Spatial and temporal variability of the Aleutian climate. Fish. Oceanogr

• Main Authors: Sergei N. Rodionov, E. Overland, Nicholas, A. Bond
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2005
• Subjects: temperature; trend; Pacific; Alaska; Aleutian Islands
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.511.6500; http://www.pmel.noaa.gov/foci/publications/2005/rodiL526.pdf

The objective of this paper is to highlight those characteristics of climate variability that may pertain to the climate hypothesis regarding the long-term population decline of Steller sea lions (Eumetopias jubatus). The seasonal changes in surface air tem-perature (SAT) across the Aleutian Islands are relat-ively uniform, from 5 to 10C in summer to near freezing temperatures in winter. The interannual and interdecadal variations in SAT, however, are sub-stantially different for the eastern and western Aleu-tians, with the transition found at about 170W. The eastern Aleutians experienced a regime shift toward a warmer climate in 1977, simultaneously with the ba-sin-wide shift in the Pacific Decadal Oscillation (PDO). In contrast, the western Aleutians show a steady decline in winter SATs that started in the 1950s. This cooling trend was accompanied by a trend toward more variable SAT, both on the inter- and intra-annual time scale. During 1986–2002, the vari-ance of winter SATs more than doubled compared to 1965–1985. At the same time in Southeast Alaska, the SAT variance diminished by half. Much of the in-crease in the intra-seasonal variability for the western Aleutians is associated with a warming trend in November and a cooling trend in January. As a result, the rate of seasonal cooling from November to January has doubled since the late 1950s. We hypothesize that this trend in SAT variability may have increased the environmental stress on the western stock of Steller sea lions and hence contributed to its decline.