The Relationships Between the North Atlantic Oscillation and Southern Baltic Coast Ice Conditions

Abstract

This paper focuses on relationships between the North Atlantic Oscillation (NAO) Index in selected months and periods and the ice conditions along the southern coast of the Baitic Sea. The data on ice conditions, including the number of days with ice (L) and the length of ice season (counted in days; 8|. cover 25 observation regions located between Arkona in the West and Kaliningrad in the East for winters ofthe 1950/51-1989/90 period. The NAO Index, understood to be the difference between normalized values of atmospheric pressure in Gibraltar and Reykjavik, was applied.Correlation and regression analysis methods were applied to determine and study the relationships between NAO (independent variable! and the parameters of ice conditions L and S Idependent variables). The linear relationships recorded for sheltered basins (Szczecin Lagoon, Puck Bay Small, Vistula Lagoon) were stronger than those calculated for unsheltered ones (e.g., open Baltic Sea coast). The majority of relationships of ice conditions (L and S) to winter monthly NAO values, particularly for January (NAO,) and February {NAOi,) in sheltered basins, are statistically significant, some of them even at the level of a ~ 0.01. The linear correlation coefficients, in most cases, were included within the range from -0.3 to -0.7. The strongest of them were calculated for January and February and encompassed the range from -0.5 to -0.7. The strength of these relationships tended to increase when particular months were connected into several-month periods of NAO Index, especially during the January-March and December-March periods. During these periods the correlation coefficients were usually in the -0.7 to -0.8 interval. In addition, the relationships ofthe NAO index with L were distinctly stronger than those with S. The strongest relationships, with linear correlation coefficients exceeding -0.80. were obtained for the number of days with ice rLi in protected areas, e.g.. in Vistula Lagoon for a period of December-March (NAO^^,,.,,,! and in Puck Bay for January-March period (NAO, 1, 1). These relationships are weaker in unsheltered area.s, where tbe correlation coefficient does not exceed the value of -0.75. The strongest of them concern the estuarine regions of large rivers (Dziwnow, Swibnol and bays (Migdzyzdrojei, whereas the relationships between the NAO Index and L and 8 did not differ significantly from each other in unsheltered basins. However, for the NAO periods of December-March and January-March, they were stronger with S than with L.The correlation coefficients show a decreasing tendency eastward along the southern Baltic Sea coast from Pomeranian Bay to Gdansk Bay (northward ofthe Hel Peninsula). They become stronger in the western part ofthe Gulf of Gdansk and in the mouth ofthe Vistula and again decrease eastward. During some extremely severe or very mild winters, the extreme ice conditions do not always match the extreme NAO index values. During extremely severe winters, the ice cover could exist for a relatively long period, which is a ...

The relationships of the North Atlantic Oscillation to water temperature along the southern Baltic Sea coast

“…The relationships of the NAO index to ice conditions are weaker in comparison with the water temperature; the correlation coefficients of the NAO index with ice conditions in Mecklenburg Bay (Koslowski and Glaser, 1999), Baltic Sea (Omstedt and Chen, 2001), or Estonian coast (Jevreyeva, 2002) amounted to ca −0.50. Similar correlation coefficients also apply to the southern Baltic Sea coast (Girjatowicz, 2005). They are the strongest (up to −0.80) in coastal lagoons and lakes (Girjatowicz, 2003a).…”

“…However, when the NAO index values are low (negative), predominantly polar-continental air masses flow in over the European continent. In winter these are cold air masses causing not only a decrease in the water temperature, but also an intense development of ice phenomena on the southern Baltic Sea coast (Girjatowicz, 2005).…”

Remote Sensing of Ice Phenology and Dynamics of Europe’s Largest Coastal Lagoon (The Curonian Lagoon)

“…The regional climate fluctuations over the study site are known to be related to the North Atlantic Oscillation [60,61]. There were many studies aimed at displaying its effect on the variability of the ice cover in the Baltic Sea [62][63][64]. The comparison between the three ISD types in the Curonian Lagoon, winter NAO index (NAO DJFM ), and cumulative negative air temperature (T CN a ) during 2002-2017 is further shown in Figure 15.…”

Ice phenomena in investigations of Polish lakes

“…The conducted research confirmed the noticeable influence that changing climatic conditions, caused by different intensity of the North Atlantic Oscillation, had on the regime of lake ice phenomena in the temperate zone (Hurrell 1996; Magnuson Benson et al 2012). The transitional character of the climate in northern Poland was marked by the varied dates of ice cover occurrence, its duration, and the degree of ice cover duration (Girjatowicz 2003(Girjatowicz , 2005Skowron 2003;Wrzesiński et al 2013Wrzesiński et al , 2015. In the positive phase of the North Atlantic Oscillation, during warm and moist winters, the duration of the ice cover and its thickness were significantly smaller than for winters with a negative NAO index (Marsz 1999).…”

“…Apart from a few works mentioned above, it is worth citing those that refer to analyses of the ice cover of individual lakes (Chojnowski and Ciszewski 1964;Górniak 1999;Borowiak and Barańczuk 2004;Dąbrowski 2008;Pius and Marszelewski 2016) and groups of lakes (Barańczuk and Marchlewicz 2003;Girjatowicz 2003Girjatowicz , 2004Barańczuk and Borowiak 2005), as well as in the supra-regional aspect (Marszelewski andSkowron 2006, 2009). These problems mostly Skowron 2009), the influence of climate -especially the winter NAO index on the course of ice cover (Girjatowicz 2003(Girjatowicz , 2005Borowiak and Barańczuk 2004;Skowron 2008aSkowron , 2009Wrzesiński et al 2013Wrzesiński et al , 2015.…”