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This study examines the relative roles of the Arctic freshwater exported via different pathways on deep convection in the North Atlantic and the Atlantic meridional overturning circulation (AMOC). Deep water feeding the lower branch of the AMOC is formed in several North Atlantic marginal seas, including the Labrador Sea, Irminger Sea, and the Nordic seas, where deep convection can potentially be inhibited by surface freshwater exported from the Arctic. The sensitivity of the AMOC and North Atlantic to two major freshwater pathways on either side of Greenland is studied using numerical experiments. Freshwater export is rerouted in global coupled climate models by blocking and expanding the channels along the two routes. The sensitivity experiments are performed in two sets of models (CM2G and CM2M) with different control simulation climatology for comparison. Freshwater via the route east of Greenland is found to have a larger direct impact on Labrador Sea convection. In response to the changes of freshwater route, North Atlantic convection outside of the Labrador Sea changes in the opposite sense to the Labrador Sea. The response of the AMOC is found to be sensitive to both the model formulation and mean-state climate. [ABSTRACT FROM AUTHOR]

A novel bacterial strain, designated 170(T), was collected from high latitude Arctic locations (77 degrees 30' N to approximately 81 degrees 12' N), including the Canadian Basin and Greenland Sea. Phylogenetic analysis based on 16S rRNA gene sequence comparisons showed that strain 170(T) was related to members of the genus Glaciecola and had the highest 16S rRNA gene sequence similarity to Glaciecola mesophila. Cells were Gram-negative, psychrophilic, motile rods. The temperature range for growth was 4-15 degrees C, with optimum growth at 12 degrees C and at approximately pH 6.0-9.0. Strain 170(T) contained C(16 : 1)omega7c, C(16 : 0), C(12 : 1) 3-OH and C(18 : 1)omega7c as major fatty acids. The genomic DNA G+C content was 42.9 mol%. On the basis of phenotypic characterization, phylogenetic analysis and DNA-DNA relatedness data, strain 170(T) is considered to represent a novel species of the genus Glaciecola, for which the name Glaciecola psychrophila is proposed. The type strain is 170(T) (=CGMCC 1.6130(T)=JCM 13954(T)).