the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 05 Oct 2023
Key ingredients in regional climate modeling for improving the representation of typhoon tracks and intensities
Patrick Olschewski
Jianhui Wei
Zhan Tian
Laixiang Sun
Harald Kunstmann
Patrick Laux
Abstract. There is evidence of an increased frequency of rapid intensification events of tropical cyclones (TCs) in global offshore regions. This will not only result in increased peak wind speeds but may lead to more intense heavy precipitation events, leading to flooding in coastal regions. Therefore, high impacts are expected for urban agglomerations in coastal regions such as the densely-populated Pearl River Delta (PRD) in China. Regional climate models (RCMs) such as the Weather Research and Forecasting (WRF) model are state-of-the-art tools commonly applied to predict TCs. However, typhoon simulations are connected with high uncertainties due to the high number of parameterization schemes of relevant physical processes (including possible interactions between the parameterization schemes) such as Cumulus (CU) and Micro Physics (MP), and other crucial model settings such as domain setup, initial times, and spectral nudging. Since previous studies mostly focus on either individual typhoon cases or individual parameterization schemes, in this study a more comprehensive analysis is provided by considering four different typhoons of different intensity categories with landfall near the PRD, i.e., Neoguri (2008), Hagupit (2008), Hato (2017), and Usagi (2013), as well as two different schemes for Cu and MP, respectively. Moreover, the impact of the model initialization and the driving data is studied by using three different initial times and two spectral nudging settings. Compared with the best-track reference data, the results show that four typhoons show some consistency. For track bias, nudging only horizontal wind has a positive effect on reducing the track distance error; for intensity, compared with a convective-permitting (CP; nudging potential temperature and horizontal wind; late initial time) model, using Kain-Fritsch scheme (KF; nudging only horizontal wind; early initial time) configuration shows relatively lower minimum sea level pressures and higher maximum wind speeds which means stronger typhoon intensity. Intensity shows less sensitivity to two MP schemes compared with the CP, nudging, and initial time settings. Furthermore, we found that compared with the CP, using the KF scheme shows a relatively larger latent heat flux and higher equivalent potential temperature, providing more energy to typhoon development and inducing stronger TC. This study could be used as a reference to configure WRF for historical and future TC simulations and also contributes to a better understanding of the model simulation performance of principal TC structures.
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Qi Sun et al.
Status: open (until 08 Dec 2023)
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RC1: 'Comment on hess-2023-222', Anonymous Referee #1, 17 Oct 2023
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Please see attacehd.
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RC2: 'Comment on hess-2023-222', Anonymous Referee #2, 07 Nov 2023
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The authors did a good job in presenting interesting analyses and results to the scientific community. However, as there are a few things requiring improvement in the manuscript at this point, it is suggested that the article should go through minor revisions and thorough English editing before accepting and publishing. Specific review comments are provided to the authors as follows.
- Lines 046 – 101: Although plenty of studies have been reviewed in the INTRODUCTION part, the authors are encouraged to review and include some more relevant works published recently. For example, Hsu et al. (2023; https://doi.org/10.5194/nhess-2023-49) analyzed how storm characteristics (e.g., TC path, intensity, heading direction, and translation speed) affect storm surge and wave runup along the coast during three historical Atlantic hurricanes. Zhang et al. (2023; https://doi.org/10.1016/j.oceaneng.2023.113977) used a storm surge model to study the wave and storm characteristics as well as how they responded to land reclamations in the Pearl River Estuary between 1990 and 2020. Furthermore, given the background of global warming, the effects of typhoon intensity increase on changes in waves and storm surges brought on by reclamations were also demonstrated.
- Lines 114 – 116: The authors are encouraged to rewrite this sentence to make it clearer for the readers to follow.
- Lines 187 – 189: First, what the authors wanted to express here may be confusing. Did the authors mean “For spectral nudging, we investigated the nudged horizontal wind above 500 hPa, the nudged horizontal wind, and the nudged potential temperature.”? The authors are encouraged to rephrase and rewrite the statement. In addition, did the authors mean “For the initial condition, we define the starting time of the simulation based on the TC intensity with an attempt to assess which initial time produces the most accurate results.”? The authors are encouraged to rephrase and rewrite these statements to make it clearer for the readers.
