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Sir Gilbert Walker - the Initiator | ||
Sir Gilbert Walker - The Walker Circulation was named after the man who first predicted that weather is a global phenomenon (thanks to University of Washington) At the turn of this century, scientists still believed this strange phenomenon occurred independently of any other weather patterns. During the 1920s, while scientists in South America were busy documenting the local effects of El Niņo, Sir Gilbert Walker was on assignment in India, studying monsoons. A British scientist, Walker, who was the head of the Indian Meteorological Service, had been asked in 1904 to try to figure out how to predict the vagaries of India's monsoons after an 1899 famine that was caused by monsoon failure.
His Findings Though essentially studying the failure of the monsoons in 1899, Walker decided to find a way of forecasting the yearly changes in monsoons. He was convinced they were in some way tied to global weather. As he sorted through world weather records, he recognized some patterns of rainfall in South America and associated them with changes in ocean temperatures. He also found a connection between barometer readings at stations on the eastern and western sides of the Pacific (Tahiti [French Polynesia] and Darwin, Australia, to be exact). He noticed that when pressure rises in the east, it usually falls in the west, and vice versa. He coined the term Southern Oscillation to dramatize the ups and downs in this east-west "seesaw" effect. He also realized that Asian monsoon seasons under certain barometric conditions were often linked to drought in Australia, Indonesia, India, and parts of Africa and mild winters in western Canada. Not only did he see the relationship between oscillations of air pressure in the eastern and western Pacific and the monsoons in India but also rainfall in Africa. He also noted that temperatures in Western Canada were above normal during these oscillations. Walker was convinced that all these events were part of the same phenomenon. This cycle lasts three to five years as can be seen by the peaks of the graph. Walker found out that the random failure of the monsoons in India often coincides with low pressure over Tahiti, high pressure over Darwin, and relaxed trade winds over the Pacific. As the first person to claim there was a connection between monsoons in India and unusually mild winters in Canada, naturally he took some grief. In a modern rendition of "the world is flat" scenario, he was publicly criticized for suggesting that climatic conditions over such widely separated regions of the globe could be linked. Furthermore, colleagues questioned his writings because they were skeptical of theories that gave a simple, single explanation for world-wide weather patterns. However, he was unable to translate this into a scheme that predicts the nature of the monsoons. Walker conceded that he couldn't prove his theory but predicted that whatever was causing the connection in weather patterns would become clear once wind patterns above ground level, which were not routinely being observed at that time, were thrown into the equation. He was right. As a consequence, Walker’s results fell into oblivion until Jacob Bjerknes, in 1960, expressed his interests in discovering the secrets behind El Niņo. Continue and learn about Jacob's Bjerknes' contributions.
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