the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
MIPAS ozone retrieval version 8: middle atmosphere measurements
Maya García-Comas
Bernd Funke
Thomas von Clarmann
Norbert Glatthor
Udo Grabowski
Sylvia Kellmann
Michael Kiefer
Alexandra Laeng
Andrea Linden
Gabriele P. Stiller
Abstract. We present a new version of O3 data retrieved from the three MIPAS observations modes of the middle atmosphere (MA, UA and NLC). The O3 profiles cover altitudes from 20 up to 100 km altitudes for daytime and up to 105 km at nighttime, for all latitudes, and the period 2005 until 2012. The data has been obtained with the IMK–IAA MIPAS level 2 data processor and are based on ESA version 8 re-calibrated radiance spectra with improved temporal stability. The processing included several improvements with respect to the previous version, such as the consistency of the microwindows and spectroscopic data with those used in the nominal mode V8 data, the O3 a priori profiles, and updates of the non-LTE parameters and of the nighttime atomic oxygen. Random errors are dominated by the measurement noise with 1σ values for single profiles for daytime of <5 % below ~60 km, 5–10 % between 60 and 70 km, 10–20 % at 70–90 km and about 30 % at 95 km. For nighttime, they are very similar below 70 km but smaller above (10–20 % at 75–95 km, 20–30 % at 95–100 km and larger than 30 % above 100 km). The systematic error is ~6 % below ~60 km (dominated by uncertainties in spectroscopic data), and 8–12 % above ~60 km, mainly caused by non-LTE uncertainties. The systematic errors in the 80–100 km range are significantly smaller than in the previous version. The major differences with respect to the previous version are: 1) The new retrievals provide O3 abundances in the 20–50 km altitude range larger by about 2–5 % (0.2–0.5 ppmv); 2) O3 abundances reduced by ~2–4 % between 50 and 60 km in the tropics and mid-latitudes; 3) reduced O3 abundances in the nighttime O3 minimum just below 80 km, leading to a more realistic diurnal variation; 4) larger daytime O3 concentrations in the secondary maximum at the tropical and mid-latitudes (~40 %, 0.2–0.3 ppmv); and 5) nighttime O3 abundances in the secondary maximum reduced by 10–30 %. The O3 profiles retrieved from the nominal mode (NOM) and the middle atmosphere modes are fully consistent in their common altitude range (20–70 km). Only at 60–70 km daytime O3 of NOM seems to be larger than that of MA/UA by 2–10 %. Compared to other satellite instruments, MIPAS seems to have a positive bias of 5–8 % below 70 km. Noticeably, the new version of MIPAS agrees much better than before with all instruments in the upper mesosphere/lower thermosphere, reducing the differences from ~ ±20 % to ~ ±10 %. Further, the diurnal variation of O3 in the upper mesosphere (near 80 km) has been significantly improved.
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Manuel López-Puertas et al.
Status: final response (author comments only)
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RC1: 'Comment on amt-2023-118', Chris Boone, 07 Jul 2023
This paper seems quite thorough and generally well written, except for a few patches where the English usage could be improved (discussed below). Detailed comments are provided below, none of them particularly concerning.
> Line 60: “…we have maintained the same retrieval setup as in the O3 NOM dataset A comparison…”
Missing period after ‘dataset’
> Line 106: “…along the LOS.”
The acronym LOS is not defined.
> Line 150: “and the apodization of calculated spectra used a wider frequency range.”
What apodization is being used?
> Line 201: Daytime
No numbering on the subsection. Same for line 213 (Nighttime)
> Line 255: “The updated figures for version V8 are shown in Sec. D.”
Appendix D
> Line 268: “data with smaller values are considered non-trustful”
…non-trustworthy
> Line 309: missing paragraph indent
> Line 369: “…information on the confidence limits of the error margins…”
I cannot decipher what this means. Are you saying some uncertainties (e.g., for intensities) are unavailable, or you don’t know if the errors provided are 1-sigma or 2-sigma, or something else?
> Line 333: “The uncertainties of the spectrally interfering molecules with ozone which are not jointly fitted (e.g. as in the case of water vapour), as well as their vertical covariances, are estimated from the error covariance matrices of previous MIPAS data version V5.”
I do not see anywhere an indication of which interferers (other than H2O and a passing mention of CO2 laser lines) are being included in the analysis.
