THE SOUTH
EQUATORIAL
CURRENT
SYSTEM
Sushmita Patwardhan,PhD Candidate,Graduate Program in Oceanography
 Southern Hemisphere.
 In Indian, Pacific and Atlantic oceans.
 THE SOUTH EQUATORIAL CURRENT
 THE SOUTH EQUATORIAL UNDER CURRENT
 THE SOUTH EQUATORIAL COUNTER CURRENT
THE SOUTH EQUATORIAL
CURRENT
 Westward flowing current with a depth of 100 m.
 Northern boundary is at 4°N and southern boundary is
between 15°S- 25°S depending on time of the year and
longitude.
 It’s a geostrophic flow.
 It can be divided into three branches:
1.Southern South Equatorial Current (SSEC)
2.Central South Equatorial Current (CSEC)
3.Northern South Equatorial Current (NSEC)
CURRENTS OF THE
WORLD
SOUTHERN SOUTH EQUATORIAL
CURRENT
 It flows westwards.
 It is fed by the Benguela Current.
 SSEC turns northwards at 30°W.
 Bulk of the flow joins the North Brazil Current.
 Northern branch also feeds SECC.
 A small part flows south pole wards and joins the Brazil
Current.
 Sluggish flow.
 Average transport is 20 Sv for upper 500m.
CENTRAL SOUTH
EQUATORIAL CURRENT
 Located between South Equatorial Undercurrent and South
Equatorial Counter Current.
 It bifurcates around 5-6°S.
 Northern flow merges with North Brazil Current.
 Part of the northern flow turns north-eastwards and supplies
to the SEUC.
 Southern part initially flows southwestwards and then makes
a turn towards the north around 9°S and joins the
southernmost part of the SSEC.
 Average transport is 17 Sv in upper 200m and maximum is
29Sv.
THE NORTHERN SOUTH
EQUATORIAL CURRENT
 Located between 1°N and SEUC (3-5°S).
 Speed is 30cm/s.
 Volume transport is 12 Sv in upper layer.
TEMPERATURE AND
SALINITY
 The Southern South Equatorial Current is more saline
than the Central and Northern branches.
 Salinity of:
SSEC: 37-37.2
CSEC and NSEC: 36-36.2
 Temperature: 26-28°C at the surface and 22-24°C at a
depth of 100m.
 The annual temperature is pretty stable with a season
variability of 4°C.
THE SOUTH EQUATORIAL
UNDERCURRENT
 Eastward flowing subsurface current.
 Depth is between 100-1000m.
 Flow is maximum in boreal fall i.e. Sept-Oct and minimum in
boreal spring i.e. April-June.
 The SEUC has oxygen rich water.
 Flow in the surface above the SEUC is towards the east
during austral summer and towards the west during austral
winter.
 The transport is about 15 Sv.
 Salinity is less then 36
THE SOUTH EQUATORIAL
COUNTER CURRENT
 It flows eastwards.
 Flow is from surface to depth of 400m.
 Is formed around 30°W.
 Crosses the South Atlantic up to Prime Meridian.
 Around 5°S it is entrained by the CSEC.
 Surface water is warm and salty.
 High oxygen concentration.
 Salinity 36.2 at surface and 38 at depth of 400m.
IMPORTANCE OF THE
SECS
 It transfers net heat from the Southern Hemisphere to
the Northern Hemisphere.
 It links the two important subtropical gyres of the
Atlantic Ocean.
 The Brazil current is an important western boundary
current in the South Atlantic gyre.
 Plays a role in formation of Gulf stream.
 Replenishes water in the North Indian Ocean.
REFERENCES
 http://oceancurrents.rsmas.miami.edu/atlantic/southequatorial.html
 http://oceanmotion.org/html/introduction-general.htm
 Lothar Stramma.1991. Geostrophic transport of the South
Equatorial Current in the Atlantic. Journal of Marine
Research,49,281-294.
 http://www.gfdl.noaa.gov/bibliography/related_files/sgp0102
.pdf