|The Gulf Stream and other major ocean currents are similar to the major wind bands in the atmosphere in that they both distribute heat as part of Earth's large scale circulation. On different scale, the atmosphere also circulates heat by storms--the largest being hurricanes. The oceans also circulate heat by "storms"- called eddies. The largest and most energetic eddies in the ocean are rings that shed off the Gulf Stream. Thus, Gulf Stream rings are an important component of the Atlantic circulation.
A ring is a type of mesoscale eddy that forms when Gulf Stream meanders break off the Stream creating independent circulatory systems. The formation of a Gulf Stream ring is the only way that warm tropical water located south of the Gulf Stream can be moved north of the Gulf Stream. Ring formation is also the only way cold nutrient rich shelf water located north of the Gulf Sream can be moved south of the Gulf Stream. Therefore, ring formations are a very important way for the ocean to distribute heat and energy.
There are two types of Gulf Stream rings, warm core rings and cold core rings. Warm core rings form off a northward bending meander and are always found north of the Gulf Stream. Cold core rings form off a southward bending meander and are found south of the Gulf Stream. Other differences between warm and cold core rings will be discussed on the next page.
The four illustrations below depict the formation of a warm core ring. Is is called a warm core ring since warm Sargasso Sea water is trapped in the center of the ring during formation. The arrows on the diagram indicate the direction of flow.
|A. Gulf Stream meander develops|
|B. Amplitude of the meander increases|
|C. Meander forms a loop and begins to pinch off|
|D. Ring separates from the Gulf Stream|
|Rings play an important role in transferring water across the strong frontal boundary of the Gulf Stream.The Gulf Stream can be accurately thought of as a barrier between the cold waters to the north and the warm waters to the south.The formation of a warm ring results in unproductive Sargasso Sea water transferred into the productive waters of the continental margin.Warm core ring formation results in Sargasso Sea water being transported into continental shelf water. This is the only mechansim to transport surface waters across the Gulf Stream|