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Criteria ENSO phase


Criteria ENSO phase


 

 

El Niño

El Niño WATCH

All of the following criteria need to be satisfied:

  1. Current climate state: ENSO phase is currently neutral or declining La Niña.

2.       

    • Either:
      SOI analogues: Of the 10 years that most closely resemble the current SOI pattern, 4 or more have shown El Niño characteristics.
    • Or:
      Sub-surface: Significant sub-surface warming has been observed in the western or central equatorial Pacific Ocean.
  1. Models: One-third or more of surveyed climate models show warming to at least 0.8 °C above average in the NINO3 or NINO3.4 regions of the Pacific Ocean by late winter or spring.

The chance that an El Niño will occur (based on historical data) is at least 50%.

El Niño ALERT

Any three of the following criteria need to be satisfied:

  1. Sea surface temperature: A clear warming trend has been observed in the NINO3 or NINO3.4 regions of the Pacific Ocean during the past three to six months.
  2. Winds: Trade winds have been weaker than average in the western or central equatorial Pacific Ocean during any two of the last three months.
  3. SOI: The two-month average SOI is –7 or lower.
  4. Models: A majority of surveyed climate models show warming to at least 0.8 °C above average in the NINO3 or NINO3.4 regions of the Pacific Ocean by the late winter or spring.

The chance that an El Niño will occur (based on historical data) is at least 70%.

EL NIÑO

Any three of the following criteria need to be satisfied:

  1. Sea surface temperature: Temperatures in the NINO3 or NINO3.4 regions of the Pacific Ocean are 0.8 °C warmer than average.
  2. Winds: Trade winds have been weaker than average in the western or central equatorial Pacific Ocean during any three of the last four months.
  3. SOI: The three-month average SOI is –7 or lower.
  4. Models: A majority of surveyed climate models show warming to at least 0.8 °C above average in the NINO3 or NINO3.4 regions of the Pacific until the end of the year.

Valid until the El Niño is officially declared over by the Bureau of Meteorology.


La Niña

La Niña WATCH

All the following criteria need to be satisfied:

  1. Current climate state: ENSO phase is currently neutral or declining El Niño.

2.       

    • Either:
      SOI analogues: Of the 10 years that most closely resemble the current SOI pattern, 4 or more have shown La Niña characteristics.
    • Or:
      Sub-surface: Significant sub-surface cooling has been observed in the western or central equatorial Pacific Ocean.
  1. Models: One-third or more of surveyed climate models show cooling to at least 0.8 °C below average in the NINO3 or NINO3.4 regions of the Pacific Ocean by late winter or spring.

The chance that a La Niña will occur (based on historical data) is at least 50%.

La Niña ALERT

Any three of the following criteria need to be satisfied:

  1. Sea surface temperature: A clear cooling trend has been observed in the NINO3 or NINO3.4 regions of the Pacific Ocean during the past three to six months.
  2. Winds: Trade winds have been stronger than average in the western or central equatorial Pacific Ocean during any two of the last three months.
  3. SOI: The two-month average SOI is +7 or higher.
  4. Models: A majority of surveyed climate models show cooling to at least 0.8 °C below average in the NINO3 or NINO3.4 regions of the Pacific Ocean by the late winter or spring.

The chance that a La Niña will occur (based on historical data) is about 70%.

LA NIÑA

Any three of the following criteria need to be satisfied:

  1. Sea surface temperature: Temperatures in the NINO3 or NINO3.4 regions of the Pacific Ocean are 0.8 °C cooler than average.
  2. Winds: Trade winds have been stronger than average in the western or central equatorial Pacific Ocean during any three of the last four months.
  3. SOI: The three-month average SOI is +7 or higher.
  4. Models: A majority of surveyed climate models show cooling to at least 0.8 °C below average in the NINO3 or NINO3.4 regions of the Pacific Ocean until the end of the year.

Valid until the La Niña is officially declared over by the Bureau of Meteorology.

NEUTRAL

An ENSO event is not active in the tropical Pacific Ocean and there are no signs of an El Niño or La Niña developing.

 

 

 

The below table summarises the ENSO Tracker status by month from 1980 to present.

ENSO status legend

ENW El Niño WATCH
LNA El Niño ALERT
EN EL NIÑO
 
LNW La Niña WATCH
ENA La Niña ALERT
LN LA NIÑA
N NEUTRAL

El Niño and La Niña years

Shading of text in the year column refers to years in which El Niño (red) or La Niña (blue) events began.

  JanFebMarAprMayJunJulAugSepOctNovDec
1980 N N ENW ENW ENW ENW ENW N N N N N
1981 N N N N N N N N N N N N
1982 N N N N ENW ENA EN EN EN EN EN EN
1983 EN EN LNW LNW LNW LNW LNW LNW LNA LNA LN LN
1984 LN LNW LNW LNW LNW LN LN N N N N N
1985 N N LNA LNA N LN N N N N N N
1986 N N N N N N ENA ENA ENA ENA EN EN
1987 EN EN EN EN EN EN EN EN EN EN EN EN
1988 EN EN LNW LNA LNA LN LN LN LN LN LN LN
1989 LN LN LN ENW ENW N N N N N N N
1990 ENW ENW ENA ENA N N N N N N N N
1991 N N ENW N ENA EN EN EN EN EN EN EN
1992 EN EN EN EN EN EN N N N N N N
1993 N N ENA ENA EN EN N N N N N N
1994 N N N N ENW ENA N ENA N EN EN EN
1995 EN EN N LNW LNW LNW N LNA LN LN LN LN
1996 N N ENW ENW ENW ENW N N N N N N
1997 ENW ENW ENW ENW ENA EN EN EN EN EN EN EN
1998 EN EN LNW LNW LNW LNA LNA LN LN LN LN LN
1999 LN LN LN LN LN LN LN LN LN LN LN LN
2000 LN LN ENW ENW ENW ENW N N N LNA LNA LNA
2001 LN N ENW ENW ENW N ENW N N N N N
2002 N N ENW ENA ENA ENA EN EN EN EN EN EN
2003 EN N N N LNW LNW N N N N N N
2004 N N N N N N ENW ENA ENA ENA ENA ENA
2005 N N N ENW N N N N N N N N
2006 N N N N N N ENW ENA EN EN EN EN
2007 EN N LNW LNW LNA LNA LNA LN LN LN LN LN
2008 LN LN LNA LNA N N N N N N LNA LN
2009 LN LN ENW ENW ENW ENW ENW ENA ENA ENA EN EN
2010 EN EN EN LNW LNA LNA LN LN LN LN LN LN
2011 LN LN LN N N N N N LNA LN LN LN
2012 LN LN N N ENW ENW N N N N N N
2013 N N N N N N N N N N N N
2014 N ENW ENW ENA ENA ENA ENA ENW ENW ENW ENA ENA
2015 ENA N ENW ENA na na na na na na na na

Historical values of the ENSO Tracker status prior to 2014 are based on the set criteria alone. Values from the beginning of 2014 include expert analysis by climatologists at the Bureau of Meteorology to make the final assessment on a status level having been reached.

نویسنده : | در : چهارشنبه 16 ارديبهشت 1394 ساعت: | دیدگاه: ()
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