Remotely Sensed Seasonal Shoreward Intrusion of the East Australian Current: Implications for Coastal Ocean Dynamics
Round 1
Reviewer 1 Report
The authors have took up a subject on the East Australian Current detection off northern New South Wales using monthly Sea Surface Temperatures from the Advanced Very High Resolution Radiometer. The results show that the EAC intrusion exhibits seasonal cycles, moving closer to the coast in austral summer than in winter. Moreover the authors showed its impacts on coastal upwelling and the shelf circulation. Although the topic of studies is important for proper understanding of processes in the marine environment I have a couple of remarks concerning the manuscript. First I found insufficient information on data and methodology used. I also suggest to improve other parts of the ms.
Specific comments are given below:
Page 1, Lines 17-18: In my view, rather than informing that the EAC intrusion was studied first time, in the abstract give more quantitative information on your results.
Page 1, Introduction: write a little about coastal upwelling and shelf circulation off the New South Wales coast as well as features of the East Australian Current
Page 1, Lines 24-25 and many other examples: format the manuscript and citing of references according to Remote Sensing standards included in the Microsoft Word template.
Page 2, Lines 86-92: I found only a little information on the monthly AVHRR SST images. Write more about technical details, algorithms used for retrieving SSTs. What is the accuracy of the SST images?
Page3, starting from Line 101: I found very scrimpy and insufficient information on the Topographic Position Index algorithm and in general on methods used in the study.
Page 9, subchapter 4.2: How was the coastal upwelling detected? Write in the method section about the upwelling detection method, please
Page 10: the chapter dealing with conclusions contains only one paragraph. Draw quantitative conclusions from your study, please
Page 10, In my view the sentences in lines 370-373 “Acknowledgments: In this section, you can acknowledge any support given which is not covered by the author contribution or funding sections. This may include administrative and technical support, or donations in kind (e.g., materials used for experiments).” should be removed.
Page 11: Enumerate references according to Remote Sensing standards.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
For the authors:
Line 341-342: The ENSO effects in the South Pacific are remarkable. I strongly suggest adding 4.4 paragraph in order to discuss the implication in the interannual (ENSO) to decadal variability of the complex current system in the EAC (Holbrook et al. 2011).
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
SERIOUS comments:
The reviewer found that the important results mentioned by the author in this manuscript are highly similar to the author's published paper in other journals (Xie, S., Huang, Z., Wang, XH, & Leplastrier, A. (2020). Quantitative Mapping of the East Australian Current Encroachment Using Time Series Himawari‐8 Sea Surface Temperature Data. Journal of Geophysical Research: Oceans, 125(10), e2019JC015647. https://doi.org/10.1029/2019JC015647)
The abstract and conclusion in this manuscript mentioned "EAC intrusion exhibits seasonal cycles, moving closer to the coast in austral summer than in winter." has been mentioned in the abstract and results of Xie et al., (2020) .
The author's claim that "provide new insights into seasonal upwelling and shelf circulation" is wrong. In lines 244 to 247, the author pointed out that the data used by Xie et al., (2020) was too short to confirm seasonality. However, reviewing the article by Xie et al., (2020) reveals that the author claims to have significant seasonal changes in the article. The reviewer also found that the research area and analysis method of this manuscript are almost similar to Xie et al., (2020), except that the data is changed from Himawari-8 to long-term AVHRR. However, the results of the study clearly did not have any breakthrough.
Major comments:
- The format of the reference does not meet the requirements, please correct it.
- I am surprised that the authors discuss East Australian Current but there is no image showing the current field. This is necessary to show and discuss, which should appear in the Introduction chapter and Figure 1. It is strongly recommended to display the long-term statistical results on the new graph. And the monthly average flow field of September-2009 is shown on the current figure 1.
- Lines 101-110, the Topographic Position Index is an important method of this manuscript. The author should not state that "one can refer to Xie et al. (2020).", but should be introduced here in detail, including formulas and calculation processes.
- The author discusses coastal upwelling in section 4.2, but there is no image showing upwelling at all, and there is no characteristic.
