Warm Core Ring

[phantom power]

The Loop Current commonly bulges out in the northern Gulf of Mexico and sometimes will shed a clockwise rotating ring of warm water that separates from the main current (Figure 1). This ring of warm water slowly drifts west-southwestward towards Texas or Mexico at about 3-5 km per day. This feature is called a "Loop Current Ring", "Loop Current Eddy", or "Warm Core Ring", and can provide a key source of energy to fuel rapid intensification of hurricanes that cross the Gulf, in addition to the Loop Current itself. The Loop Current pulsates in a quasi-regular fashion and sheds rings every 6 to 11 months. When a Loop Current Eddy breaks off in the Gulf of Mexico at the height of hurricane season, it can lead to a dangerous situation where a vast reservoir of energy is available to any hurricane that might cross over. This occurred in 2005, when a Loop Current Eddy separated in July, just before Hurricane Katrina passed over and "bombed" into a Category 5 hurricane. The eddy remained in the Gulf and slowly drifted westward during September. Hurricane Rita passed over the same Loop Current Eddy three weeks after Katrina, and also explosively deepened to a Category 5 storm.



So, a key question to ask this hurricane season, is when will the next Loop Current Eddy break off, creating a ready-made high-octane energy source for any hurricane that might pass by? Well, the behavior of the Loop Current over the past year can be viewed at Navy Research Lab's web site (51 Mb). This movie has arrows showing the direction of the current, plus a color coding that represents the height of the sea surface above mean level. The higher the height, the warmer the water (since warm water expands and thus raises the sea level where it is at). One can see near the beginning of the animation that the Loop Current Eddy that fueled Katrina and Rita breaks off from the Loop Current in July 2005, then slowly moves west-southwest to a point off the Texas coast by November, where it gradually dissipates. Another Loop Current Eddy breaks off eight months later in March, and lies south of Louisiana in early May. If the Loop Current maintains its 6 - 11 month periodicity shedding these eddies, the next eddy is due sometime between September and February. Oceanographic models can't forecast these events realiably, so we don't know when the most likely time is. Let's hope that this doesn't occur in September or October--we could do without another big eddy of warm water in the Gulf at the height of hurricane season, fueling explosive hurricane intensification!

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=351&tstamp=200605

[electropop]

1. Thanks for th insight!

Very helpful.

[ClintonTyree]

2. I've been looking at the Ocean and Gulf temperatures.....

for a few weeks now and it looks like there has been higher than normal water temperatures from off the west coast of Africa right into the Gulf of Mexico. Not a great increase mind you, but a few degrees can make a great difference when those huge, energy sucking machines called hurricanes start forming. I have a feeling it's going to ba another bad year. The only real question is WHERE?

[phantom power]

3. This year, I plan to watch this map with some interest:

A map of the "depth 26C isotherm." We should be able to see any warm-core eddies nicely on this map.



Actually, all four of these maps should be informative:
http://www.aoml.noaa.gov/phod/cyclone/data/at.html

[donsu]

4. thanks

nt