ICTS

This meeting is being organized as a part of the activities related to the "Mathematics of Planet Earth 2013".

The scientific themes of the Ramanujan Lectures by Prof. Majda will be modelling of wave phenomena in the tropics, study of convection and relations to clouds, and filtering or assimilation of chaotic signals in complex systems such as the atmosphere.

The discussion meeting centred around these lectures will mainly cover the following topics:

Mathematical theory of tropical meteorology

• Observations and numerical simulations of these phenomena
• Role of clouds and convection in the tropics
• Prediction and data assimilation techniques

Convection in the tropics occurs across scales, from the scale of little eddies of a few mm or less to that of clouds to the planetary scale Walker and Hadley circulations. These scales continuously interact and exchange energy. Unlike in most other fluid mechanical phenomena, the energy transfer could be a two way process in the tropical atmosphere i.e. energy released at the small scales could drive the larger scales and there could be a cascade of energy from larger to smaller scales. These interaction are important for understanding tropical circulation and hence for predicting the weather/climate in the tropics.

One of the major features of the tropical atmosphere is the Madden Julian Oscillation (MJO) which occurs at the subseasonal (10-40 day) timescale. This is known to have a major impact on other tropical phenomena such as the Indian monsoon and the El-Nino Southern Oscillation (EnSO). This meeting will focus on the mechanisms that govern these phenomena, new observations which will throw light on hitherto unknown aspects of these phenomena and also on modelling and simulating them using a hierarchy of models.

Filtering of chaotic systems, which is known as data assimilation in the context of earth sciences, is certainly very important for the study of tropical meteorology. In particular, the ocean-atmosphere interaction plays a key role in modulating the flow across different temporal and spatial scales, and assimilation of such signals is a major challenge. The meeting will thus include discussion on these topics and their relation to the other themes.