ENSO and its relation to the Kelvin and Rossby Wave

Eric Sinsky

Outline

• Basic El Nino and La Nina dynamics• The basic principles of the Kelvin Wave• The basic principles of the Rossby Wave• The Kelvin wave’s role in ENSO• The Rossby wave’s role in ENSO• An ENSO theory involving Rossby and Kelvin

waves

El Nino

La Nina

How ENSO is quantified

• ENSO is measured in SOI• Positive values signify La Nina and negative El Nino

1997-1998 El Nino

Thermocline Depth

Kelvin Wave• Shallow water wave (• Small amplitude (5-10cm)• Very long wavelength and period• Non-dispersive • C ,

Rossby Wave• Deep water wave

(• Large amplitude

at thermocline (~25m)

• Very long wavelength (500km)

• Dispersive

Kelvin Wave in ENSO

Rossby Waves in Enso

Comparing Rossby and Kelvin Waves

The Delayed Oscillator

Delayed oscillator applied to 97-98 El Nino

References• Chelton, D. B., and M. G. Schlax, 1996: Global observations of

oceanic Rossby waves. Science, vol. 272, pp. 234-238.• Knauss, John. Introduction of Physical Oceanography. Long Grove:

Waveland Press, 1997.• Stewart, Robert. Introduction to Physical Oceanography. Texas

A&M University, 2005. • Cipollini, Paolo. Rossby Waves: what are they? University of

Southamton, 2000.• Anonymous. A Curious Pacific Wave. National Aeronautics and

Space Administration Science, 2002. • Dijkstra, Henk. Nonlinear Physical Oceanography. New York:

Springer-Verlag, 2005. • Laing, Arlene, and Evans, Jenni-Louise. Introduction to Tropical

Meteorology. COMET® Program, 2011. •  Harrison, D. E. and G. A. Vecchi (2001), El Niño and La Niña—equatorial

Pacific thermocline depth and sea surface temperature anomalies, 1986–98, Geophys. Res. Lett., 28(6), 1051–1054, doi:10.1029/1999GL011307.