Word: nino
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...result, the El Nino of 1997-98 will be the most closely observed in history. In the tropical Pacific, ships, satellites and stationary buoys are gathering mountains of continuous data--on sea-surface temperatures, wind speeds and directions, and ocean currents--that scientists at universities and government laboratories are feeding into powerful computers in hopes of creating a model of the climate system that evolves...
Scientists note that something funny seems to be going on. Until recently, El Ninos came more or less periodically every two to seven years. But in the early 1990s several El Ninos appeared in a row, one right after another. Now, after dying down in 1995 and '96, El Nino is back. What is going on? scientists wonder. Are frequent El Ninos a signal of global warming caused by human tampering with the atmosphere? Or do they arise from random fluctuations in the natural cycle? There are as yet no good answers to these questions. Observes Michael Glantz...
...terms of the climate machine, El Nino is more than just a sudden warm current off Peru. It refers to a rise in sea-surface temperatures over much of the equatorial Pacific as well as a change in winds and ocean currents. Indeed, there is a kind of climatic flip-flop, with a reversal of conditions across a wide stretch of ocean. Consequently, climate experts no longer refer to El Nino alone but speak of the El Nino Southern Oscillation. Rather like a pendulum, the ENSO cycle swings between an El Nino state and its opposite, a cold-water state...
...feet lower off Peru than it is off Indonesia. The difference, although seemingly small, has important consequences: to replace the water that the winds have swept away, cold, nutrient-rich water from the depths wells up, and so Peru's waters are loaded with fish. But when an El Nino gets started, the pattern shifts. The trade winds dwindle, and may even start blowing from the west. The upwelling off Peru stops, and anchovies and other fish move to different feeding grounds...
Coastal Peru is hardly the only area affected. El Nino alters winds and currents throughout the tropics, producing what climatologist Nicholas Graham of the Scripps Institution of Oceanography calls "a weird kind of sloshing." As the trade winds slacken, he explains, they give rise to slow-moving waves that surge from west to east and exert downward pressure on the thermocline. This is the boundary layer of chilly water that separates the much colder water in the ocean depths from the sun-warmed water near the surface. Normally, the eastern Pacific's thermocline lies at a shallow depth and thus...