Effect of the North Atlantic Thermohaline Circulation on Changes in Climatic Conditions and River Flow in Poland
Round 1
Reviewer 1 Report
It is a well written manuscript.
Some small improvements are needed:
- line 34: please cite a few authors that studied "trends in hydrological and climatological variables, mainly precipitation and air temperature, followed by analysis of their correlations with river flows".
- line 38: here, in the introduction section, and in the entire manuscript, there is cited a very Poland-centered literature; it will be useful to discuss a little more the observations of other people; see, for example, some papers of David Labat regarding the relationship between river runoff and climatic oscillations; papers of other people would also be useful for the Discussion section.
- citations like that of line 40 ("including [5-9]") or line 89 ("while [19] identified") might be better replaced by something like "some authors [5-9]" or "while X and Y [19] identified" because it is much easier for the reader to remember a name, rather than a number; for other cases of this type, see lines: 92, 100, 148, 150, 196, 202, 213, 226, 375.
- lines 79-90: very similar phrases with those used by Dariusz Wrzesiński and Leszek Sobkowiak in "Detection of changes in flow regime of rivers in Poland" (https://doi.org/10.1515/johh-2017-0045); please rewrite the Study area section.
- there is a nice map at Fig. 1, well done in the geographycal style; I would also add a North arrow.
- lines 158-160 - please rewrite them as I am not sure what you intend to say; more specifically, please replace "adopted" with "chosen" (or do you intend to say "adapted"?), avoid the high distance between subject and predicate, and specify if the 11 years period is somehow related to the sunspots cycle.
- line 162 - it would be useful to see some results of the Student's t-test in a supplementary material or annex.
- lines 292-295: a map with different signs for the various significances of the correlations [DG3L vs parameters) found for each station will also be useful.
-line 306: "The study proves that the intensity of NA THC has impact on river flow in 306 Poland." has to be replaced with something like "This study provides pieces of evidence regarding the intensity of NA THC has impact on river flow in 306 Poland."
-figure 8 has so many subfigures that their information is too small and even with a zoom in by using the digital manuscript I am unable to extract information from maps; that would be a waste for the reader and you should split fig. 8 into 2 separate figures, each one containing a column of the original figure.
Author Response
First of all, we would like to thank the Reviewer for valuable comments. Below please find the original comments and our responses (in bold) explaining how the original manuscript was amended during the revision.
It is a well written manuscript.
Some small improvements are needed:
Response to Reviewer:
Thank you. We have done our best to improve quality of the paper according to your remarks.
- line 34: please cite a few authors that studied "trends in hydrological and climatological variables, mainly precipitation and air temperature, followed by analysis of their correlations with river flows".
Response to Reviewer:
Four papers [1-4] related to the extreme droughts and river flows in Poland have been added.
- line 38: here, in the introduction section, and in the entire manuscript, there is cited a very Poland-centered literature; it will be useful to discuss a little more the observations of other people; see, for example, some papers of David Labat regarding the relationship between river runoff and climatic oscillations; papers of other people would also be useful for the Discussion section.
Response to Reviewer:
Selected papers [9-12] of Prof. David Labat and other authors have been cited and discussed shortly in ‘Introduction’ and ‘Discussion’.
- citations like that of line 40 ("including [5-9]") or line 89 ("while [19] identified") might be better replaced by something like "some authors [5-9]" or "while X and Y [19] identified" because it is much easier for the reader to remember a name, rather than a number; for other cases of this type, see lines: 92, 100, 148, 150, 196, 202, 213, 226, 375.
Response to Reviewer:
Citations of the selected papers have been replaced in accordance to the suggestion.
- lines 79-90: very similar phrases with those used by Dariusz Wrzesiński and Leszek Sobkowiak in "Detection of changes in flow regime of rivers in Poland" (https://doi.org/10.1515/johh-2017-0045); please rewrite the Study area section.
Response to Reviewer:
The ‘Study area’ section has been rewritten. Information on topography and differences in runoff has been added.
- there is a nice map at Fig. 1, well done in the geographycal style; I would also add a North arrow.
Response to Reviewer:
Thank you. Figure 1 has been supplemented with the North arrow.