> Line 382: “…requires in the photochemical model described above…”
required
> Line 382: “…was estimated in 7%.”
in -> to be
> Line 384: “…ingoing uncertainties affecting the retrieval were reported…”
Perhaps “…various contributions to retrieval uncertainties were reported …”? Starting in the last few paragraphs, the level of English seems worse than the text up to that point. The issue continues for this section (4.2). I will provide no further specific comments on English usage, but I would suggest this section be rewritten to improve grammar and phrasing. The level of English improves again following this section, although Section 6 could also use a mild rewrite for English usage.
> Line 395: “In the figures…”
In Fig. 5
> Line 396: “T-LOS”
Terminology is not used consistently. Sometimes T-LOS, sometimes T+LOS (in the figures), sometimes TLOS. It is not made clear that LOS refers to the line of sight and relates to the tangent altitude determination.
> Line 410: “(so-called “headache errors” (see von Clarmann et al., 2022).”
unmatched parentheses
> Page 21, caption to Figure 7: Titles on the leftmost panels explicitly assume m = 5, MA measurements (i.e., they indicate 561-522), and the caption assumes m=5 for V8 (V8 561) but leaves m as a variable elsewhere. This creates some confusion. Are you comparing V8 MA results only to MA results from V5 or to results from all other V5 measurement modes? The same question applies to Figure 8.
> Figure 7: The color scale for the rightmost panels extends from -10 to +10 %, but there are contours in the plots labeled as 20 and -20. Is the expectation that the reader will mentally extrapolate the color scale (e.g., brighter red means even more positive)?
> Line 566: “…the differences are caused by inconsistencies between the spectroscopic data in those spectral regions.”
It has been shown that O3 intensities in HITRAN 2016 (the basis of ACE v4 retrievals) are too weak by about 3% (doi:10.1016/J.JQSRT.2019.01.004), consistent with this assumption.
> Line 620: “…Microwindows and spectroscopic data were also update in order to be consitent…
update -> updated, consitent -> consistent
> Line 666: data availability should probably include all the data plotted in the paper: MLS, ACE-FTS, SMILES, etc. Some links are provided in the text but are more appropriately listed here. ACE-FTS has no data availability information provided. The link provided for MLS is broken.
Citation: https://doi.org/10.5194/amt-2023-118-RC1 -
AC1: 'Reply on RC1', Manuel López-Puertas, 11 Sep 2023
The comment was uploaded in the form of a supplement: https://amt.copernicus.org/preprints/amt-2023-118/amt-2023-118-AC1-supplement.pdf
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AC1: 'Reply on RC1', Manuel López-Puertas, 11 Sep 2023
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RC2: 'Comment on amt-2023-118', Anonymous Referee #2, 07 Aug 2023
Referee Comments, 7 August 2023
MIPAS ozone retrieval version 8: middle atmosphere measurements
By Lopez-Puertas et al.Summary
The paper presents an update to the high-altitude ozone measurements retrieved
using the MIPAS/Envisat instrument between 2002-2012. The update makes use of
recalibrated L1B spectra as well as several modifications to the non-LTE
retrieval scheme. Apart from describing the changes to the processing, the paper
presents a revised, TUNER-compliant, error budget.The paper also updates a useful intercomparison exercise involving five other
instruments and their latest data versions, which could have been a
separate paper in itself.The authors appear to have been careful and thorough, and the paper is
essentially publishable as it stands.I have just one significant concern which is the ad-hoc adjustment of
the k3 chemical quenching reaction rate (L187-189) which seems to have
been largely on the basis of bringing the retrieved O3 more into line
with other instruments. While this is not unreasonable, I would like
this highlighted in the abstract so that future researchers, perhaps
also with similarly high O3 measurements, will not automatically assume that
they must be incorrect since it disagrees with all previous results.Other than that my comments are minor and typographical, as follows.
Minor comments
1) L32: Rather than 'ample', it would be more informative to give the actual
spectral range.2) L51-52: It would be helfpul to have a table giving the details of
the scan patterns used for these three modes (which could, for
example, incorporate additional information such as total number of
days of each and horizontal spacing). Also instead of L81-83.3) I found the nomenclature for the different versions of L1b and the
ozone product inconsistent and confusing. Eg L74 implies
that 'V8' is being used to refer to L1B v8.03 and in the next line
it is also referred to as 'V8R'. Similarly does V5 refer to L1B or O3?.
