As was the case in 2014,significant anomalous cooling occurred across thetropical and subtropical Atlantic during the winter of 2014/2015. The current
SST
pattern (Figure 16) across the Atlantic looks more like a negative Atlantic Multidecadal
Oscillation (
AMO) pattern with anomalously cool water in the North Atlantic, subtropical
eastern Atlantic and tropical Atlantic. In addition, warm
SST anomalies off of the US
East Coast are typically associated with a negative
AMO. Much of this anomalous
cooling is due to a persistent positive phase of the North Atlantic Oscillation (
NAO) since
late November of last year (Figure 17). A positive phase of the
NAO is associated with a
strengthened Atlantic subtropical high pressure gyre (Figure 18) and anomalously strong
trades across the tropical Atlantic. This promotes enhanced mixing as well as upwelling
of cold water. Anomalously strong westerly winds in the mid-latitudes also promote
anomalous ocean currents out of the north, which contributes to general cooling SSTs
throughout the North Atlantic basin.
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