|Real-time SOI Data|
Numerical data from here and values are calculated using the 1887-1989 base period. This information is usually updated every weekday at 2:00pm (AEST), public holidays excluded.
|Date||Pressure at Tahiti (hPa)||Pressure at Darwin (hPa)||Daily value||30-day average SOI||90-day average SOI|
|ENSO Wrap Up (Source: here)|
Issued on 10 April 2018
El Niño–Southern Oscillation influence on the climate remains weak
The El Niño–Southern Oscillation (ENSO) remains neutral—neither El Niño nor La Niña. Most models predict a neutral ENSO pattern will persist through the southern autumn and winter.
Most atmospheric and oceanic indicators of ENSO are at neutral levels. Sea surface temperatures in the central Pacific are close to average for this time of year. Beneath the surface, the tropical Pacific Ocean is slightly warmer than average, but well within the neutral range. In the atmosphere, cloud and pressure patterns remain weakly La Niña-like, but trade winds are close to average.
Climate models indicate that tropical Pacific Ocean sea surface temperatures will continue to rise, but remain ENSO neutral for the remainder of the southern autumn and winter.
The Indian Ocean Dipole (IOD) is currently neutral. Most models indicate a neutral IOD is likely for autumn and early winter. However, two of six models indicate a negative IOD is possible during winter. During negative IOD events, southern Australia typically experiences a wetter than average winter-spring.
Climate model outlooks for ENSO and the IOD have lower accuracy during autumn than at other times of the year. Hence, current model outlooks of these climate drivers should be viewed with some caution.
The 30-day Southern Oscillation Index (SOI) to 8 April was +12.4, while the 90-day SOI remains within the neutral range at +6.5. The SOI tends to fluctuate during the southern hemisphere summer due to the movement of tropical weather systems. During the southern hemisphere monsoon season, the 90-day SOI is typically a better reflection of the overall climate state.
Sustained positive values of the SOI above +7 typically indicate La Niña while sustained negative values below −7 typically indicate El Niño. Values between +7 and −7 generally indicate neutral conditions.
The central Pacific Ocean has warmed in the past fortnight. Sea surface temperatures (SSTs) are now close to average along the equator.
The latest values for the week ending 8 April are: NINO3 −0.1 °C, NINO3.4 −0.3 ° and NINO4 0.0 °C. Persistent NINO3 or NINO3.4 values cooler than −0.8 °C are typically indicative of La Niña, while persistent values warmer than +0.8 °C are typical of El Niño.
Warmer than average SSTs persist across the south Pacific and the Tasman Sea with the ocean in this region more than 1 °C above average. The surface of the Tasman Sea has been persistently warmer than average since the second half of November 2017. This was a record-breaking event.
To the north of Australia, weak warm SST anomalies remain across the Maritime Continent.
All eight of the surveyed international climate models indicate equatorial Pacific sea surface temperatures are likely to continue rising over the coming months. A neutral ENSO state is the most likely outcome for the remainder of the southern hemisphere autumn and winter. The Bureau's model predicts the equatorial Pacific will continue to gradually warm throughout winter but remain within the neutral range.
Last Accessed: Sun Apr 22 2018 08:54:32 HKT
Last Modified: Sun Jul 10 2016