The vertical structure of a recently detached Loop Current Eddy (LCE) is studied using in situ data collected with an underwater glider from August to November 2016. Altimetry and Argo data are analyzed to discuss the context of the eddy shedding and evolution as well as the origin and transformation of its thermohaline properties. The LCE appeared as a large body of nearly homogeneous water between 50 and 250 m confined between the seasonal and main thermoclines. A temperature anomaly relative to surrounding Gulf's water of up to 9.7^∘ C was observed within the eddy core. The salinity structure had a double core pattern. The subsurface fresh core had a negative anomaly of 0.27 practical salinity unit, while the deeper saline core's positive anomaly reached 1.22 practical salinity unit. Both temperature and salinity maxima were stronger than previously reported. The saline core, of Caribbean origin, was well conserved during its journey from the Yucatan Basin to the Loop Current and at least 7 months after eddy detachment. The fresher homogeneous core resulted from surface diabatic transformations including surface heat fluxes and mixing within the top 200 m during the winter preceding eddy detachment. Heat and salt excess carried by the LCE were large and require important negative heat fluxes and positive fresh water input to be balanced. The geostrophic velocity structure had the form of a subsurface intensified vortex ring.

This study describes in detail the water masses of the Gulf of Mexico (GoM) west of 88^°W based on their thermohaline properties and dissolved oxygen concentration. The existent historical information is complemented with new data from 14 cruises, Argo floats and over one year of continuous glider monitoring. The results describe the general hydrography of the central and western GoM with focus on the difference between the water properties inside and outside Loop Current Eddies (LCEs). Caribbean Surface Water, Subtropical Underwater and 18°C Sargasso Sea Water (18SSW) are exclusive of the LCEs, and they are found along the LCEs preferred path between 23°N and 27°N. Outside the LCEs, the prominent characteristics of these water masses erode, and the Gulf Common Water is ubiquitous in the subsurface. It is shown that the water masses in the GoM need to be described in the frame of the dominant mesoscale features that take place there, and that the dissolved oxygen is a key variable to identify some water masses of Caribbean origin as the Tropical Atlantic Central Water and the 18SSW. The previous potential temperature and salinity limits of the water masses within the GoM were revised and redefined in terms of Absolute Salinity and Conservative Temperature in the frame of the Thermodynamic Equation of Seawater, 2010 (TEOS‐10). While temperature values after conversion have little variation compared to the previous ones, the Absolute Salinity is in average 0.2 units greater than the former practical salinity.

In this study, we harness the 25‐year satellite‐altimeter record, in concert with a vast array of in situ measurements, to estimate the heat content anomaly of 32 warm‐core rings in the Gulf of Mexico (GoM). The decay rate of these mesoscale eddies is studied in detail, and it is shown that they release the majority of their heat as they drift in the central GoM (away from topographic obstacles). The surface heat fluxes from the eddies are shown to be small in comparison to the total rate of heat loss from the eddies, suggesting that heat is primarily released toward the surrounding water masses. Integrating the total heat evolution equation over the warm‐core rings yields an estimate of their effective lateral diffusivity coefficient. The long‐term impact of warm‐core rings on heat and salt balance in the GoM is also discussed.

The 8 September 2017 M8.2 Tehuantepec, Mexico, earthquake ruptured an ~150‐km‐long high‐angle normal fault below the subduction zone megathrust. A tsunami was generated by the event with surveyed runup as large as 3 m. Tide gauges in the region show a remarkably long duration of the tsunami with oscillations within the very wide and shallow Tehuantepec shelf lasting as long as 3 days. Here we produce a model of the tsunami and validate it by comparing it to the tsunami survey and to the time and frequency domain features of regional tide gauges. We analyze the model results and show that the long‐lived oscillations are a result of wholesale resonance of the shelf as well as very efficient trapping of edge waves at the shore. These resonant features are the result of the Tehuantepec shelf morphology and illuminate a previously unidentified tsunami hazard for the region.