Response of the global surface ozone distribution to Northern Hemisphere sea surface temperature changes: implications for long-range transport

Yi, Kan; Liu, Junfeng; Ban-Weiss, George; Zhang, Jiachen; Tao, Wei; Cheng, Yanli; Tao, Shu

doi:https://doi.org/10.5194/acp-17-8771-2017

Articles | Volume 17, issue 14

https://doi.org/10.5194/acp-17-8771-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue:

Global and regional assessment of intercontinental transport...

https://doi.org/10.5194/acp-17-8771-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 17, issue 14

Research article

|

19 Jul 2017

Research article |

| 19 Jul 2017

Response of the global surface ozone distribution to Northern Hemisphere sea surface temperature changes: implications for long-range transport

Kan Yi, Junfeng Liu, George Ban-Weiss, Jiachen Zhang, Wei Tao, Yanli Cheng, and Shu Tao

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Final revised paper (published on 19 Jul 2017)
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Preprint (discussion started on 05 Dec 2016)
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Interactive discussion

Status: closed

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

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SC1: 'ENSO and trans-Pacific transport of Asian pollution', Meiyun Lin, 09 Dec 2016
- AC3: 'Response to Dr. Meiyun Lin', Junfeng Liu, 13 Mar 2017
RC1: 'Review comments', Anonymous Referee #1, 19 Dec 2016
- AC1: 'Response to Anonymous Referee #1', Junfeng Liu, 13 Mar 2017
RC2: 'Reviewer comment', Anonymous Referee #3, 22 Jan 2017
- AC4: 'Response to Anonymous Referee #3', Junfeng Liu, 13 Mar 2017
RC3: 'Review of "Response of Global Surface Ozone Distribution to Northern Hemispheric Sea Surface Temperature Changes"', Anonymous Referee #2, 30 Jan 2017
- AC2: 'Response to Anonymous Referee #2', Junfeng Liu, 13 Mar 2017

Peer-review completion

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

AR by Junfeng Liu on behalf of the Authors (25 Mar 2017) Manuscript

ED: Referee Nomination & Report Request started (05 Apr 2017) by Frank Dentener

RR by Anonymous Referee #1 (15 Apr 2017)

Suggestions for revision or reasons for rejection

Yi et al. have addressed most of the concerns raised by the reviewers. I have only one suggestion that may help in better highlighting the value of those idealized experiments: The authors have performed the additional experiment in which the SST changes are applied over the entire tropical regions. However, the authors barely present it in the manuscript. I think the authors should discuss it more, in particular, in my opinion, it would make more sense to have this simulation as the main experiment. Then the authors can use the other sensitivity studies to understand the changes seen in the main experiment. Otherwise, it is difficult to understand the rationale behind the warming of only in one basin rather than another.

Few minor suggestions:

L98 SST changes affect solar radiation indirectly through changes in atmospheric circulation and cloud cover. How it is written it seems that SST directly affect solar radiation. (same in LL360-361)

LL101-102 “Numerous studies have shown that SST changes over different oceans and at different latitudes lead to significantly different meteorological sensitivities …” what do the authors mean by “meteorological sensitivities”?

LL117-118 “The North Atlantic Ocean pronounces various modes of low-frequency SST variability” what do the authors mean by “pronounces”?

LL126-136 The authors stated that ozone stratospheric intrusions associated with ENSO for winter and spring. However, the authors mentioned “Stratospheric intrusion events, which lead to vertical down mixing of ozone-rich air, can significantly elevate surface O3 during spring and summer” (LL60-61). Is there any study relating tropical SST and O3 stratospheric intrusion in summer?
Actually to my knowledge in summer stratospheric intrusions are few and not very important. Taken from Lin et al. 2012 cited by the authors in L62:
“The impacts of deep STT events on surface O3 are strongest at Northern Hemisphere extratropical latitudes in late winter and spring, likely reflecting a combination of peak O3 abundances at the tropopause [e.g., Prather et al., 2011], more frequent storms [e.g., Holton et al., 1995] and a longer O3 lifetime than in summer, and stronger surface heating that enhances the turbulent mixing between the free troposphere (FT) and the planetary boundary layer (PBL) compared to early winter.”

LL192-193 Specify climatological monthly SSTs.

Section 2.2
The author should present the all-basin experiments here rather than in LL282-291.

LL264-266 “Surface O3 changes in response to positive and negative SST anomalies
generally pronounce a consistent spatial pattern but are opposite in sign, suggesting robust relationships between surface O3 levels and SST anomalies (Figure 1).” What do the authors mean by “pronounce”? produce?

