Whither ENSO? Assessing El Ni ñ o/Southern Oscillation risks for the coming decades
El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns
-
Upload
erasmus-decker -
Category
Documents
-
view
26 -
download
3
description
Transcript of El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns
![Page 1: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/1.jpg)
Evans Maru Magdalene WanjikuNoah AdamPurity Mueni Adrajow Admasu
![Page 2: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/2.jpg)
What Is El Niño?El Niño is a term that refers to anomalously
warmer than average Sea Surface Temperatures
(SSTs) in the eastern and central equatorial Pacific
Ocean. It is normally characterized by warming of
the subsurface layers and large scale weakening of
the trade winds in the region.
These changes have important consequences over
weather/climate around the globe, including East
Africa.
![Page 3: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/3.jpg)
La Nina
Scientists refer to the event when
exceptionally cool water lies off the coast
of South America as La Nina Strong La
Nina events have been responsible for the
opposite effects on climate as El Nino.
![Page 4: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/4.jpg)
Strongest El Niño's
4
Very strong El Nino events occurred in 1965-
1966, 1982-1983, and 1997-1998. They caused
significant flooding and damage from California to
Mexico to Chile. Effects of El Nino are felt as far
away from the Pacific Ocean as Eastern Africa
including Kenya.
NB: An El Nino year correspond to the first three
months of the ENSO year namely October,
November, and December. For example, the
ENSO year 1970 starts October 1970 and ends
September 1971.
![Page 5: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/5.jpg)
5
The El Nino of 1997
![Page 6: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/6.jpg)
Strongest La Ninas
6
Strong La Nina events occurred in 1955-56,
1964-65, 1973-74, 1988-89 and 1998-2000.
They were associated with drought over most
parts of Eastern Africa including Kenya.
NB: An La Nina year correspond to the first
three months of the ENSO year namely
October, November, and December. For
example, the La Nina year of 1988 started in
October 1988 and ended in September 1989.
![Page 7: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/7.jpg)
The La Nina of 1988
7
![Page 8: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/8.jpg)
Classification El Ninos & La Ninas
8
El Ninos & La Ninas are classified as either
Weak, Moderate or Strong depending on the
extent of warming/cooling in the Nino areas.
![Page 9: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/9.jpg)
Sub-Surface Temperature Departures in the Equatorial Pacific
![Page 10: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/10.jpg)
Since mid September, positive subsurface
temperature anomalies have stretched across
most of the equatorial Pacific.
Recently, positive subsurface anomalies in the
central Pacific are expanding eastward. Negative
anomalies in the eastern Pacific are
strengthening at depth.
![Page 11: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/11.jpg)
Recent Evolution of Equatorial Pacific SST Departures (oC)
![Page 12: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/12.jpg)
Average SST Departures (oC) in the
Tropical Pacific During the Last Four Weeks
![Page 13: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/13.jpg)
Weekly SST Departures during the Last Four WeeksDuring the last four weeks, positive SST
anomalies persisted along the equatorial
Pacific and strengthened in the eastern
Pacific.
From 15 October to 05 November 2014,
equatorial SSTs were above average across
most of the Pacific.
![Page 14: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/14.jpg)
ONI (ºC): Evolution since 1950
The most recent ONI value (August – October 2014)
is 0.2oC.
![Page 15: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/15.jpg)
CPC/IRI Probabilistic ENSO Outlook Updated: 6 November 2014
The chance of El Niño is 58% during the Northern Hemisphere winter and decreases into Spring/summer 2015.
![Page 16: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/16.jpg)
IRI/CPC Pacific Niño 3.4 SST Model Outlook Most models favor El Niño (greater than or equal to +0.5ºC) to develop during October-December 2014 and persist through Northern Hemisphere spring 2015.
Figure provided by the International Research Institute (IRI) for Climate and Society (updated 16 October 2014).
![Page 17: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/17.jpg)
Summary
ENSO Alert System Status: El Niño Watch
ENSO-neutral conditions continue.*
Positive equatorial sea surface temperature
(SST) anomalies continue across most of the
Pacific Ocean.
There is a 58% chance of El Niño during the
Northern Hemisphere winter, which is favored to
last into the Northern Hemisphere spring 2015.*
![Page 18: El Ni ñ o/La Ni ñ a & The Influence Rainfall Patterns](https://reader035.fdocuments.in/reader035/viewer/2022062407/56812cdb550346895d919dfe/html5/thumbnails/18.jpg)
Merci et a
u
revoir