We revisited the "Great Salinity Anomaly" of the 1970s (GSA'70s; Dickson et
al., 1988) and documented the newly identified "Great Salinity Anomaly" of
the 1980s thence termed GSA'80s), both propagated around the North Atlanti
c in a similar fashion. The advective mechanism, initially proposed to expl
ain the observed sequence of low-salinity, low-temperature events during th
e GSA'70s, apparently holds also for the GSA'80s. The latter was successive
ly observed in the West Greenland Current (1982), the Labrador Current (198
3), the Flemish Pass (1984), near the Charlie-Gibbs Fracture Zone (1984-198
5), in the Rockall Channel (1985), south of Iceland (1985-1988), in the Nor
th Sea (1986-1987), Norwegian Sea (1987-1988), Barents Sea (1988-1989) and
Iceland Sea (1989-1990). The advection speed of the GSA'80s seems to be gre
ater than the one of the GSA'70s: The 1980s anomaly reached the Barents Sea
6 to 7 years after peaking in the West Greenland Current, while the 1970s
anomaly traveled the same route in 8 to 10 years. These anomalies, however,
seem to be of different origin. The GSA'70s was apparently boosted remotel
y, by a freshwater/sea ice pulse from the Arctic via Fram Strait, Consequen
tly, the GSA'70s was accompanied by a large sea ice extent anomaly in the G
reenland and Iceland Seas, which propagated into the Labrador Sea. In contr
ast, the GSA'80s was likely formed locally, in the Labrador Sea/Baffin Bay
mainly because of the extremely severe winters of the early 1980s, but supp
lemented with a possible contribution of the Arctic freshwater outflow via
the Canadian Archipelago (facilitated by strong northerly winds) which woul
d have enhanced stability and ice formation. This anomaly was also associat
ed with a positive sea ice extent anomaly in the Labrador Sea/Baffin Bay wh
ich, however, had no upstream precursor in the Greenland Sea. Thus the GSAs
are not necessarily caused solely by an increased export of freshwater and
sea ice from the Arctic via Fram Strait. These results are corroborated by
the early 1990s data when a new fresh, cold anomaly was formed in the Labr
ador Sea and accompanied by a large positive sea ice extent anomaly. The ha
rsh winters of the early 1990s were, however, confined to the Labrador Sea/
Baffin Bay area while the atmospheric and oceanic conditions in the Greenla
nd, Iceland, and Irminger Seas were normal. The Labrador Sea/Baffin Bay are
a appears therefore to play a key role in formation of GSAs as well as in p
ropagation of the GSAs formed upstream. A likely contribution of the enhanc
ed Canadian Archipelago freshwater outflow to the GSA formation also seems
to be significant. Two major modes of the GSA origin are thus identified, r
emote (generated by an enhanced Arctic Ocean freshwater export via either F
ram Strait or the Canadian Archipelago) and local (resulting from severe wi
nters in the Labrador Sea/Baffin Bay). Both modes should be taken into acco
unt to model decadal variability of the coupled ocean-ice-atmosphere system
in the North Atlantic/Arctic Basin. (C) 1998 Elsevier Science Ltd. All rig
hts reserved.