- lines 158-160 - please rewrite them as I am not sure what you intend to say; more specifically, please replace "adopted" with "chosen" (or do you intend to say "adapted"?), avoid the high distance between subject and predicate, and specify if the 11 years period is somehow related to the sunspots cycle.
Response to Reviewer:
The sentence has been rewritten and structure of sentences has been corrected. Regarding the 11-year period: the studied period is 1971-2015 (45 years). From this period we selected values with the highest (> 1.55) and lowest (<-0.56) DG3L indices, corresponding to the third and first quartiles of the whole 45-year data set. In that way we obtained 11 years (cases), we took for further analyses. They result from the statistical distribution of DG3L values in the studied period and have no connections with the 11-year period of the sunspots.
- line 162 - it would be useful to see some results of the Student's t-test in a supplementary material or annex.
Response to Reviewer:
Given a large number (516) of the analyzed gauging stations it would be difficult to add results of the Student’s t-test as a supplementary material in the tabular form. So, finally we decided to present the spatial distribution of significance of relationships between river flows for DG3L> 1.56 and DG3L < -0.54 in Figures 8 and 9 (renumbered during corrections).
- lines 292-295: a map with different signs for the various significances of the correlations [DG3L vs parameters) found for each station will also be useful.
Response to Reviewer:
In fact, the coefficients of correlation have been calculated during our analyses, but we decided not to present their spatial distributions. Instead, we presented in Figure 7 the percent shares of the positive and negative coefficients of correlation between monthly and annual flows and the DG3L index (A), and also the percent share of the statistically significant coefficients of correlation (B). Additionally, we illustrated deviations of monthly (Figures 8 and 9) and annual (Figure 10) river flows in the negative (DG3L -) and positive (DG3L +) phases of DG3L compared to the average values from the years 1971-2015, and their statistical significance (p). In our opinion this form of visualization of the obtained results is better as it allows to determine not only the direction, but also the size and statistical significance of changes of the observed river flows, depending on the intensity of the DG3L index.
-line 306: "The study proves that the intensity of NA THC has impact on river flow in 306 Poland." has to be replaced with something like "This study provides pieces of evidence regarding the intensity of NA THC has impact on river flow in 306 Poland."
Response to Reviewer:
The sentence has been rewritten accordingly.
-figure 8 has so many subfigures that their information is too small and even with a zoom in by using the digital manuscript I am unable to extract information from maps; that would be a waste for the reader and you should split fig. 8 into 2 separate figures, each one containing a column of the original figure.
Response to Reviewer:
The original maps in Figure 8 have been split into two separate Figures: 8 (winter half-year) and 9 (summer half-year).
Reviewer 2 Report
The study uses correlations between something called the DG-3L index (meant as a measure of North Atlantic thermohaline circulation intensity) and river flow in Poland. The conclusions are summed up in a flow chart on p. 14 and the novel aspect of this is that changes in the NA THC affect river runoff not via changes in precipitation but rather via changes in evapotranspiration. This is supported by statistical correlations between the index and various climate variables. Apart from a few problems with the English, the article is written in a fashion that makes it unconvincing (and doesn't inspire the reader to look further on his or her own). No convincing case is made that the index used is a credible measure of NA THC strength and no alternative indices are tested. For example, the index is mentioned in the abstract as if it were a well known and commonly used one, but the two references offered are sefl-citations. I suggest a resubmission that assesses the robustness of the principal links in the flow chart (e.g,. ocean to upper level atmosphere - to lower level atmosphere to conditions affecting evapotranspiration) using multiple indices, more standard indices of ocean circulation / temperature (in addition to the one used here). The English will also have to be cleaned up. Much of this is simply non-native speaker problems (e.g., 'The presented in the paper results' instead of 'The results presented in the paper'). The figures should also be improved and figure captions should be complete and clear (e.g., what are the lines in Fig 3, 4?).
NB, My expertise is that of a scientist interested in how ocean circulation affects climate, but my comments should be taken as those of someone outside of this the authors' immediate field. I nonetheless think that my judgement that the authors should do more to put their work in a broader context (e.g., using better-known and multiple indices, showing how the DG-3G index relates to more commonly used ones, etc) has merit.
Author Response
First of all, we would like to thank the Reviewer for valuable comments. Below please find the original comments and our responses (in bold) explaining how the original manuscript was amended during the revision.
