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Overview

The ASIRI: RAWI project is a research program designed to capture and study intraseasonal phenomena by observing across the equator with measurement stations at eastern atolls of Seychelles and Sri Lanka and Singapore, spanning time scales from minutes to months. It is funded by the Northern Arabian Sea Circulation Autonomously Researched (NASCar) Initiative of the Office of Naval Research (ONR).

The equatorial Indian Ocean is considered a hot spot of Earth’s weather and climate variability.  Akin to this pervasive influence is the coupling of energetic, small to decadal scale, atmospheric disturbances originated over the Indian Ocean (IO) with a myriad of oceanic processes, the understanding of which remains nascent. On the subseasonal scale, the active and break phases of South Asian monsoons trigger remarkable response in both the atmospheric and oceanic sides, and the origins of these oscillations have been attributed to equatorial disturbances, for example, the Madden Julian Oscillations, planetary waves, transients of Hadley circulation and Kelvin-Rossby wave packets. Conceivably, smaller scale processes such as convection and turbulent entrainment can be the triggers for these phenomena. Despite their importance, in-situ data available from the IO on subseasonal phenomena are scant, and to understand coupled, multi-scale variability it is necessary to sample key phenomena at appropriate scales. We propose a research program to capture and study intraseasonal phenomena by observing across the equator with measurement stations at eastern atolls of Seychelles and Sri Lanka and Singapore, spanning time scales from minutes to months. The aim is to (i) capture eastward and northeastward propagating disturbances over one year using profiles of moisture and velocity, (ii) observe entrainment of upper air into the marine boundary layer using LiDAR and ground (tower) based measurements, and (iii) delineate the role of small-scale atmospheric processes in determining air-sea property exchanges. Data of international observational networks as well as simulations of the Weather Research and Forecasting (WRF) model will augment the analyses. The project has an outreach component, wherein governmental and non-governmental organizations as well as universities from Sri Lanka, Seychelles and Singapore will be participating in observations and analysis.

Indian Ocean