The Benguela Niño 1995 observed in Angolan waters
Working paper
Permanent lenke
http://hdl.handle.net/11250/105384Utgivelsesdato
1995Metadata
Vis full innførselSamlinger
Originalversjon
This report is not to be cited without prior reference to the authorsSammendrag
During the cruise by R/V ''Dr. Fridtjof Nansen" in February-March 1995, we observed that the
upper ocean layers were very warm and brackish. Comparing with a similar cruise performed
in 1994, the water temperature was up to 8°C warmer, and the salinity some 5 psu lower. The
maximum salinity differences was found at the surface, but the temperature deviations were
maximum at typically 30 to 50m depth. The thermocline was found at 20 to 30m greater
depths than usual. The horizontal and vertical distribution of the phenomenon is discussed, as
well as the time-evolution.
We believe this is an Benguela ''Niño", a phenomenon similar to the well known "El
Niño" in the Southern Pacific. While the Pacific "El Niño" occurs up to several times per
decade, the South Atlantic counterpart has been observed about once per decade. The former
''Niños" were also characterized by warm surface water, but in contrast to Niño-95 the surface
salinity have usually been observed to be higher than normal. The Benguela Niños are believed
to be caused by warm, saline water advected from north or north-west. The low salinity of the
Niño-95 corresponds to an excess off-shore precipitation of the order of 3000 mm above
normal.
The significance of Benguela Niño-95 as a global climate perturbation is discussed.
During the Niño-95 the abundance estimates of three important pelagic species were very
low.