the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 02 Jul 2026
Conditional Modulation of Extreme Internal Solitary Waves in the Lombok Strait
Abstract. Using 13 months of continuous mooring observations at the Lombok Strait (November 2023–December 2024), we identify 302 internal solitary wave (ISW) packets and 618 individual solitons with amplitudes up to 104 m. ISW occurrence peaks in boreal winter–spring (March: 45 packets/month) and drops to near-zero in summer (July: 3 packets/month). The observations reveal an amplitude-dependent dynamical structure. ISW occurrence for both amplitude classes is primarily modulated by the ITF: normal-amplitude ISWs (25–65 m) are seasonally suppressed during enhanced ITF periods—when thermocline stratification is concurrently elevated—indicating that the apparent negative N²–ISW correlation is a seasonal covariance with ITF strength rather than a direct stratification effect. Extreme ISWs (>65 m) show negligible stratification dependence and instead tend to coincide with transient ITF weakening as a precondition for nonlinear amplification. Low-pass filtered acoustic Doppler current profiler records show that extreme events consistently coincide with northward velocity pulses in the 50–200 m layer that substantially reduce Doppler retardation, consistent with the existence of episodic dynamic windows favorable for nonlinear wave amplification.
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Status: open (until 17 Nov 2026)
- RC1: 'Comment on egusphere-2026-2805', Anonymous Referee #1, 10 Jul 2026 reply
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RC2: 'Comment on egusphere-2026-2805', Anonymous Referee #2, 06 Nov 2026
reply
Review of the manuscript, entitled of “Conditional Modulation of Extreme Internal Solitary Waves in the Lombok Strait”, by Wang et al., submitted to EGUsphere. This study investigates internal solitary wave (ISW) dynamics in the Lombok Strait based on mooring observations, with particular emphasis on the modulation of extreme ISW events by background conditions, such as stratification and background currents. The motivation for this study is reasonable, and the observational dataset is potentially valuable. However, several critical issues need to be addressed before the manuscript can be considered for publication. In particular, the generation and propagation mechanisms of the observed ISWs are not adequately described, and the variability in ISW amplitude and its underlying physical processes require more thorough investigation and discussion. My specific comments are provided below.
Major comments
1. Insufficient description of the study area and ISW generation and propagation
The manuscript lacks fundamental information typically required in observational studies of internal tides and ISWs. No map is provided showing the study area, mooring location, bathymetry, or possible generation sites and propagation pathways of the observed ISWs. More importantly, the manuscript does not adequately explain how and where the observed ISWs are generated and how they propagate toward the mooring site. The authors should provide observational or analytical evidence to characterize these fundamental processes, rather than simply assuming a particular generation mechanism or propagation pathway.Furthermore, only a single example of the observed ISWs is presented in Figure 1, despite the large number of detected events. Additional examples showing ISW characteristics under different tidal and background current conditions would help readers understand the observed variability. Without a clearer characterization of the generation, propagation, and observed structures of ISWs, it is difficult to evaluate the physical interpretations and discussions presented in the manuscript.
2. Uncertainty in the use of the 18°C isotherm as an indicator of ISW amplitude
The use of the 18°C isotherm to estimate ISW amplitudes throughout the observation period is not sufficiently justified. Since the temperature structure of the main thermocline likely varies seasonally, this isotherm may not consistently represent the same part of the thermocline. Could this affect the estimated ISW amplitudes and the reported relationship between N² and ISWs? Furthermore, it is unclear whether ISWs can always be adequately captured within the limited observational depth range of 70–190 m. The authors should examine these uncertainties and justify the validity of their approach.3. Lack of analysis of the relationship between ISWs and tidal forcing
Although the Introduction states that ISWs are generated by tidal forcing, the manuscript provides little analysis of the relationship between the observed ISWs and tides. In particular, the effects of the spring–neap cycle and semidiurnal and diurnal tidal variability are not examined. This is a major weakness, as tidal forcing is fundamental to ISW generation in this region. The authors should clarify the role of tidal forcing before attributing ISW variability to background currents and stratification.4. Unclear relationship between background currents and ISWs
The relationship between background currents and ISW variability remains unclear. Although some correlations are statistically significant, the scatter plot do not show particularly strong relationships. More importantly, as noted in Comment 1, the generation and propagation processes of the observed ISWs are insufficiently described. It is therefore difficult to determine whether the background currents influence ISW generation, propagation, or nonlinear evolution. Without addressing these fundamental processes, the physical interpretation of the statistical relationships remains unconvincing.Minor Comment
The manuscript requires improvement in its overall presentation and organization. For example, abbreviations and symbols such as ITF and N^2 appear in the Abstract without proper definitions. All abbreviations and symbols should be defined at first use, and the manuscript should be carefully revised to improve clarity and consistency.Citation: https://doi.org/10.5194/egusphere-2026-2805-RC2
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Please see detailed review in the attachment.