A Lagrangian description on the troposphere-to-stratosphere transport changes  associated with the stratospheric water drop around the year 2000

Hasebe, Fumio; Noguchi, Taisuke

doi:https://doi.org/10.5194/acp-16-4235-2016

Articles | Volume 16, issue 7

https://doi.org/10.5194/acp-16-4235-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-16-4235-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 16, issue 7

Research article

|

04 Apr 2016

Research article |

| 04 Apr 2016

A Lagrangian description on the troposphere-to-stratosphere transport changes associated with the stratospheric water drop around the year 2000

Fumio Hasebe and Taisuke Noguchi

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Final revised paper (published on 04 Apr 2016)
Preprint (discussion started on 19 Oct 2015)

Interactive discussion

Status: closed

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

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- Supplement

RC C9140: 'Review', Stephan Fueglistaler, 10 Nov 2015
- AC C10565: 'Reply to Dr.\ S. Fueglistaler (referee)', Fumio Hasebe, 18 Dec 2015
RC C9195: 'Review', Anonymous Referee #1, 12 Nov 2015
- AC C10582: 'Reply to Anonymous Referee #1', Fumio Hasebe, 18 Dec 2015

Peer-review completion

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

AR by Fumio Hasebe on behalf of the Authors (18 Dec 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (21 Jan 2016) by Patrick Jöckel

RR by Anonymous Referee #2 (15 Feb 2016)

Suggestions for revision or reasons for rejection

The revised version of Hasebe and Noguchi carefully addresses most
of the suggestions and concerns of my review. I still have some
concerns regarding the interpretation of the trajectory results - perhaps
my concerns were not sufficiently clearly expressed in the review.
However, the manuscript is quite carefully worded, and I am happy
to recommend the manuscript for publication.

The following comments may be useful for the final version.

Line 116: "... the diabatic ascent is driven by radiative heating, ..."
The broadly accepted consensus is that the upwelling is
dynamically forced, and the radiative heating is a result,
not the cause of the upwelling.

Line 250ff: The decomposition into average mixing ratio, and probability,
of a grid cell "j" is straightforward. The product of the two is of
course the contribution of grid cell "j" to the total entry mixing
ratio. However, the interpretation of changes in the product of
these two terms is not straightforward. For example:

Line 262ff: "it is interesting to note the increase of E(LCP e j)
despite the decrease in SMR(LCP e j) ..." Why do you write
"despite"? First, we should know how the SMR in this region
changed compared to the tropical average - if it has cooled
compared to the tropical average, we actually would expect
that the probability P(...) is increasing (this is one of the
key results of Fueglistaler and Haynes [2005]).

How would you interpret the following scenario:
In period "before", grid cell "j" is very warm, and 0 trajectories
experience their last saturation in that cell, i.e. P(j)=0.
Hence the contribution E(..) is 0.
Now, in period "after", grid cell "j" has cooled more than all
other locations and is now the coldest location. Correspondingly,
a very large fraction of trajectories experience their last
saturation there, and P(j) * SMR(j) > 0. Now you take the
difference: E(j)_after - E(j)_before which is greater than 0.
If I understand your interpretation of Figure 7
(Line 264: "In this sense, it is not appropriate to attribute the
cooling over the western and central Pacific to the drop ..."),
you would then say that grid cell "j" has NOT contributed to
the decrease in [H2O]entry?
The following statements (Line 265 ff) are also difficult to follow,
I have difficulties understanding to which plot and which area
exactly you refer; I don't know whether labels and/or "arrows"
in the figures are possible, but it would help if you would
refer to Figure-X/Panel-Y for each statement, so the reader
can better follow your interpretation.

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ED: Publish subject to technical corrections (16 Feb 2016) by Patrick Jöckel

AR by Fumio Hasebe on behalf of the Authors (28 Feb 2016) Author's response Manuscript

Short summary

This paper tries to answer the long-standing question in middle-atmosphere science on the mechanism of the sudden drop in stratospheric water vapor around the year 2000. Our findings indicate that the location where the air experiences cold temperature before entering the stratosphere shifted in the northern summer of 2000. It may have been led by the eastward expansion of warm water in the tropical Pacific causing the interaction of the heating between Pacific Ocean and the Tibetan Plateau.