class: center, middle .title[Insights into the Gulf of Mexico circulation from the historical surface drifter dataset ] .author[Jonathan Lilly] .institution[Theiss Research] .date[April 4, 2017] .center[[{www.jmlilly.net}](http://www.jmlilly.net)] .footnote[Created with [{Remark.js}](http://remarkjs.com/) using [{Markdown}](https://daringfireball.net/projects/markdown/) + [{MathJax}](https://www.mathjax.org/)] --- class: center ##A Combined Surface Drifter Dataset
--- class: center ##Mean Velocity Vectors
Note Loop Current, Campeche Gyre, western coastal current. --- class: center ##Variance Ellipses
Ellipses represent variability of velocity vector about its mean. --- class: center ##Mean Streamlines
Color represents initial longitude in streamline calculation. --- class: center ##Mean Streamlines including NGOM
Including the NGOM (Eddy Watch) drifters changes the mean flow. --- class: center ##Mean Velocity Vectors from AVISO
AVISO does not resolve coastal current or the Campeche Gyre. --- class: center ##Mean Velocity Vectors
This indicates the importance of Lagrangian observations. --- class: center ##Max Diffusivity for any Time Interval
Loop Current and coastal current regions are diffusivity maxima, Campeche Gyre and continental shelves are minima. --- class: center ##Time Interval of Maximum Diffusivity
Short decorrelation times over Campeche Gyre and Loop Current. --- class: center ##Variability of the Campeche Gyre
Campeche Gyre shows strong variability, cause unknown. --- class: center ##Some Eddy-Trapped Drifter Trajectories
Trajectories of drifters trapped in some long-lived eddies. --- class: center ##Residual after Removing Eddy Motions
Small oscillations are due to harmonics from non-elliptical shapes. --- class: center ##Coherent Eddy Motions
Longitude and latitude records for these trajectories. --- class: center ##Removal of Coherent Eddy Motions
Residual longitudes and latitudes after removing eddies. --- class: center ##Composite Annual Cycle of Eddy Ellipses
--- class: center ##All Eddy Ellipses
--- class: center ##Coherent Eddy Parameter Space
Cyclonic eddies are very high Rossby number events. --- class: center ##Eddy Center Translation Velocity
Blue = anticyclonic eddies, red = cyclonic eddies. Cyclones are seen propagating
into
Campeche Gyre. --- class: center ## Vorticity in the NEMO Model
What is the source of the strong cyclonic vorticity? --- class: center ## Currents in the Inertial Band
Strong inertial currents in Campeche Gyre and north central Gulf. --- class: center ## Annual Cycle of Inertial Currents
Very different annual cycles. --- class: center ## Annual Cycle of Wind Stress
Southern max matches wind stress, northern max does not. --- class: left ## Conclusions Lagrangian data provides a very valuable source of information into the Gulf of Mexico circulation, from large scale to submesoscale. 1. An active coherent eddy field is found, including strong cyclonic eddies of unknown origin. 2. The Campeche Gyre is a prominent circulation feature, not yet completely understood. 3. Strong inertial oscillations are observed in two different regions, with apparently different causes. Further work: (i) more comparision with numerical models; (ii) dispersion and diffusivity; (iii) examining other datasets, especially hydrography. --- class: center, middle # Thank you! .center[This talk is available at].center[[http://www.jmlilly.net/talks/lilly17-sener.html](http://www.jmlilly.net/talks/lilly17-sener.html)] .center[.footnote[P.S. Like the way this presentation looks? Check out [{Liminal}](https://github.com/jonathanlilly/liminal).]]