Preprints
https://doi.org/10.5194/egusphere-2023-918
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/egusphere-2023-918
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
08 May 2023
| 08 May 2023
Intraseasonal and interannual variability of sea temperature in the Arabian Sea Warm Pool
Na Li
School of marine sciences, Sun Yat-sen University &Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
Xueming Zhu
School of marine sciences, Sun Yat-sen University &Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
Hui Wang
Key Laboratory of Research on Marine Hazards Forecasting, National Marine Environmental Forecasting Center, Beijing, China
Institute of Marine Science and Technology, Shandong University, Qingdao, China
School of marine sciences, Sun Yat-sen University &Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
Xidong Wang
School of marine sciences, Sun Yat-sen University &Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
Key Laboratory of Marine Hazards Forecasting, Ministry of Natural Resources, Hohai University, Nanjing, China
Abstract. The Arabian Sea Warm Pool (ASWP) is a part of the Indian Ocean Warm Pool, formed in the Arabian Sea before the onset of the Indian Ocean summer monsoon. The ASWP has a significant impact on climate change in the Indian Peninsula and globally. In this study, we examined the Intraseasonal and interannual variability of sea temperature in the Arabian Sea Warm Pool using the latest 5-day SODA reanalysis dataset. We quantified the contributions of sea surface heat flux, advection, and vertical entrainment to the sea surface temperature using mixed-layer heat budget analysis. We also used a lead lag correlation method to examine the relationship between the interannual variability of the ASWP and various large-scale modes in the Indo-Pacific Ocean. We found that the ASWP formed in April and decayed in June. Its formation and decay processes were asymmetrical, with the decay rate being twice as fast as the formation rate. During the ASWP development phase, the sea surface heat flux had the largest impact on the mixed layer temperature with a contribution of up to 85 %. Its impact was divided into the net heat flux at the sea surface (0.41–0.50 °C/5 day) and the short-wave radiation loss penetrating the mixed layer (from –0.08 °C/5 day to –0.17 °C/5 day). During the decay phase, the cooling effect of the vertical entrainment (from –0.05 °C/5 day to –0.18 °C/5 day) on the temperature variation increased and dominated the temperature variation jointly with the sea surface heat flux. We also found that the ASWP has strong interannual variability related to the consistent warming of the Indian Ocean basin. The lead lag correlation indicated that ASWP had a good synchronous correlation with the Indian Ocean Dipole. ASWP had the largest correlation coefficient at a lag of 5–7 months of niño3.4 index, showing the characteristics of modulation by ENSO. The ASWP was more significant (insignificant) in the following year before the summer monsoon after an El Niño (La Niña) event that peaked in the previous winter.
How to cite. Li, N., Zhu, X., Wang, H., Zhang, S., and Wang, X.: Intraseasonal and interannual variability of sea temperature in the Arabian Sea Warm Pool, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2023-918, 2023.
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Journal article(s) based on this preprint
17 Oct 2023
Intraseasonal and interannual variability of sea temperature in the Arabian Sea Warm Pool
Na Li, Xueming Zhu, Hui Wang, Shouwen Zhang, and Xidong Wang
Ocean Sci., 19, 1437–1451, https://doi.org/10.5194/os-19-1437-2023, https://doi.org/10.5194/os-19-1437-2023, 2023
Short summary
Short summary
Observations of the sea surface temperature in the Arabian Sea show exceptional warming before the onset of the Indian Ocean summer monsoon. The sea surface temperature change is mainly caused by sea surface heat flux forcing, horizontal advection, and vertical entrainment. Here, we quantify the contribution of those factors to the Arabian Sea warm pool using heat budget analysis and highlight how large-scale ocean modes control its change.
Na Li et al.
Interactive discussion
Status: closed
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
| : Report abuse
-
RC1: 'Comment on egusphere-2023-918', Anonymous Referee #1, 10 Jul 2023
I appreciate the hard work put in to create this manuscript. However, I strongly think the authors need to rethink on the focus of the paper. Currently, there are many directions. Also, i suggest to use some tool for spell and grammar check to improve the overall quality of the paper. Â
Â
Minor
- Line 91 : ‘scientists’ to be replaced with ‘studies’
- Line 93: Citations needed for definition
- Line 183-195 : Quite repetitive writing. Rephrasing needed.
- The paper is loosely written. At many places, it seems authors meant something else but have written something else.
- Line 292 : based on a 0.5 sigma criterion .
- Figure 13, and its caption : N should be capital In Niño and in all other places.
