the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Modelling the interannual variability of Maipo and Rapel river plumes off central Chile
Julio Salcedo-Castro
Antonio Olita
Freddy Saavedra
Manuel Castillo
Gonzalo S. Saldías
Raúl Cruz-Gómez
Abstract. River plumes have a direct influence on coastal environments, impacting coastal planktonic and benthic communities, including fishery resources. In general, the main drivers of river plume dynamics are the river discharge and the alongshore wind stress, whereas the tides and topography play a secondary role. In the Central parto of Chile, rivers flowing into the eastern Pacific have a relatively short path on the land, with a high slope; further they are characterized by a mixed snow-rain regime. This study aims to understand the interannual variability of the plumes of the Maipo and Rapel rivers in the Coastal/shelf area off Chile and its influence on local ocean dynamics. We used the Coastal and Regional Ocean Community model (CROCO), with 1 km resolution and 20 sigma levels, to simulate the ocean dynamics of the area over the period 2003–2011. The results show that the plume’s area coverage and coastal ocean salinity are strongly correlated to the river discharges. The predominant southwestern wind controls the plumes orientation toward northwest; however, episodes of wind changing direction from northwest in winter can reverse the plumes direction, making them squeezed to the coast and moving southward. Results also show, for the decade under evaluation, a salification trend linked to the severe droughts hitting Central Chile during the studied period. This salification determines a change in local dynamics.
Julio Salcedo-Castro et al.
Status: open (until 14 Apr 2023)
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RC1: 'Comment on egusphere-2023-98', Anonymous Referee #1, 14 Mar 2023
reply
This manuscript investigates the dynamics of the river plumes of Maipo and Rapel rivers, in central Chile, using numerical simulations. The model chosen is the CROCO, with detailed horizontal resolution (1 km) and appropriated number of vertical levels (20 levels in this sigma coordinate model). The main focus is in the interannual variability of the plumes. Considering the importance of the plumes in affecting biological communities, I believe this is an interesting topic of investigation and deserves attention. However, some work is still need before publication and my comments follow below, separated in major and minor concerns.
Major issues:
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One of the purposes of this study is understanding the rive plumes dynamics in a interannual variability scale. However, the authors only provided 9 years of simulation which, in the best scenario, is capable of record 3 or 4 interannual events/cycles. I believe this period is very short for this purpose;
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Although the simulations seem reasonable, there is no comparison with any data set. For this period (2003-2011), the authors can find satellite SSS and SST, which could be compared to the simulation results and give some idea of the actual performance and limitations of the model. I strongly believe this is a necessary step to give more confidence on the results to other researchers interested in the subject.
Minor issues:
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Line 3 (Abstract): “In the central part” instead of “In the central parto”;
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Line 23 (Abstract): “Study” seems more appropriated then “work”;
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Figure 1: The resolution of it is very coarse and should be improved;
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Equations (1) to (6): Every term in the equation should be clearly stated, even when it looks obvious. Some of the terms are not described;
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Line 124: Reference is given as “(e.g. Olita et al. (2011a))” and should be, I believe, “(e.g. Olita et al., 2011a)”. Please, check if are other references with the same problem;
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Line 127: Considered instead of considering?;
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Figure 3: Units should be mentioned, preferably in the color bar;
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Figure 3: Why logarithmic scale? Is this really the case? It does not look like and, if so, I’d suggested using linear scale;
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Figure 3 (legend): Avoid terms such as “logically associated to”. Everything either needs a reference or be proven;
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Lines 140 to 145: The authors give a limit to salinity values to define the river plume, which is fine. I believe, however, that a better description of the SSS in the region should be part of the Introduction, so the reader can better understand why that limit was chosen;
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Line 165: The first two sentences are repetitive. Please, rephrase them;
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Line 167: 66.7, 9.1, 5.5 and 4.9 are percentages, correct?
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Figure 10: The resolution of it is very coarse and should be improved;
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Line 169: “system variability varies” sounds weird. Please, rephrase it;
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Lines 178 to 181: I believe you could be more assertive, since you are dealing with numerical simulations and are capable of analyzing all the data without a gap;
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Line 225: “correlated to ENSO”;
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Lines 244 and 245: everything after the comma is quite confusing. Please, rephrase it;
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Line 250: “Have so impact”?;
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Line 252: “This” instead of “thus”?;
Citation: https://doi.org/10.5194/egusphere-2023-98-RC1 -
Julio Salcedo-Castro et al.
Julio Salcedo-Castro et al.
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