Evaluation of the dual-polarization weather radar quantitative precipitation estimation using long-term datasets

Voormansik, Tanel; Cremonini, Roberto; Post, Piia; Moisseev, Dmitri

doi:https://doi.org/10.5194/hess-25-1245-2021

Articles | Volume 25, issue 3

https://doi.org/10.5194/hess-25-1245-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/hess-25-1245-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 25, issue 3

Research article

|

12 Mar 2021

Research article |

| 12 Mar 2021

Evaluation of the dual-polarization weather radar quantitative precipitation estimation using long-term datasets

Tanel Voormansik, Roberto Cremonini, Piia Post, and Dmitri Moisseev

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Final revised paper (published on 12 Mar 2021)
Preprint (discussion started on 10 Jan 2020)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review of hess-2019-624', Anonymous Referee #1, 06 Feb 2020
- AC1: 'Reply to Anonymous Referee #1', Tanel Voormansik, 09 Apr 2020
RC2: 'Review', Hidde Leijnse, 12 Feb 2020
- AC2: 'Reply to Referee #2', Tanel Voormansik, 09 Apr 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (further review by editor and referees) (11 May 2020) by Laurent Pfister

AR by Tanel Voormansik on behalf of the Authors (13 May 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (18 May 2020) by Laurent Pfister

RR by Anonymous Referee #1 (15 Jun 2020)

Suggestions for revision or reasons for rejection

Review of revised version of Manuscript hess-2019-624

Applicability of dual-polarization weather radar quantitative precipitation estimation for climatological purposes

Voormansik et al., 2020

GENERAL COMMENTS

The paper has been revised by the authors and some additional explanations and clarifications concerning the data and the processing methods have been brought. Some references have been added. This is highly appreciated. I would like to thank the authors for the careful attention given to most specific comments.
However, some majour concerns I expressed in my review remain in the revised version and, unfortunately, some suggestions for improving the paper have not been considered by the authors. The following issues remain :

- the focus of the paper is still unclear. The title has been changed but the focus is still on the use for climatological purpose while the scope of the paper is on the evaluation of the performance of the QPE methods.

- the tuning that was applied to optimize the processing is still unclear. The settings have been selected in order to produce the optimal results but very little is said on how the evaluation of the quality of the results has been performed in order to find the best parameters.

- the impact of re-calibrating the horizontal reflectivity has not been analyzed as suggested in the review.

- using the Italian data, it was possible to analyse the impact of the temporal sampling, 5-min versus 15-min. A simple method was proposed that would have allowed to evaluate errors resulting from temporal sampling.

- the original aspect of the present study does not clearly appear
The paper has been improved but, in my view, only minor modifications have been brought by the authors.

SPECIFIC COMMENTS

Abstract

The length of the dataset is now mentioned. It is 5 years for both radars. It remains very short for climatological applications.

1. Introduction

The aim of the study is described like this in the introduction :
“The main aim of this study is to evaluate the potential of using polarimetric weather radar QPE for climatological evaluation of precipitation regimes.”
What do the authors mean with “precipitation regimes” ?

2. Data and methods
2.1 Rain gauge measurements

A short description has been added. Can the authors explain which kind of “weather sensor data” they use in the manual quality control ?

2.2 Weather radar precipitation estimates

Some additional information is provided in the revised version concerning the processing of the raw PHIDP data to derive KDP. However, some questions remain. For example, what is the resolution in range of the derived KDP ? Based on which criteria are the results considered as optimal ?

The selection criteria based on PHIDP and Delta PHIDP are not perfectly clear (L 142 to 148). It is indicated that bins with PHIDP larger than 12 deg. are removed and that ΔPHIDPobs should be larger than 8 deg. Is this not too restrictive ?
How is the 25 dBZ threshold selected ? The authors explain that this threshold is chosen because it is the one which performs best without explaining in the revised version how this performance is evaluated. Which time period is used to make this evaluation ?

2.3 Comparison framework

Concerning hail, the following sentence was added by the authors : “Possible occurrence of hail was not removed from the data because of the intention to keep additional data processing minimal and allow level comparison of the various QPE methods.”.
I don’t catch what “level comparison” means.

3. Results and discussion

The discussion of the results has been improved but the interpretation remains sometimes unclear.

TYPOS AND FORMULATIONS

Some strange formulations and spelling errors remain present throughout the text. I would recommend having the text proofread by a native English speaker.

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RR by Anonymous Referee #3 (07 Oct 2020)

Suggestions for revision or reasons for rejection

The Manuscript deal with a relatively long period of 5 summer seasons of two weather radar observations in Italy and Estonia. The motivation of the work is convincing to me although 5-seasons cannot be properly defined as climatological dataset. This must be stressed through the manuscript. The results are not really new as implicitly recognised by the Authors. However, the relatively long time period and sites analysed are worth to be considered for a possibile publications.

I am in doubt about the appropriateness of the journal with respect the novelty of the work presented.

Specific Comment:

- Since the manuscript focuses on summer seasons I guess that convective events mainly populate the analysed dataset. The representativeness of the dataset considered is then biased toward more severe events. So, maybe the manuscript’s title is not fully appropriate. Please consider this option “Applicability of dual-polarization weather radar quantitative rainfall estimation for climatological extremes”

- Path attenuation in convection can be severe at C band but is not corrected by the authors to avoid introducing further errors. On the other hand, Pdp (Kdp actually) is used for QPE. So If you trust in Kdp for QPE you should do the same for path attenuation compensation too. Isn’t it?

- Conclusions of the work are not really new. See for example ( https://doi.org/10.1175/JAMC-D-10-05024.1 and https://doi.org/10.3390/atmos8020034)

Minor comments:
- Introduction L 30 “Detailed surface rainfall information is of great importance in many fields not only for agricultural or hydrological applications but also for assimilation purposes within numerical weather models and climatologies.”
I do not think rain is directly assimilated into NWP. About Climatological models verify their output with large scale (100km at best) satellite retrievals . Thus the required rain fields for climatology do not need to be too much “detailed ”. By reading next It is clear what do you mean but I suggest to rephrase the beginning of the manuscript.

- Could you please give more explicit detail on the automatic gauge quality control?

- Page 5, “self_const (self-consistency factor) “ is not explained.

- please increase the readability of figure 9 and 10

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ED: Publish subject to revisions (further review by editor and referees) (22 Oct 2020) by Laurent Pfister

AR by Tanel Voormansik on behalf of the Authors (03 Dec 2020) Author's response Manuscript

ED: Publish subject to revisions (further review by editor and referees) (22 Dec 2020) by Laurent Pfister

ED: Referee Nomination & Report Request started (05 Jan 2021) by Laurent Pfister

RR by Anonymous Referee #3 (25 Jan 2021)

ED: Publish subject to technical corrections (02 Feb 2021) by Laurent Pfister

AR by Tanel Voormansik on behalf of the Authors (08 Feb 2021) Manuscript

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Short summary

A long set of operational polarimetric weather radar rainfall accumulations from Estonia and Italy are generated and investigated. Results show that the combined product of specific differential phase and horizontal reflectivity yields the best results when compared to rain gauge measurements. The specific differential-phase-based product overestimates weak precipitation, and the horizontal-reflectivity-based product underestimates heavy rainfall in all analysed accumulation periods.