We had one of those days from which you recover by eating food you don’t have to make.
First off was class, then Blue Heron’s for art – Anthozoans memorialized in glass, then lunch on his stoop, then off to Folly Beach to look for corals and sponges, then drop off Brooks at Karate, then to Grice Marine Labs for the Friday afternoon lectures, and finally home.
However, the Ft. Johnson Lecture was sooooooooo worth the drive. It was more in my realm of physics. Whhooooo Hoooo. Dr. Alexander (Sasha) Yankovsky from the University of South Carolina in land-locked Columbia spoke about Long-wave Response of the Coastal Ocean to Hurricane Landfall.
The long and short of this is. There are two types of long waves.
1. Sub-inertial Coastal Trapped Waves (Kelvin waves). These are waves propagating with the coast moving to the right in the Northern Hemisphere. Their effects are interconnected with the Earth’s rotation.
2. Edge Waves. These are refractions of long gravity waves which propitiate in both directions (north and south) along the coast.
Apparently until now few people believed that hurricanes brought other large waves beyond the storm surge. Dr. Yankowsky studied results from 30 different wave and barometric collection devices in the immediate 50 mile radius of the point of impact of hurricane Wilma. These results are the beginning of his theory. He looked at the period of the waves that came in before, during, and after the hurricane. He found that 6 hours after the initial storm surge another wave hit – this was a long period wave whose effects took 4ish hours to pass. He likened it to the type of wave in the deep ocean propagated during tsunamis – only not nearly as severe. You don’t see it until right before it hits.
His summary is that:
1. The Earth’s rotation has less affects on slowly moving hurricanes.
2. Fast moving storms cause the highest (although shortest) wave period (but the slowest contain the most energy); waves crossing the slightly sloped continental shelf at an oblique angle cause the highest waves.
3. Wave energy is dissipated both north and south along the coast affecting areas which might not see the majority of the storm surge or wind driven waves.
The boys enjoyed the discussion and this clear graphs helped explain his points well. Plus they saw Dr. Wiseman again – his crab from two weeks ago may be a new species!