A modelling study of an extreme rainfall event along the northern coast of Taiwan on 2 June 2017
- 1Department of Earth Sciences, National Taiwan Normal University, Taipei, 11677, Taiwan
- 2Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601, Japan
- 3Department of Atmospheric Sciences, Chinese Culture University, Taipei, 11114, Taiwan
- 1Department of Earth Sciences, National Taiwan Normal University, Taipei, 11677, Taiwan
- 2Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601, Japan
- 3Department of Atmospheric Sciences, Chinese Culture University, Taipei, 11114, Taiwan
Abstract. In this study, the extreme rainfall event on 2 June 2017 along the northern coast of Taiwan is studied from a modeling perspective. While a peak amount of 645 mm was observed, two 1-km experiments produced about 400 and 541 mm, respectively, using different initial and boundary conditions, and thus are compared to isolate the key reasons for a higher total amount in the second run. While the conditions in frontal intensity and its slow movement are similar in both runs, the frontal rainband remains stationary for a long period in this second run due to a frontal disturbance that acts to enhance the pre-frontal southwesterly flow and focus its convergence with the post-frontal flow right across the coastline. Identified as the key difference, this low-pressure disturbance is supported by the observation, and without it in the first run, multiple slow-moving rainbands pass through the coastal region and produce more widely spread but less concentrated rainfall, resulting in the lower peak amount by comparison.
To explore and test the effects of Taiwan’s topography in this event, three 3-km runs are also used. It is found that the removal of the terrain in northern Taiwan makes only minor differences, in contrast to the result of a recent study. Only when the entire island topography of Taiwan is removed, does the result show significant differences. In this case, the blocking and deflecting effects on the pre-frontal flow are absent, and the heavy rainfall in northern Taiwan does not occur.
-
Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
-
Preprint
(7456 KB)
-
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
Journal article(s) based on this preprint
Chung-Chieh Wang et al.
Interactive discussion
Status: closed
-
RC1: 'Comment on acp-2022-377', Anonymous Referee #1, 18 Jul 2022
-
AC1: 'Reply on RC1', Chung-Chieh Wang, 07 Oct 2022
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-377/acp-2022-377-AC1-supplement.pdf
-
AC1: 'Reply on RC1', Chung-Chieh Wang, 07 Oct 2022
-
RC2: 'Comment on acp-2022-377', Anonymous Referee #2, 22 Aug 2022
Authors designed 5 cloud model runs to simulate and discuss an extreme rainfall event along the northern coast of Taiwan on 2 June 2017. The 24-h rainfall maximum along the northern coast is well simulated (541 mm) in the F1 experiment (1-km run) as compared with the rain gauge observation (645 mm). Analyses on mei-yu frontal movement and the roles of frontal disturbance are valuable. There are some major comments about the model experiments. I would suggest authors to modify the paper according to my comments to make the manuscript more complete and solid. The paper could be publishable in Atmospheric Chemistry and Physics with major revisions.
Major comments:
- In the S3 experiment (3-km experiment), the surface front arrived at northern Taiwan too early, by about 9 h. Authors state that this situation is acceptable for the third day simulation. However, the arrival time error of surface front is too large (~ 9h). It means that model failed to simulate the large-scale/mesoscale weather patterns in real atmosphere (including circulations, radiation, thermodynamic processes and etc.). Thus, it is not acceptable to use the simulation of S3 to analyze the frontal characteristics. Also, one important question is that: if the authors know that there are great errors for the third-day simulation, why do author use the third-day simulation to analyze the front/frontal rainband characteristics? I strongly suggest that authors compare model simulated 24-h rainfall accumulation and rain gauge observation from CWB by presenting the same time period during 1600 UTC 1 June to 1600 UTC 2 June (0000-2400 LST 2 June) [Figs. 6 and 9b].
- To test and clarify the role played by the topography on the mei-yu front, authors remove topography of Taiwan (and northern Taiwan) in S3 experiment, referring to S3-NT and S3-NNT experiments. Since the frontal arrival time error is about 9 h, it is not appropriate to use S3, S3-NT, and S3-NNT experiments (3-km experiments) to discuss the interactions between mei-yu frontal system and topography over Taiwan. Instead, authors should use F1 experiment (1-km experiment; the best simulation of frontal arrival time and propagation speed in this manuscript) as the CTRL run and design the sensitivity tests of topography based on F1 experiment (e.g., F1-NT and F1-NNT).
Minor comments:
- Line 219-221: “This is because without the terrain, the near-surface (and low-level) southwesterly winds can blow across the flattened island without the blocking effect (Figs. 7g-i),”
should be “… (Figs. 7g-i).” - Line 275: delete “say,”
- Section 7 (Line 380-383) and Figure 1b: For the “NNT” (remove northern Taiwan) run, do authors remove Datun Mountain only in the model or both Datun Mountain and Linkou Plateau? Please specify.
