July 2023 Sea Surface Temperature Assessment
A. Niño Regions
Niño sea surface temperature (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.
For the month, above average sea surface temperature anomalies (SSTAs) across the central and eastern equatorial Pacific further strengthened (greater than 1.0ºC anomaly up to the central Pacific). The strong warming at the eastern equatorial Pacific were consistent to observe more than 3ºC warmer than average and expanding westward. However, near average SSTAs were observed in most of the western Pacific, east of the Philippines while in the South China Sea and around Indonesia, positive anomalies were also evident.
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.
The IOD value were still within neutral levels for July, with the western equatorial Indian Ocean showing slightly warmer than average than the eastern equatorial Indian Ocean.