No convincing case is made that the index used is a credible measure of NA THC strength and no alternative indices are tested. For example, the index is mentioned in the abstract as if it were a well known and commonly used one, but the two references offered are sefl-citations.
Response to Reviewer:
The introduced DG3L index is a relative measure of the amount of heat transported by NA THC from the Atlantic tropics to the north. So far, there is no other index that could more precisely characterize the intensity of THC. AMO (Atlantic Multidecadal Oscillation), due to its construction (detrended, with the SST values smoothened using the moving average etc.), imperfectly characterizes thermal state of the North Atlantic waters (“warmer than average”, “cooler than average”). In addition, it strongly suppresses the real amplitude of existing changes. The phase changes of AMO are only one of the manifestations of the THC intensity. AMM (Atlantic Meridional Mode) is regionally limited to 20-30 °N, and doesn’t provide information about the NA THC flows or the amount of heat transported north beyond 30 °N. Because the AMO index doesn’t show statistically significant connections with the variability of climate elements in Central Europe (while it is assumed to have impact on its climate), there was a need to construct index other than AMO. This has been done by some of the authors of the reviewed paper (Marsz and Styszyńska – retired professors of the Department of Meteorology and Nautical Oceanography, Gdynia Maritime University, Poland).
The analyzed properties of the DGL3 index show that it is strongly correlated with the annual global temperature anomalies, the Northern Hemisphere temperature anomalies, temperature of the Arctic (64-90 ° N) and of the temperate zone of the Northern Hemisphere (44-64 ° N). Furthermore, it is correlated with: SST in the eastern part of the North Atlantic (both in individual grids and averaged areas), the surface of sea ice in the Arctic, the height of the geopotential in 35-60 °N and 10 °W-50 °E, the frequency of macrotypes of the central tropospheric circulation in the Atlantic Eurasian circulation sector and air temperature at most stations in Europe etc. The DG3L index is also correlated with sunshine duration, relative humidity and temperature at meteorological stations in Poland, and it demonstrates the maximum correlations in spring and summer, which is then reflected in the course of hydrological processes.
Because that index is relatively new, the published so far papers on its climatic activity have been written only in Polish. Thus, the index is neither known, nor cited in the English-language scientific literature. For this reason, the time series of its values (Appendix A) and a brief explanation of its calculation (chapter 2.2 - Methods) are described in the submitted paper, while the detailed physical justification of its construction is omitted, as it would require a several-page explanation (in fact, this was described in the Polish language in one of self-cited papers: Marsz A.A. Model of changes in the Arctic sea-ice extent (…), 2015).
I suggest a resubmission that assesses the robustness of the principal links in the flow chart (e.g,. ocean to upper level atmosphere - to lower level atmosphere to conditions affecting evapotranspiration) using multiple indices, more standard indices of ocean circulation / temperature (in addition to the one used here).
Response to Reviewer:
The flowchart summarizes in a simplified form the sequence of impacts of NA THC changes (in positive and negative phases), which result in changes of evapotranspiration, and consequently – river flows. As we have just explained, the detected correlations between the DG3L index and the annual global temperature anomalies etc. provide evidences for its usefulness in prediction of selected elements of climate and water balance. Of course, since the introduced index is relatively new, it requires further analyses, including assessment of the robustness of the links using more standard indices, mentioned by the Reviewer, which is going to be done as the next step of our research.
The English will also have to be cleaned up.
Response to Reviewer:
The English language has been corrected.
The figures should also be improved and figure captions should be complete and clear (e.g., what are the lines in Fig 3, 4?).
Response to Reviewer:
Captions in Figures 3 and 4 have been supplemented with: „Marked are regression line (solid line) and 95% confidence level (dashed lines)”. Additionally, the original maps in Figure 8 have been split into two separate Figures: 8 (winter half-year) and 9 (summer half-year). Also, Figures 6, 7, 8, 9 and 10 have been improved by putting higher resolution maps.
Reviewer 3 Report
Review of “Circulation on Changes in Climatic Conditions and River Flow in Poland” by Wrzesiński et al. (2019)
Major Comments: This paper presents the North Atlantic temperature change and its relationship with river flows in Poland. Although Manuscript is organized and writing needs to be improved a lot. Other major comments is that I would like to see the spatial correlation map river flow with DG3L. Most of the figure captions needs to be revised and explained clearly.
