EAS Seminar Series -- Jagadish Shukla
2146 Snee Hall
Predictability and Prediction of Monsoon Rainfall
Gilbert Thomas Walker came to India in 1904 with a singular purpose of forecasting Indian summer monsoon rainfall, and there he discovered the Southern Oscillation. In the same year, Vilhelm Bjerknes, considered to be the greatest meteorologist and fluid dynamicist of that time, proposed that it should be possible to make weather prediction by solving a system of equations describing the basic laws of physics and using current weather observations as the initial conditions.
The seminar will present a bird’s eye view of the current status of both Walker’s ideas to use past data and regression equations to predict monsoon rainfall, and Bjerknes’s idea of using a system of equations and only the current observations of weather as initial conditions to predict future atmospheric conditions.
As it is well known, Bjerknes ideas established the scientific foundation for remarkable advances in meteorology and numerical weather prediction in 1960s. The enthusiasm was short lived because at about the same time, Lorenz discovered chaos and butterfly effect. Butterfly effect was such a dominant paradigm in weather prediction research in 1970s that there was widespread pessimism about the prospects of making predictions beyond weather. Yet, today, routine dynamical seasonal predictions are produced by a number of national weather services.
The first part of the seminar will describe the evolution of scientific ideas that established that in spite of chaos and butterfly effect, there is a scientific basis for prediction beyond the limits of deterministic weather prediction, and dynamical seasonal prediction beyond weather is possible. As an illustration, the second part of the seminar will use the example of prediction of monsoon rainfall. Finally, physical and dynamical processes limiting predictability, and challenges and prospects of improved seasonal forecasts, which are critical for adaptation in a changing climate, will be described.
J. Shukla was born in 1944 in a small village (Mirdha) in the Ballia district of Uttar Pradesh, India. This village had no electricity, no roads or transportation, and no primary school building. Most of his primary school education was received under a large banyan tree. He passed from the S.R.S. High School, Sheopur, in the first class with distinction in Mathematics and Sanskrit. He was unable to study science in high school because none of the schools near his village included science education. His father, the late Shri Chandra Shekhar Shukla, asked him to read all the science books for classes 6 through 10 during the summer before he was admitted to the S.C. College, Ballia, to study science. After passing the twelfth grade from S.C. College, he went to Banaras Hindu University (B.H.U.) where, at the age of 18, he passed BS (honors) with Physics, Mathematics, and Geology in the first class and then earned the MS in Geophysics in the first class in 1964. He received PhD in Geophysics from BHU in 1971 and ScD in Meteorology from MIT in 1976.