Content area
Full Text
Elevated sea surface temperatures (SSTs) related to the warm 'Blob' continued to dominate the physical and biological oceanography of the northeast Pacific through summer-autumn 2014 (Bond et al., 2015) and into winter, spring and early summer of 2015. The anomalous blob of warm surface waters that had been present throughout the North Pacific in summer 2014 was associated with a weak North Pacific High (NPH) and a delay to the start of the coastal upwelling season in the northern California Current (NCC). Upwelling, as tracked by the Bakun Upwelling Index, did not begin until June 2014. By late summer, with a weakening of the NPH, the Blob began to move eastward and onshore in the northern California Current (Fig. 1). The date of arrival at Newport, Oregon (44.6°N latitude), was September 16, 2014 (Fig. 2) shown by a sudden increase in SST of nearly 7°C that occurred over the course of one hour! The untimely arrival of this event, coupled with a delay in the onset of coastal upwelling, resulted in the shortest upwelling season on record for the NCC. The onshore movement of the Blob and cooling in the Central Pacific produced a spatial pattern of SST that resembled a positive PDO pattern - PDO values were the most positive ever recorded for winter months (+ 2.51 in December 2014 and + 2.45 in January 2015). Higher positive PDO values have been observed previously, but only during the summer months (the five highest summertime PDO values: July 1983, 3.51; August 1941, 3.31; June 1942, 3.01; August 1984, 2.83; and June 1997, 2.76).
The water which moved shoreward and into the coastal California Current had surface temperature and salinity characteristics of warm and fresh water (11-12°C and salinity ~ 31); this water type was present over the upper 50-80 m of the water column in shelf and slope waters of the NCC. Farther offshore, extending out to 200 miles (320 km) from the coast in January and April 2015 were surface waters of 11-12°C and salinity of ~ 32.5. Below this layer, the waters were 'normal' during winter 2014-15 with T-S at a depth of 150 m in slope waters of 8.51°C and 33.69 (climatology 8.46°C and 33.77; Huyer et al., 2007); oceanic waters...