El Niño- An irregularly occurring and complex series of climatic changes affecting the equatorial Pacific region and beyond every few years, characterized by the appearance of unusually warm, nutrient-poor water off northern Peru and Ecuador, typically in late December.
La Niña- the positive phase of the El Niño Southern Oscillation and is associated with cooler than average sea surface temperatures in the central and eastern tropical Pacific Ocean.
The El Niño-Southern Oscillation (ENSO) is a naturally occurring phenomenon that involves fluctuating ocean temperatures in the equatorial Pacific. ... When temperatures in the ENSO region of the Pacific are near average it is known as ENSO neutral, meaning that the oscillation is neither in a warm nor cool phase.
The exact cause of the weakened trade winds is unknown; however, scientists have noticed an oscillation of water surface temperatures in the Pacific ocean, referred to as the El Niño Southern Oscillation. ... Normally, the warmer waters of the Pacific Warm Pool are pushed westward by the trade winds.
La Niña is caused by a build-up of cooler-than-normal waters in the tropical Pacific, the area of the Pacific Ocean between the Tropic of Cancer and the Tropic of Capricorn. Unusually strong, eastward-moving trade winds and ocean currents bring this cold water to the surface, a process known as upwelling.
Although the exact initiating causes of an ENSO warm or cool event are not fully understood, the two components of ENSO – sea surface temperature and atmospheric pressure are strongly related. During an El Niño event, the easterly trade winds converging across the equatorial Pacific weaken.
During El Niño, the jet stream is oriented from west to east across the southern portion of the United States, making the region more susceptible to severe weather outbreaks. Some benefits of El Niño: Fewer hurricanes and other tropical cyclones in the north Atlantic. Milder winters in southern Canada and the northern continental United States. Replenishment of water supplies in the southwestern U.S.
La Niña causes mostly the opposite effects of El Niño, above-average precipitation across the northern Midwest, the northern Rockies, Northern California, and the Pacific Northwest's southern and eastern regions. Meanwhile, precipitation in the southwestern and southeastern states is below average.
Esno- Fewer hurricanes and other tropical cyclones in the north Atlantic. Milder winters in southern Canada and the northern continental United States. Replenishment of water supplies in the southwestern U.S. Less disease in some areas due to drier weather (like malaria in southeastern Africa.)
There are several means used for El Niño detection; satellites, moored ATLAS and PROTEUS buoys, drifting buoys, sea level analysis, and XBT's
Through February 25th, the 2011-2012 winter season was warmer and wetter than normal but had below normal snowfall at both Fort Wayne and South Bend as a weak to moderate La Nina episode was occuring.