August 2021 Sea Surface Temperature Assessment
A. Niño Regions
Niño SST Indices are based on the average of SST anomalies across the given regions: Niño 1+2 (0-10S, 90W-80W), Niño 3 (5N-5S, 150W-90W), Niño 3.4 (5N-5S, 170W-120W) and Niño 4 (5N-5S, 160E-150W). These indices are used to monitor the conditions in the Tropical Pacific for the occurrence of El Niño or La Niña.
The sea surface temperature anomalies (SSTAs) across the central and eastern equatorial Pacific remained below to near average (0ºC to -0.5ºC) for the month, while in the western Pacific near Indonesia, near to above average SSTAs were observed (0°C to > 1.0°C).
B. Indian Ocean Dipole (IOD)
The Indian Ocean Dipole mode Index (DMI) is defined as the difference between the SST anomalies (ºC) of Western (10ºS-10ºN & 50ºE-70ºE) and Eastern (10ºS-0ºN & 90ºE-110ºE) Equatorial Indian Ocean regions (WEST-EAST). The DMI values represent the intensity of the Indian Ocean Dipole (IOD); DMI values above +0.4 °C is referred as the positive IOD, DMI values below −0.4 °C is referred as the negative IOD and DMI values between +0.4 °C and -0.4 °C is referred as the neutral IOD.
Negative IOD value was still observed in August, but within neutral level, as SSTs in the eastern equatorial Indian Ocean were slightly warmer than the western equatorial Indian Ocean.