I would recommend major revision for this manuscript. Since most of the comments are before discussion, I would recommend to revise the whole manuscript when these comments are addressed.
Other Comments:
Line 16-19, Page 1: What is the DG3L index? Second sentence of the abstract shows the new term without introducing that. Sentence is too long and confusion with “climate elements and river flow”.. What are the climate elements used that is also not defined before this..
The title is about the river flow and climate condition, but there is a strong correlation between DG3L and temperature in particular months, but what is the correlation with river flow is not mentioned.
Abstract should be rewritten with more expansion.
Line 47-48, Page 2: “Enfield et al. [10] associated these variations with differences in precipitation recorded in the positive and negative phases of AMO” This sentence does make sense and needs to be rewritten.
Line 72-75: Need to rewrite this sentence as well. Same problem with long sentence here too.
Figure 1: How the runoff is calculated in m and it is spatially distributed? This needs to be explained.
Line 84-85: “In addition,….meteorological elements”. This sentence is not clear to me. What does mean “regionally differentiated influence”?? Revise this.
Line 86-90: “ ….values…” what are values. Are not these data? Poorly chosen word.. I don’t like to have a whole paragraph with single sentence here too. Make two sentence with right wording.
Why do you need to mentioned here who provided the data. You can include that sentence in acknowledgement.
How did you calculate the coefficient (0.42, 0.33 and 0.25) in Equation 2? Need more explanation.
Figure 2: Y-axis title says, STD? what is the difference between DG3L index and this one? It is not consistent. Is this anomaly or standard deviation?
Line 146-153: …macrotypes W, E and C & circulation type C2D and D2C…” these types need to be defined in the paper, just referring other paper does not make sense here. Authors asked to read other papers to learn this paper which is not right.
Overall the Methodology section needs to be written.
Line 171-173: The starting of result is mentioned the final result. This sentence needs to be written or removed.
Line 179-184: This paragraph explained some results, without referring any Figure or references, how?
Line 188: what is the meaning of below? Can be said like “ is considered here”… something like that..
Line 193-195: “changes …” This sentence is odd with starting from changes and needs to be revised..
Line 196: Same here to mentioned the macrotype, but don’t know what is that?
Figure 3: what are the lines here? Figure caption does not explain these..
Same for Figure 4..
Figure 6: Which months are considered for the temperature? It looks like average annual temperature is considered during +ve and -ve DG3L, but it is not explained clearly neither in the text nor in Figure caption.
Instead of taking the negative and positive, Can you make the correlation map of temperature with DG3L index? That would show some clear message here..
Line 266-267: Air temperature ….. this sentence is incomplete with missing verb..
I would recommend to make the spatial correlation map of DG3L with river flow similar to Figure 8 as well.
Author Response
First of all, we would like to thank the Reviewer for valuable comments. Below please find the original remarks and our responses explaining how the original manuscript has been improved during the revision.
Major Comments: This paper presents the North Atlantic temperature change and its relationship with river flows in Poland. Although Manuscript is organized and writing needs to be improved a lot. Other major comments is that I would like to see the spatial correlation map river flow with DG3L. Most of the figure captions needs to be revised and explained clearly.
We have made a number of improvements, including two new maps (Figures 8 and 11) added to the manuscript.
I would recommend major revision for this manuscript. Since most of the comments are before discussion, I would recommend to revise the whole manuscript when these comments are addressed.
Thank you. We have revised the whole manuscript according to the Reviewer’s comments.
Other Comments:
1) Line 16-19, Page 1: What is the DG3L index? Second sentence of the abstract shows the new term without introducing that. Sentence is too long and confusion with “climate elements and river flow”.. What are the climate elements used that is also not defined before this..
Response to Reviewer: the ‘Abstract’ section has been rewritten accordingly. Supplementary information has been added.
2) The title is about the river flow and climate condition, but there is a strong correlation between DG3L and temperature in particular months, but what is the correlation with river flow is not mentioned.
Response to Reviewer: we have added two figures: Figure 8 showing spatial distribution of correlations between monthly river flows and the DG3L index with their statistical significance (p), and also Figure 11 with spatial distribution of correlations between annual river flows and the DG3L index and their statistical significance (p). Relevant comments have also been added in the text.
