Sounds of La Nina.............???

by Dr. Rekha Nianthi

Sea surface temperatures play a major role in global weather patterns. El Nino and La Nina patterns often lead to weather extremes around the world. Sea Surface Temperatures (SST) indicates that there will be a La Nina condition this year...... La Nina is described as cooler than normal sea surface temperatures in the Central and Eastern Pacific Ocean, near the equator off the west coast of South America. El Nino is like La Nina’s brother, the totally opposite event occurs in the ocean.

This is described as warmer than normal Sea Surface Temperatures in the Pacific Ocean. The name La Nina originated from Spanish, meaning as “the girl”, analogous to El Nino meaning “the boy”. La Nina sometimes called as “anti-El Nino”. El Nino corresponds to a higher sea surface temperature by a deviation of at least 0.5 Centrigate. La Nina is often preceded by a strong El Nino. La Nina and El Nino events can affect Asia’s monsoons and rainfall patterns from Australia to Peru.

There was a strong La Nina episode during 1988-1989. La Nina also formed in 1995, and in 1999-2000. A minor La Nina occurred in 2000-2001.

The last La Nina was a moderate one, which developed in mid 2007 and lasted until early 2009.

In the 2009-2010 Wet Season’s strong El Nino, La Nina conditions have been rapidly developed in the equatorial Pacific Ocean. Most of the Climate Prediction Centers are forecasting,(in their forecast models),...............there will be a moderate to strong La Nina for the 2010-2011 wet season. Typically a La Nina lasts 9 to 12 months, while an El Nino will last roughly about a year.

El Nino Southern Oscillation (ENSO) is a water temperature cycle that occurs in the equatorial Pacific Ocean. This cycle, historically cycles every 3-5 years. When average Sea Surface Temperatures (SSTs) in this region reach 0.5 Centrigate above the historical average, El Nino conditions exist. When they reach 0.5 Centrigate below the historical average, La Nina conditions exist.

During a period of La Nina, the sea surface temperature across the equatorial Eastern Central Pacific Ocean will be lower than normal by 3-5 Centrigate.

Simply speaking, the main reason of this event is an easterly formation of trade winds. A trade wind blowing over the Equatorial Pacific Ocean is responsible for both phenomenons. For La Nina, the easterly trade winds strongly strengthen. This blows more warm water west, and allows cold water below the ocean’s surface to push towards the top near the South American coast to replace the warm water. In an El Nino, the opposite mechanism occurs. The easterly trade winds become weaker, and can even reverse their directions. The warm Pacific Ocean becomes nearly stationary or pushes eastward and gains more heat in this time.....affecting weather patterns of the respective regions.

More simply, once the atmosphere responds to the ocean SST patterns, an El Nino or La Nina begins to affect atmospheric circulations and make more complicated weather. Therefore day-to-day weather can be change within the short period of time and will make troubles to man and his environment.