Organization of convective ascents in a warm conveyor belt

Blanchard, Nicolas; Pantillon, Florian; Chaboureau, Jean-Pierre; Delanoë, Julien

doi:https://doi.org/10.5194/wcd-1-617-2020

Articles | Volume 1, issue 2

https://doi.org/10.5194/wcd-1-617-2020

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

https://doi.org/10.5194/wcd-1-617-2020

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

Articles | Volume 1, issue 2

Research article

|

20 Oct 2020

Research article |

| 20 Oct 2020

Organization of convective ascents in a warm conveyor belt

Nicolas Blanchard, Florian Pantillon, Jean-Pierre Chaboureau, and Julien Delanoë

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Final revised paper (published on 20 Oct 2020)
Preprint (discussion started on 24 Jun 2020)

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

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RC1: 'Review of wcd-2020-25', Anonymous Referee #1, 23 Jul 2020
- AC1: 'Response to Referee #1', Jean-Pierre Chaboureau, 07 Sep 2020
RC2: 'Review of ‘Organization of convective ascents in a warm conveyor belt’ by Nicolas Blanchard, Florian Pantillon, Jean-Pierre Chaboureau, and Julien Delanoë', Anonymous Referee #2, 14 Aug 2020
- AC2: 'Response to Referee #2', Jean-Pierre Chaboureau, 07 Sep 2020

Peer-review completion

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

AR by Jean-Pierre Chaboureau on behalf of the Authors (07 Sep 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (19 Sep 2020) by Juerg Schmidli

RR by Anonymous Referee #2 (05 Oct 2020)

RR by Anonymous Referee #1 (06 Oct 2020)

For final publication, the manuscript should be

accepted as is

accepted subject to technical corrections

accepted subject to minor revisions

reconsidered after major revisions

I would be willing to review the revised paper, if the editor considers it necessary.

I am not willing to review the revised paper.

rejected

Suggestions for revision or reasons for rejection

1 General Comments
After the first review, the manuscript’s clarity and structure have improved
and my previous concerns and questions have been addressed. I appreciate the
additional comments and replies to my questions by the authors. I have a few
additional questions and specific comments, but I recommend the paper for
publication in Weather and Climate Dynamics.
• l. 21: typo ”continously” >> ”continuously”
• l. 25: ”PV” has not been introduced before. Please add potential vorticity
(PV) when the variable is first introduced.
• l. 91: typo ”an horizontal” >> ”a horizontal”
• l. 141: The ”grey” contours in Fig. 2 are now colored contours.
• l. 156: The authors could replace ”fly over” by ”observe”.
• l. 173: ”The specific value of the threshold has been set at a value equal to
that used by Oertel et al. (2019) for comparison purposes.” To my under-
standing, Oertel et al. (2019) used a higher threshold of 320 hPa (2h) −1
for convective ascent, following also Rasp et al. (2016) who mentioned a
threshold of 400 hPa in 2.5 h?
• l. 229: ”The large overlap in altitude between fast and slow ascents sug-
gests that convection is partly embedded in the slantwise flow, at least
where their location also overlap (Fig. 5)”. Could the authors please pro-
vide some more information where the spatial overlap occurs, as this is
difficult to directly see in Fig. 5.
• l. 230: type ”location” >> ”locations”
• l. 236: Please rephrase this part of the sentence ”(...) and greater along
anticyclonic than cyclonic trajectories”.
• l. 239: I think you here refer to Oertel et al. (2020).
• l. 240: ”This is consistent with the relatively low values of vertical ve-
locity.” I think the lower graupel content is ”due to” the reduced vertical
velocity. Hence, the lower graupel content might not necessarily be a
contrasting result, but rather a consequence of the differing ascent char-
acteristics of the chosen ascents.
• l. 248: Fig. 7b >> Fig. 7c.
• l. 249: Please replace ”under the dry intrusion” by ”below the dry intru-
sion”.
• l. 250: ”The most intense, with reflectivities greater than 15 dBZ suggest-
ing a convective origin, extends over a 20 km width.” The most intense
what? I think a word is missing here.
• l. 255: Fig. 7b >> Fig. 7c. General comment: The RASTA measurements
are referenced as Fig. 7/9b instead of (c) several times in the manuscript.
Please correct throughout.
• l. 297: Please rephrase this sentence: ”Under these high clouds are low
and middle layer clouds highlighted by larger, positive reflectivity values.”
• l. 305: I think Fig. 9c should be 9d.
• l. 336: ”Note that the three regions largely encompass the rapid segments
occurring in the vicinity of observations at 16:00 UTC.” I’m not quite
sure if I understand this correctly. Do you mean rapid segments in the
observations at 15 UTC, because the blue and yellow box are rather far
away from the observations at 16 UTC?
• l. 354ff: I appreciate the streamlining of the PV discussion. However, I do
not understand the decrease and subsequent increase of PV for mid-level
convection. Which processes lead to a decrease in PV along ascending
trajectories?
• l. 358: This is related to the above comment: ”Instead, the evolution at
mid levels is similar to that found by Oertel et al. (2020) for trajectories
passing through a region under convective influence.” Could the authors
please elaborate on that?
• l. 425-426: See comment to l. 173, about the threshold used by Rasp et
al. (2016) and Oertel et al. (2019).
• l. 455-458: As I understand Harvey et al. (2020) and Oertel et al. (2020),
localised heating results in quasi-horizontal PV dipoles located to either
side of the ascent region, but does not directly explain a decrease of PV
along ascending trajectories followed by an increase. Could the authors
please describe and discuss the relevant processes more thoroughly? This
comment is also related to the comment to l. 354ff.
• l. 477: ”This combination makes it possible to identify coherent struc-
tures, while elevated convection remains partly absent from the analysis
and would require a specific approach.” I think the analysis of elevated
convection is an interesting topic. Could the authors please add a short
sentence about what is meant with ”specific approach”?
• l. 470: I think the authors here refer to Oertel et al. (2020). It might also
be worth to mention other studies that address convective PV dipoles,
e.g. Chagnon et al. (2009), Weijenborg et al. (2015), Weijenborg et al.
(2017), and Müller et al. (2020), even though they do not explicitly refer
to convection in WCBs.
• relevant literature: Since the last review an additional discussion paper
was published in WCDD which would be worth to mention in this study:
Flack et al., 2020 (https://wcd.copernicus.org/preprints/wcd-2020-43/),
who also analyse the ’Stalactite cyclone’ (IOP 6 of NAWDEX).

Referee Report: PDF

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ED: Publish subject to revisions (further review by editor and referees) (12 Oct 2020) by Juerg Schmidli

AR by Jean-Pierre Chaboureau on behalf of the Authors (13 Oct 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (14 Oct 2020) by Juerg Schmidli

RR by Anonymous Referee #1 (14 Oct 2020)

ED: Publish as is (14 Oct 2020) by Juerg Schmidli

AR by Jean-Pierre Chaboureau on behalf of the Authors (14 Oct 2020)

Short summary

The study presents the first results from the airborne RASTA observations measured during the North Atlantic Waveguide and Downstream Impact Experiment (NAWDEX). Our combined Eulerian–Lagrangian analysis found three types of organized convection (frontal, banded and mid-level) in the warm conveyor belt (WCB) of the Stalactite cyclone. The results emphasize that convection embedded in WCBs occurs in a coherent and organized manner rather than as isolated cells.