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How To Catch El-Nino

April 02, 2002

The scientists from Obninsk Institute of Experimental Meteorology know how to predict the coming of El-Nino - a phenomenon, which causes the ocean surface in Equatorial and South-East parts of the Pacific Ocean to heat too fast. The temperature rises on 3-4 degrees in 24 hours, but the consequences may be catastrophic - they may result in many unfavourable cataclysms all over the world.
        
El-Nino, which means "child Christ", appears in summer with a period of two to seven years. It may be the reason for devastating hurricanes and other weather anomalies in the whole world. For many countries El-Nino is a real disaster with tough economical consequences. Besides low harvest, the catch of anchovy (the base of agriculture system) also falls. For several decades El-Nino was being studied, however, the reasons for it are not known yet.
        
Russian scientists decided to develop an already known idea that the appearance of El-Nino is linked to tropic cyclones in Philippine Sea region. Both typhoons and El-Nino are a result of accumulation of excess heat in the ocean surface. The difference between them is that typhoons happen many times a year and El-Nino - once in several years. It comes in summer and ends in the first half of the next year. The signs for the coming of the current are seen in many parameters: ocean surface layer temperature, humidity, wind speed. There is a special coefficient, based on these and some other factors (multivariant El-Nino Index or MEI). The Russian scientists have found its dependency upon the amount of typhoons and El-Nino phenomenon for the last 30 years.
        
The scientists believe that El-Nino is formed in the following way. Trade-winds carry a large amount of heat to the north-west part of the Pacific Ocean. That`s why the temperature there often exceeds 30 degrees and most powerful storms arise. However, typhoons release the heat into the atmosphere, therefore, cooling the ocean surface and locking the thermal energy deep inside. This prevents new typhoons from forming and surplus energy is carried away by strong meridian currents, such as Kurosio. They deliver the heat to higher latitudes, levelling the temperature differences between tropics and higher latitudes. This way the trade-winds activity comes down and, consequently, equatorial upwellings weaken or even cease to be. Upwellings are vertical water movements which make the cold deep waters come up to the surface and cool it. The scientists believe that at this moment, when the ocean cooling system fails, El-Nino is being formed to throw out the heat excess.
        
This cycle lasts for several months, so in the beginning of the year, when El-Nino comes, there should be more typhoons in the Philippine Sea. And in the year when El-Nino ends, their number should drop. Meteorologists have calculated that at the beginning of the phenomenon the number of nasty days is twice more than at the end. This means that their number can predict the coming of El-Nino. The trajectory of the tropic cyclones also changes. The last strong El-Nino, which happened in 1997-1998, has finally proved the link between tropic cyclones in the North-West Pacific and the El-Nino phenomenon.

Informnauka (Informscience) Agency