- Line 328 : Please rewrite the descripition of IOD if needed in correct tense. This is grammatically incorrect.
- Reqrite section 5 with more conciseness and clarity.
Â
Major :
Â
- Section 2.3 : Are the units consistent in this formulation of Heat budget? The units of ENT1 and ENT2 is degC/s. The units of ENT3 is deg C-m/s. Kindly check and clarify.
- Line 136 : What is advection of mixed layer depth and how is it different from advection : ADV? Please explain. This is very confusing. What is tendency of MLD? Is it the tendency of how depth changes?
- Section 2.3 Line154 ; Wh is the bottom of mixed layer? Is it the depth? I understand it is the vertical velocity at the base of the mixed layer from the calculation. However, please write it carefully. It is important for the readers to understand this.
- Why do you need a dimensionless number H in the heat budget equation?
- Figure 1 & Figure 2 : You define warm pool by 30deg C, but in figure 1, there is no cold pool after 26 May. How do you plot the maximum temperatures in figure 2, it is not clear what area did you choose for it? In Line 151, it is mentioned that area of warm pool has been chosen, but there is no warm pool on those dates.
- The ASWP is defined historically in the SEAS, from 31 May onwards the pool seems to be shifting to extreme North of coast. Did you use a latitudinal boundary to define the warm pool, or have the authors taken June 5 contour of 30deg C to calculate area and temp of warm pool?
- Line 195: This is anyway clear from blue line in Figure 3.
- Line 188 : How do authors say that Qnet is due to air sea interaction and Qloss is due to SWR penetration. Qloss is due to all factors of Heat flux – Sensible, latent, longwave etc and not only because of reduced SWR penetration. If the authors are too confident about SWR reduction, it should be explained more. Always : Q = Qnet + Qloss, so saying the SWR penetrated less is not always correct.
- Line 200 onwards : Here SWR penetration is explained. It is not clear at what level have the authors taken SWR in their calculation. Is it at the TOA or Surface of the ocean?
- Is the MLD response to reduced SWR immediate? Or is there a difference in the rate of decay of MLD temperature due to SWR reduction?
- Line 211 : what is certain lag?
- Line 220 : how does MLD inhibit penetration of SWR. I am not clear with this mechanism. The authors may explain please.
- Line 228 onwards : Comment no 1,2,3. I am not clear what each of those terms mean, it is not clearly defined as well. Kindly explain. I only understand ENT1.
- Line 236 -238 : Do the authors mean that -Low wind speed made MLD more sensitive to heat flux? What is the meaning of this line? I understand MLD is always sensitive to heat flux, atmospheric conditions determine heat flux, the sensitivity is always there because MLD included the Sea surface which is always in contact with the atmosphere. I think the authors mean to write something else, but it is not clear. At the same time, how shallow MLD makes the upper sea water increase rapidly?
- Line 240 onwards : Thermocline and Isothermal layer are not the same. They cannot be used interchangeably.
- After reading through, it is not possible for me to point out each and every concern in the vertical entrainment term of heat budget. There is a diverse explanation ranging from penetration of SWR to Rossby waves. The timescales, space scales need a mention. This section needs a major overhaul and rewriting, it is very confusing currently. At the same time, the terms and mechanisms have to be explained carefully and clearly. This section has too many issues to point out and may be worked again.
- Section 3.2.3 : The theory of EICC and NEC is explained. But how is it connected with what happens in April- June ASWP is not mentioned. Also, have the authors looked at the current systems during the months of analysis, because putting everything on NEC for the months of April-June may not be okay. The current changes its direction again in these months itself.
- The authors write at Lines 158-159 that they will explain the mechanism of slow decay, however, I failed to find a clear explanation of the same. The authors may end the section with a small paragraph explaining exactly the mechanism of slow decay.
- Section 4.1 : Line 282 : how do authors know that? Citations?
- Why in strong ASWP years is the average maximum temperature also high?
- What is Climate state averaging?
- How do you define warming phase and cooling phase? Do you do it separately for each year? Or is there any other technique being used.
- Line 300 : No clear meaning. I cannot understand what authors mean.
- Section 4.2: Which data has been used for this? How much is the variance explained by each mode can be mentioned in the figure 12 itself. Please mention. The text seems vague for variance explained.
- Line 313-314 : What is IOB consistent mode? Citation please.. Line 313 is not clear, rewrite.
- What is B in IOB in Line 318?
- Probably this is the place (after Line 316/317) where Line 282 should be mentioned rather than there.