L79 then refers to O3 'version 7' but it is unclear which L1B data is used.
It is not helped by varying references to 'L1b', 'level 1b' and 'level-1b'
and 'level 1' data. L92-93 - again unclear whether V8R, V5R refer to
L1b or ozone products. Some figure captions (7,8) also revert to long
notation.4) Is a '2-points horizontal temperature gradient' the same as a 'linear
temperature gradient' ?5) L111-112: this is confusing. Do you mean that the offset is assumed to
be same for all microwindows in each band, with just altitude variation?
This seems a strange assumption given that the offset is presumably of
unknown origin and therefore probably has some spectral dependence.
Anyway, please rephrase more clearly. Also, there should be some
definition within this paper (eg Table A1) of the spectral ranges of the A
and AB bands.6) The spectral structure that the forward model is required to resolve is
the Doppler broadened O3 line. It would be useful to have this mentioned
at this point, along with a value for this.
I didn't understand what you meant by the grid for absorption cross-sections
- I assumed this would be the forward model grid, but if not that suggests
some further interpolation is required (and the figure 0.00097656... seems
oddly specific - is there a reason for this number?)
By my calculation the 0.001cm-1 grid resolution just matches
the O3 Doppler half-width, so I'm slightly surprised this is adequate unless
your grid is adapted to the line-centres rather than a fixed grid.7) I may be wrong, but if your Tikhonov regularisation is applied to the shape
of the VMR profile then it seems it would change the total ozone amount
retrieved due to the non-linearity between VMR and partial column amount,
even if the regularisation maintains the same average local VMR value.8) Table 1: it would be clearer to put the actual rate constants in this table,
along with assumed uncertainties used in the error budget.9) Eq 1 shows the k2 reaction being neglected but the text seems to refer to
this reaction simply as 'chemical production', which seems an obscure way
of referring to it.10) L406. Does this mean by two 'identical' instruments? which includes
calibration errors, forward model assumptions etc. In that case errors
due to interfering species would also be the same, so not contribute to
the random error.Typography/Grammar
General comment: frequent use of hyphen (-) rather than en-dash (-- in LaTeX)
to indicate a range of numbers.L2: Unecessary repetition of 'altitudes' in same sentence.
L3: 'data' used as both singular and plural in same sentence.
L2: 'data' omitted after 'MIPAS'.
L27: I think you can, eg, 'provide a review' but not 'report a review'
L28: Superfluous comma after 'measurements'.
L40: Might be less confusing just to say 'latter' rather than 'latter three'.
L46: 'middle/atmosphere' - presumably 'middle/upper atmosphere'.
L55: I think 'respects' sounds more conventional than 'aspects'
L61: Missing '.' after dataset.
L143: 'is the concentrations' doesn't sound right. Perhaps 'is the handling
of the concentrations' ...L178: Did you really mean 'e.g.' here? Or should it be 'i.e.'? In other words,
are there species other than O and H?L180: Here you give O3(v1,v2,v3) but elsewhere you only refer to O3(v1,v3).
Is that intentional?Fig 1: 'solstice' would better describe NDJ rather than DJF, similarly
'equinox'.
L221 & 253: 'night-time' (no hyphen when used elsewhere)L279/280: 'in Clarmann2022)' - missing 'von ... et al ('
L310: I'm not sure 'notoriously' is the right word to use here. Maybe just
'notably' or 'significantly'.L311: 'so is' should go before 'MIPAS sensitivity'.
L322: '0.00029' - oddly specific, particularly for an error estimate. Perhaps
better just rounded to 0.0003?L368: 'as it was required' ? perhaps 'as would be required' was meant.
L410: Extra ')' required.
L485: 'not in vain' - not sure what this means here, perhaps just remove it
and the bracketed phrase still makes sense).L620: 'consistent' (spelling).
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Citation: https://doi.org/10.5194/amt-2023-118-RC2 -
AC2: 'Reply on RC2', Manuel López-Puertas, 11 Sep 2023
The comment was uploaded in the form of a supplement: https://amt.copernicus.org/preprints/amt-2023-118/amt-2023-118-AC2-supplement.pdf
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AC2: 'Reply on RC2', Manuel López-Puertas, 11 Sep 2023
Manuel López-Puertas et al.
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