CR 23:67-79 (2002)  -  doi:10.3354/cr023067

Is there a link between the unusually wet autumns in southeastern Norway and sea-surface temperature anomalies?

Rasmus E. Benestad*, Arne Melsom

The Norwegian Meteorological Institute, PO Box 43, 0313 Oslo, Norway

ABSTRACT: During November 2000, Bjørnholt (near Oslo, Norway) received 564 mm of rain, the highest ever recorded by far. The extreme rainfall over south-eastern Norway accompanied a persistent circulation pattern advecting moisture from the south, leaving no doubt as to the role of the prevailing winds. However, there may be additional factors affecting the total rainfall amount, and one candidate is sea-surface temperature (SST). There were unusually warm SST anomalies off the coast of Newfoundland, and one central question is: Did the North Atlantic SSTs play a role? An analysis of the historical record of November rainfall from Bjørnholt is presented in order to explore plausible connections with the SST anomalies in the North Atlantic Ocean. It is found that the November rainfall is influenced by the SST in addition to the sea-level pressure (SLP). The SST anomalies cannot account for all of the 564 mm of rain, but the SSTs can nevertheless explain as much of the rainfall during unusually wet November months in 2000 and 1970 as the SLP. The November rainfall record coincides with the warmest SST anomalies on record in parts of the North Atlantic, and it is speculated as to whether this incidence can be related to a warming trend.

KEY WORDS: Rainfall · Sea-surface temperature · Sea-level pressure · Regression analysis

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