What makes up a PhD in oceanography?

On Thursday, I defended my PhD in Applied Ocean Science at Scripps Institution of Oceanography. Starting during the summer five years ago, I moved to San Diego after deciding lab work would be more fun if it was focused on the ocean.

At Scripps, my research focused on internal waves on the inner shelf, the region of the coastal ocean between roughly 10-100m depth and home to lots of physical and biological processes. I studied two specific types of internal waves: superinertial coastal trapped waves (CTWs) and shoaling non-linear internal waves (NLIWs).

The mouthful title that somehow covers five years of my work.

The first chapter is a rewrite of my first peer-reviewed paper, where I describe how these CTWs drive stronger currents than the tides do. The paper answers a question going back nearly 60 years in this region: why is the sea surface elevation at the semidiurnal frequency not correlated with the currents on the inner shelf?

To follow up this paper, we ran a nonlinear model that showed these waves are coherent over long distances, as in 100s of kilometers. We also reanalyzed the data to show that the inner shelf currents can actually be predictable, finding that more than half of the current 90 days out is explainable by this CTW signal. This paper is currently in review and one that I feel very proud of.

And to close out the dissertation, the final paper pivoted to detection of the NLIWs on a fiber optic instrument. Using machine learning algorithms from self-driving cars, I built an algorithm that automatically detects these waves on the instrument in real time and used it to show how these shoaling waves lead to a significant portion of the mixing on the inner shelf. This one will be submitted soon as I finish up a postdoc at Scripps.

All together, these three chapters add a bit of understanding to the inner shelf dynamics of the Southern California Bight, with applications to other regions where similar signatures have been observed: Tasmania, Hawaii, etc. for the CTWs and the Oregon coast, offshore of Japan, etc. for the NLIWs.

It has been a process of ups and downs, wave jokes a necessary evil in the field. This is one of the ups and it is nice to share some of the work that I have done with you; I hope you enjoyed this one.

Further Reading:

When my dissertation is published, I will send it to anyone interested.