the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Intense rains in Israel associated with the 'Train effect'
Abstract. 'Train effect' is defined as a cloud system in which several convective cells pass over the same place in a short time. Trains produce large amount of rainfall, frequently leading to flash floods, reported mainly over North America during spring and summer. Thirty train events were identified, using radar images, calibrated by rain-gauges, for four winters, all associated with Cyprus Lows (CL). The dynamic factors responsible for their formation in Israel were examined, utilizing the ECMWF Integrated Forecast System of 0.1° resolution.
Seventeen out of the 30 events share common features. Each one was found at the cold sector in the southern periphery of a CL at its occluded stage, and located in the left flank of a maximum wind belt, where cyclonic shear vorticity exists. The trains cross the Israeli coast near 32.2° N, with a mean length of 45 km, last 1–3 hours, and yield ~35 mm rainfall. The maximum wind belts right of the trains were found to delineate the limit of the precipitative region of the CLs. Unlike classical trains, activated by thermal or frontal forcing, the EM trains that develop in cold air-mass, can be entitled 'cold trains', rather than the classical 'warm trains'.
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RC1: 'Comment on nhess-2023-215', Anonymous Referee #1, 28 Jan 2024
General comments:
This paper summarizes the results of a well designed and well carried out study into the characteristic dynamical feature associated with a “Train Effect” phenomenon in the eastern Mediterranean during winter. The authors identify the main dynamical features associated with the a train of precipitating convective cells moving from sea to land in the southern coastal region of Israel and compare and contrast them to features identified in previously studied train effect in the U.S. summer.
The paper can benefit from editing to improve its presentation quality by attending to grammatical and sentence structure errors. I indicated some of those below.
Specific comments (in order of appearance in the text):
- Page 1, line 18: “yield ~35 mm rainfall”. Here and in the paper text the authors refer to rain amounts and it is not clear if the numbers imply rain rate (i.e., about per unit time) of the amount of precipitation falling over the entire life time of the phenomenon. I suggest being more specific regarding the values given here and in other cases in the text.
- Page 1, lines 29-30: Where is the sentence part put in quotes taken from (citation is missing)?
- Page 4, line 112: “characterized AS A Mediterranean-TYPE climate”, can you provide reference for “Mediterranean-type Climate”?
- Page 4, lines 119-121: “persisted 3.5 hours and generated heavy rain, with a maximum of > 60 mmh -1(as inferred from Fig. 3a-e), summing up to > 60 mm for the entire event (Fig. 3f). The integrated rainfall during the event exceeded 40 mm along the train.” The numbers don’t’ make sense to me.
- Page 9, sentence on lines 184-187: This is confusing. In Fig 4A the train is south of the maximum wind, i.e., to the right of it. The situation is different in Fig. 4b, where the train is on the left. So the relation of the train to the maximum wind depends on the level of the wind, right?
- Page 11, lines 228-29: So there is a common dynamical element between the two phenomena?
Editorial comments:
Page 2, line 43: in reference to the LLJ - change “tend” to “tends”.
Page 2, line 46: “in the form of A train” (missing “a”) or “in the form of TRAINS” (in plural).
Page 2, line 50: “Heavy rains …….. HAVE been identified”
Page 2, line 53: “convergence of A land breeze.” (Missing “a”) or “convergence of land BREEZES.” (Refer to the land grease phenomenon in plural.
Page 2, line 54: “convergence between A southerly land-breeze”
Page 3, line 68: “took THE lives of 10 people.
Page 3, line 73: “and ATEMPS to generalize”
Page 3, line 77: “The rain data ARE”
Page 3, line 77: “with 200-270 mm” - over what time interval? The entire time span of the phenomenon?
page 4, line 117: 60 mm over what time?
Page 4, lines 117-118: “form of A train”
Page 4, line 122: “ON the order of” (same on page 5 line 131).
Page 6, line 148: Use “included in the study” instead of “composing the study”
Page 7, line 155: Use “orientation was around” instead of “orientation is around” (past tense fits better with the previous and following sentences).
Page 7, line 130: “which IMPLIES a high potential”
Page 10, line 211: Instead of using “the factors are irrelevant” ), i.e., as if there are factors like that here and they are not material, I suggest stating that: “The factors relevant for EM trains are different”
Page 11, line 220: Instead of using the terms “left flank” or “right flank” here and before why not use more geographical term such as “north flank” and “south flank”?
Citation: https://doi.org/10.5194/nhess-2023-215-RC1 - CC1: 'Comment on nhess-2023-215', Hadas Saaroni, 25 Apr 2024
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RC2: 'Comment on nhess-2023-215', Anonymous Referee #2, 29 Apr 2024
General comments:
In general, I think this is an interesting study to explore the dynamics of the “cold train” phenomena over the eastern Mediterranean region. This research could provide more insight into the causes of high impact weather event in the region. There are several places where additional explanations might be needed to increase clarity and readability. I recommend minor revision.
Specific comments:
Lines 81-84: Is there any reason this dataset is used instead of ERA5?
Lines 85-89: It might be useful to include a schematic diagram to better illustrate how this is defined in the current study.
Lines 92-94: I am a bit confused here. What is the “reference point” (e.g. is it “train”-centred?) of these transformations? For example, how do the authors know how much should an atmospheric field need to rotate/scale/move?
Fig. 2: I was originally a bit puzzled by the red line as the train but then when I saw Fig. 3f, it makes perfect sense. Would the authors consider moving Fig. 3f to Fig. 2?
Lines 156-158: The authors suggested that there is a positive relation between longitude of the cyclone center and the train orientation. However, it is not very clear to me whether this is the case. Perhaps the author could show the result of correlation analysis to support their statement?
Lines 160-162: I think it might be worthwhile to include some figures in the supplementary to support these statements, e.g. overlay of 925 hPa GPH and precipitation of those events.
Table 1: Perhaps the event entries should be in chronological order (event no. 15 and 16).
Section 4:
- It would be better to separate Summary and discussion. It is because certain core ideas of this study only appear in this section (and in the abstract), which should have been discussed in earlier sections. E.g. the notion of cold trains and warm trains only appears in the abstract and in Section 4. The authors should introduce such notion in the introduction to increase readability. Furthermore, the dynamical framework of “cold train” is one of the core results of this study. This alone deserves its own section.
- [related to introduction] In the introduction, the authors should explicitly indicate the existing “warm train” model could not explain the “train” observed over EM. Then this section would make more sense.
Lines 231-236: I am a bit confused. At the beginning of the paragraph, it seems that “friction exerted by the sea surface” is not a contributing factor but at the end it appears to suggest that it is?
Figure 6: What level(s) of pressure, wind, etc are shown in the figure?
Lines 269-274: Could this research be applied to improve nowcasting/short-range forecast?
Appendix A: This section is not mentioned in the main text. Since it is related to the train formation, perhaps the authors should consider including this section in the main text rather than in the appendix.
Citation: https://doi.org/10.5194/nhess-2023-215-RC2
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