Thursday, June 25, 2015

Encircling 'The Blob'

It’s not often that climate phenomena penetrate the realm of popular media. The ‘Polar Vortex’ certainly has, becoming a bugbear for the extreme winters that the American Northeast has experienced in these last couple years. ‘The Blob’ is another such feature that has reached regional notoriety in the Pacific Northwest. It’s been blamed for everything between sending salmon north to Canada to the lack of a ski season in the Cascades. ‘The Blob’ manifests itself as, well, a large blob of water sitting in the Gulf of Alaska that is warmer than usual forced by an unusual high pressure ridge. As can be seen in the figures below, you can see the Blob’s ever-shifting form skirted by our cruise track.

Snapshots of daily sea surface temperature taken from satellite during our cruise. Red colors indicate warmer than averages temperatures. Black line is the cruise track, including the steam to Seattle at the end.
 In addition to the water sampling that we do from the rosette, one of the ship’s sensors collects surface temperature and salinity continuously while underway. Despite the fact that we never crossed the core of the blob, we still saw its influence north of 37ºN with higher-than-average temperatures.

Daily averaged surface temperatures from the ship’s underway sensor. The influence of the Blob can be seen in the top panel as positive temperature anomalies north of 37ºN and in the bottom panel as the difference between the red and black lines (37ºN was crossed on 06/05).

If you’re interested in the origins and effects of the Blob check out the blog posts by UW Atmospheric Scientists Cliff Mass and Dennis Hartmann:

“Did "THE BLOB" cause our warm summer?”

“The tropics as a prime suspect behind the warm-cold split over North America during recent winters”

By Andrew Shao