ENSO update

As a very strong La Nina winds down, we are entering an “ENSO neutral” phase that should last through the summer.  I say hurray to that: I will be working in the Galapagos in July and during La Nina, it is REALLY cold there, especially mid year.

In fact, I was in the Galapagos last week and it was incredibly warm; we were snorkeling comfortably without wetsuits, a rare thing. You can see the warm anomaly (water that is warmer than normal for this time of year) as the red blob west of Ecuador in the NOAA figure below:


Wondering what the heck ENSO and La Nina are?  go here

From the NOAA Climate Prediction Center.  Updates May 5.

ENSO-neutral conditions are expected to develop during May-June 2011 and continue through the Northern Hemisphere summer 2011.

During April 2011, La Niña continued to weaken as indicated by increasing surface and subsurface temperature anomalies across the equatorial Pacific Ocean. The latest weekly Niño indices reflected below-average sea surface temperatures (SSTs) in the central and east-central Pacific (–0.6oC in Nino-4 and Nino-3.4 regions), and near-average to above-average SSTs in the eastern Pacific (–0.1oC in Nino-3 and +0.8oC in Nino-1+2 regions; Fig. 1 and Fig. 2). The subsurface oceanic heat content anomalies (average temperatures in the upper 300m of the ocean, Fig. 3) increased slightly, due to an expanded area of above-average temperatures at thermocline depth (Fig. 4). Consistent with other transitions to ENSO-neutral conditions, the atmospheric circulation anomalies related to La Niña remained considerable over the tropical and subtropical Pacific. Convection was enhanced over much of Indonesia and suppressed over the western and central equatorial Pacific (Fig. 5). Also, anomalous low-level easterly and upper-level westerly winds have persisted in this region. Collectively, these oceanic and atmospheric anomalies reflect a weakening La Niña, but with ongoing global impacts.

2 Responses to “ENSO update”

  1. Mi says:

    Correct me if I’m wrong, but I’m pretty sure that a higher temperature anomaly will generate chronic stress and should therefore not be celebrated.

    • John Bruno says:

      Mi, thanks for your comment/question. I was being somewhat facetious but in the Galapagos, temperature varies enormously from year to year due to the ENSO cycle. We are leaving a cool La Nina phase. In general, populations there are adapted to deal with year-to-year temperature fluctuations, however, intense El Nino phases can cause a lot of distress as upwelling and primary production decline. Although for many organisms, eg corals, the cold phase can be the more stressful of the two.

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