Characteristics of Convective Parameters Derived from Rawinsonde and ERA5 Data Associated with Hailstorms in Northeastern Romania

Round 1

Reviewer 1 Report

Review for Article entitled:

Characteristics of Convective Parameters Derived from Rawinsonde and ERA5 Data Associated with Hailstorms in North-eastern Romania

By Szymon Vasilică Istrate *, Dorin Podiuc, Dragoș Andrei Sîrbu, Eduard Popescu, Emil Sîrbu and Doru Dorian Popescu

General Comments

The article reports on convective parameters and statistical analyses linked to hailstorm occurrence. These analyses are directly related to forecasting of hailstorm activity, an issue of a challenging research and operational goals and in this frame this article is interesting and welcome.

Generally, the article examines good data sets with appropriate convective parameters and follows an interesting and accepted methodology.

Overall, I recommend acceptance of the article with some minor corrections and some suggestions that may be helpful in improving the paper.

Some suggestions and minor corrections

l In ABSTRACT, line 10, the year “20981” should be also corrected.

l In MATERIALS and METHODS, a definition of hail day should be given.

l In MATERIALS and METHODS, line 91, the “3 hail days/year” average should be clarified if it is a regional or point hail day frequency.

l In MATERIALS and METHODS, line 126, the final hail day number sample used from April to October should be mentioned.

l Some clarifications are needed about “Parcel Parameters”, as included in Table 1 and described in 3.1.1, specifically if they are calculated as “SB-surface based” or “ML-mean layer” or “MU-most unstable”, so be comparable with similar literature values.

l There is some concern about the Sounding data used, some values of 12:00 UTC seem not reasonable compared to 00:00 UTC corresponding values, i.e. CAPE, KI and TT. A question is arisen about the representativeness in space and time of the hail event. Sounding data should be re-checked and only the representative and proximity soundings be used in the analysis, i.e. those radiosonde stations located downwind and in a distance less than 150 km form the hail event location.

l Figure 1a is not necessary be included, Romania is a well known European country.

l Figure 1c should be changed in colors becoming more clearly read.

l The number of references is too large and should be limited in those referred mostly to hail and hailstorms.

Overall the English of the manuscript should be checked and improved.

Author Response

Many thanks for the review and the constructive comments made. The suggested corrections have been made in the text as well as in the case of the figures. The list of references has been revised and those not related to the subject of the paper have been removed. English has also been revised and grammatical errors corrected.

Author Response File: Author Response.pdf

Reviewer 2 Report

General Comment:

The authors present interesting research that aims to advance in the characterization of the convective parameters associated with hailstorms in northeastern Romania. By combining multiple sources of hail occurrence data and sounding and reanalysis data, they are able to describe the main characteristics of the convective parameter space associated with hail days in the region.

The Figures are well presented, although I found the manuscript hard to read in some sections. I believe that a general grammar revision (maybe with some of the free available online grammar tools such as grammarly) is needed to assure that the ideas presented will be understandable to everyone.

I’ve made some specific comments in the section below. My recommendation is that the manuscript will be accepted with minor revisions.

Specific Comments:

Abstract: “Using a database of 378 hail days between 20981 and 2020…”. 

There is a typo in the year.

Line 35: “For example, CAPE or the thermal gradient in the middle troposphere causes the increase of the updraft and implicitly the increase of hailstones [8-18]”

Do you mean the increase in the updraft speed? There should be a caution statement here. Although it is true that stronger updrafts are capable of supporting larger hailstones, it is not clear yet that a direct relationship between CAPE and hail size exists. 

See for example: 

Lin, Y., and M. R. Kumjian, 2022: Influences of CAPE on Hail Production in Simulated Supercell Storms. J. Atmos. Sci., 79, 179–204, https://doi.org/10.1175/JAS-D-21-0054.1.

Line 38: “ for hail forecasting [12].Specialists within…”

Missing space after dot.

Line 43: “ther representative parameters” 

There is a missing “O” at the start of the sentence.

Line 58: “Alternative forecast techniques such as one-dimensional and convective cloud models (HAILCAST) to estimate potential hail size based on the vertical profile of the atmosphere [35,36]”

Consider adding a verb to the sentence. I.e:

“Alternative forecast techniques such as one-dimensional and convective cloud models (HAILCAST) to estimate potential hail size are based on the vertical profile of the atmosphere [35,36]”

Line 70: “For hailstorms, a convective environment appears as a case study of exceptional events [46,47,48,49].”

This sentence is confusing, please consider rewriting it. 

Line 72: “The lifted Index linked with the values of temperature laps in the middle troposphere…”

Consider “lapse rates” instead of “laps”.

Line 96: “Hail data.”

Is there any indication of hail size from the sources used in this study? It will be interesting to see if there are any differences between the convective parameter space for situations of large hail vs small hail.

Line 119: “For a comparison the convective parameters, was used ERA5 database [65].”

Consider rewriting this sentence, maybe:

“For a comparison of the convective parameters, the ERA5 database was used [65].”

Also, is the ERA5 data compared at the sounding station location or at the closest gridpoint to the hail report? Please clarify. 