LL297-316 This part should go on the methods section 2.3

L367 “at the continent below” change to “surface”

L375 Clouds do not block but reduce solar radiation at the surface.

L504 “The corresponding anomalous cyclone should be responsible” change to read as something like:
“The corresponding anomalous cyclonic circulation may be responsible”

L528 again “pronounce” that I believe should be “produce”

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RR by Anonymous Referee #3 (04 May 2017)

RR by Anonymous Referee #2 (08 May 2017)

Suggestions for revision or reasons for rejection

Second review of: “Title: Response of the Global Surface Ozone Distribution to Northern Hemisphere Sea Surface Temperature Changes: Implications for Long-Range Transport” by Yi et al.

This paper reports on the response of continental ozone distributions to basin-wide increases or decreases in SST. For the most part it is well written and clear and represents a thorough analysis. Nevertheless at this point I cannot recommend publication for essentially the same reasons articulated in my first review. It is too bad the authors did not design their simulations to be more relevant to the atmosphere-ocean system. In their reply the authors essentially re-articulated again what initially stated in the paper. They did include a few additional sensitivity simulations, but overall my main objections remain the same.

My main objection has to do with the size and justification for the SST modifications the authors use in their study. They state in their reply that “in previous studies, idealized, uniform SST anomalies have been widely used to explore ocean-atmosphere relationships in the climate systems (e.g., Taschetto et al., 2016; Fan et al., 2016; Hu and Veres, 2016, Kushnir et al., 2002 and so on)”. I have briefly examined the studies listed and in none of them did the authors use basin wide SST perturbations. Taschetto et al., added warming patches to understand the atmospheric teleconnections associated with El Nino. In addition to : “further facilitate this comparison, two additional “semi-realistic experiments were carried out …”. Fan et al. (2016) changed the SST in small patches to understand the impact on the Asian monsoon. Hu and Veres (2016) examined the patches of SST in relation to the AMO oscillation. The patches were relevant to those seen during the AMO. Kushnir et al. (2002) used SST perturbations from idealized GCM experiments to “capture only the salient features of observed anomaly patterns.” “The prescribed SST anomalies are stripped of details to capture the “essential features” of the observed patterns”. In each of these cases: (i) the SST was prescribed to capture in a basic way observed SST patterns and the resulting atmospheric dynamics and (ii) the authors could relate their simulations to observations. In the present paper the SST perturbations are not related to any observed pattern. Furthermore the key results showing differences in upwind and downwind responses are not related specifically to observed changes.

I had originally thought that the results might possibly relate to the SST changes expected in a future climate. In climate change experiments large-scale SST forcing is sometimes used (e.g. Shaw and Voigt, 2015: Nature Geoscience 8, 560–566 (2015) doi:10.1038/ngeo2449). However, in these simulations the climate response is a “tug of war” between that due to changes in the SST and that due to direct radiative forcing. In the present simulations the direct radiative forcing due to climate change is not simulated. Moreover, even in the case of climate induced SST warming I don’t see why the SST perturbations would only include the N.H.

Furthermore, it is apparent the results are sensitive to the SST perturbation used. For example, the authors claim that when the SST perturbation raises the ocean temperature above 29oC the increased convection changes the circulation. What if the ocean temperatures had only been modified north of 25o: would the same results be expected?
The authors state in the response that their SST forcing is straightforward since their objective is to examine mid-latitude air quality. However, in fact mid-latitude circulation patterns are sensitive to tropical SSTs through well known teleconnection patterns.

To conclude: (i) I don’t see a physical justification to the SST perturbations applied in this study (in contrast to the above referenced studies). (ii) I don’t see how the present study sheds light on any observed phenomena, neither interannual variability or climate change. Or the authors did not clearly point out the connections. (iii) As the SST perturbations are rather arbitrary (why not put the southern boundary at 25o N, or at the equator?) the results may differ in unknown ways when other SST perturbations are used or when more realistic SST perturbation patterns are used.

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ED: Reconsider after minor revisions (Editor review) (29 May 2017) by Frank Dentener

AR by Junfeng Liu on behalf of the Authors (06 Jun 2017) Author's response Manuscript

ED: Publish as is (22 Jun 2017) by Frank Dentener

AR by Junfeng Liu on behalf of the Authors (23 Jun 2017)

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Short summary

In this study, we find that SST increases of a specific ocean in the Northern Hemisphere tend to increase summertime surface O₃ concentrations over upwind continents while reducing those over downwind regions. It also promotes a more stagnant climate, which tends to suppress O₃ long-range transport. Our findings indicate a robust linkage between basin-scale SST variability and continental surface O₃ pollution, which should be taken into account for air quality management.