Gilbert Walker

For the 19th-century provisional governor of Virginia, see Gilbert Carlton Walker. For the English cricketer, see Gilbert Walker (cricketer).

Gilbert Walker
Born	Gilbert Thomas Walker (1868-06-14)14 June 1868 Rochdale, Lancashire
Died	Coulsdon, Surrey
Fields	Meteorology, Statistician
Institutions	University of Cambridge
Alma mater	Trinity College, Cambridge Imperial College London
Notable awards	Fellow of the Royal Society Adams Prize (1899)

Sir Gilbert Thomas Walker, CSI, FRS (14 June 1868 – 4 November 1958) was a British physicist and statistician of the 20th century. Walker studied mathematics and applied it to a variety of fields including aerodynamics, electromagnetism and the analysis of time-series data before taking up a teaching position at Cambridge University. Although he had no experience in meteorology, he was recruited for a post in the Indian Meteorological Department where he worked on statistical approaches to predict the monsoons. He developed the methods in the analysis of time-series data that are now called the Yule-Walker equations. He is known for his groundbreaking description of the Southern Oscillation, a major phenomenon of global climate, and for discovering what is named after him as the Walker circulation, and for greatly advancing the study of climate in general. He was also instrumental in aiding the early career of the Indian mathematical prodigy, Srinivasa Ramanujan.

Early life and education

He was born in Rochdale, Lancashire on 14 June 1868, the fourth child and eldest son of Thomas Walker and Elizabeth Charlotte Haslehurst. Thomas was Borough Engineer of Croydon and had pioneered the use of concrete for town reservoirs. He attended Whitgift School where he showed an interest in mathematics and got a scholarship to study at St Paul's School. He obtained a degree in Metallurgy from Imperial College London and attended Trinity College, Cambridge where he was Senior Wrangler in 1889. His hard studies led to ill-health and he spent several winters recuperating in Switzerland where he learnt skating and became quite expert. He became a lecturer at Trinity College from 1895.

Career

Walker was an established applied mathematician at the University of Cambridge when he took up a position as assistant to the meteorological reporter in 1903. He was elevated to the position of director general of observatories in India in 1904. Walker had never worked on meteorology but the previous director of the Indian Meteorological Department, John Eliot. Another predecessor in the Indian Meteorological Department, Henry Francis Blanford, had noticed the pattern that the summer monsoon in India and Burma was correlated with the spring snow cover in the Himalayas. In India, the failure of the Indian Ocean monsoon had brought severe famine to the country in 1899 and meteorology had great economic value. Walker developed Blanford's idea with quantitative rigour and came up with correlation measures (with a lag) and regression equations (or in time-series terminology, autoregression). The methods he introduced for time-series regression are now partly named after him (the other contributor was Udny Yule who studied sun-spot cycles) as the Yule-Walker equations. Analyzing vast amounts of weather data from India and lands beyond, over the next fifteen years he published the first descriptions of the great seesaw oscillation of atmospheric pressure between the Indian and Pacific Ocean, and its correlation to temperature and rainfall patterns across much of the Earth's tropical regions, including India. This is now called the El Niño Southern Oscillation. He was made a Companion of the Order of the Star of India in 1911.

Walker also took an interest in several other fields. He made mathematical studies on bird flight and boomerangs. His interest in boomerangs came early in undergraduate years and he had earned the nickname of "Boomerang Walker". In Simla, he used to throw a boomerang on the grounds of Annadale attracting the attention even of the Viceroy of India. He published a summary of his ten years of research in Nature in 1901.

Walker continued his studies of yearly weather and climate change even after his retirement from India (in 1924 when he was knighted) and acceptance of a professorship in meteorology at Imperial College London. He had only mixed success in his original goal, the prediction of monsoonal failures; however, his theories and broad body of supporting research represented an invaluable step forward, allowing his successors in climate study to move beyond local observation and forecasting toward comprehensive models of climate worldwide. He served as president of the Royal Meteorological Society from 1926 to 1927.

Walker was elected a Fellow of the Royal Society in 1904, long before his work on meteorology on the strength of his work in applied mathematics and applications to electromagnetism. Walker, with his talent for mathematics, was among the first to recognize the abilities of the Indian mathematical prodigy Srinivasa Ramanujan and wrote a letter to the University of Madras to support a scholarship.

In a review of a book, Walker noted the growing insularity of specialists:

There is, to-day, always a risk that specialists in two subjects, using languages full of words that are unintelligible without study, will grow up not only, without knowledge of each other’s work, but also will ignore the problems which require mutual assistance.

Walker married Mary Constance Carter in 1908 and they had a son and a daughter. He died at Coulsdon, Surrey on 4 November 1958. He was 90 years old. The Walker Institute in the United Kingdom, established to study climate, is named in his honour.

External links

• Biography of Walker from The Walker Institute