Minor comments:
- Line 13, please add the longitude.
- The unit of Figure 1c should be degree C.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors have corrected the ms according to most of my suggestions improving the quality of ms. Nevertheless I have a comment regarding the discussion in section 4.2 and the response of authors. The authors carried out the discussion on implications of the EAC’s shoreward intrusion for coastal upwelling however they didn’t even show any image with upwelling. In my view, showing at least the areas of coastal upwelling occurrence would be very useful for a potential reader. Moreover it would highlight your results (for example the intensified coastal upwelling during summer, lines 299-301). Moreover rather than writing a verb “hypothesize” (Line 299) it’s better to rewrite the sentence using a verb “conclude” or some other relevant verb. Hypotheses are usually presented in a first part of ms, and then they are verified during a research process. In line 299 the sentence looks like a conclusion from your work. Finally correct a format of sentence in lines 362-364
Author Response
Point 1: The authors carried out the discussion on implications of the EAC’s shoreward intrusion for coastal upwelling however they didn’t even show any image with upwelling. In my view, showing at least the areas of coastal upwelling occurrence would be very useful for a potential reader. Moreover it would highlight your results .
Response: Thank you for this comment. Actually, Figure 1 a, b & c have provided an image showing EAC-driven coastal upwelling which features lower water temperature and negative TPI. In this new revision, we have added explanations for the upwelling event shown in Figure 1. Please see line 105-106; and 283-285.
Point 2: Moreover rather than writing a verb “hypothesize” (Line 299) it’s better to rewrite the sentence using a verb “conclude” or some other relevant verb.
Response: Thank you for this comment. We have revised “hypothesize” to "suggest".
Reviewer 3 Report
Please see attached file.
Comments for author File: Comments.docx
Author Response
Point 1: From the Introduction chapter, the reviewer found that the authors wanted to discuss the 26-year long-term variations. The authors also stated that the AVHRR data from April 1992 and March 2018 was used, but why does Figure 1 only show the case of September 2009? In the manuscript before Figure 1, the reviewer found no explanation. Figure 1 usually represents the main research characteristics of the entire manuscript. Readers will want to see the 26-year average characteristics, and even the difference between the monthly average and the seasonal average. The author has stated in the title to provide seasonal research results, but from Figure 1, readers have no idea whether there are seasonal changes in the EAC waters? Or all months are similar to the case of September 2009. Although the results of Quantitative maps are provided in Figure 4, the reader has been confused earlier in the article. The reviewer strongly recommends that Figure 1 should be revised to the each monthly average SST, TPI, SST profile, and current field, so that readers can easily understand the author's contribution and greatly increase the value of the research.
Response: As we've explained in the first round, the mapping method used in this paper has been developed and validated in a previous paper (Xie et al., 2020, Journal of Geophysical Research: Oceans). Therefore, the main purpose of creating the Figure 1 in this paper is to generally demonstrate the mapping methodology and procedure, and readers who are interested in the details of the EAC mapping should refer to Xie et al., 2020. Too much illustrations on the EAC mapping are deemed unnecessary, as this would make the paper very similar to Xie et al., 2020. To avoid this, In Figure 1 we just simply demonstrate the mapping mothods, but then we focus on the time-series wavelet analyses and spatial analyses on the EAC's seasaonal shoreward intrusion, which is the innovative aspect and thus the main point of this paper. Importantly, in Figure 4, the seasonal EAC shoreward intrusion has been clearly illustrated.
Point 2: Line 136: The author declares that the "area" of the continental shelf refers to Figure 1a (according to Line 116, it seems to be the area between the coast and the shelf break), but Line 119 states that the "distance" is only the range of the green line in Figure 1d. This is confusing, it seems that the range of "area" (28S~32.5S) and "distance" (28+1/6S ~ 31+5/6S) are different. The author needs to explain why a different range is selected for comparison or recalculate the data and reanalyse.
Response: The definitions of "area" and "distance" were presented in line 121-127. "28S~32.5S" is a total study area, and we calcualted the "area" and "distance" of the "on-shelf" EAC waters within this area.
