Spatial heterogeneity of sea surface temperature trends in the Gulf of Alaska

Abstract

State-space models were used to derive non-parametric sea surface temperature (SST) trends from 26 locations in and around the Gulf of Alaska for the period 1950–97. The SST trends reflect important large-scale climate impacts associated with El Niño events and regime shifts, but also reveal significant spatial heterogeneity across the region. The SST trends cluster into five distinct regions that define a robust zonal and meridional asymmetry. The meridional differences reflect the relative impact of El Niño events, while the zonal differences reflect variations in the timing and amplitude of a region-wide post-1970 warming trend. The 1976 regime shift is evident primarily as an accelerated warming in the northern and eastern portions of the Gulf of Alaska. The climate signals identified in the SST series are of sufficient magnitude and duration that they could potentially foster changes in lower trophic productivity and structure, which could lead to a broader ecosystem reorganization. Regional differences in Steller sea lion population trends may have resulted from a spatially heterogeneous upper-ocean response to large-scale climate variability. © 2005 Taylor & Francis Group, LLC.