El Nino Essay -- essays research papers

El Nino     Typically, the level of ocean body of piddle around the world is higher in thewestern peaceful and lower in the eastern, near the Western coast of South andNorth America. This is due primarily to the presence of easterly winds in the peaceful, which drag the surface water westward and raise the thermoclinerelatively all the way up to the surface in the east and dampen it in the west.During El Nino conditions, however, the easterlies move east, reducing the keep interaction between wind and sea, allowing the thermocline to becomenearly flat and to plunge several feet below the surface of the water, allowingthe water to grow warm and expand. With the help of the subject area Oceanic andAtmospheric Administrations weather satellites, tracking shifting patterns ofsea-surface temperatures can be made easier. Normally, a "pool" of warm water inthe western Pacific waters exists. Under El Nino conditions, this "pool" driftssoutheast towar ds the coast of South America. This is because, in a normal year,there is upwelling on the western South American coastline, and cold waters ofthe Pacific rise and push westward. However, during an El Nino year, upwellingis suppressed and as a result, the thermocline is lower than normal. Finally,thermocline rises in the west, making upwelling easier and water colder. Air squeezes at sea level in the South Pacific seesaw back and forth between twodistinct patterns. In the high index phase, also called "Southern Oscillation",pressure is higher near and to the east of Tahiti than farther to the west nearDarwin. The east-west pressure difference along the equator causes the surfaceair to tend westward. When the atmosphere switches into the low index phase,barometers rise in the west and fall in the east, signaling a reduction, or evena reversal the pressure difference between Darwin and Tahiti. The flattening ofthe seesaw causes the easterly surface winds to weaken and retrea t eastward.The "low index" phase is usually accompanied by El Nino conditions.     The easterly winds along the equator and the southeasternly winds thatblow along the Peru and Ecuador coasts both tend to drag the surface water alongwith them. The Earths rotation then deflects the resulting surface currentstoward the right (northward) in the... ...rface water. In thepresence of sunlight, phytoplankton can produce chlorophyll, a tiny green plantsubstance. In turn, this substance feeds zooplankton, which in turn feeds highermembers of the food chain. During El Nino conditions, the water level rises inthe east and lowers in the west, forcing many changes to happen among the plantand animal life. Sea birds in the east must leave their nests, abandoning theiryoung and curious for food which is not there, because the critical upwellingwhich causes the plankton and other lower members of the food chain to beproduced is not there. Water temperature is above no rmal, and tropical fish aredisplaced poleward or migrate, along with the anchovy and sardines. On land,the effects produced a great amount of rainfall, making the desert lands into agrassland with lush vegetation and abundant life. Grasshoppers come, fuelingtoad and bird populations, and the increase in rainfall produces lakes whichfish come to inhabit, fish that had migrated upstream during floods produced bythe rain and become somehow trapped. In some flooded coastal cities, shrimpproduction set records. So too did the number of mosquito-borne malaria cases.