-
AC2: 'Reply on RC2', Chung-Chieh Wang, 07 Oct 2022
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-377/acp-2022-377-AC2-supplement.pdf
- In the S3 experiment (3-km experiment), the surface front arrived at northern Taiwan too early, by about 9 h. Authors state that this situation is acceptable for the third day simulation. However, the arrival time error of surface front is too large (~ 9h). It means that model failed to simulate the large-scale/mesoscale weather patterns in real atmosphere (including circulations, radiation, thermodynamic processes and etc.). Thus, it is not acceptable to use the simulation of S3 to analyze the frontal characteristics. Also, one important question is that: if the authors know that there are great errors for the third-day simulation, why do author use the third-day simulation to analyze the front/frontal rainband characteristics? I strongly suggest that authors compare model simulated 24-h rainfall accumulation and rain gauge observation from CWB by presenting the same time period during 1600 UTC 1 June to 1600 UTC 2 June (0000-2400 LST 2 June) [Figs. 6 and 9b].
Peer review completion






Interactive discussion
Status: closed
-
RC1: 'Comment on acp-2022-377', Anonymous Referee #1, 18 Jul 2022
-
AC1: 'Reply on RC1', Chung-Chieh Wang, 07 Oct 2022
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-377/acp-2022-377-AC1-supplement.pdf
-
AC1: 'Reply on RC1', Chung-Chieh Wang, 07 Oct 2022
-
RC2: 'Comment on acp-2022-377', Anonymous Referee #2, 22 Aug 2022
Authors designed 5 cloud model runs to simulate and discuss an extreme rainfall event along the northern coast of Taiwan on 2 June 2017. The 24-h rainfall maximum along the northern coast is well simulated (541 mm) in the F1 experiment (1-km run) as compared with the rain gauge observation (645 mm). Analyses on mei-yu frontal movement and the roles of frontal disturbance are valuable. There are some major comments about the model experiments. I would suggest authors to modify the paper according to my comments to make the manuscript more complete and solid. The paper could be publishable in Atmospheric Chemistry and Physics with major revisions.
Major comments:
- In the S3 experiment (3-km experiment), the surface front arrived at northern Taiwan too early, by about 9 h. Authors state that this situation is acceptable for the third day simulation. However, the arrival time error of surface front is too large (~ 9h). It means that model failed to simulate the large-scale/mesoscale weather patterns in real atmosphere (including circulations, radiation, thermodynamic processes and etc.). Thus, it is not acceptable to use the simulation of S3 to analyze the frontal characteristics. Also, one important question is that: if the authors know that there are great errors for the third-day simulation, why do author use the third-day simulation to analyze the front/frontal rainband characteristics? I strongly suggest that authors compare model simulated 24-h rainfall accumulation and rain gauge observation from CWB by presenting the same time period during 1600 UTC 1 June to 1600 UTC 2 June (0000-2400 LST 2 June) [Figs. 6 and 9b].
- To test and clarify the role played by the topography on the mei-yu front, authors remove topography of Taiwan (and northern Taiwan) in S3 experiment, referring to S3-NT and S3-NNT experiments. Since the frontal arrival time error is about 9 h, it is not appropriate to use S3, S3-NT, and S3-NNT experiments (3-km experiments) to discuss the interactions between mei-yu frontal system and topography over Taiwan. Instead, authors should use F1 experiment (1-km experiment; the best simulation of frontal arrival time and propagation speed in this manuscript) as the CTRL run and design the sensitivity tests of topography based on F1 experiment (e.g., F1-NT and F1-NNT).
Minor comments:
- Line 219-221: “This is because without the terrain, the near-surface (and low-level) southwesterly winds can blow across the flattened island without the blocking effect (Figs. 7g-i),”
should be “… (Figs. 7g-i).” - Line 275: delete “say,”
- Section 7 (Line 380-383) and Figure 1b: For the “NNT” (remove northern Taiwan) run, do authors remove Datun Mountain only in the model or both Datun Mountain and Linkou Plateau? Please specify.
-
AC2: 'Reply on RC2', Chung-Chieh Wang, 07 Oct 2022
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-377/acp-2022-377-AC2-supplement.pdf
- In the S3 experiment (3-km experiment), the surface front arrived at northern Taiwan too early, by about 9 h. Authors state that this situation is acceptable for the third day simulation. However, the arrival time error of surface front is too large (~ 9h). It means that model failed to simulate the large-scale/mesoscale weather patterns in real atmosphere (including circulations, radiation, thermodynamic processes and etc.). Thus, it is not acceptable to use the simulation of S3 to analyze the frontal characteristics. Also, one important question is that: if the authors know that there are great errors for the third-day simulation, why do author use the third-day simulation to analyze the front/frontal rainband characteristics? I strongly suggest that authors compare model simulated 24-h rainfall accumulation and rain gauge observation from CWB by presenting the same time period during 1600 UTC 1 June to 1600 UTC 2 June (0000-2400 LST 2 June) [Figs. 6 and 9b].
Peer review completion






Journal article(s) based on this preprint
Chung-Chieh Wang et al.
Chung-Chieh Wang et al.
Viewed
HTML | XML | Total | BibTeX | EndNote | |
---|---|---|---|---|---|
203 | 89 | 12 | 304 | 2 | 4 |
- HTML: 203
- PDF: 89
- XML: 12
- Total: 304
- BibTeX: 2
- EndNote: 4
Viewed (geographical distribution)
Country | # | Views | % |
---|
Total: | 0 |
HTML: | 0 |
PDF: | 0 |
XML: | 0 |
- 1
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(7456 KB) - Metadata XML