var note01 = "The ENSO cycle is an irregular oscillation of the climate system with a period of roughly 3 to 4 years. It consists of a warm phase, El Niño, and a cold phase, La Niña.";
var note06 = "At some locations along the Peru coast, surface temperature anomalies peaked at 8° to 9°C above normal between December 1997 and March 1998 (Climate Analysis Center, U.S. Dept. of Commerce, Climate Diagnostics Bulletin, May 1998, Washington, DC).";
var note10 = "Advection of the eastern edge of the warm pool is an important feature of previous El Niño events [M. J. McPhaden and J. Picaut, Science 250, 1385 (1990); J. Picaut and T. Delcroix, J. Geophys. Res. 100, 18393 (1995); J. Picaut, M. Ioualalen, C. Menkes, T. Delcroix, M. J. McPhaden, Science 274, 1486 (1996)]. Details of how high-frequency wind forcing can rectify into low-frequency eastward expansion of the warm pool were described in W. S. Kessler, M. J. McPhaden, K. M. Weickmann, [J. Geophys. Res. 100, 10613 (1995)].";
var note15 = "This aspect of delayed oscillator theory was anticipated by K. Wyrtki [J. Phys. Oceanogr. 5, 572 (1975)].";
var note21 = "B. Wang and X. Xie [J. Clim. 11, 2116 (1998)] have shown theoretically how the MJO can amplify over warm surface water through ocean-atmosphere interactions. L. Yu and M. M. Reinecker [Geophys. Res. Lett. 25, 3537 (1998)] also present evidence that cold air outbreaks from East Asia and the western North Pacific contributed to the intensification of the MJO at the beginning of the 1997-98 El Niño.";
var note22 = "M. J. McPhaden and X. Yu [Proceedings of the Second Hayes Symposium on Seasonal-to-Interannual Climate Variability-1997/1998 ENSO Cycle, Dallas, TX, 10 to 15 January 1999 (American Meteorological Society, Boston, MA, 1999), pp. 38-42] use a wind-forced model to compare boundary versus wind-forced Kelvin wave amplitudes during the onset and termination phase of the 1997-98 El Niño. During the onset phase, directly wind-forced downwelling Kelvin waves were about 10 times larger than those generated at the western boundary by reflecting Rossby waves. During the termination phase, boundary versus wind-forced upwelling Kelvin waves were of similar amplitudes. ";
var note25 = "J. Picaut, F. Masia, Y. du Penhoat [Science 277, 663 (1997)] have suggested that zonal advection associated with eastern boundary-generated Rossby waves may be important in producing ENSO SST anomalies. These Rossby waves result from the reflection of incoming equatorial Kelvin waves along the coast of South America. For the 1997-98 event, eastern boundary reflections appear to be of secondary importance during the onset phase, given the strength of direct wind forcing along the equator. Similarly, termination of the El Niño was related more to the sudden trade wind-driven upwelling of cold water from below the surface rather than wave-related zonal advection of cool water from the east. Zonal advection due to boundary-generated Rossby waves would have brought warmer rather than colder water from the east in early 1998, because the normal east-west SST gradient along the equator was reversed at that time. Once the surface cooling was underway, however, wave-related zonal advection from eastern boundary reflections may have contributed to the westward spreading of cold SST anomalies evident in Fig. 2.";
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