Mindanao Current
It is a low-latitude western boundary current that follows the eastern coast of the Philippine island group and its namesake, Mindanao.
The MC forms from the North Equatorial Current (NEC) that flows from east to west between 10-20°N.
As it travels west, the NEC reaches its western limit: the coast of the Philippines.
[1] Once it encounters shallower waters near land, it “splits” into two branches: one moves northward and becomes the Kuroshio current and one moves southward and becomes the Mindanao Current.
The Mindanao Current flows towards the equator and is most intense near the surface, reaching maximum speeds of
[2] Overall, the Mindanao Current is critical in the circulation within the whole Pacific basin.
[3] It flows alongside the contours of the Philippine coast, approximately following the mean dynamic bathymetry based on underwater glider observations.
The MC feeds the equatorial currents, including the North Equatorial Countercurrent and the Indonesian Throughflow which transports water from the Pacific to the Indian Ocean.
Thus, the Mindanao Current serves a role in the global overturning circulation.
It often interacts with the nearby Mindanao Eddy which is a semi-permanent cyclonic recirculation to the east.
Both the MC and its undercurrent are pathways for the exchange of water in the tropical Pacific.
[2] Identified by its salinity signature, the MC waters from the surface to
depth are North Pacific Tropical Water (NPTW) while the layer at
depth is North Pacific Intermediate water (NPIW).
As the water mass is advected southward by the MC, it evolves: the salinity maximum decays by
[2] The MC originates from the southern branch of the NEC bifurcation.
The Kuroshio must travel a larger distance to gain speed than the Mindanao Current which is strong closer to the bifurcation location.
As a consequence, the bifurcation location is northward with increasing depth, i.e., at the shallowest layer (
[2] Observations from December 2010 to August 2014 show that the surface MC (specifically
It is stronger during boreal or Northern Hemisphere spring and weaker during fall.
, it is stronger in spring and fall and weaker in summer and winter.
Seasonal variations in the MC are controlled by large-scale upper ocean circulation.
[5] Under the influence of climate change, models predict that western boundary currents will be affected in different ways.
[6][7] Climate affects the circulation of the western Pacific and on the yearly timescale, ENSO is a major driver.
These variations are probably due to the wind, but the specific mechanism varies with latitude.
[3] Profiles of the water column show that the surface salinity is highest during the 2010/11 El Niño and freshest at the end of the 2010/11 La Niña.
[8] The Mindanao Current is difficult to observe and model because of the strength of the current, the extreme topography of the region, and complicating factors such as wind stress fluctuations and eddies.
[2] The most extensive observations of the Mindanao Current were performed during the following research programs:
