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News research using network analysis techniques suggests a three-in-four chance that an El Nino Pacific Ocean warming event will take place later this year.
The research, published this week in the scientific journal proceedings of the National Academy of Sciences (PNAS), was completed in September 2013 and claims to have developed a mechanism for predicting El Ninos around a year out compared with more conventional forecasting techniques which achieve a six-month warning.
This comes as the Australian Bureau of Meteorology published its latest update of the so called El Nino Southern Oscillation (ENSO) – the long term alternation of the pacific between El Nino warming events, La Nina cooling events and so called neutral states, where the Pacific is neither warming nor cooling. The BOM says: “Most international climate models surveyed by the Bureau suggest the tropical Pacific Ocean will warm through the austral autumn and winter. Some, but not all, models indicate central Pacific Ocean temperatures may approach El Niño levels by early winter.”
The authors of the paper discuss the impact of an El Nino in 2014 on the so called global warming pause – or hiatus (the recent levelling off in the long term rise in surface temperatures). Full abstract and citation below.
Here is the text of the BOM report:
Issued on Tuesday 11 February 2014
The El Niño–Southern Oscillation (ENSO) state is neutral, with climate models suggesting neutral conditions will persist at least until the end of the austral autumn. However, some warming of the Pacific is likely in the coming months.
Most international climate models surveyed by the Bureau suggest the tropical Pacific Ocean will warm through the austral autumn and winter. Some, but not all, models indicate central Pacific Ocean temperatures may approach El Niño levels by early winter. Model outlooks that span autumn tend to have lower skill than outlooks made at other times of the year, hence long-range outlooks should be used cautiously at this point. Neither neutral nor El Niño states can be discounted for the second half of 2014.
In the last fortnight, a westerly wind event over the far western tropical Pacific led to some warming beneath the surface of the tropical Pacific Ocean, though surface temperatures remain close to average. The current high values of the SOI are expected to reduce as recent volatile weather near Darwin and Tahiti eases.
The Indian Ocean Dipole is typically too weak to have a significant influence on the Australian climate from December to April.
The sea surface temperature (SST) anomaly map for January shows SSTs are near average along most of the equatorial Pacific. Weak cool anomalies remain in the far eastern Pacific south of the equator between around 10°S and 30°S, while weak warm anomalies persist west of the Date Line between the Maritime Continent and the South Pacific Convergence Zone (SPCZ).
SST anomalies across the tropical Pacific remained largely unchanged over the past fortnight. The anomaly map for the week ending 9 February shows weak cool temperature anomalies along the equator east of 150°W, with weak warm anomalies west of the Date Line and north of the Maritime Continent. Warm anomalies also continue around the SPCZ, as do weak cool anomalies in the eastern Pacific between around 10°S and 30°S.
During January, much of southern Australia experienced extreme heat, which contributed to warming of much of the surface waters to the south of Australia.
The four-month sequence of sub-surface temperature anomalies (to January) shows waters are cooler than average in the sub-surface of the equatorial Pacific east of the Date Line; a pattern which has strengthened over the past two months. Water in an area of the eastern equatorial Pacific Ocean sub-surface between 140°W and 120°W at around 120 m depth is more than 4 °C cooler than average. Warm anomalies are present throughout most of the water column west of the Date Line and have increased in magnitude recently.
The sub-surface map for the 5 days ending 9 February shows temperatures in the sub-surface of the western equatorial Pacific are more than 3 °C warmer than average between around 100 and 250 m depth, while a small area of weak cool anomalies exist around 110°W and 80 m depth in the eastern equatorial Pacific. Warming of the western equatorial Pacific sub-surface has continued over the past month, as expected following strong westerly wind anomalies over the western tropical Pacific in recent weeks.
The Southern Oscillation Index (SOI) has dropped slightly after continuing to rise over the past two weeks, though this is thought to be largely due to short term local weather variations rather than larger scale climate shifts. It is expected to decrease over the next fortnight, as large daily values drop out of the 30-day average. The latest approximate 30-day SOI value to 9 February is +13.0.
Sustained positive values of the SOI above +8 may indicate a La Niña event, while sustained negative values below −8 may indicate an El Niño event. Values of between about +8 and −8 generally indicate neutral conditions.
Trade winds have returned to near-average strength across the far western tropical Pacific and are now near-average along the entire equator (see anomaly map for the 5 days ending 9 February).
During La Niña events, there is a sustained strengthening of the trade winds across much of the tropical Pacific, while during El Niño events there is a sustained weakening of the trade winds.
Cloudiness near the Date Line has generally been slightly below average since early January and remained so over the past two weeks.
Cloudiness along the equator, near the Date Line, is an important indicator of ENSO conditions, as it typically increases (negative OLR anomalies) near and to the east of the Date Line during an El Niño event and decreases (positive OLR anomalies) during a La Niña event.
Six of the seven international climate models surveyed by the Bureau indicate that SSTs in the equatorial Pacific Ocean are likely to slowly warm, although remaining ENSO-neutral until at least the end of autumn. Some models suggest this warming may approach El Niño thresholds during winter.
The predictability of El Niño or La Niña conditions for the period extending through and beyond autumn is less strong than for forecasts at other times of the year (known as “the autumn predictability barrier”), hence long-range model outlooks should be used cautiously at this time.
The Indian Ocean Dipole (IOD) remains neutral, with the latest weekly index value (9 February) −0.1 °C.
Climate models surveyed in the model outlooks favour neutral IOD values over the coming months. The IOD is typically not an active influence on Australian climate during summer and early autumn. During this time of year, establishment of negative or positive IOD patterns is largely inhibited by the development and position of the monsoon trough in the southern hemisphere.
Here is the abstract and citation for the PNAS paper:
The most important driver of climate variability is the El Niño Southern Oscillation, which can trigger disasters in various parts of the globe. Despite its importance, conventional forecasting is still limited to 6 months ahead. Recently, we developed an approach based on network analysis, which allows projection of an El Niño event about 1 year ahead. Here we show that our method correctly predicted the absence of El Niño events in 2012 and 2013 and now announce that our approach indicated (in September 2013 already) the return of El Niño in late 2014 with a 3-in-4 likelihood. We also discuss the relevance of the next El Niño to the question of global warming and the present hiatus in the global mean surface temperature.
Very early warning of next El Niño by Josef Ludescher, Avi Gozolchiani, Mikhail I. Bogachev, Armin Bunde, Shlomo Havlin,and Hans Joachim Schellnhuber published in PNAS 2014 111 (6) 2064-2066; published ahead of print February 11, 2014,doi:10.1073/pnas.1323058111
Read abstract and get the paper here.
BOM ENSO Wrap Up here.
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