Monday, August 10, 2020

Strange Aspects of Local Sea Surface Temperatures Plus the Blob Returns

Note:  the next blog will be entitled:  Kristalnacht, Brownshirts, and the KNKX Firing.  I have a lot to say, including information that is not well known.  I should also note my blog on the Seattle's violent outbreaks was restored to its original form.
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There are a lot wild aspects of our sea surface temperatures during the summer:  unexpected jumps, rapid declines, and huge changes in relatively short distances.  Take a look at the sea surface temperatures today (see below, blue is cold, red is warm).  Huge contrasts, with MUCH colder temperatures near the coast, particularly from central Oregon to central CA.   


Why so cold?  Because of upwelling of cold water from below.   Such upwelling occurs preferentially near the coast and is controlled by the surface winds.  Strong northerly flow increases upwelling and that is usually associated with high pressure offshore, which is the predominant pattern during summer. 

Want to see?  Below is the sea level pressure and low level wind pattern for Saturday afternoon. You can see the offshore high and the wind barbs indicating strong northerly winds.  Colors are lower atmosphere temperatures.


So you could take a short boat trip from Brookings, on the southern Oregon coast, and head west, and the water would go from the upper 40s into the lower 60s within 100 miles.  Different fish offshore as well.

But if that isn't startling enough, the water temperatures can change rapidly in time as the winds change.  Why?   Well, consider if you have strong northerly winds along the coast, and thus powerful upwelling and cool waters.  But if the winds weaken or even reverse, the upwelling can die and water temperatures can surge.  Or vice versa. 

Let's take a look at water temperatures of a buoy off the WA Coast (46041). The location is shown below by the arrow.

The temperatures there were around 60-61F a few days ago, but then plummeted to about 55F earlier today.  Why?  It was due to strengthening northerly winds.  And with major wind direction shifts and speed changes double that change can occur.


Off the Oregon coast (buoy 46015) temperatures have dropped into the upper 40sF!.


 But while we "enjoy" some cool water along the coast, the offshore waters have warmed as a result of persistent high pressure.  The latest sea surface temperature anomaly map (difference from normal) shows an amazingly warm north Pacific Ocean, with some warm anomalies getting to 3-4C . 

We have a name for a big pool of warm water like that.  A feared name.  The BLOB.  And some folks call is a marine heat wave.  This week I will enjoy going to a talk on this subject by a graduate student who did her Ph.D. research on the topic Lauren Schmeisser.    Finally, look at the tropical Pacific.  What do you see?  Blue color--cold water.  A sign of the upcoming La Nina.



9 comments:

  1. Thanks for explaining this. As someone who lives almost at river level in Sultan, I live with the reality of winter floods, and your blogs are very helpful in helping me take measures to mitigate damage.

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  3. Even more alarming on that map is the temperature anomalies of the Arctic Ocean, Bering sea, Barents Sea, Hudson Bay and Baffin Bay. Also I know persistent high pressure causes the blob but once in place does that contribute to a stormier wetter pattern for our region? Similar to the way the Gulf Stream "feeds" Nor'easters in the north Atlantic?

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  4. Cliff, Would you be so god as to do a post on the interrelations between PDO, ENSO, MJO and SST anomalies for a big picture view of the Pacific? thanks!

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  5. Presently reading "Modern Times," by Paul Johnson--a close reading (800 pages) of events between 1920 and 1990. It is frightening how history repeats itself--and it's no joke. Good people must speak out.

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  6. Out on the Oregon Coast this past weekend. The winds picked up quite a bit Sunday and Monday. Earlier it was pretty nice.

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  7. How does this affect prospects for a La Nina winter?

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  8. Cliff,

    Looking forward to your next blog!

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  9. A fairly active windstorm season should take care of that pesky blob.

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