Improved water vapour retrieval from AMSU-B and MHS in the Arctic

Triana-Gómez, Arantxa M.; Heygster, Georg; Melsheimer, Christian; Spreen, Gunnar; Negusini, Monia; Petkov, Boyan H.

doi:https://doi.org/10.5194/amt-13-3697-2020

Articles | Volume 13, issue 7

https://doi.org/10.5194/amt-13-3697-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/amt-13-3697-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 13, issue 7

Research article

|

09 Jul 2020

Research article |

| 09 Jul 2020

Improved water vapour retrieval from AMSU-B and MHS in the Arctic

Arantxa M. Triana-Gómez, Georg Heygster, Christian Melsheimer, Gunnar Spreen, Monia Negusini, and Boyan H. Petkov

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Final revised paper (published on 09 Jul 2020)
Preprint (discussion started on 30 Jul 2019)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Referee comments', Anonymous Referee #1, 09 Oct 2019
- AC1: 'Authors response', Arantxa Triana, 21 Nov 2019
RC2: 'Review AMT-2019-253', Anonymous Referee #2, 23 Oct 2019
- AC2: 'Authors comments to Referee 2', Arantxa Triana, 21 Nov 2019

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Arantxa Triana on behalf of the Authors (21 Nov 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (26 Nov 2019) by Isaac Moradi

RR by Anonymous Referee #1 (16 Dec 2019)

RR by Anonymous Referee #3 (21 Jan 2020)

ED: Reconsider after major revisions (07 Feb 2020) by Isaac Moradi

AR by Arantxa Triana on behalf of the Authors (20 Mar 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (08 Apr 2020) by Isaac Moradi

RR by Anonymous Referee #1 (16 Apr 2020)

RR by Anonymous Referee #3 (21 Apr 2020)

Suggestions for revision or reasons for rejection

Second review of ‘Improved water vapour retrieval from AMSU-B/MHS in the Arctic’ by Triana-Gomez et al.

The authors are commended on their in-depth and thoughtful responses to the many comments and criticisms given by myself and the other reviewers in the previous round of peer review. My main hesitations about allowing this paper through toward publication in AMT have been allayed. The expansion of the analysis to include comparison with ERA5 makes it a much stronger paper, and its argument overall is much improved. The conclusions now better match the results presented, with the language more careful and exact. I have given below one small issue that I would like to see rectified, plus a few very minor textual comments, but I recommend that the paper be published and I do not require seeing it again. Thanks again to the authors for the excellent response and the improved manuscript.

A note on ERA5 section:
In the response to reviewers, the authors state that ERA5 is not an independent estimate of TWV due to its assimilation of some of the observations used as verification here, namely radiosondes. This is a key point, and it would be best if this were mentioned explicitly in the manuscript. I would suggest adding a paragraph to the beginning of Section 3.3 stating what the ERA5 reanalysis data represents, in that ERA5 assimilates radiosonde data, but also that it is a hybrid of model and observations. It is unfortunate that there is not yet a peer-reviewed overview paper of ERA5 and its satellite data usage specifically, but in this context it is worth mentioning that ERA5 does assimilate some 183GHz data over sea ice and snow-covered surfaces (see Table 1 in Bormann et al. 2017 for data usage in the IFS for a version quite similar to that used in ERA5). Specifically, the higher peaking MHS channels are currently assimilated over such surfaces (see link below for real-time example), and some SSMIS 183GHz (F-17) data have been assimilated over snow and sea ice for several years now. It is unclear from the documentation exactly which sensors would’ve been available and assimilated within ERA5 in the specific months analysed in this study. However, this may provide useful context for readers, in that ERA5 estimates of TWV are neither independent of radiosondes nor entirely independent of microwave humidity sounder radiances. I don’t think this does or should change any of the authors’ conclusions, but it is important to note.

Bormann et al. paper: https://www.ecmwf.int/sites/default/files/elibrary/2017/17674-assessment-forecast-impact-suface-sensitive-microwave-radiances-over-land-and-sea-ice.pdf
Link for current MHS data usage in the IFS: https://www.ecmwf.int/en/forecasts/charts/obstat/mhs_allsky_mhs_allsky__geo_0001_plot_o_geo_mhs_allsky_mhs_allsky?facets=Category,Satellite%20Data%3BInstrument,SSMIS&time=2020041800&Satellite=METOP-B&Channel=4&Data=STDV%20Obs&Flag=Used

Minor comments:
P9 L24: Typo or missing text: ‘ow’
Fig. 8: Change ‘AMSU’ on y-axis title to ‘AMSU-B’

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ED: Publish subject to minor revisions (review by editor) (21 Apr 2020) by Isaac Moradi

AR by Arantxa Triana on behalf of the Authors (01 May 2020) Author's response Manuscript

ED: Publish as is (09 May 2020) by Isaac Moradi

AR by Arantxa Triana on behalf of the Authors (17 May 2020)

Short summary

In the Arctic, in situ measurements are sparse and standard remote sensing retrieval methods have problems. We present advances in a retrieval algorithm for vertically integrated water vapour tuned for polar regions. In addition to the initial sensor used (AMSU-B), we can now also use data from the successor instrument (MHS). Additionally, certain artefacts are now filtered out. Comparison with radiosondes shows the overall good performance of the updated algorithm.