The Hotspot in the North Pacific

I received a couple of emails over the weekend about a news article that mentioned sea surface temperature anomalies as high as 7 deg F in the North Pacific. I took a quick look for the article but wasn’t been able to find it, so I can’t provide a link.  There was a pocket of high sea surface temperature anomalies in the northeast North Pacific last week. See the sea surface temperature anomaly map for the week centered on Wednesday January 29th, Figure 1.

01 SST a Map

Figure 1

Sea surface temperatures for the extratropical North Pacific were unusually warm last year, and now they’re still above their typical seasonal levels.  See Figure 2, which presents the (volatile) weekly sea surface temperature anomaly data for the extratropical North Pacific.

02 Weekly Extratrop No Pac SSTa

Figure 2

The hotspot has been in the northeastern North Pacific for a couple of months and appears to have migrated east from the Kuroshio-Oyashio Extension (east of Japan). See Animation 1, which is available from Unisys here.  Three weeks ago, sea surface temperature anomalies were close to 7 deg F (3.9 deg C) above normal for the primary hotspot.  But sea surface temperatures there have dropped since then.

Animation 1 sst_anom_loop

Animation 1

Weather events are not limited to the surface of the continental land masses.

Back in August, we discussed the unusual warming event in the extratropical North Pacific sea surface temperature anomalies.  Then I stated:

It will probably be a year or so before someone publishes a paper about it, but I suspect the sudden upward spike in extratropical North Pacific sea surface temperatures was caused by a shift in wind patterns, related to a change in sea level pressure. In other words, it’s likely weather related.

WHAT CAUSED IT?

I don’t know for sure.  I suspect there are a number of causes for the unusual warming in the extratropical North Pacific.  Here are a few things to consider.

A blocking high?  There was a period of high sea level pressure at the high latitudes of the North Pacific last summer, Figure 3, which likely interrupted the normal poleward transport of heat to the Arctic (thus explaining part of the “rebound” of Arctic sea ice).

03 High Lat No Pac SLP

Figure 3

As you can see there have been other spikes in sea level pressure at the high latitudes of the North Pacific.  Now consider that there were also unusual conditions in the tropical Pacific in 2013, with ENSO neutral conditions in the central equatorial Pacific (NINO3.4 region), but strong La Niña-like conditions in the far eastern equatorial Pacific (NINO1+2) for much of last year, especially during the boreal summer.  See the weekly NINO3.4 and NINO1+2 data toward the end of the December 2013 Sea Surface Temperature (SST) Anomaly Update.  So I suspect, if there’s a paper that tries to explain the warming in the extratropical North Pacific this past year, there will be a number of influences, so that it turns out to be nothing more than a weather event.

And for those interested, Figure 4 is a graph of the ARGO-era NODC ocean heat content data for the extratropical North Pacific. There was no unusual warming (or cooling) event for the top 700 meters, so the warming event appears to be surface related.

04 Extratrop No Pac OHC

Figure 4

DATA SOURCES

The weekly sea surface temperature data and map are available through the NOAA NOMADS website here.

The ICOADS sea level pressure and NODC ocean heat content data are available through the KNMI Climate Explorer.

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About Bob Tisdale

Research interest: the long-term aftereffects of El Niño and La Nina events on global sea surface temperature and ocean heat content. Author of the ebook Who Turned on the Heat? and regular contributor at WattsUpWithThat.
This entry was posted in SST Update, The Blob. Bookmark the permalink.

19 Responses to The Hotspot in the North Pacific

  1. earwig42 says:

    Thanks, Bob. I always learn something from your posts. They are much appreciated.

  2. Thanks Bob, I was wondering about this North Pacific hot spot. Now I know I was not the only one.
    We know so little about the functioning of the Earth’s climate system!

  3. Steve Keohane says:

    Thanks again Bob, I enjoy your always informative posts.

  4. hmmm says:

    I hypothesize it was a maintenance man on the job, temporarilly breathing on his thermometers. He is now hidden in the deep ocean, so you will have to take my word for it.

  5. Retired Engineer John says:

    Isn’t this the area where La Nina develops a high pressure region? Could it be that a strong La Nina is developing?

  6. timetochooseagain says:

    There seems to be a sudden change in the amplitude or phase of the seasonal cycle after 1994. Doesn’t look real. Hm…

    Anyway, I also noted that kinda warm “blob” back in December, and saw a probable connection with then extant weather patterns over the US. Looks like it’s sticking around.

  7. Bob Tisdale says:

    timetochooseagain, the newspaper article referred to post confirmed that the weather pattern in the U.S. was in part caused by that hotspot in the North Pacific.

    Regards

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  9. Pamela says:

    Opinion: If the weakening of the polar vortex continues (stays weak or gets even weaker), allowing it to loop up and down in response to sea surface temperature changes caused by meandering pools of warmer or colder than usual sea surface temperatures, we will continue to see unsettled weather patterns across the US. Other parts of the globe in the NH will also continue to feel the affects of that loopy polar vortex as sea surface temperatures set up blocking pressure systems that the vortex must climb up over and slide down. I base my opinion on the fact that the blocking high developed over that warm pool when it arrived in the northern Pacific so I think that is the likely cause of the blocking high. The expanded softened edge of the polar vortex than had to loop up and down around it.

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