Monday, August 17, 2015

Comparing Temperatures -- This El Niño vs. The 1997-98 El Niño

This year's El Niño is neck-and-neck with the 1997-98 El Niño, according to the Niño3.4 index (sea surface temperature anomalies in a central region of the eastern equatorial Pacific ocean). But surface temperatures (right-hand scale) are about 0.3°C warmer:


It's almost like something has been causing the surface to warm in the interim.....

Note 8/19/15: issues with incorrect graph labeling have been corrected.

7 comments:

John said...

" ... like something has been causing the surface to warm in the interim ... ? Since 1997-98?

Like a rate of global heating only a bit lower than the maximum observed in the prior 55-75 years?

(See "hiatus," below.)

John Puma

drewsil111 said...

Certainly more than 0.3C. Possibly close to 0.45C on the year so far versus 1997

Oale said...

thus pretty normal strong el nino?

JoeT said...

The labeling in your graph is a bit off. The blue dotted line is the 2015 Nino3.4 anomaly, not 2014. The red dotted line is 1997 only, not 1997-98. Solid blue is 2015 GISS, not 2014. Solid red is 1997, not 1997-98. Also, 1997 GISS has only 11 points; you missed one.

But I have a physics question that is more interesting. As we see in in the 1997 Nino3.4 as well as for other El Nino years, the index really does peak around the end of the year. Hence the whole baby Jesus thing. The question is why? What's happening in the atmosphere/ocean circulation that begins to kill off the El Nino around the end of the year?

David Appell said...

Joe T: Thanks for pointing out the incorrect graph labels. I've corrected them.

I don't know the answer, off the top of my head, to your question....

JoeT said...

David, I should have mentioned as well how much I enjoy reading your blog. I check it out almost every day. The hockey stick BOE explanation itself was insightful.

As a follow-up to my question above, I tried asking this exact same question on the NOAA ENSO blog. And got nowhere. How is that even possible? Clearly the models predict a peaking of Nino3.4 in late fall, early winter. The data for past El Ninos clearly supports this. What's the physics behind the name?

Might make a good article to be published somewhere.

David Appell said...

Joe: I really don't know, off the top of my head, why or how an El Nino ends.