Line 112: “Data from sounding stations in the vicinity of the studied area, namely Bucharest-Băneasa, Cluj-Napoca, Cernăuți and Odesa, as well were used reanalysis data from ERA5.”

I’m not familiar with the local climatology and circulation patterns, but I have a concern about the representativity of the “Cluj-Napoca” soundings when analyzing the conditions in the area of study. This location is to the west of the mountain barrier, and it may be that the low-level conditions could be very different that the ones observed to the east, especially affecting those convective parameters associated with low-level humidity. I believe this could be an issue. Do you have an estimate of in how many cases the “hail days” have been estimated using this sounding?

Line 127: “from April to October and for the 00:00 (03:00 AM local time) and 12:00 PM GMT (12:00 PM local time) of the day.”

If 0000 UTC is 0300 Local Time, 1200 UTC cannot be 1200 LT. Please correct.

Line 138: “...and 505 J/kg for the asounding…”

Remove the extra “a” in “sounding”.

Figures 2 to 6 and along the paper in general: Why do you compare the ERA5 data with the observed soundings only for some parameters (CAPE, Wmax, CIN, LCL) and not others (LI, SW, EL, H_cl)? Please justify the election of those parameters and why some of them are not computed for the ERA5 data.

Line 180: “The other two indices in this category LR_0-7 and LR_5-8 provide an image of some thermal and humidity characteristics of the low troposphere, respectively of the middle troposphere (Figure 3). LR_0-7 represents, from this point of view, in general the situation in the first 3 km of the troposphere. Its values from 12 UTC, in the case of both data sources, are between 6.5 and 9.5 0C/Km indicating the presence of an amount of moisture located below the planetary boundary layer.”

Please revise this section. Why is there a relationship between the lapse rates in these ranges and the boundary layer moisture?

Line 195: “..calculated for all hail days analyzed begine from 75% in the…”

Consider changing “begine” to “begin”.

Line 252: “relations betwin”

Consider changing “betwin” to “between”.

Line 254: “Good correlations were considered those with values of rs greater than…”

The abbreviation “rs” has not been defined before.

Line 256: “The most obvious are the high correlations between the indices calculated based on the particle theory and those between them and the moisture parameters, respectively the composite parameters.”

This sentence is confusing. I do not understand if there is a high correlation between indices calculated based on parcel theory (ICBPT) and the moisture parameters, between ICBPT and the composite parameters, between ICBPT and both. Is there a correlation between moisture and composite parameters? Please revise the writing.

Table 2: I do not understand which values correspond to ERA5 data and which to sounding data. Where do these values come from? For example, the couple CAPE-LCL at 0000 UTC shows a value of 0.60. Figure 7 shows an insignificant correlation (grey) between those parameters. Figure 9 shows a value of -0.1. Please revise or comment on where those values came from.

Line 308: “For the same region [57] found that highest MUCAPE characterizing the north-easterly anticyclonic.”

Please revise the writing. Is the north-easterly anticyclonic flow in the region associated with large MUCAPE, as found by [57]?

Line 314: “The first category of indices also correlate very well with the amount of moisture in the lower troposphere, expressed by MLMIXR and RH850. Therefore, a higher amount of

moisture in the lower troposphere causes a lower temperature gradient and increases the

cloud base height approximated by the LCL index.”

Table 2 does not show a correlation value for any of the parcel parameters and RH850 or LCL. Additionally, one should expect that an increase in the boundary layer moisture will lower the LCL height. Please revise.

Line 319: “The negative correlation between LCL and UR850...”

I believe is “RH850” instead “UR850”, please revise.

Line 329:  What is a “hail grelon”? I don’t believe I read this term before when referring to a hailstone. Please revise.

Line 380: “The mail conclusion…”

Consider changing “mail” to “main”.

Author Response

Many thanks for the review and the constructive comments made. The suggested minor corrections have been made in the text of the article. Indeed the methodology used has weaknesses but we consider this research as exploratory. Some of your suggested changes would result in a substantial modification of the paper. We appreciate the value of your comments, which in the future will contribute to improving the quality of our research.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript is generally well organized and the visuals are well prepared. Many convective parameters have been analyzed using climatological data sets for many years. There are typos and grammatical errors. I have listed some of them below. I suggest language correction before the next revision. 

Revisions:

1) P1, L10, recheck the period, “… between 20981 and 2020 ….”.

2) P1, L14, add ‘the’ before “average value”.

3) P1, L16, change “high correlations between” to “high correlations among”.

4) P1, L17, remove ‘the’ before “humidity indices” and “complex indices”.

5) P1, L18, change “low level” to “low-level”.

6) P2, L43, there is a typo at the beginning of the paragraph.

7) P3, L96, remove “.” from the title.

8) P3, L97-99, recheck this long sentence and its use of conjuctions.

9) Table 1,  Index names must be capitalized.

10) The verb “analyze” has two different uses in the paper. Please choose only one of them. Check P4, L126, analyses or analyzes?

There are typos and grammatical errors.

Author Response

Thank you for your corrections and suggestions. The changes suggested by you and the other reviewers have been made in the new form of the paper. The English also was improved

Author Response File: Author Response.pdf