George Philander

Knox Taylor Professor of Geosciences,

  Director of AOS Program

Ph.D. Harvard University

 Department of Geosciences 
M47 Guyot Hall
Princeton University,
Princeton, NJ 08544
Phone: (609) 258-5683
E-Mail:gphlder@princeton.edu

Research: Ocean-Atmospheric Interactions; Climate Fluctuations including El Niño and La Niña;  Paleoclimates

The sea surface temperature patterns in the lower panel of this figure have curious features: although the intensity of sunlight is independent of longitude, the surface waters are far colder in the eastern than western equatorial Pacific; although the intensity of sunlight is symmetrical about the equator, where it has a maximum, the warmest waters are confined to a band north of the equator.  Such intriguing patterns are possible because the tropical thermocline, which separates warm surface waters from cold water at depth, is so shallow that a change in its slope, because of  changes in the winds, alters sea surface temperature patterns, which in turn affect the winds. This circular argument -  the winds are both the cause and consequence of surface temperature changes - implies unstable ocean-atmosphere interactions. Those interactions profoundly affect climate as is evident from the remarkably high correlation between the patterns of surface temperature and rainfall in the top panel of the figure. Our research concerns  the phenomena associated with ocean-atmosphere interactions and range from  El Niño and La Niña  to the Ice Age cycles over the past 3 million years. .

The modulation of El Niño, on timescales of decades and longer, is of interest in connection with the possible consequences of global warming. Whereas the interannual  warming of the surface waters of the eastern equatorial Pacific corresponds to the essentially adiabatic redistribution of the warm surface water,  variability on timescales of decades and more involve diabatic processes; it involves variations in the volume of warm water  and hence in the spatially averaged depth of the thermocline.  Under certain conditions the thermocline becomes so deep that El Niño becomes a permanent rather than intermittent phenomena.  We are developing models to explore such possibilities, but how will we check the results? Some of the very different climates the Earth has experienced during its long history probably involved changes in the thermal structure of the ocean. For example, there is evidence that, up to 3 million years ago when the cycle of Ice Ages started, El Niño was a permanent phenomenon. Is it possible that global warming will restore such conditions? Can El Niño be implicated in the recurrent ice Ages? These are some of the questions we are addressing.

Teaching:  A few decades ago El Niño was a curiosity known to few, welcomed as a joyful event along the shores of Ecuador and northern Peru. (The name refers to the Child Jesus.) Today the same phenomenon is widely known and is perceived as a global climate hazard that affects the lives of millions of people adversely. The story of this remarkable change in our perceptions of El Niño tells us much about interactions between the worlds of science and of human affairs, and makes the phenomenon a wonderful vehicle for bridging the divide between scientists and nonscientists.

Classes

GEO 220 - Weather and Climate
GEO 425 / MAE 425 Introduction to Physical Oceanography
AOS 573 / GEO 573 - Physical Oceanography

Some Recent Publications:

Philander S.G. Our Affair with El Niño (How we Transformed an Enchanting Peruvian Current into a Global Climate Hazard) Princeton University Press  2004.  1 prologue. PDF

Boccaletti G., R. Pacanowski, S.G. Philander and A. Fedorov:   The Thermal Structure of the Ocean  J. Phys. Oceanogr. 34, 888-902, 2004  steady.pdf

Philander, S. G., and A. V. Fedorov, Role of tropics in changing the response to Milankovich forcing some three  million   years ago, Paleoceanography, 18(2), 1045, doi:10.1029/2002PA000837, 2003. ice_ages_final_2003.pdf

Philander S.G. and A.V  Fedorov,  Is El Niño Sporadic or Cyclic? Annual Reviews of Earth and Planetary Sciences  31, 579-594, 2003. El Nino Ann Rev.pdf

Fedorov A.V., S.L. Harper, S.G. Philander, B. Winter and A. Wittenberg:  How    Predictable is El Niño?  Bull. Amer. Met. Soc. 84, 911-919, 2003. bams_predict200.pdf

Fedorov A. and S. G. Philander:  A stability analysis of tropical ocean-atmosphere interactions. J. Climate 14, 3086-3101,   2001.

Fedorov A. and S. G. Philander: Is El Niño changing? Science 288, 1997-2001, 2000.