2-9: Climate Variability (El Nino, La Nina)

Pre-Class Preparation

Objectives

• To explore natural perturbations to the global climate system.
• To understand the processes that link El Nino and La Nina events to global climate.

Procedure

1. Read the learning unit.

   Class images

2. Take the learning unit quiz. Quizzes are available from your portfolio. You may access your portfolio via the list of students participating in this years course, as represented by the icon below.
   
   
3. Additional Required Reading. Although you are not ultimately responsible for content listed in this section, we encourage you to fully explore the links in order to provide a better scope on the upcoming class discussion.

   	El Nino 3-D sketch
   	El Niño and global warming: What's the connection?
   	ENSO Teleconnections (Note: This link is currently being updated.)
   	Latest ENSO advisory
   	NOAA home page
   	NOAA/PMEL TOGA-TAO Home Page: TOGA-TAO Observing Array in the Tropical Pacific.
   	The 1990-1995 El Nino-Southern Oscillation event: Longest on record. Kevin E. Trenberth and Timothy J. Hoar, 1996. Geophysical Research Letters 23(1), 57-60.
   	The Record Setting 1990-95 El Nino: Harbinger of a Changing Climate? UCAR News Release, 5 January 1996.
   	What is an El Nino? (from NOAA)
   	Houghton, J.T., G.J. Jenkins, J.J. Ephraums, eds, 1990: 1990 Intergovernment Panel on Climate Change, Cambridge University Press, 223-233.

Class Discussion

• Problem to ponder...
  

• Class Discussion Summary: submitted by classmates Lea Bonebrake and Heather Freidhof

  Southern oscillation is a link between pressure and temperature as seen by the time series of Darwin and Tahiti. Ocean circulation in normal conditions is a slow east to west drift along the equator. In an El Nino year this drifting slows down and sometimes reverses to a west to east flow. Normally there is a maximum block of rainfall just east of Australia but in an El Nino year, the rain moves further east. The maximum is then located on the dateline. The implication of an El Nino is not to actually increase the amount of precipitation. El Nino´s effect is a tendancy to have stationary highs and lows in areas as opposed to the normal variability. When highs and lows are stationary, one area experiences the same weather for a longer period of time. Walker circulation changes direction during El Nino. El Nino varies in the length of its duration. It can last for a few months or many months. Its effects do not end when it ends either. Droughts can occur for up to a year after the El Nino has ended. When sea surface temps change abruptly from warm to cold causing a draught, such as the one that occurred in the midwest in 1987, this is called La Nina. This year´s El Nino showed a February average of 3 degrees above normal. Moored bouys in the ocean give us this data.

Post-Class Activities

• Participate in the electronic dialog. Use this forum for:
  • continuing class discussion;
  • posing new questions to students or the instructor;
  • responding to issues/questions raised by students in class/electronic dialog.

  Visitor Access (Visitors are welcome to participate in the dialog. Just click on the icon below)	Student Access (Students must post all dialog from their portfolio. Click on the icon below to access the student list.)

• Recommended Reading Materials

  	ENSO Homepage From Climate Diagnostics Center - NOAA.
  	Complementary Satellite Measurements Suggest El Nino is Brewing Again. (From Jet Propulsion Laboratory, NASA)
  	Complementary Satellite Measurements Suggest El Nino is Brewing Again. (From Jet Propulsion Laboratory, NASA)
  	Knutson, T. R., R. E. Tuleya, Y. Kurihara, 1998: Simulated increase of hurricane intensities in a CO2-warmed climate. Science 279, 1018-1020.
  	Leetmaa, Ants, 1990: The interplay of El Nino and La Nina. Oceanus 32, 30-34.

• References

  	AIRS - Atmospheric Infrared Sounder home page of the Jet Propulsion Laboratory
  	Animation of tropical cyclones
  	El Nino bibliography developed by Florida State University library
  	El Nino resource page
  	El Nino Southern Oscillation - ENSO - page from NOAA Office of Global Programs
  	El Nino Theme Page
  	El Nino/La Nina Websites
  	The ENSO SIGNAL
  	Environmental News Network Special Report on El Nino
  	Satellite Altimetry data from TOPEX/POSEIDON processed by the NOAA Laboratory for Satellite Altimetry traces the evolution and continuation of the 1997 El Nino event
  	Sea Surface Temperature from 1981 to Present
  	Southern Africa Climate Outlook Forum, with emphasis on the effects of El Nino.
  	The "Web of Life"
  	Allan, R., 1996: El Nino, Southern Oscillations and Climate Variability. CSIRO Publication.
  	Mayewski, P. A., M. S. Twickler, S. I. Whitlow, L. D. Meeker, Q. Yang, J. Thomas, K. Kruetz, P. M. Grootes, D. L. Morse, D. J. Steig, E. D. Waddington, E. S. Saltzman, P.-Y. Whung, and K. C. Taylor, 1996: Climate change during the last deglaciation in Antarctica. Science, 272.
  	McGowan, J. A., D. R. Cayan, and L. M. Dorman, 1998: Climate-ocean variability and ecosystem response in the northeast Pacific. Science 281, 210-217.