Arctic Warmth to Play the Spoiler? Ocean Surface, Atmosphere Show Anomalous Heat Spike in Advance of Predicted El Nino

18 March, 2014

Pacific Ocean monitoring stations around the world are now calling for a 50-67 percent chance of El Nino later this year. A warming of the Eastern Pacific that, should it emerge, is likely to result in record atmospheric and ocean temperatures as the human greenhouse gas heat forcing emerges, once more, from the oceans. But, so far, the Eastern Pacific remains in a somewhat cool ENSO-neutral state. It is a trend that should lead to global atmospheric temperature averages somewhat hotter than the ocean surface. A trend that should not show ocean temperatures spiking, with atmospheric values rising at a slower rate.

But over the past week, according to both GFS model assessments and NOAA observational data, average global ocean surface temperatures have been surging.

(Sea surface temperature anomaly from the already warmer than normal 1971 to 2000 base period. Image source: NOAA.)

Large zones of well above average sea surface temperature now cover vast regions of the global ocean system so that anomalous heat now is plainly the dominant feature. Pools of hotter than typical water where averages range from 1 to 4 C above normal now appear off both coasts of South America, through the Indian Ocean between Africa and Australia, off the East Coast of the United States, south of Alaska and in a zone stretching from Norway to Svalbard. By contrast only small cool zones remain in the Eastern Pacific, in the passage between South America and Antarctica, in a swatch of the Tropical Atlantic near Africa, and in isolated regions of the Central and Western Pacific.

Arctic Warmth Drives Temperatures Higher

But the zone of hottest temperatures appear, according to GFS model data below, in the Arctic, where much of the surface waters and ice sheet are warmer than average by 4 C or more. This heat bleed from the Arctic Ocean tips Northern Hemisphere values far above average and is a primary contributor to Arctic atmospheric temperatures in the range of 3-4 C above average (1979-2000) for mid to late March.

During the past few days, the effect of this warm surface was enough to drive temperature anomalies for the oceans higher than .9 degrees Celsius above the 1979 to 2000 global average according to GFS observational data. Understanding that the 1979 to 2000 global sea surface temperature (SST) average was already about .28 C above the 1880s average,we are now seeing SST daily values in excess of 1.18 C above 1880s averages before El Nino comes into play.

(Sea surface temperature anomaly for March 18, 2014 vs the, already warmer than normal, 1979-2000 average. Image source: University of Maine.)

Even more impressive are the sea surface temperature values seen during the past two days (March 17-18) — hitting a .99 C positive anomaly or +1.27 C above 1880s values.

For comparison, the global sea surface temperature average for 2013, according to the National Climate Data Center, was .42 degrees Celsius above the 1880s average and the hottest year for ocean surface temperatures, 2003, was .52 degrees Celsius hotter than the 1880s average. The average for the past two days, should the GFS observation stand, is +.75 above the highest annual average on record.

Daily values for even the entire ocean system can show rather large swings, but this high temperature trend is somewhat new and has been ongoing now for about a week.

Oceans dumping heat into the atmosphere without El Nino

By contrast, global atmospheric temperatures within the first two meters, according to the same GFS data, are, on March 18, .69 C above the 1979-2000 average. It is a reading .3 C below current sea surface temperature values. Yet it is also a reading about 1 C over 1880s values and about .3 C above annual global high temperature records set in 2010.

With ocean surface temperatures higher than 2 meter air temperatures, it appears the ocean is now dumping some of its latent heat back into the atmosphere through radiative transfer. This is a situation opposite of what has been observed for much of the past 13-14 years running when Pacific Decadal Oscillation (PDO) went negative and the oceans underwent rapid warming as they sucked up atmospheric heat.

What we now observe in the preliminary GFS data is evidence that the ocean is dumping a bit of this stored and massive volume of heat back into the atmosphere. And we are seeing significant positive oceanic and atmospheric heat forcing well before any major level of Eastern Pacific Ocean warming and associated El Nino have come into play.

Links:

NOAA ESRL

University of Maine

National Climate Data Center

UCAR GFS

UCAR: El Nino or La Nada?