Dear all,
The next WISE zoominar on the topic of Waves in Extreme Conditions will be on 2024-05-30T15:00:00Z. Please note the schedule of additional zoominars at the end of the email.
Join us via https://tudelft.zoom.us/my/wisezoominars
First speaker: Momme Hell, NCAR
Title: Swell generation under extra-tropical storms
Abstract: Storms propagate over the ocean and create moving patches of strong winds that generate swell systems. Here, we describe the dynamics of wave generation under a moving storm by using a simple parametric model of wave development, forced by a temporally and spatially varying moving wind field. This framework reveals how surface winds under moving storms determine the origin and amplitude of swell events. Swell systems are expected to originate from locations different than the moving high-wind forcing regions. This is confirmed by a optimization method that back-triangulates the common source locations of swell using their dispersion slopes, simultaneously measured at five wave-buoy locations. Hence, the parametric moving fetch model forced with reanalysis winds can predict the displacement between the highest winds and the observed swell source area. The model further shows that the storm’s peak wind speed is the key factor determining swell energy since it determines surface wind gradients that lead to the spatial convergence of wave energy into a much smaller area than the wind fetch. Swell generation can then be described to follow a three-stage process that outlines a focus area where swell energy is enhanced and slightly displaced from the maximum wind locations. This analysis provides an improved understanding of the effective fetch for extra-tropical swell systems.
Second speaker: Trygve Halsne, University of Bergen
Title: Wave modulation in a strong tidal current and its impact on extreme waves
Abstract: Accurate estimates of extreme waves are central for maritime activities, and stochastic models are the best option available for practical applications. However, the way currents influence the statistics of space-time extremes has not been properly assessed. Here we demonstrate impacts of the wave modulation caused by one of the world’s strongest open ocean tidal currents, which reaches speeds of at least 3 m/s, by using spectral wave models. Two characteristic met-ocean conditions have been analyzed: i) a bimodal sea state in a horizontally uniform tidal current, and ii) a swell system opposing a tidal jet. We find that the most intense interactions occur when the dominating wave fields opposes the tidal current and that the current-induced modulation in the spectral steepness causes an increase in the expected maximum space-time crests. We also find that the tidal modulation in the narrow-bandedness parameter, at times, decreases the expected wave heights.
Please note that WISE Zoominars including the Q&A will be recorded and posted on the WISE YouTube Channel afterwards ( https://www.youtube.com/@wisezoominars). By participating, you consent to any information you share to be included in the recording and shared.
Online add-on talks: Waves in Storms
In order to accommodate potential speakers in diverse time zones, we will begin to solicit and post pre-recorded talks. These pre-recorded talks will maintain the familiar WISE Zoominar format of two speakers under a common theme. We will release the recordings on YouTube (https://www.youtube.com/@wisezoominars). If you are interested in sending us a recorded talk, send a note to wisezoominars@gmail.com.
First online speaker: Carolina Gramcianinov, Helmholtz-Zentrum Heron
Title: Climatology of Tropical Cyclones: Extreme Wave Heights
Second online speaker: Guisela Mattheson, University of Melbourne
Title: Changes in extreme wave events in southwestern South Atlantic Ocean
Best wishes,
Jessica, Tripp, Alvise, Nick, Morteza and Ton
(The WISE Zoominar organizing committee)
