Geometric estimation of volcanic eruption column height from GOES-R near-limb imagery – Part 1: Methodology

Horváth, Ákos; Carr, James L.; Girina, Olga A.; Wu, Dong L.; Bril, Alexey A.; Mazurov, Alexey A.; Melnikov, Dmitry V.; Hoshyaripour, Gholam Ali; Buehler, Stefan A.

doi:https://doi.org/10.5194/acp-21-12189-2021

Articles | Volume 21, issue 16

https://doi.org/10.5194/acp-21-12189-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Satellite observations, in situ measurements and model simulations...

https://doi.org/10.5194/acp-21-12189-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 21, issue 16

Research article

|

16 Aug 2021

Research article |

| 16 Aug 2021

Geometric estimation of volcanic eruption column height from GOES-R near-limb imagery – Part 1: Methodology

Ákos Horváth, James L. Carr, Olga A. Girina, Dong L. Wu, Alexey A. Bril, Alexey A. Mazurov, Dmitry V. Melnikov, Gholam Ali Hoshyaripour, and Stefan A. Buehler

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Final revised paper (published on 16 Aug 2021)
Supplement to the final revised paper
Preprint (discussion started on 23 Mar 2021)
Supplement to the preprint

Interactive discussion

Status: closed

RC1:
'Comment on acp-2021-155', Anonymous Referee #1, 03 Jun 2021
General comments:

The authors present a geometric methodology for estimating the height of volcanic clouds using the near-limb portion of geostationary imagery. I think the manuscript is really very clear and detailed. This methodology is interesting and seems to provide good results.

Unfortunately, as pointed out by the authors themselves, this geometric method is not applicable in all cases:

Only volcanoes in near-limb position

Only daytime images and nearly vertical columns near the vent

Pixels indicating the top of the cloud are chosen by visual inspection (difficult to automate, not in near-real time)

Anyway the method can be surely a useful complementary to established techniques.

Specific comments:

Row 40: just a comment to say that obviously the temperature profile can be obtained not only from a numerical forecast but also, for example, from a reliable measurement such as radiosounding if available in space and time concomitance with the eruption. Since we are here in the introduction of the paper, I would give a more general explanation to the BT method.

I have no other specific comments: the methodology is well presented and therefore clear enough even for those who do not have specific knowledge of the problems related to the geometry of satellite images. The validation with the altitude of the mountain peaks shows excellent results. The figures are ok.
Citation: https://doi.org/10.5194/acp-2021-155-RC1
RC2: 'Comment on acp-2021-155', Anonymous Referee #2, 16 Jun 2021

“Geometric estimation of volcanic eruption column height from GOES-R near-limb imagery – Part 1: Methodology” is a very interesting manuscript presenting a relatively simple method with good accuracy for estimating the top height of volcanic clouds. Considering that there are a few geostationary satellites available, it is possible to observe Etna, as an example of a well studied volcano, from Meteosat over Indian Ocean with the proposed technique.

The manuscripts seem at first sight a little bit long, but there are no repeating parts, everything is written with a high level of detail. From the structure and the language point of view, I have not many comments. The only thing I would like to address is the conclusion - at the moment it seems more like a summary to me, make it more concise - focus on your scientific contribution and a relation to part 2.

Besides some minor remarks, just below, I have no further major comments, thus I suggest publishing the manuscript after technical correction.

Section 3.2. What about the case when the volcanic cloud contains a lot of “topography”? Then measuring the length from the side considered only the height of the side of the cloud.

Your list of references is good, but considering your geometric approach, I would suggest adding:

https://www.mdpi.com/2072-4292/11/7/785

https://www.sciencedirect.com/science/article/abs/pii/S0034425718300737

Citation: https://doi.org/10.5194/acp-2021-155-RC2
AC1: 'Comment on acp-2021-155', Akos Horvath, 02 Jul 2021

We thank the Referees for their constructive comments. In the following, we give a point-by-point response to each of the issues raised.
Referee #1

Row 40: just a comment to say that obviously the temperature profile can be obtained not only from a numerical forecast but also, for example, from a reliable measurement such as radiosounding if available in space and time concomitance with the eruption. Since we are here in the introduction of the paper, I would give a more general explanation to the BT method.
We have modified the sentence to state that the temperature profile can be obtained from a radiosounding or a numerical forecast.
Referee #2

The only thing I would like to address is the conclusion - at the moment it seems more like a summary to me, make it more concise - focus on your scientific contribution and a relation to part 2.
We have made the Summary more concise by removing discussion not strictly pertinent to the presented methodology. We have also added a segue into Part 2.
Section 3.2. What about the case when the volcanic cloud contains a lot of “topography”? Then measuring the length from the side considered only the height of the side of the cloud.
We have added a sentence to the first paragraph of section 3.2, noting that for a significantly bumpy plume top the surface-measured shadow length leads to height underestimation, because the highest plume point might cast its shadow on the lower and wider parts of the plume itself.
Your list of references is good, but considering your geometric approach, I would suggest adding:

https://www.mdpi.com/2072-4292/11/7/785

https://www.sciencedirect.com/science/article/abs/pii/S0034425718300737
We have included the de Michele et al. (2019) and Zakšek et al. (2018) references in section 3.4, as suggested.

Citation: https://doi.org/10.5194/acp-2021-155-AC1

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

AR by Akos Horvath on behalf of the Authors (02 Jul 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (06 Jul 2021) by Peter Haynes

AR by Akos Horvath on behalf of the Authors (08 Jul 2021)

Short summary

We give a detailed description of a new technique to estimate the height of volcanic eruption columns from near-limb geostationary imagery. Such oblique angle observations offer spectacular side views of eruption columns protruding from the Earth ellipsoid and thereby facilitate a height-by-angle estimation method. Due to its purely geometric nature, the new technique is unaffected by the limitations of traditional brightness-temperature-based height retrievals.