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Saturday, July 18, 2009

The Unusual SST Anomaly Pattern in the Pacific

I’ve moved to WordPress.  This post can now be found at The Unusual SST Anomaly Pattern in the Pacific
Figure 1 shows the Global SST anomalies for June 2009. The pattern in the Pacific is unusual, at least for the months of May, June, and July from 1982 to 2008, as will be shown. While preparing my recent post “Animations of Weekly SST Anomaly Maps from January 3, 1996 to July 1, 2009” and the future posts that animate SST anomalies back through 1982, I’ve downloaded more than 1,000 SST anomaly maps of the Pacific. I can’t recall that pattern in any of them regardless of the month. Note how most of the Tropical Pacific (bordered in green) has positive SST anomalies. There are a few areas with neutral or slightly negative anomalies, but for the most part the anomalies are positive. That by itself is unusual. And the pattern in the Mid-to-High Latitudes of the North Pacific is also unusual. I’ve never seen it before. It may have occurred before 1982, it may have occurred during prolonged negative PDO periods decades ago, but I do not remember seeing it in any of the maps since 1982.
Figure 1

To illustrate this, I prepared a video that compares the June 2009 Global SST anomaly map to the June maps from 1982 to 2008, alternating between them and June 2009 as the video progresses--similar to a long-term blink comparator. Since 1982, the same pattern occurred in no other June. I also repeated the process for the May and July maps, comparing them to June 2009, and again the same pattern has not occurred. Has it been present during other months since 1982? I don’t know for sure. Has it occurred at any time before 1982? I don’t know. I have documented is that it has not occurred during the months of May, June, or July from 1982 to 2008. And I believe that extending the comparisons beyond those months would be fruitless.

Video: Unusual Pacific Ocean SST Anomaly Pattern for June 2009


The first possible explanation that comes to mind for the unusual SST anomaly pattern in the Pacific is a shift in cloud cover, but I have not been able to find either a cloud cover or cloud amount dataset that is updated through June 2009.

Any other ideas for the shift in the pattern?


SST anomaly maps and data are available through the NOAA NOMADS website:


HowSmart said...

Has the decline in tropical cyclone activity interrupted the transport of heat towards the poles, leading to the tropical build?

Bob Tisdale said...

hswiseman: Thanks for that thought. It will be interesting to watch as the season progresses.

Also, as the El Nino builds and equatorial SSTs rise, will the elevated tropical SST outside the NINO areas drop in response to the increase in convection along the equator?

I'll provide a mid-month update tomorrow when the data is updated.

tallbloke said...

Hi Bob. I think this bears out what I was saying to you about heat coming out of the oceans everywhere due to the transition from heat absorption phase to heat emission phase. The long solar minimum has allowed the momentum to build, and the low trade winds have not disturbed the picture through surface currents or cloud anomalies so much. OLR is still running high.


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