive Nitrogen and Ozone Related to the QBO

et al. 2017

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The stratospheric quasi‐biennial oscillation (QBO) dominates interannual variability of dynamical variables and trace constituents in the tropical stratosphere and provides a natural experiment to test circulation‐chemistry interactions. This work quantifies the relationships among ozone (O3), reactive nitrogen (NOy), and source gas N2O, and their links to the QBO, based on satellite constituent measurements and meteorological data spanning 2005–2014 (over four QBO cycles). Data include O3, HNO3, and N2O from the Aura Microwave Limb Sounder and an NOx proxy derived from Optical Spectrograph and Infrared Imager System NO2 measurements combined with a photochemical box model (= NOx*). Results are compared to simulations from the Whole Atmosphere Community Climate Model, version 4 incorporating a QBO circulation nudged to assimilated winds. Cross correlations and composites with respect to the QBO phase show coherent 180° out‐of‐phase relationships between NOy and N2O throughout the stratosphere, with the NOx/HNO3 ratio increasing with altitude. The anomalies in NOy species propagate coherently downward with the QBO. Ozone is anticorrelated with reactive nitrogen in the middle stratosphere above ~28 km due to NOx control of ozone catalytic loss cycles. Quantitative comparisons of nitrogen partitioning and O3 sensitivity to NOx show good overall agreement between satellite observations and model results (suggesting closure of the NOy budget), although the model results show larger (up to ~20%) N2O, NOx, and O3 variations near ~35 km compared to observations. These analyses serve to assess the consistency of diverse satellite‐based data sets and also to evaluate nitrogen partitioning and NOx‐dependent ozone chemistry in the global model.

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The decrease in mid-stratospheric tropical ozone since 1991

Cited by 23 publications

References 32 publications

Unusual stratospheric ozone anomalies observed in 22 years of measurements from Lauder, New Zealand

Unusual stratospheric ozone anomalies observed in 22 years of measurements from Lauder, New Zealand

Regional and seasonal stratospheric temperature trends in the last decade (2002–2014) from AMSU observations

Variability of Stratospheric Reactive Nitrogen and Ozone Related to the QBO

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