Figure 1.
Temperate North Pacific realm, and the 16 MEOW ecoregions included in this paper.
Major surface circulation pathways are labeled on the map and indicated with blue arrows, including the North Pacific Current (NPC), California Current System (CCS), North Equatorial Current (NEC), Kuroshio Current System (KCS), Kuroshio Extension (KE), Oyashio Current (OC), East Kamchatka Current (EKC).
Figure 2.
Annual cycle metrics analyzed in this study.
Generalized illustration and tabular description of metrics used to evaluate the annual SST cycle in the North Pacific ecoregions. Individual, ecoregion-specific annual cycles are depicted in Figure 3.
Figure 3.
Monthly-mean SST in each of the Temperate North Pacific ecoregions based on a 29-year dataset.
The horizontal axis represents months (e.g. 1 = January, 12 = December). The solid lines show the monthly-mean SST values. The dotted lines show the upper 95th and lower 5th quantiles of SST, which is a measure of within-month variation.
Figure 4.
Fraction of missing data points for each month aggregated over the 29-year SST time series.
Each individual month (e.g. all 29 Januarys) has over half-a-million possible SST point values. Although subarctic ecoregions tend to have a greater percent of missing data compared to lower-latitude ecoregions, at least 40,000 SST values meeting the quality criteria were present in the Temperate North Pacific study area for each of the months evaluated.
Table 1.
Number of months in various temperature intervals for ecoregions of the Temperate North Pacific.*
Figure 5.
Hierarchical clustering dendrogram of 16 Temperate North Pacific ecoregions based on monthly-mean SST values.
Clustering was performed with PRIMER [25] using 3000 iterations in SIMPROF. Distances are Euclidean. Red, dotted branches indicate no significant difference between linked ecoregions. NEP = Northeast Pacific; NWP = Northwest Pacific.
Figure 6.
Ecoregions plotted by maximum monthly versus minimum monthly-mean SST over the 29-year record.
The y = x line indicates where minimum and maximum temperatures within an ecoregion are identical. Hence, proximity to the line indicates minimal variability in seasonal monthly SST. The Euclidean distances of 8.7 and 17 were obtained through clustering analysis. Solid lines connect ecoregions in order of latitude along the NEP and NWP.
Figure 7.
Boundary comparison among the thermal patterns based on our SST cluster analysis, marine climates of Hall [40], SST clusters based on cluster analysis, and NOAA's Large Marine Ecosystems of the World (LMEs).
The LMEs are denoted by the outer colored areas. Hall's marine climates are indicated by the dotted black lines, while the SST clusters derived by clustering MEOW ecoregions by SST are delineated by the inner colored outlines.