Walker, Gilbert Thomas (1868–1958)

GILBERT THOMAS WALKER is the British physicist and statistician who first described the phenomenon of Southern Oscillation, a coherent interannular fluctuation of atmospheric pressure over the tropical Indo-Pacific region that produces wind anomalies. This was part of Walkers project to determine the connections between the Asian monsoon and other climatic fluctuations in the global climate in an effort to predict unusual monsoon years that cause drought and famine to the Asian sector. Although he was not a meteorologist by education, Walker greatly advanced the study of global climate with his discovery.

Gilbert Thomas Walker was born on June 14,1868, in Rochdale, Lancashire. He was the eldest son and fourth child in a large family of eight. Soon after his birth, his family relocated to Croydon, where his father became the borough's chief engineer. From 1876 on, Gilbert attended Whitgift School, and in 1881 he won a scholarship to St. Pauls School. He already excelled in mathematics from these early years and passed the London matriculation in 1884. However, he did not stay in London for his degree, opting instead for Trinity College, Cambridge, where he enrolled in 1886, thanks to a scholarship. In 1891, he was elected a Trinity Fellow. He received an M.A. in 1893, and two years later, he was appointed a lecturer in mathematics. The heavy work necessary to attain these successes eventually took their toll on Walker's health, which broke down in 1890, forcing the mathematician to spend the next three winters in Switzerland. As a result of his precarious health, Walker did not publish many significant papers in the following years, but his 1899 work “Aberration and Some Other Problems Connected With the Electromagnetic Field” earned him the prestigious Adams Prize from Cambridge University. Walker was elected a fellow of the Royal Society in 1904, the same year that he received a Sc.D. from Cambridge University.

In the summer of 1903, Walker resigned his academic positions to become assistant to Sir John Eliot, who was the meteorological reporter to the government of India and director-general of Indian Observatories. The choice of Walker as special assistant was surprising, as Walker was not a meteorologist but a mathematician. At the end of 1903, Eliot retired, and Walker became the sole person responsible for the Indian Meteorological Department. He continued Eliot's quest for professional individuals to become members of his staff. He made prestigious appointments including J.H. Field, J. Patterson, and G.C. [Page 1072]Simpson, who later became directors of meteorological services in India, Canada, and the United Kingdom, respectively From the beginning of his appointment, Walker devoted his research to the problems of monsoon and, in 1909, published his first meteorological papers. In 1908, Walker also gave lectures at the University of Calcutta, which were then published in 1910 by Cambridge University Press. Walker married May Constance Carter in 1908, and the couple had a son and a daughter.

Walker's interest in the monsoon resulted from the famine that the absence of rains had caused in India in 1899. Walker soon understood that he could not tackle meteorological problems through mathematical analysis and tried to develop more empirical techniques. He called his methodology seasonal foreshadowing, rather than weather forecasting, as the phrase indicated a vaguer prediction. Walker calculated statistical delay correlations between antecedent meteorological events both within and outside India and the subsequent behavior of the Indian monsoon. He was one of the first scientists to establish relationships between apparently separate events. The sets of relationships that he established, subsequently called Walker circulation in his honor, create a system resembling a global heat engine influencing the worlds climate. The Walker circulation works like a swing in which warm, moist air rises in the western Pacific, becomes drier at high elevation, and displaces eastward, where heavy air sinks and returns westward. The phenomenon thus creates high air currents moving from the west to the east and, at the same time, east-to-west trade winds near the ocean surface. Global warming theorists have predicted that the rising temperatures will eventually slow down this mechanism.

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