Atmospheric bias teleconnections in boreal winter associated with systematic sea surface temperature errors in the tropical Indian Ocean

Zhao, Yuan-Bing; Žagar, Nedjeljka; Lunkeit, Frank; Blender, Richard

doi:https://doi.org/10.5194/wcd-4-833-2023

Articles | Volume 4, issue 4

https://doi.org/10.5194/wcd-4-833-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/wcd-4-833-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 4, issue 4

Research article

|

05 Oct 2023

Research article |

| 05 Oct 2023

Atmospheric bias teleconnections in boreal winter associated with systematic sea surface temperature errors in the tropical Indian Ocean

Yuan-Bing Zhao, Nedjeljka Žagar, Frank Lunkeit, and Richard Blender

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Final revised paper (published on 05 Oct 2023)
Supplement to the final revised paper
Preprint (discussion started on 22 May 2023)

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2023-917', Ronald Kwan Kit Li, 19 Jun 2023

General comments:

This study investigates how the tropical Indian Ocean SST biases that are typically seen in climate models may affect atmospheric teleconnections. To simplify the complex atmosphere-ocean coupling situation, this study makes use of a simpler atmospheric model framework where the SST biases are prescribed to force the atmospheric circulation. There are three well-posed research questions which are answered with sufficient analyses, including interpretations of dynamical fields, depiction of wave propagations connecting the tropics to the extratropics, and more elaborated analyses on modal space.

Specific comments:

L130-131: Maybe the authors can further justify their choice of the SST bias center location, amplitude and spatial extent. Perhaps a composite map of the SST bias from those cited studies could be provided, so the readers can see how much the idealized SST bias used in this study resembles that in the coupled models. This may help place the experimental design in better context with existing knowledge.

L250-263: Maybe also briefly describe Figs 3c and 3d.

L275-276: Maybe further elaborate on how they should account for the extratropical precipitation biases in Fig 3.

L277-278: Maybe suggest why the northward shift doesn’t seem to have a large impact on the circulation biases.

L294: Maybe suggest why the magnitudes are smaller i .e., non-linearity of the response to positive and negative SST biases.

L320-321: The wave in EXP_IOD also seems to terminate earlier before reaching North Africa, unlike the other two experiments. Perhaps this is related to the spatial extent of the jet stream wave-trapping?

L360: To understand this energy budget, the reader needs to refer to equation 16. Maybe consider citing the equation here again to facilitate understanding. Similarly, equation 17 for L371.

L364-366: This seems to explain why I and E both decrease together in Figs 9c and 9d for EXP_IOD. Taking a step back, what is the reason of why I and E decrease in EXP_IOD but increase in the other three experiments?

L367: Similarly, why do I and E decrease in all experiments except EXP_NEG where they increase in Fig 9e?

L374-376: While the indication from Fig 9 is clear, the readers may also wonder if there is an explanation behind it.

L380-382 and L473-475: Again, the readers may wonder if there is an explanation for why EXP_NEG increases V.

L479-486: The authors have highlighted the limitations of this study. It would be also useful if the authors could highlight the implications of this study on the interpretation of CMIP5 and CMIP6 model results, based on the results from this intermediate complexity model.

Technical corrections:

L55: tropical-extratropical coupling

L107: Clausius

L135: specifies the longitude and latitude of the center location respectively

L282: are yet to be fully understood

Fig 8a: maybe label the horizontal axis.

L347: do the authors mean Figs 8c and 8d instead?

L348: do the authors mean Figs 8e and 8f instead?

Fig 9 caption: maybe briefly remind the readers what the symbols used in the horizontal axis stand for, which were described in Section 2.

Citation: https://doi.org/10.5194/egusphere-2023-917-RC1
- AC1: 'Reply on RC1', Yuan-Bing Zhao, 29 Jun 2023
  
  Thank you for your detailed review!
  Point-by-point resplies to your comments will be provided at a later time.
  
  Citation: https://doi.org/10.5194/egusphere-2023-917-AC1
- AC3: 'Reply on RC1', Yuan-Bing Zhao, 01 Aug 2023
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-917/egusphere-2023-917-AC3-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2023-917-AC3
RC2:
'Comment on egusphere-2023-917', Anonymous Referee #2, 29 Jun 2023

The authors investigated the multidecadal atmospheric bias teleconnections caused by the TIO SST bias and their impacts on the simulated atmospheric variability using an intermediate-complexity atmospheric model. The authors found that the atmospheric circulation biases caused by the TIO SST bias have a Gill-Matsuno-type pattern in the tropics and a Rossby wave-train distribution in the extratropics. They also showed that the TIO SST bias could influence interannual variations in the tropical Indo-West Pacific region, Australia, south and northeast Asia, the Pacific-North America region, and Europe.
It is important to understand how the tropical SST bias in the model could generate atmospheric teleconnection biases. I have read the manuscript with much interest. It was especially interesting to see the response of the teleconnections.
The paper is well-written and well-organized. Thus, I suggest the work be accepted subject to some minor revisions.
L230–235: Focusing on the boreal winter is fine. However, if you want to say "Indeed, the circulation bias in the tropics has the same pattern throughout the year, only with varying magnitude, and the extratropical biases are primarily observed in the Northern Hemisphere during boreal winter and in the Southern Hemisphere during boreal summer, albeit with much weaker intensity", please show it. The IO has strong seasonality. So, I expected the seasonality to be critical. If you focus only on the boreal wintertime, the authors should add "boreal wintertime" in the title.L137–145: Please add some references to explain why you set the EXP and EXP_10N as similar to EXP_IOD.
Fig. 7: Why not show EXP_10N? I expect that EXP_10N may influence RWS and WAF more than EXP_POS/NEG.
The authors analyzed the years 1931–2010. As the authors may know, the Indian Ocean has warmed faster than the global average. So I believe that atmospheric bias teleconnections associated with IO SST bias may change. Although the topic is beyond the main scope, it might be better to slightly touch on the problem.

Citation: https://doi.org/10.5194/egusphere-2023-917-RC2
- AC2: 'Reply on RC2', Yuan-Bing Zhao, 29 Jun 2023
  
  Thank you for your time and effort! Point-by-point resplies to your comments will be provided later.
  I noticed you mentioned the Indian Ocean Warming in the review. It is an interesting topic. In fact, we have already started the research, starting with reanalysis data and then combining with idealized experiments, to understand its impact on the global circulation and variability.
  Thanks again for your interest in our research.
  
  Citation: https://doi.org/10.5194/egusphere-2023-917-AC2
- AC4: 'Reply on RC2', Yuan-Bing Zhao, 01 Aug 2023
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-917/egusphere-2023-917-AC4-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2023-917-AC4

Peer review completion

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

AR by Yuan-Bing Zhao on behalf of the Authors (01 Aug 2023) Author's response Author's tracked changes Manuscript

ED: Publish as is (10 Aug 2023) by Tim Woollings

AR by Yuan-Bing Zhao on behalf of the Authors (17 Aug 2023) Manuscript

Post-review adjustments

AA: Author's adjustment | EA: Editor approval

AA by Yuan-Bing Zhao on behalf of the Authors (20 Sep 2023) Author's adjustment Manuscript

EA: Adjustments approved (20 Sep 2023) by Tim Woollings

Short summary

Coupled climate models have significant biases in the tropical Indian Ocean (TIO) sea surface temperature (SST). Our study shows that the TIO SST biases can affect the simulated global atmospheric circulation and its spatio-temporal variability on large scales. The response of the spatial variability is related to the amplitude or phase of the circulation bias, depending on the flow regime and spatial scale, while the response of the interannual variability depends on the sign of the SST bias.