- Lines 201 – 202: “Propagating westward and passing over the Sulu Sea and then moving gradually to the northwest.” This sentence does not have a subject or verb. The authors are encouraged to rephrase and rewrite the statement.
- Lines 204 – 204: The authors are encouraged to revise “The difference between Typhoon Neoguri and the other considered storms is …” to “One of the main differences between Typhoon Neoguri and the other considered storms is …” because there are numerous differences between storms (e.g., path, intensity, radius of maximum wind).
- Lines 210 – 212: The authors are encouraged to indicate the UTC times for each relevant instant. For example, the authors are encouraged to rewrite the statement like “At 2017-08-20-00 UTC, Typhoon Hato originated over the sea east of the Philippines … Three hours later (i.e., 2017-08-20-03 UTC), it attained Super Typhoon intensity …”. (Note that the times here are only examples. The authors are encouraged to indicate the correct times similarly.) This comment also applies to the statements regarding all the considered typhoons (e.g., lines 201—203, lines 214—216).
- Lines 237 – 237: While the full name of MSLP was given in line 126, the authors are encouraged to indicate the full name of the abbreviation “SLP” here as this is the first time it appeared in the manuscript.
- Lines 255 – 255: The authors are encouraged to express the statement more precisely. For example, this sentence may be clearer to be revised as “Typhoon track prediction could be significantly enhanced by nudging horizontal wind, which influences large-scale circulation patterns and steering flow.”
- Lines 262 – 262: The authors are encouraged to use an en-dash to describe any range of numbers/values instead of a hyphen. This also applies to all the other places describing a range of numbers/values in the document (e.g., lines 264, 268, 271, 272, 284, 287, 295, 298, 304, 306, 308, 323, 325, 332, 338, 344, 363, 375, 382, 394, 476, 484, 491, 518, 519, and 527).
- Lines 286 – 287: The authors are encouraged to rewrite this statement to make the subjects clearer. For example, “Compared to the best tracks of the other three storms, the lowest simulated MSLP during Typhoon Neoguri is around 5–10 hPa higher.”
- Lines 289 – 290: The authors are encouraged to revise the sentence as “In this study, we use ERA5 with a 0.25 horizontal resolution, the bias is still inevitable despite its relatively high resolution compared to other reanalysis datasets.” There are numerous instances of such grammar problems throughout the document. It is recommended that the authors thoroughly examine and verify the work before submitting it again.
- Lines 315 – 317: While the authors used “resulted in” in the first statement, the authors used “leads to” in the second sentence. It is recommended that authors stick to the same tense for similar descriptions throughout a single paragraph.
- Lines 317 – 319: The authors are encouraged to indicate the meaning of the three solid dots shown in the bottom-left corner of Figure 3d. Do they indicate the initial times corresponding to TD, TS, and ST? If yes, please indicate in the figure caption properly. In addition, the authors are encouraged to indicate the meaning of the shaded areas shown in Figure 3a–d. These comments also apply to Figure 4d.
- Lines 324 – 325: When describing the differences and/or variations, the authors are encouraged to use numbers or percentages to quantitatively describe it instead of only using the words like “higher”, “relatively longer”, “weaker intensity”, “similar values”, or “more intense”. This comment also applies to other places with similar issues (e.g., lines 314, 330, 331, 333, 380—382). However, while there are many, the authors are encouraged to change the more relevant ones instead of all.
- Lines 411 – 411: The authors are encouraged to revise “6 m s-1” to “6 m s-1”.
- Lines 454 – 455: Some of the curves (e.g., WRF-ST) are hard to observe in the figure. The authors are encouraged to make the curves easier to observe and add grid lines in the figure (like Figure 7). This comment also applies to Figures 10 and 12.
- Lines 534 – 534: The dot between “Cha et al” and “(2011)” was missing. The authors are encouraged to revise it as “Cha et al. (2011)”.
The reviewer is willing to review the revised version if needed.
Citation: https://doi.org/10.5194/hess-2023-222-RC2
Qi Sun et al.
Qi Sun et al.
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