3) Abstract should be rewritten with more expansion.
Response to Reviewer: the ‘Abstract’ section has been rewritten accordingly.
4) Line 47-48, Page 2: “Enfield et al. [10] associated these variations with differences in precipitation recorded in the positive and negative phases of AMO” This sentence does make sense and needs to be rewritten.
Response to Reviewer: the sentence has been corrected.
5) Line 72-75: Need to rewrite this sentence as well. Same problem with long sentence here too.
Response to Reviewer: the sentence has been corrected.
6) Figure 1: How the runoff is calculated in m and it is spatially distributed? This needs to be explained.
Response to Reviewer: The map in Figure 1 presents the spatial distribution of the outflow value H (not in meters [m], as the Reviewer wrote, but in millimeters [mm]). The value of the flow coefficient is calculated in accordance with the widely recognized standards in hydrology. The authors believe that this is so universal (and fundamental) that there is no need to explain how the flow coefficient was estimated.
7) Line 84-85: “In addition,….meteorological elements”. This sentence is not clear to me. What does mean “regionally differentiated influence”?? Revise this.
Response to Reviewer: the sentence has been corrected.
8) Line 86-90: “ ….values…” what are values. Are not these data? Poorly chosen word.. I don’t like to have a whole paragraph with single sentence here too. Make two sentence with right wording.
Response to Reviewer: the sentence has been corrected.
9) Why do you need to mentioned here who provided the data. You can include that sentence in acknowledgement.
Response to Reviewer: the sentence has been moved to ‘Acknowledgements’.
10) How did you calculate the coefficient (0.42, 0.33 and 0.25) in Equation 2? Need more explanation.
Response to Reviewer: the full explanation of this question would be very extensive and in our opinion does not fit the topic of the article. So, we have added a short explanation how the coefficients had been calculated. Moreover, relevant literature, in which the structure of this index (DG3L) and its physical foundations are discussed in detail, is cited in the text.
11) Figure 2: Y-axis title says, STD? what is the difference between DG3L index and this one? It is not consistent. Is this anomaly or standard deviation?
Response to Reviewer: the Y axis is labelled with the DG3L designation, which is the variable name, while in square bracket there is the variable designation [STD] - standard deviation. This is the standard denotation, in which a given variable, if it is not a physical unit (eg. m, s, kg etc.), must be supplemented with an explanation (eg. speed [m · s-1]). The construction of the DG3L variable is described in lines 115-137, just before Figure 2. From the description (formula (3) directly above Figure 2) it can be seen that the variable DG3L is a standardized deviation (anomaly) from the average calculated for the period 1901-2000.
12) Line 146-153: …macrotypes W, E and C & circulation type C2D and D2C…” these types need to be defined in the paper, just referring other paper does not make sense here. Authors asked to read other papers to learn this paper which is not right.
Response to Reviewer: the concept of macrotypes W, E and C according to the classification by Vangengeima-Girs is widely used in various analyzes by climatologists in Eastern Europe. This does not mean that it is unknown in Western Europe, or generally in the English-language scientific literature related to climatology. It is - maybe not very often - cited in published scientific articles, but also in more advanced textbooks or monographs on climatology. For example, the classification by Vangengeima-Girs is discussed and the long-wave systems at the level of 500 hPa according to that classification are presented in the form of figures in the following fundamental monographs:
1. Lamb H.H., 1978. Climate: Present Past and Future; vol. I, Fundamentals and Climate Now. Methuen & Co LTD, 1-613. (p. 267, fig. 7.6),
2. Barry R.G., Carleton A.M., 2001. Synoptic and Dynamic Climatology. Routledge, London and New York; 1-620. (p. 570, Fig. 7.9).
Fulfilling the postulate of the Reviewer would have required rewriting some textbooks or monographs. In the Authors’ opinion this is not necessary. Unfortunately, sometimes, if there are any doubts about an issue, the Reader may be forced to refer to literature cited in the paper.
