Measurement report: Regional trends of stratospheric ozone
evaluated using the MErged GRIdded Dataset of Ozone Profiles
(MEGRIDOP)

Sofieva, Viktoria; Szeląg, Monika E.; Tamminen, J.; Kyrölä, E.; Degenstein, D. A.; Roth, Chris; Zawada, Daniel; Rozanov, A.; Arosio, Carlo; Burrows, John P.; Weber, Mark; Laeng, Alexandra; Stiller, G. P.; Clarmann, T. von; Froidevaux, L.; Livesey, N. J.; Roozendaël, Michel Van; Retscher, Christian

doi:10.5194/acp-2020-1117

Cited by 6 publications

(9 citation statements)

References 20 publications

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“…Both changes are consistent with the positive tropical trend from 30 to 35 km and the near zero zonal mean Arctic trend at 35 km for 2004–2018 reported by Sofieva et al. (2021). Both the observations and simulation show QD O 3 decreases from 20° to 50°S, 20–7 hPa where the QD O 3 P‐L is near zero.…”

Section: Dynamically Driven Changes In O3 Loss Cycles and O3 Impactssupporting

confidence: 92%

Faster Tropical Upper Stratospheric Upwelling Drives Changes in Ozone Chemistry

Strahan

Coy

Douglass

et al. 2022

Geophysical Research Letters

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Total column O 3 trends are used to identify ozone layer recovery and assess the Montreal Protocol's impact, but attributing their cause can be difficult because many processes affect O 3 and the process balance changes with altitude. Below 28 km, O 3 is predominantly controlled by transport because of its relatively long photochemical lifetime, but above, chemistry becomes increasingly important (Chipperfield et al., 1994). Gas phase stratospheric O 3 loss from 50 to 2 hPa (20-44 km) is predominantly controlled by the chemically reactive chlorine and nitrogen families, ClO x (Cl, Cl 2 , ClO, (ClO) 2 , OClO, and HOCl) and NO x (NO, NO 2 , NO 3 , and N 2 O 5 ) (Brasseur et al., 1999). NO x is responsible for 50%-80% of O 3 loss from ∼30 to 5 hPa but decreases in importance above as loss by ClO x increases to 30%-40% near 2 hPa; loss by HO x dominates above 2 hPa. Nitrous oxide (N 2 O), emitted at the surface, reacts with O 1 D in the tropical middle and upper stratosphere and is the primary source of NO x . NO y is the sum of reactive (NO x ) and reservoir nitrogen species (HNO 3 and ClONO 2 ); it behaves like a long-lived trace gas. Chlorofluorocarbons (CFCs), emitted at the surface and photolyzed in the stratosphere, are the primary sources of ClO x . Most of the chlorine released forms the relatively unreactive reservoir species, HCl and ClONO 2 , which then become sources for ClO x radicals involved in ozone loss cycles.Tropospheric trends in long-lived source gases cause trends in O 3 through changes in their reactive product gases. Stratospheric O 3 is expected to increase because chlorine from manmade chlorocarbons has been declining at ∼5%/decade since 2000 due to the Montreal Protocol (Engel et al., 2018), but the 3.0%/decade increase in tropospheric N 2 O (Lan et al., 2020) offsets some of that increase; stratospheric cooling reduces O 3 loss by NO x,

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Section: Dynamically Driven Changes In O3 Loss Cycles and O3 Impactssupporting

confidence: 92%

Faster Tropical Upper Stratospheric Upwelling Drives Changes in Ozone Chemistry

Strahan

Coy

Douglass

et al. 2022

Geophysical Research Letters

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“…The NOAA-19 component for 2011 to 2013 has been reprocessed since the LOTUS19 report with enhanced calibrations but no algorithm change, and OMPS-NPP extends the data from 2014 to 2020. For better comparison with ground-based datasets, we also use the new MErged GRIdded Dataset of Ozone Profiles (MEGRIDOP) record (Sofieva et al, 2021). This dataset has a resolved longitudinal structure and is derived by merging six limb and occultation satellite datasets (GOMOS, SCIAMACHY and MIPAS on Envisat, OSIRIS, OMPS-LP, and Aura MLS), using a similar methodology as for SAGE-CCI-OMPS (Sofieva et al, 2021).…”

Section: Merged Satellite Recordsmentioning

confidence: 99%

“…In the lower and middle stratosphere, negative trends were found in the tropics during all seasons, along with trends of varying sign depending on the season in the northern and southern midlatitudes. Another study by Sofieva et al (2021) evaluated regional trends from the new MErged GRIdded Dataset of Ozone Profiles (MEGRIDOP) that combines ozone profile data from six limb-viewing satellite instruments. Zonal trend estimates agreed with previously published results.…”

