Implications of the 2015–2016 El Niño on Coastal Mississippi-Alabama Streamflow and Agriculture

Round 1

Reviewer 1 Report

The manuscript assesses the impact of 2015-2016 El Nino event on the agriculture (mainly cotton and peanuts) of Alabama and Mississippi. Because the summer season following strong winter EN events is usually dry, such crops would been impacted, also considering the lack of impoundments and irrigated lands. Introduction, Data and Methods, and Results are satisfying presented. However, Discussion and Conclusions are poorly developed.

In my opinion it is necessary to discuss the findings in the broadest spectrum of the specific literature. The sentence "Past research has failed to provide information on the seasonal signal of streamflow, specifically, the summer season" [283-284 lines] is ambiguous and should be edited.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments on “Impacts of the 2015-2016 El Niño on Coastal Alabama – Mississippi Agriculture” by Sahar Sadeghi, Glenn Tootle, Venkat Lakshmi, Matthew Therrell, Emily Elliott, Ajay Kalra (2019).

Summary

Sadeghi et al. well reviewed the agriculture production during the 2015/16 super El Nino, especially several crops that have deep implication for the US economics. The streamflow from several gauges are analyzed and its prediction using the El Nino historical statistics is discussed. The paper is suitable for the journal “hydrology”. However, I still have a concern about the 2015/16 super El Nino background, which has been widely reported. The authors should well review those recent publications.

Major comments

The introduction is not well organized in this version. The streamflow is mainly associated with precipitation, which is remotely related to El Nino. The impact of the super El Nino on regional (US, China, Australia, Europe) rainfall has been well studies in literature. However, the authors did not review those references (https://doi.org/10.1007/s00376-017-6260-x; https://doi.org/10.1007/s13351-016-6101-3; ). A brief review is needed to well understand the 2015/16 super El Nino and its impact.

Other comments:

The title: It is better to emphasize the 2015/16 event is a “super” El Nino. The main result in this study is the streamflow volume and its prediction in five gauges, but this title does not mention.

L14-15: Ill sentence. Moisture, not moister.

L18: Delete “however”. No turning is found.

L39-40: Ill sentence. “have been …do not”?

L43-44: Inconsistent for the two sentences. “A … probability, … the … probability…”? Use the indefinite article word to keep consistent.

L46-49: The EP and CP ENSO have been well studies. There should be more space for a review on recent publications in literature (https://doi.org/10.3354/cr01560).

L51-53: It is not true that “positive temperature is the indication of ENSO”. Where? How? “ENSO phase causes…” (you use “cause”).

L62-75: You say too much for reference [16]

L79: Typo. There are two continuous stop points.

L86: Typo. Delete the prime sign (apostrophe).

L130-131: And also China. See the suggested references aforementioned.

L138: “…there is little to no understanding…”? Please clarify your meaning.

L155: Did you use the Nino3.4 index. There are several ONIs. Be more specific by using “Nino3.4 index”.

L196: Rephrase like “The results can be used to predict…”

L209-211: All variable should be written in Italic fonts. m n

Section 3 mainly reports the streamflow and its statistical prediction, which is the focus of the study. But I can not find anything about it in the title.

L283: Could you add some figures plotting the precipitation if you want to emphasize it?

L351-352: Ref 21 and 22??

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

This paper examines the impact of El Nino on streamflow in coastal Mississippi-Alabama and discusses the further impact on local agriculture.  Forecasts for 2016 winter, spring and summer streamflow are also made based on past El Nino events similar to the 2015/2016 El Nino.  The topic is interesting and the results are potentially important to local agriculture.  However, the results and discussions presented in the manuscript need some improvements.  Therefore, I suggest that the paper could be published pending major revisions.  My major concerns and some minor points are listed below.

Major concerns

1. The title of the manuscript does not reflect the results of the analysis presented in the manuscript.  The results in section 3 focus on the impact of El Nino on streamflow, rather than agriculture. 

2. I feel that the study is incomplete.  For example, all the impacts of ENSO on agriculture were taken from previous studies and reports.  The authors may want to conduct further analysis to provide evidence on the linkage between ENSO and local agriculture.

3. The methodology described in lines 186-205 to forecast streamflow is basically the so-called ensemble streamflow prediction (ESP).  A reference paper is needed if the methodology is not developed by the authors.  The forecast skill of this method can also be assessed through cross-validations (leave-one-out method) over past ENSO years.

4. Seasonal precipitation plays a major role in determining local streamflow in both winter and summer.  The authors find increased streamflow in El Nino winter and decreased streamflow in summer following El Nino in the coastal Mississippi-Alabama (MS-AL).  This is consistent with previous studies (Wang and Fu 2000; Wang et al. 2012), in which the relationships between El Nino and precipitation in this region were well documented.  For example, the precipitation in winter months over the coast MS-AL is above normal during El Nino (Wang and Fu 2000, their Fig. 1).  In summer following an El Nino, in contrast, precipitation in the coast MS-AL is below normal (Wang et la. 2012, their Figs. 1b, 3f) due to an eastward shift of tropical forcing associated with sea surface temperature (SST) anomalies.  Although the forecast for summer streamflow in this manuscript was based on preseason SST (e.g., ASO SST, Fig. 2), the tropical forcing for local precipitation is actually closely related to summer SST.  Therefore, it would be interesting to see if the evolution of SST during the four El Nino years after ASO is similar to that of 2016, especially in the eastern tropical Pacific.

References:

Wang, H.; Fu, R. Winter monthly mean atmospheric anomalies over the North Pacific and North America associated with El Nino SSTs. Journal of Climate, 2000, Vol 13(19), pp. 3435-3447.

Wang, H.; Kumar, A.; Wang, W.; Jha, B. U.S. summer precipitation and temperature patterns following the peak phase of El Nino. Journal of Climate, 2012, Vol 25(20), pp. 7204-7215.

Minor edits

1. Lines 14-15: Change to “increased soil moisture” (delete “in”) or “increase in soil moisture” (delete “d” after “increase”).

2. Line 62: Change to “ENSO phases” (Change “P” to “p” for “phases”).

3. Line 71: Change “were” to “was” (The influence … was also evaluated).

4. Line 79: Delete repeated “.” after “cotton”.

5. Line 79: Replace “N” by “n” for “neutral years”.

6. Line 82: Delete “,” after “whereas”.

7. Line 90: Change to “is economically the most important crop”.

8. Lines 114-116: Change to single space for Fig. 1 caption.

9. Line 114: Replace “C’ by “c” for “coastal”.

10. Line 165: Add “.” after “[23]”.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

All of my concerns are addressed.

Reviewer 3 Report

The authors have taken considerable steps in revising the manuscript, and comprehensively addressing my earlier comments.  I recommend acceptance of the paper.