Another issue is the Reviewer's suggestion of explaining the types of circulation C2D and D2C. Since the typology of the lower and middle circulation by Osuchowska-Klein (1978, 1991) may generally be unknown outside Eastern Europe, the authors attached a schematic diagram of the atmospheric pressure distribution corresponding to the circulation types mentioned in the text (C2D and D2C circulation types - Figure 5 in the paper).
13) Overall the Methodology section needs to be written.
Response to Reviewer: the ‘Methodology’ section has been improved accordingly.
14) Line 171-173: The starting of result is mentioned the final result. This sentence needs to be written or removed.
Response to Reviewer: this section of the paper refers to methodology applied in our study. First, we explain the available data sets and then methods used to analyze them. In our opinion this is a logical sequence of any research. Consequently, we would like to leave this section without changes.
15) Line 179-184: This paragraph explained some results, without referring any Figure or references, how?
Response to Reviewer: we added a relevant book as a reference [38].
16) Line 188: what is the meaning of below? Can be said like “ is considered here”… something like that..
Response to Reviewer: the sentence has been corrected accordingly.
17) Line 193-195: “changes …” This sentence is odd with starting from changes and needs to be revised..
Response to Reviewer: the sentence has been corrected accordingly.
18) Line 196: Same here to mentioned the macrotype, but don’t know what is that?
Response to Reviewer: introduction to macrotypes E and W of the mid-atmospheric circulation is presented in lines 184-189 and later in lines 233-237. As we explained earlier, more detailed explanations would have required rewriting some textbooks or monographs, which in our opinion is not necessary (please refer to remark No. 12).
19) Figure 3: what are the lines here? Figure caption does not explain these..
Response to Reviewer: as it is explained in the figure caption: “Marked are: regression line (solid line) and 95% confidence level (dashed lines)”. We would like to leave this explanation without changes.
20) Same for Figure 4..
Response to Reviewer: as it is explained in the figure caption: “Marked are: regression line (solid line) and 95% confidence level (dashed lines)”. We would like to leave this explanation without changes.
21) Figure 6: Which months are considered for the temperature? It looks like average annual temperature is considered during +ve and -ve DG3L, but it is not explained clearly neither in the text nor in Figure caption.
Response to Reviewer: Figure 6, as the caption explains, shows the deviation of the annual air temperature from the long-term average (1971-2015) in Poland during the occurrence of the positive and negative phases of DG3L, respectively. Individual months are not considered, since the whole year is taken into account. We have added a word “average” in the figure caption to make it more precise (the same in Figures 11 and 12).
22) Instead of taking the negative and positive, Can you make the correlation map of temperature with DG3L index? That would show some clear message here..
Response to Reviewer: maps of the correlation coefficients mentioned by the Reviewer would only present the distribution of the combined strength (in the form of isocorelates). This would only explain the strength of the relationship between two variables (DG3L & temperature (t), DG3L & flows (H)). However, it would not explain what are the average deviations (Δt, ΔH) of air temperature and flows in the negative and positive phases of DG3L. For example, in the area of eastern Wielkopolska and Kujawy, which are the most exposed to the occurrence of hydrological drought in Poland, the correlation coefficient between the DG3L index and the annual flow is about -0.56. This value informs about the strength of the relationship. On the other hand, regression analysis indicates that in the negative phases of DG3L annual flows in this area grow by about 30%, while in the positive phases they decrease by about 30-40% in relation to the average flows in 1971-2015. This information seems to be more important to hydrologists than that about the strength of the relationship. The authors believe that regarding the problem analyzed in the submitted paper, the regression approach is more reliable and precise, explaining what are the specific values of air temperature and river flow (in percent of average monthly and annual flows) in different NA THC phases.
23) Line 266-267: Air temperature ….. this sentence is incomplete with missing verb..
Response to Reviewer: the sentence has been corrected by adding a word “shown”.
24) I would recommend to make the spatial correlation map of DG3L with river flow similar to Figure 8 as well.
Response to Reviewer: relevant maps have been added. A newly added Figure 8 shows spatial distribution of correlations between monthly river flows and the DG3L index with their statistical significance (p), while Figure 11 presents spatial distribution of correlations between average annual river flows and the DG3L index and their statistical significance (p).
Thank you once again!
Author Response File: 
Author Response.pdf
Round 2
Reviewer 3 Report
The revised version of manuscript addresses most of my comments and I recommend to accept.
