Projections of Directional Spectra Help to Unravel the Future Behavior of Wind Waves

Abstract

Based on a novel approach, present-day and future spectral wind-wave conditions in a high-emission scenario from a seven-member wave climate projection ensemble are compared. The spectral analysis at the selected locations aids in understanding the propagation of swell projected changes from the generation areas across the ocean basins. For example, a projected increase in the energy from Southern Ocean swells can be observed in all ocean basins and both hemispheres, which is especially relevant in the west coast of North America due to the penetration of these swells beyond 30°N. Similarly, a consistent decrease in the energy of large northern Atlantic swells is noted close to the equator. This work provides evidence that assessments based on only integrated wave parameters (e.g., significant wave height and mean wave period) can mask information about the sign, magnitude, and robustness of the actual wave climate changes due to the offset of positive and negative variations within the spectrum, leading to a significant underestimation of the change associated with certain wave systems.

Projected 21st Century Wind‐Wave Climate of Bass Strait and South‐East Australia: Comparison of EC‐Earth3 and ACCESS‐CM2 Climate Model Forcing

“…These increases are a result of a projected increase in swell (Figure S1 in Supporting Information ), which is associated with the projected increase in Southern Ocean wave conditions for the EC‐Earth3 and ACCESS‐CM2 global wave climate models (Meucci et al., 2022). These results are also consistent with previous results of projected increases in the Southern Hemisphere (e.g., Tasmania, Ecuador and Chile) wave spectra, which relate to the intensification of Southern Ocean swell (Lobeto et al., 2021b). The stronger Southern Ocean swell also results in a counterclockwise rotation of D p in the west (∼1° under SSP126 scenario (Figures 8c and 8f) and ∼3° under SSP585 scenario (Figures 8l and 8o)) and a bifurcation behind Tasmania.…”

Wind-wave characteristics and extremes along the Emilia-Romagna coast

“…It also demonstrates the useful application of PDFs to the estimate of hazards along coastal belts. The study also highlights the need for extensive wave spectra comparisons (Lobeto et al, 2021) with measurements for selected locations on the coastal belt, which will update the coastal wave database. The early detection of hazards such as coastal erosion and associated shoreline changes are still challenging (Le Cozannet et al, 2020) due to the non-availability of long-term observations.…”

Future changes and seasonal variability of the directional wave spectra in the Mediterranean Sea for the 21st century

“…Biascorrection techniques are widespread in climate and hydrological impact studies dealing with variables such as precipitation and temperature but their application to wave and wind variables still remains an open and challenging issue due to the multivariate behavior and the spatial and temporal variability of wave climate (Lemos et al 2020). More specifically, the bias-adjustment of 2D directional wave spectra data is yet to be addressed and further research is required to allow a better understanding of biases of the different wave systems taking into account their frequency and direction (Lobeto et al 2021).…”

“…Therefore, the analysis of projections of directional spectra could provide information on future changes in the energy spread over frequency and direction therefore allowing to analyze the wave systems, their development and evolution, crucial for longshore sediment transport and shoreline stability assessment in a changing climate. Recently, Lobeto et al (2021) presented an analysis of wave spectra on different locations of the world based on future and base-period simulations for a wave climate ensemble forced by GCMs surface winds highlighting the need for spectral analysis in order to properly characterize the propagation of swell projected changes. Given that the wave projections were forced using GCMs, the analysis does not include a location in the Mediterranean Sea where, due to the characteristic regional wind and wave climate circulation, high-resolution regional wave climate projections are needed to accurately represent its behavior.…”

“…The use of bias-adjustment methods for GCM/RCM outputs is extended in climate and hydrological impact studies but their application to wave climate still remains an open and challenging issue due to the multivariate behavior, the spatial correlation and diverse temporal variability of wave climate (Lemos et al 2020). Additionally, the use of bias-correction techniques to wave spectra has not been addressed given the 2D characteristics of the wave density spectra (Lobeto et al 2021). To the authors knowledge, a detailed assessment of projected changes in wave directional spectra with respect to hindcast using high-resolution RCMs in the Mediterranean Sea has not been previously studied.…”