Section: Introductionmentioning

confidence: 99%

Updated trends of the stratospheric ozone vertical distribution in the 60° S–60° N latitude range based on the LOTUS regression model

et al. 2022

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Abstract. This study presents an updated evaluation of stratospheric ozone profile trends in the 60∘ S–60∘ N latitude range over the 2000–2020 period using an updated version of the Long-term Ozone Trends and Uncertainties in the Stratosphere (LOTUS) regression model that was used to evaluate such trends up to 2016 for the last WMO Ozone Assessment (2018). In addition to the derivation of detailed trends as a function of latitude and vertical coordinates, the regressions are performed with the datasets averaged over broad latitude bands, i.e. 60–35∘ S, 20∘ S–20∘ N and 35–60∘ N. The same methodology as in the last assessment is applied to combine trends in these broad latitude bands in order to compare the results with the previous studies. Longitudinally resolved merged satellite records are also considered in order to provide a better comparison with trends retrieved from ground-based records, e.g. lidar, ozonesondes, Umkehr, microwave and Fourier transform infrared (FTIR) spectrometers at selected stations where long-term time series are available. The study includes a comparison with trends derived from the REF-C2 simulations of the Chemistry Climate Model Initiative (CCMI-1). This work confirms past results showing an ozone increase in the upper stratosphere, which is now significant in the three broad latitude bands. The increase is largest in the Northern and Southern Hemisphere midlatitudes, with ∼2.2 ± 0.7 % per decade at ∼2.1 hPa and ∼2.1 ± 0.6 % per decade at ∼3.2 hPa respectively compared to ∼1.6 ± 0.6 % per decade at ∼2.6 hPa in the tropics. New trend signals have emerged from the records, such as a significant decrease in ozone in the tropics around 35 hPa and a non-significant increase in ozone in the southern midlatitudes at about 20 hPa. Non-significant negative ozone trends are derived in the lowermost stratosphere, with the most pronounced trends in the tropics. While a very good agreement is obtained between trends from merged satellite records and the CCMI-1 REF-C2 simulation in the upper stratosphere, observed negative trends in the lower stratosphere are not reproduced by models at southern and, in particular, at northern midlatitudes, where models report an ozone increase. However, the lower-stratospheric trend uncertainties are quite large, for both measured and modelled trends. Finally, 2000–2020 stratospheric ozone trends derived from the ground-based and longitudinally resolved satellite records are in reasonable agreement over the European Alpine and tropical regions, while at the Lauder station in the Southern Hemisphere midlatitudes they show some differences.

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“…The largest biases (up to 10 %) are observed in the tropical lowermost stratosphere as well as polar latitudes. However, these largest differences in the tropical lowermost stratosphere (and upper troposphere) cannot be correctly validated as most satellite retrievals show largest uncertainties in this region (Rahpoe et al, 2015;Steinbrecht et al, 2017;Sofieva et al, 2021). Similarly, for the non-MLS period, the biases in the polar stratosphere could be due to the lack of observational ozone profiles during polar night.…”

Section: Comparison With Pressure Level Datamentioning

confidence: 98%

ML-TOMCAT: machine-learning-based satellite-corrected global stratospheric ozone profile data set from a chemical transport model

Dhomse

Arosio

Feng

et al. 2021

Earth Syst. Sci. Data

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Abstract. High-quality stratospheric ozone profile data sets are a key requirement for accurate quantification and attribution of long-term ozone changes. Satellite instruments provide stratospheric ozone profile measurements over typical mission durations of 5–15 years. Various methodologies have then been applied to merge and homogenise the different satellite data in order to create long-term observation-based ozone profile data sets with minimal data gaps. However, individual satellite instruments use different measurement methods, sampling patterns and retrieval algorithms which complicate the merging of these different data sets. In contrast, atmospheric chemical models can produce chemically consistent long-term ozone simulations based on specified changes in external forcings, but they are subject to the deficiencies associated with incomplete understanding of complex atmospheric processes and uncertain photochemical parameters. Here, we use chemically self-consistent output from the TOMCAT 3-D chemical transport model (CTM) and a random-forest (RF) ensemble learning method to create a merged 42-year (1979–2020) stratospheric ozone profile data set (ML-TOMCAT V1.0). The underlying CTM simulation was forced by meteorological reanalyses, specified trends in long-lived source gases, solar flux and aerosol variations. The RF is trained using the Stratospheric Water and OzOne Satellite Homogenized (SWOOSH) data set over the time periods of the Microwave Limb Sounder (MLS) from the Upper Atmosphere Research Satellite (UARS) (1991–1998) and Aura (2005–2016) missions. We find that ML-TOMCAT shows excellent agreement with available independent satellite-based data sets which use pressure as a vertical coordinate (e.g. GOZCARDS, SWOOSH for non-MLS periods) but weaker agreement with the data sets which are altitude-based (e.g. SAGE-CCI-OMPS, SCIAMACHY-OMPS). We find that at almost all stratospheric levels ML-TOMCAT ozone concentrations are well within uncertainties of the observational data sets. The ML-TOMCAT (V1.0) data set is ideally suited for the evaluation of chemical model ozone profiles from the tropopause to 0.1 hPa and is freely available via https://doi.org/10.5281/zenodo.5651194 (Dhomse et al., 2021).

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Measurement report: Regional trends of stratospheric ozone evaluated using the MErged GRIdded Dataset of Ozone Profiles (MEGRIDOP)

Cited by 6 publications

References 20 publications

Faster Tropical Upper Stratospheric Upwelling Drives Changes in Ozone Chemistry

Faster Tropical Upper Stratospheric Upwelling Drives Changes in Ozone Chemistry

Updated trends of the stratospheric ozone vertical distribution in the 60° S–60° N latitude range based on the LOTUS regression model

ML-TOMCAT: machine-learning-based satellite-corrected global stratospheric ozone profile data set from a chemical transport model

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