Upcoming observations with underwater gliders

Underwater glider SG610, deployed on July 14, is located in the Caribbean Sea. This glider navigated in a SW, then in a SE, and now in a SW direction since it was deployed. The temperature and salinity profile observations indicate that on July 25 this glider started sampling waters of a cyclonic eddy that is now centered at approximately 16.5°N, 67.5°W, and has a radius of ~0.75deg as derived from satellite altimetry observations. These profile observations show a decrease in the salinity maximum, and a shallowing of the depth of this maximum salinity and of the depth of the 26°C isotherm. The surveyed portion of this cyclonic eddy has a sea surface temperature (SST) of 28°C, sea surface salinity (SSS) of 35.2 PSU, mixed layer depth (MLD, based on temperature) approximately 75m deep, and a salinity maximum of 36.9 PSU at around 150m. The depth of the 26°C at the glider's current location (16.3°N 66.80°W) is approximately 100m. East of this cyclonic eddy, an anticyclonic eddy is also observed and centered at approximately 15.5°N and 65.25°W. Numerical modeling results indicate that on its current track, the glider is being directed towards the center of this cyclonic ring.

Figure 1. Altimetry-derived surface geostrophic currents (NOAA/AOML). Background color is the dynamic height.

In the North Atlantic, the underwater glider SG609 that was deployed on July 19, traveled in an approximately northward direction at 66°W, turned east at 19.73°N and then north at 67°W. It is currently located at 20.5°N, 67°W, where it will begin traveling inside a large anticyclonic eddy, which at this moment is centered at approximately 21°N. On July 31, when the glider was located at 20.17°N, 67°W, observations indicated that the value of the salinity maximum decreased from 37.2 to 36.9 PSU. The most recent measurements indicate that the SST is approximately 28°C, the SSS is 36.3 (higher than in the Caribbean Sea), and the MLD is approximately 50m (shallower than in the Caribbean Sea). The depth of the 26°C at the glider's current location (20.5°N, 67°W) is approximately 100m, same as in the Caribbean Sea.

Figure 2. Forecasted averaged top 150m temperature for August 2 (provided by NDBC).