The Malvinas Current (MC) is an ocean current that runs along the Patagonian continental shelf and it covers 1800 kilometers from the Drake Passage- which divides South America from the Antarctic-, to Mar del Plata latitude approximately. It is a permanent injection of cold sub polar waters organized in what experts call jets, that is to say, flows that move at high speed.
“The jets are cold waters with high content of dissolved nutrients, which are are necessary for phytoplankton growth, the base of the marine food chain”, Alberto Piola, CONICET principal investigator at the Naval Hydrographic Service, explains.
The continental shelf is the submerged area with depths ranging from 200 to 4000 meters deep. The investigation conducted by Piola and his collaborators was published in the scientific magazine American Geophysical Union in May of this year. The study suggests that the persistent flow of cold waters along the shelf and its height differences promote upwelling- the process in which deep, cold waters with high content of nutrient rise towards the surface.
Thus, with the arrival of cold waters, the subtropical latitudes of the current generate unique environmental and oceanographic conditions in the southern hemisphere: a combination between the high availability of nutrients, which characterizes sub polar regions, with the high availability of light, which is typical in subtropical regions.
This investigation sheds light on the MC conformation, where, for the first time, it is described as being formed by two main cores or jets. “Their velocity in the water is not impressive, but what is known in oceanic terms, such as the fact that the current transport reaches 50 millions cubic meters per second whereas the Amazon river waters get 100 thousand in comparison”, Piola comments.
As the current approaches the bottom of the sea, its speed declines but it increases when its course is near the surface. The main core within the Malvinas Current is located over a flat portion of the bottom, referred to as the Perito Moreno terrace, which extends from 50 to 45ºS. In this area, the sea bed is between 150 and 160 meters depth and the current records temperatures ranging from 4° and 5° C.
The data used in the study was obtained from various research campaigns on board the Puerto Deseado Oceanographic Vessel, and from different instruments such as surface drifters, which are local platforms which allow to obtain a descriptive statistics of the currents’ superficial circulation and take samples of temperatures and satellite data.
On the basis of these observations, together with systemic and geological evidence, it could be inferred that the variation in the Malvinas Current played a leading role essential for deposits’ configuration of the sea bed in the western shelf of the Argentine Basin.
The French-Argentinean Mixed International Unit UMI-IFAECI (CNRS/CONICET-UBA) organizes an international workshop called “Role of the Malvinas Current on the Patagonia Continental Shelf dynamics and biophysical environment” which will be held on June 24th, 25th and 26th at the Pablo Cassará Foundation auditorium located in Av. de Mayo 1190,City of Buenos Aires, Argentina.
- By Alejandro Cannizzaro.
- About investigation:
- Alberto Piola. Doctoral fellow. Servicio de Hidrografía Naval. CONICET.