Guest Post by Bob Tisdale
The following four animations of Sea Surface Temperature (SST) anomalies were created using the mapping feature (Full Version) of the NOAA NOMADS system for the weekly OI.v2 SST data:
The “Contour interval for var1” was set at 0.2 deg C to bring out the lower-intensity temperature anomalies. “white” was set at “0” so that blues represented negative anomalies and reds represented positive anomalies. All four videos last for approximately 2 1/2 minutes.
Please click on the videos to watch them in a larger size at YouTube. There they can be expanded to full screen and set to high definition.
The North Atlantic has the highest SST anomaly linear trend of all of the ocean subsets. Refer to my post Putting The Short-Term Trend Of North Atlantic SST Anomalies Into Perspective. And of the three major ocean subsets, the Atlantic Ocean has the highest OHC linear trend. This is illustrated in my post Levitus et al (2009) Ocean Heat Content – Comparison of The Ocean Basin Data. Does the Atlantic SST Anomaly Animation help show the reasons?
In addition to the surges of heat in the North and South Atlantic during El Nino events, there are a number of paths that warm SST anomalies enter the South Atlantic during ENSO neutral and La Nina periods. Occasionally, the Benguela Current carries these warm water anomalies north along the Southwest Coast of Africa, where they are then carried west by the Atlantic Equatorial Currents. The warm anomalies either return to the South Atlantic, following the currents of the South Atlantic gyre, or they enter the North Atlantic. Once in the North Atlantic, they travel north, and appear to do that quickly. These additions of elevated SST anomalies during La Nina and ENSO-neutral periods also help explain why There Are Also El Nino-Induced Step Changes In The North Atlantic.
Atlantic Ocean SST Anomaly Animation 1996 to 2009
The Indian Ocean animation shows very “noisy” SST anomalies, without any obvious reoccurring pattern. I was hoping to illustrate evidence of the Indian Ocean Dipole. In a future post, I’ll try to do so.
Indian Ocean SST Anomaly Animation 1996 to 2009
ENSO events stand out in the Pacific Ocean SST anomaly animation. It is possible to differentiate between traditional El Nino events like the 1997/98 El Nino (initially forms in the eastern equatorial Pacific) and the El Nino Modoki events of 2002/03 and 2004/05 (initially form in the central equatorial Pacific). Occasionally, the Pacific Decadal Oscillation (PDO) pattern in the North Pacific (north of 20N) makes its presence known, as does the basin-wide pattern of the Interdecadal Pacific Oscillation (IPO).
In a future post, I’ll discuss a sequence of events that appears to occur during traditional El Nino events. Note how, before the formation of the 1997/98 El Nino, the Humboldt Current carries warm Southern Hemisphere SST anomalies up along the west coast of South America to the eastern equatorial Pacific. Yet RSS MSU TLT Time-Latitude Plots (refer to RSS MSU TLT Time-Latitude Plots…) clearly show that the majority of the heat from the 1997/98 El Nino was transported to the mid-to-high latitudes of the Northern Hemisphere. Does this mean that El Nino events transport heat from the Southern Hemisphere to the Northern Hemisphere?
Pacific Ocean SST Anomaly Animation 1996 to 2009
In addition to the processes that appear in the videos of the three major oceans and the interactions between them, the Global SST anomaly animation also shows the seasonal shifts in the SST anomalies within the Northern and Southern Hemispheres. There also appears to be a shift between them, where the higher SST anomalies appear during the summer months for each hemisphere.
Note also that the Indian Ocean anomalies no longer seem so noisy.
Global SST Anomaly Animation 1996 to 2009