ENSO and Sea Surface Temperatures
The tropical Pacific Ocean is in a neutral state (no El Niño or La Niña), but equatorial Pacific sea surface temperature (SST) anomalies remain positive. The Southern Oscillation Index (SOI) has been near zero during June and July, with the 3- month May – July mean at –0.4. The NINO3, NINO4, and NINO3.4 SST anomalies were all between +0.6 and +0.7°C in July, and have been near those levels for most of 2005. Equatorial SST anomalies have risen recently west of the Date Line. The main feature in Equatorial Pacific subsurface temperature profile is a region of negative anomalies below 100m depth in the central Pacific, which has intensified in the last few weeks. Outgoing longwave radiation (OLR) anomalies show a region of enhanced convection west of of the Date Line, where convection had previously been suppressed.
OLR anomalies elsewhere remain small. The Madden Julian Oscillation (MJO) has been inactive for the past two months.
Most available models indicate neutral conditions (mostly with positive NINO3.4 anomalies) through the rest of 2005. The Scripps/MPI and LDEO dynamical models develop a warm event over the summer, while the Linear Inverse Model predicts a cooling over the next several months. The latest NCEP/CPC statement suggests neutral conditions through the rest of the year, but with positive SST anomalies in the “Niño regions”. The IRICP summary gives a 70-75% chance of neutral conditions persisting through to December, with a 25% chance of an El Niño developing, and 5% for La Niña.
Sea surface temperature anomalies (°C) for July 2005
Mean sea surface temperatures (°C) for July 2005
