Seasonal and interannual variability of the Odden ice tongue and a study of environmental effects

The Odden ice tongue is an ice cover phenomenon in the Greenland Sea that c overs all or part of the area of influence of the Jan Mayen Current and tha t encloses a bay of open water called Nordbukta. The yearly attributes of t he spatial distribution of the Odden from 1979 through 1998 have been quant ified in terms of average concentration, standard deviation of ice concentr ations, persistence, maximum extent, and anomalies in extent, and the resul ts show vastly different formation characteristics and seasonalities during different years. The monthly average extents of the Odden are shown to hav e a strong negative correlation with monthly surface air temperatures recor ded at Jan Mayen Island and monthly temperatures retrieved from satellite i nfrared data, with correlation coefficients of 0.74 and 0.89, respectively. Wind effect is also shown to be an important factor at daily and shorter t imescales, directly influencing size and shape and sometimes initiating the formation of Nordbukta. The Odden was most extensive in 1979, 1982, 1986 a nd 1997 and most persistent in 1988, 1989, and 1997 but did not appear in 1 984, 1994. and 1995, suggesting decadal periodicity for the 20 year period. With the use of the 75 year temperature record at Jan Mayen Island as a pr oxy for Odden size, spectral analysis also shows a periodicity of 10-12 yea rs. A correlation study of North Atlantic Oscillation (NAO) indices with ex tents of the Odden, as derived from satellite data, yields a correlation co efficient of 0.4, which suggests that the interannual variability of the Od den may be influenced but not controlled by NAG. Regression analysis of the Jan Mayen surface temperature record also yields a slight warming (0.06 K decade (-1)) and a decrease in Odden area (-0.14 x 10(4) km(2) decade(-1)) from 1979 to 1996, but during the past 75 years, there has actually been a slight cooling (-0.15 K decade(-1)), suggesting either that the Odden had a ctually been smaller in size several decades ago or that it had occurred fa rther north.