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https://doi.org/10.5194/egusphere-2024-1304
https://doi.org/10.5194/egusphere-2024-1304
04 Jun 2024
 | 04 Jun 2024

Verifying the relationships among the variabilities of summer precipitation extremes over western Japan in the d4PDF climate ensemble, monsoon activity, and Pacific sea surface temperature

Shao-Yi Lee, Sicheng He, and Tetsuya Takemi

Abstract. Upper 99th percentile hourly and 90th percentile daily rainfall over western Japan was calculated for June–July every year, using two observation-based and one simulation-based datasets. These were 54 rain-gauges over the 1952–2022 period, 1 km resolution radar/rain-gauge merged precipitation data over the 2006–2022 sub-period, and the 5 km resolution d4PDF (database for Policy Decision-making for Future climate changes) climate ensemble over the 1952–2010 sub-period. Grid-points over western Japan were clustered by applying the HDBSCAN (Hierarchical Density-Based Spatial Clustering of Applications with Noise) algorithm. Spearman correlation was calculated between rainfall extremes of the clusters, and standardised scores of four modes from the rotated extended Principle Component Analysis of Pacific Sea Surface Temperature (SST) anomalies. These modes represent ENSO (El Niño-Southern Oscillation) growth, ENSO decay, warming trend, and PDV (Pacific Decadal Variability). Based on the clustering, 10 sub-regions were selected for analysis. The correlation coefficients between rainfall extremes and SST modes were at most moderate (|R| ⩽ 0.60) over most sub-regions, reflecting correlation with ENSO decay and warming trend, both directions with a spatial pattern for ENSO growth, and anti-correlation with PDV. These relationships could be partially explained through the strength and location of the monsoon jet in relation to different ENSO phases. d4PDF reflected similar relationships for the first three modes, although it showed both spatial and strength biases. Correlation between rainfall extremes and ENSO decay was likely excessively strong in d4PDF due to the regional climate model's over-response to the monsoon jet wind speed. For the PDV mode, the model could not reproduce the observed relationship of spatially widespread anti-correlation with rainfall extremes. Based on the mostly weak long-term correlations, we concluded that individual SST modes modulated rainfall extremes but were not controlling factors in their occurrence. However, we hypothesize that multiple modes may stack in ways that greatly strengthen their modulating effect, and recommend further investigation in this using sensitivity simulations on case studies.

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Journal article(s) based on this preprint

08 Jul 2025
Verifying the relationships among the variabilities of summer rainfall extremes over Japan in the d4PDF climate ensemble, Pacific sea surface temperature, and monsoon activity
Shao-Yi Lee, Sicheng He, and Tetsuya Takemi
Nat. Hazards Earth Syst. Sci., 25, 2225–2253, https://doi.org/10.5194/nhess-25-2225-2025,https://doi.org/10.5194/nhess-25-2225-2025, 2025
Short summary
Shao-Yi Lee, Sicheng He, and Tetsuya Takemi

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-1304', Anonymous Referee #1, 12 Jul 2024
    • AC1: 'Reply on RC1', Shao-Yi Lee, 22 Aug 2024
  • RC2: 'Comment on egusphere-2024-1304', Anonymous Referee #2, 01 Aug 2024
    • AC2: 'Reply on RC2', Shao-Yi Lee, 22 Aug 2024

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-1304', Anonymous Referee #1, 12 Jul 2024
    • AC1: 'Reply on RC1', Shao-Yi Lee, 22 Aug 2024
  • RC2: 'Comment on egusphere-2024-1304', Anonymous Referee #2, 01 Aug 2024
    • AC2: 'Reply on RC2', Shao-Yi Lee, 22 Aug 2024

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
ED: Reconsider after major revisions (further review by editor and referees) (02 Sep 2024) by Ricardo Trigo
AR by Shao-Yi Lee on behalf of the Authors (11 Oct 2024)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (22 Oct 2024) by Ricardo Trigo
RR by Anonymous Referee #2 (20 Nov 2024)
RR by Anonymous Referee #3 (07 Jan 2025)
ED: Reconsider after major revisions (further review by editor and referees) (10 Jan 2025) by Ricardo Trigo
AR by Shao-Yi Lee on behalf of the Authors (08 Mar 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (13 Mar 2025) by Ricardo Trigo
RR by Anonymous Referee #3 (19 Mar 2025)
ED: Publish as is (21 Mar 2025) by Ricardo Trigo
AR by Shao-Yi Lee on behalf of the Authors (27 Mar 2025)

Journal article(s) based on this preprint

08 Jul 2025
Verifying the relationships among the variabilities of summer rainfall extremes over Japan in the d4PDF climate ensemble, Pacific sea surface temperature, and monsoon activity
Shao-Yi Lee, Sicheng He, and Tetsuya Takemi
Nat. Hazards Earth Syst. Sci., 25, 2225–2253, https://doi.org/10.5194/nhess-25-2225-2025,https://doi.org/10.5194/nhess-25-2225-2025, 2025
Short summary
Shao-Yi Lee, Sicheng He, and Tetsuya Takemi
Shao-Yi Lee, Sicheng He, and Tetsuya Takemi

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Short summary
Summer rainfall extremes over western Japan were calculated every year, using radar, rain-gauges, and model. Similar regions were determined by machine learning. The relationships between regional rainfall extremes and Pacific climate modes. The modelled relationships were similar to the observed ones for the El Niño-Southern Oscillation and the warming trend. However, the model did not reproduce the relationship for Pacific Decadal Variability.
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