- Why do you show PC2 if variance explained is less than 10%?
- Line 327-328 : Are these the years in which your PC also peaks (Line315) or in which ASWP is found to be stronger (Line 279).
- Line 333: is the correlation significant?
- Line 345: What is IOWP?
- Any citation for Line 345-346.
- What is the correlation value of PC1 of ASWP with Nino? Why do you choose to analyse ENSO rather than IOD in lines 348 onwards?
- Line 364 :Vertical entrainment is completely different from what has been used here. Please use a different word. (Again, please note comment no 16.)
Â
Â
Citation: https://doi.org/10.5194/egusphere-2023-918-RC1 - AC1: 'Reply on RC1', Li na, 28 Jul 2023
-
RC2: 'Comment on egusphere-2023-918', Anonymous Referee #2, 03 Aug 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-918/egusphere-2023-918-RC2-supplement.pdf
- AC2: 'Reply on RC2', Li na, 20 Aug 2023
Interactive discussion
Status: closed
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
| : Report abuse
-
RC1: 'Comment on egusphere-2023-918', Anonymous Referee #1, 10 Jul 2023
I appreciate the hard work put in to create this manuscript. However, I strongly think the authors need to rethink on the focus of the paper. Currently, there are many directions. Also, i suggest to use some tool for spell and grammar check to improve the overall quality of the paper. Â
Â
Minor
- Line 91 : ‘scientists’ to be replaced with ‘studies’
- Line 93: Citations needed for definition
- Line 183-195 : Quite repetitive writing. Rephrasing needed.
- The paper is loosely written. At many places, it seems authors meant something else but have written something else.
- Line 292 : based on a 0.5 sigma criterion .
- Figure 13, and its caption : N should be capital In Niño and in all other places.
- Line 328 : Please rewrite the descripition of IOD if needed in correct tense. This is grammatically incorrect.
- Reqrite section 5 with more conciseness and clarity.
Â
Major :
Â
- Section 2.3 : Are the units consistent in this formulation of Heat budget? The units of ENT1 and ENT2 is degC/s. The units of ENT3 is deg C-m/s. Kindly check and clarify.
- Line 136 : What is advection of mixed layer depth and how is it different from advection : ADV? Please explain. This is very confusing. What is tendency of MLD? Is it the tendency of how depth changes?
- Section 2.3 Line154 ; Wh is the bottom of mixed layer? Is it the depth? I understand it is the vertical velocity at the base of the mixed layer from the calculation. However, please write it carefully. It is important for the readers to understand this.
- Why do you need a dimensionless number H in the heat budget equation?
- Figure 1 & Figure 2 : You define warm pool by 30deg C, but in figure 1, there is no cold pool after 26 May. How do you plot the maximum temperatures in figure 2, it is not clear what area did you choose for it? In Line 151, it is mentioned that area of warm pool has been chosen, but there is no warm pool on those dates.
- The ASWP is defined historically in the SEAS, from 31 May onwards the pool seems to be shifting to extreme North of coast. Did you use a latitudinal boundary to define the warm pool, or have the authors taken June 5 contour of 30deg C to calculate area and temp of warm pool?
- Line 195: This is anyway clear from blue line in Figure 3.
- Line 188 : How do authors say that Qnet is due to air sea interaction and Qloss is due to SWR penetration. Qloss is due to all factors of Heat flux – Sensible, latent, longwave etc and not only because of reduced SWR penetration. If the authors are too confident about SWR reduction, it should be explained more. Always : Q = Qnet + Qloss, so saying the SWR penetrated less is not always correct.
- Line 200 onwards : Here SWR penetration is explained. It is not clear at what level have the authors taken SWR in their calculation. Is it at the TOA or Surface of the ocean?
- Is the MLD response to reduced SWR immediate? Or is there a difference in the rate of decay of MLD temperature due to SWR reduction?
- Line 211 : what is certain lag?
- Line 220 : how does MLD inhibit penetration of SWR. I am not clear with this mechanism. The authors may explain please.
- Line 228 onwards : Comment no 1,2,3. I am not clear what each of those terms mean, it is not clearly defined as well. Kindly explain. I only understand ENT1.
- Line 236 -238 : Do the authors mean that -Low wind speed made MLD more sensitive to heat flux? What is the meaning of this line? I understand MLD is always sensitive to heat flux, atmospheric conditions determine heat flux, the sensitivity is always there because MLD included the Sea surface which is always in contact with the atmosphere. I think the authors mean to write something else, but it is not clear. At the same time, how shallow MLD makes the upper sea water increase rapidly?
