the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 23 Nov 2023
No severe ozone depletion in the tropical stratosphere in recent decades
Abstract. Stratospheric ozone is an important constituent of the atmosphere. Significant changes in its concentrations have great consequences for the environment in general and for ecosystems, in particular. Here, we analyse ground-based, ozonesonde and satellite ozone measurements, and reanalysis data to examine the ozone depletion in the tropics, and the spatiotemporal trends in ozone during the past five decades (1980–2020). In the tropics, the amount of column ozone is small (250–270 DU) compared to high and mid-latitudes. In addition, the tropical total ozone trend is very small (±0–0.2 DU/yr), compared to high (±1–1.5 DU/yr) and mid-latitudes (±0.75–1 DU/yr) of both hemispheres as estimated for the period 1998–2018. No measurements and no analyses show any signature of severe stratospheric ozone depletion in the tropics in contrast to a recent claim. Finally, it is very unlikely that an ozone hole would occur outside the Antarctic today with respect to the current stratospheric halogen levels.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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Supplement
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1670 KB) - Metadata XML
-
Supplement
(2440 KB) - BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2023-2574', Anonymous Referee #1, 11 Dec 2023
See attached document for detailed comments. The paper is suitable for publication in ACP but its presentation needs a bit of work.
- AC1: 'Reply on RC1', Jayanarayanan Kuttippurath, 25 Mar 2024
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RC2: 'New insights from the paper is missing', Anonymous Referee #2, 06 Jan 2024
Overall
This paper reports on stratospheric ozone trends in the tropical
region and is motivated by the recent claim by Lu (2022a, 2002b) that
a tropical ozone hole exists. A rebuttal to the paper by Lu was
published by Chipperfield et al. (2022) that argued that this claim is
not substantiated by observations and that the interpretation of galactic
cosmic rays (GCR) being a cause for this severe loss is highly unlikely.This paper confirms that there are only small tropical ozone changes
observed in the tropics over the last decades supporting the arguments
given in the rebuttal by Chipperfield et al. So far so good. My issue
with the paper is that it is not clear to me what new insights are
provided here. The small trends in the tropics have been reported
before (WMO 2022, Weber et al. 2022, Godin-Beekmann et al. 2022). I
also do not see what new arguments are delivered here with resepct to
what has been already reported by Chipperfield et al. in response to
Lu (2022).The authors need to state clearly what new aspects are brought in here
that justifies publication of this paper. A major revision is required.Other major issues
* Various ozone and reanalysis data are used in this study and trends
calculated from them. Apparently not all datasets have been updated
to end of 2022. MERRA-2, ERA5, GSG, and SBUV/OMPS MOD data are
available up to end of 2022. Stratospheric ozone trends from
GOZCARDS, SWOOSH, and reanalysis data are only shown up to 2018, why
not up to end of 2022?* To make the paper more concise (and probably shorter), the authors
should try to focus on trends in the tropical region (see paper
title), rather than global and extratropical regions, which are
extensively discussed here.* The regression model used is poorly described. It is pretty much
standard that ozone trends are derived using multiple linear
regression (MLR) that contain additional terms (proxies) describing
ozone variability (e.g. WMO 2022, Weber et al. 2022, Godin-Beekmann
et al. 2022). What is the justification for not using MLR? A
comparison between MLR (previous work) and simple linear regression
results (this work) may become difficult.Minor issues
There are many rather minor issues, but are not summarised here. They
may be reviewed after a major revision.References
Lu, Q.-B., Response to “Comment on ‘Observation of large and
all-season ozone losses over the tropics’” AIP Adv., 12, 075006
(2022)], doi: 10.1063/5.0129344, 2022b.Citation: https://doi.org/10.5194/egusphere-2023-2574-RC2 - AC2: 'Reply on RC2', Jayanarayanan Kuttippurath, 25 Mar 2024
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2023-2574', Anonymous Referee #1, 11 Dec 2023
See attached document for detailed comments. The paper is suitable for publication in ACP but its presentation needs a bit of work.
- AC1: 'Reply on RC1', Jayanarayanan Kuttippurath, 25 Mar 2024
-
RC2: 'New insights from the paper is missing', Anonymous Referee #2, 06 Jan 2024
Overall
This paper reports on stratospheric ozone trends in the tropical
region and is motivated by the recent claim by Lu (2022a, 2002b) that
a tropical ozone hole exists. A rebuttal to the paper by Lu was
published by Chipperfield et al. (2022) that argued that this claim is
not substantiated by observations and that the interpretation of galactic
cosmic rays (GCR) being a cause for this severe loss is highly unlikely.This paper confirms that there are only small tropical ozone changes
observed in the tropics over the last decades supporting the arguments
given in the rebuttal by Chipperfield et al. So far so good. My issue
with the paper is that it is not clear to me what new insights are
provided here. The small trends in the tropics have been reported
before (WMO 2022, Weber et al. 2022, Godin-Beekmann et al. 2022). I
also do not see what new arguments are delivered here with resepct to
what has been already reported by Chipperfield et al. in response to
Lu (2022).The authors need to state clearly what new aspects are brought in here
that justifies publication of this paper. A major revision is required.Other major issues
* Various ozone and reanalysis data are used in this study and trends
calculated from them. Apparently not all datasets have been updated
to end of 2022. MERRA-2, ERA5, GSG, and SBUV/OMPS MOD data are
available up to end of 2022. Stratospheric ozone trends from
GOZCARDS, SWOOSH, and reanalysis data are only shown up to 2018, why
not up to end of 2022?* To make the paper more concise (and probably shorter), the authors
should try to focus on trends in the tropical region (see paper
title), rather than global and extratropical regions, which are
extensively discussed here.* The regression model used is poorly described. It is pretty much
standard that ozone trends are derived using multiple linear
regression (MLR) that contain additional terms (proxies) describing
ozone variability (e.g. WMO 2022, Weber et al. 2022, Godin-Beekmann
et al. 2022). What is the justification for not using MLR? A
comparison between MLR (previous work) and simple linear regression
results (this work) may become difficult.Minor issues
There are many rather minor issues, but are not summarised here. They
may be reviewed after a major revision.References
Lu, Q.-B., Response to “Comment on ‘Observation of large and
all-season ozone losses over the tropics’” AIP Adv., 12, 075006
(2022)], doi: 10.1063/5.0129344, 2022b.Citation: https://doi.org/10.5194/egusphere-2023-2574-RC2 - AC2: 'Reply on RC2', Jayanarayanan Kuttippurath, 25 Mar 2024
Peer review completion
Journal article(s) based on this preprint
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Jayanarayanan Kuttippurath
Gopalakrishna Pillai Gopikrishnan
Rolf Müller
Sophie Godin-Beekmann
Jerome Brioude
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1670 KB) - Metadata XML
-
Supplement
(2440 KB) - BibTeX
- EndNote
- Final revised paper