Sea surface temperature anomalies (SSTA) in the Eastern Pacific, specifically off the Peruvian coast, have shown a recent warming. SSTA is defined as the difference between the actual temperature and normal conditions for that time of year. Negative anomalies indicate cooler than normal temperatures, while positive anomalies indicate warmer than normal temperatures. Warm anomalies greater than 2°C have been persistent off the northern to central coast of Peru for over one month. Such warming events off Peru have been historically known to precede El Niño conditions in the Equatorial Pacific. Although it is too early to determine whether such warm anomalies will lead to a shift to El Niño conditions in the Equatorial Pacific, some local effects have already been seen.
Figure 1 shows SSTA, using the State of the Ocean (SOTO) tool at the PO.DAAC, in the Pacific for 7 May 2012. Anomalies are based on the difference between the operational sea surface temperature and sea ice analysis (OSTIA) (Donlon et al., 2011) and Pathfinder v5 climatology (Casey and Cornillon, 1999). Warm anomalies over 2°C are visible off the Peruvian coast.
|Figure 2: SSTA for the week of January 8, 2012.||Figure 3: SSTA for the week of March 11, 2012.|
Figure 2 illustrates NOAA optimum interpolation sea surface temperature analysis (OIv2) (Reynolds and Smith, 1994) that shows conditions off Peru have shifted from neutral/negative anomalies to positive anomalies since January 2012. By March 2012 (Figure 3) warm anomalies over 1°C had appeared off the Peruvian coast. Figures 2 and 3 were taken directly from: http://www.emc.ncep.noaa.gov/research/cmb/sst_analysis/images/archive/weekly_anomaly/.
PO.DAAC Science Team