- Line 240 onwards : Thermocline and Isothermal layer are not the same. They cannot be used interchangeably.
- After reading through, it is not possible for me to point out each and every concern in the vertical entrainment term of heat budget. There is a diverse explanation ranging from penetration of SWR to Rossby waves. The timescales, space scales need a mention. This section needs a major overhaul and rewriting, it is very confusing currently. At the same time, the terms and mechanisms have to be explained carefully and clearly. This section has too many issues to point out and may be worked again.
- Section 3.2.3 : The theory of EICC and NEC is explained. But how is it connected with what happens in April- June ASWP is not mentioned. Also, have the authors looked at the current systems during the months of analysis, because putting everything on NEC for the months of April-June may not be okay. The current changes its direction again in these months itself.
- The authors write at Lines 158-159 that they will explain the mechanism of slow decay, however, I failed to find a clear explanation of the same. The authors may end the section with a small paragraph explaining exactly the mechanism of slow decay.
- Section 4.1 : Line 282 : how do authors know that? Citations?
- Why in strong ASWP years is the average maximum temperature also high?
- What is Climate state averaging?
- How do you define warming phase and cooling phase? Do you do it separately for each year? Or is there any other technique being used.
- Line 300 : No clear meaning. I cannot understand what authors mean.
- Section 4.2: Which data has been used for this? How much is the variance explained by each mode can be mentioned in the figure 12 itself. Please mention. The text seems vague for variance explained.
- Line 313-314 : What is IOB consistent mode? Citation please.. Line 313 is not clear, rewrite.
- What is B in IOB in Line 318?
- Probably this is the place (after Line 316/317) where Line 282 should be mentioned rather than there.
- Why do you show PC2 if variance explained is less than 10%?
- Line 327-328 : Are these the years in which your PC also peaks (Line315) or in which ASWP is found to be stronger (Line 279).
- Line 333: is the correlation significant?
- Line 345: What is IOWP?
- Any citation for Line 345-346.
- What is the correlation value of PC1 of ASWP with Nino? Why do you choose to analyse ENSO rather than IOD in lines 348 onwards?
- Line 364 :Vertical entrainment is completely different from what has been used here. Please use a different word. (Again, please note comment no 16.)
Â
Â
Citation: https://doi.org/10.5194/egusphere-2023-918-RC1 - AC1: 'Reply on RC1', Li na, 28 Jul 2023
-
RC2: 'Comment on egusphere-2023-918', Anonymous Referee #2, 03 Aug 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-918/egusphere-2023-918-RC2-supplement.pdf
- AC2: 'Reply on RC2', Li na, 20 Aug 2023
Peer review completion
AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Na Li on behalf of the Authors (20 Aug 2023)
Author's response
Author's tracked changes
Manuscript
ED: Publish subject to minor revisions (review by editor) (22 Aug 2023) by Xinping Hu
AR by Na Li on behalf of the Authors (28 Aug 2023)
Author's response
Author's tracked changes
Manuscript
ED: Publish as is (31 Aug 2023) by Xinping Hu
AR by Na Li on behalf of the Authors (02 Sep 2023)
Journal article(s) based on this preprint
17 Oct 2023
Intraseasonal and interannual variability of sea temperature in the Arabian Sea Warm Pool
Na Li, Xueming Zhu, Hui Wang, Shouwen Zhang, and Xidong Wang
Ocean Sci., 19, 1437–1451, https://doi.org/10.5194/os-19-1437-2023, https://doi.org/10.5194/os-19-1437-2023, 2023
Short summary
Short summary
Observations of the sea surface temperature in the Arabian Sea show exceptional warming before the onset of the Indian Ocean summer monsoon. The sea surface temperature change is mainly caused by sea surface heat flux forcing, horizontal advection, and vertical entrainment. Here, we quantify the contribution of those factors to the Arabian Sea warm pool using heat budget analysis and highlight how large-scale ocean modes control its change.
Na Li et al.
Na Li et al.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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(2879 KB) - Metadata XML
Short summary
Observations of the sea surface temperature in the Arabian Sea show exceptional warming before the onset of the Indian Ocean summer monsoon. The sea surface temperature change is mainly caused by sea surface heat flux, horizontal advection, and vertical entrainment. Here, we quantify the contribution of those factors to the Arabian Sea warm pool using heat budget analysis and highlight how large-scale ocean modes control its change.
Observations of the sea surface temperature in the Arabian Sea show exceptional warming before...