SIO 210 Talley Lecture 8: Variability: Monsoons, El Nino, Decadal variability

Lynne Talley, 2000
Back to lecture notes

Reading and study questions

Reading (on reserve):


Tomczak and Godfrey, ch. 11: 193-208
or Pickard and Emery, ch. 7.71
or Open University Press, 5.2

El Nino:

Wallace, J. M. and S. Vogel, 1994. Reports to the Nation on Our Changing Planet: El Nino and climate prediction. UCAR Office for Interdisciplinary Earth Studies, Boulder, CO.

Tomczak and Godfrey, ch. 19

or Pickard and Emery, 256-263

Decadal variability:

No good text references

Study questions

1. What are important timescales for ocean variability and what sets the timescales?

2. What is thermally direct circulation? What is the role of rotation in such a circulation? Is the surface pressure (atmospheric) high or low over the region of warmer temperature?

3. What causes upwelling in the Arabian Sea and during which monsoon does it occur?

4. During which part of the monsoon cycle is the tropical Indian Ocean circulation most like that of the Pacific and Atlantic?

5. What happens to surface currents along the equator during the transition between monsoons?

6. About how often do El Ninos occur and what sets this timescale?

7. What happens to the trades along the equator at the beginning of an El Nino? What is this usually in response to?

8. What happens to precipitation patterns during an El Nino?

9. What is the Southern Oscillation Index? At which phase of the El Nino/La Nina is the pressure at Tahiti high?

10. Why is biological productivity along Peru decreased during an El Nino?

11. What is the major decadal mode of variability for the Pacific? for the North Atlantic? tropical Atlantic? What are their spatial patterns? Describe changes in surface pressure, sea surface temperature that accompany the modes of variability.

Further reading and sources for viewgraphs

Indian monsoon

Knox, R.A. and D.L.T. Anderson, 1985. Recent advances in the study of the low-latitude ocean circulation. Prog. Oceanogr., 14, 259-317.

Philander, ch. 1.1 to 1.5

Wyrtki, K., 1973. An equatorial jet in the Indian Ocean. Science, 191, 262-264.

U.S. JGOFS Arabian Sea Process Study, 1991. U.S. JGOFS planning report, 13, November, 1991.

El Nino

Rasmussen, E.M. and T.H. Carpenter, 1982. Variations in tropical sea surface temperature and surface wind fields associated with the Southern Oscillation/El Nino. Monthly Weather Rev., 110, 354-384.

Philander, S.G., 1990. El Nino, La Nina and the Southern Oscillation. Academic Press. Look at the Introduction and Chapter 1.1, 1.2, 1.4, 1.5, and 1.7

Intergovernmental Oceanographic Commission technical series, 40: Oceanic interdecadal climate variability (strong emphasis on Pacific)

Atlantic variability

Cayan, D. R., 1992. Latent and sensible heat flux anomalies over the northern oceans: driving the sea surface temperature. J. Phys. Oceanogr., 22, 859-881.

Deser, C. and M.L. Blackmon, 1993. Surface climate variations over the North Atlantic Ocean during Winter: 1900-1989. J. Climate, 6, 1743-1753.

Dickson, R.R., J. Meincke, S.A. Malmberg, and A.J. Lee, 1988. The "great salinity anomaly" in the northern North Atlantic 1968-19482. Prog. Oceanogr., 20, 103-151.

Hurrell, J.W., 1995. Decadal trends in the North Atlantic Oscillation: regional temperatures and precipitation. Science, 269, 676-679.

Kushnir, Y., 1994. Interdecadal variations in North Atlantic sea surface temperature and associated atmospheric conditions. J. Clim., 7, 141-157.

Lazier, J. R. N., 1988. Temperature and salinity changes in the deep Labrador Sea 1962-1986. Deep Sea Res., 35, 1247-1253.

Nitta, T. and S. Yamada, 1989. Recent warming of tropical sea surface temperature and its relationship to the northern hemisphere circulation. J. Meteorol. Soc. Japan, 67, 375-383.

Roemmich, D. and C. Wunsch, 19484. Apparent changes in the climatic state of the deep North Atlantic Ocean. Nature, 307, 447-450.

Swift, J.H., 1984. A recent theta-S shift in the deep water of the northern North Atlantic. Climate Processes and climate Sensitivity, Geophys. Monogr. 29, Maurice Ewing Vol. 5. A.G.U.

Talley, L.D. and M.S. McCartney, 1982. Distribution and circulation of Labrador Sea Water., J. Phys. Oceanogr., 12, 1189-1205.

Pacific variability

Davis, R.E., 1976. Predictability of sea surface temperature and sea level pressure anomalies over the North Pacific Ocean. J. Phys. Oceanogr., 6, 249-266.

Ebbesmeyer, C., D. Cayan, D. McClain, W. D. Nichols, D. H. Peterson and K. Redmond, 1991. Sensitivity of marine biology to climate change in a North Pacific swath. Proceedings of the seventh annual Pacific Climate (PACLIM) workshop, Asilomar, California, April 10-13, 1990.

Hanawa, K., Y. Yoshikawa, and T. Watanabe, 1989. Composite analyses of wintertime wind stress vector fields with respect to SST anomalies in the western North Pacific and the ENSO events. Part I: SST composite. J. Met. Soc. Japan, 67, 385-400.

Latif, M. and T.P. Barnett, 1994. Causes of decadal climate variability over the North Pacific and North America. Science, 266, 634- 637.

Trenberth, K.E., 1990. Recent observed interdecadal climate changes in the northern hemisphere. Bull. Am. Met. Soc., 71, 988-993.

Trenberth, K.E. and J. W. Hurrell, 1994. Decadal atmosphere-ocean variations in the Pacific. Clim. Dyn., 9, 303-319.

Zhang, Y., J. M. Wallace and D. S. Battisti (1996) ENSO-like interdecadal variability: 1900-93. J. Climate, in press.

Southern hemisphere:

IPCC report

White, W. B. and R. Peterson, 1996. An Antarctic Circumpolar Wave in surface pressure, wind, temperature and sea ice extent. Nature, 380, 699-702.