Preprints
https://doi.org/10.5194/egusphere-2024-3711
https://doi.org/10.5194/egusphere-2024-3711
04 Dec 2024
 | 04 Dec 2024

Synoptic patterns associated with high-frequency sea level extremes in the Adriatic Sea

Krešimir Ruić, Jadranka Šepić, and Marin Vojković

Abstract. The study focuses on classification of synoptic conditions leading to episodes of extreme high-frequency sea level oscillations in the Adriatic Sea (Mediterranean). Two types of extreme episodes were obtained from sea level time series measured at six tide gauge stations: (i) HF extremes, extracted from high-frequency components (periods shorter than 2 hours) of sea level time series and defined as periods in which high-frequency component was above a threshold value; and (ii) Compound extremes, extracted from residual (de-tided) time series, and defined as periods in which both high-frequency and residual components were above their respective thresholds. Characteristic synoptic situations preceding both types of extremes were determined using the k-medoid clustering method applied on the ERA5 reanalysis data (mean sea level pressure, temperature at 850 hPa, and geopotential height of 500 hPa level). The structural similarity index measure (SSIM) was used as a distance metric. The data were divided into a training set (from the start of measurements to the beginning of 2018) and a testing set (from the beginning of 2018 to the end of 2020). For each station, k-medoid was used to obtain first 2 and then 3 clusters with characteristic synoptic patterns called medoids. Two distinct patterns, related to HF and Compound extremes were identified at all stations: (i) “summer-type” pattern – characterized by non-gradient mean sea level pressure, warm air advection from the south-southwest at 850 hPa, and a presence of a jet stream at the 500 hPa height, with all three conditions previously found to favour development of meteorological tsunamis, i.e., the strongest of atmospherically triggered high-frequency sea level oscillations; (ii) “winter-type” pattern characterized by pronounced mean sea level pressure gradients favouring winds which induce storm surges, colder low troposphere, and a presence of a jet stream at the 500 hPa level. Including the third cluster into the analysis led to extraction of either a novel “Bora-type” pattern involving strong northeast winds at stations Bakar and Rovinj, or an additional cluster with a medoid which represents refinement of summer- or winter-type patterns. The extracted medoids of clusters were used to label all days of the testing period. It was shown that HF or Compound episodes recorded in the testing period mostly appeared during synoptic situations which highly resembled extracted medoids. The potential of using k-medoid method for forecasting high-frequency sea level oscillations is discussed.

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Journal article(s) based on this preprint

01 Jul 2025
Synoptic patterns associated with high-frequency sea level extremes in the Adriatic Sea
Krešimir Ruić, Jadranka Šepić, and Marin Vojković
Ocean Sci., 21, 1183–1203, https://doi.org/10.5194/os-21-1183-2025,https://doi.org/10.5194/os-21-1183-2025, 2025
Short summary
Krešimir Ruić, Jadranka Šepić, and Marin Vojković

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-3711', Anonymous Referee #1, 02 Jan 2025
    • AC1: 'Reply on RC1', Krešimir Ruić, 07 Feb 2025
    • AC2: 'Reply on RC1', Krešimir Ruić, 07 Feb 2025
  • RC2: 'Comment on egusphere-2024-3711', Anonymous Referee #2, 11 Jan 2025
    • AC3: 'Reply on RC2', Krešimir Ruić, 07 Feb 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-3711', Anonymous Referee #1, 02 Jan 2025
    • AC1: 'Reply on RC1', Krešimir Ruić, 07 Feb 2025
    • AC2: 'Reply on RC1', Krešimir Ruić, 07 Feb 2025
  • RC2: 'Comment on egusphere-2024-3711', Anonymous Referee #2, 11 Jan 2025
    • AC3: 'Reply on RC2', Krešimir Ruić, 07 Feb 2025

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Krešimir Ruić on behalf of the Authors (24 Feb 2025)  Author's response   Author's tracked changes   Manuscript 
EF by Mario Ebel (24 Feb 2025)  Supplement 
ED: Referee Nomination & Report Request started (03 Mar 2025) by Matjaz Licer
RR by Anonymous Referee #1 (08 Mar 2025)
RR by Anonymous Referee #2 (31 Mar 2025)
ED: Publish as is (31 Mar 2025) by Matjaz Licer
AR by Krešimir Ruić on behalf of the Authors (31 Mar 2025)

Journal article(s) based on this preprint

01 Jul 2025
Synoptic patterns associated with high-frequency sea level extremes in the Adriatic Sea
Krešimir Ruić, Jadranka Šepić, and Marin Vojković
Ocean Sci., 21, 1183–1203, https://doi.org/10.5194/os-21-1183-2025,https://doi.org/10.5194/os-21-1183-2025, 2025
Short summary
Krešimir Ruić, Jadranka Šepić, and Marin Vojković
Krešimir Ruić, Jadranka Šepić, and Marin Vojković

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Short summary
This study investigates the synoptic weather patterns that cause extreme, high-frequency sea level oscillations in the Adriatic Sea. Using synoptic data from ERA5 reanalysis with 17 years of tide gauge data and advanced clustering techniques, we identify distinct weather patterns linked to these events, some of which have been unknow. These insights improve understanding of sea level variability and have potential applications in forecasting coastal hazards.
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