Disaster monitoring applications need near real-time observations in facilitating timely measures to minimise losses of lives and resources. Severe cyclones, storms, earthquakes, floods and tsunamis are categorized as disasters. One of the recent requirements is to monitor tsunami over the oceans.

A significant feature of tsunami is its manifestation as ocean surface waves caused by large-scale displacement of water from a few mm to a few metres with a high velocity of 200km/h or above. This study examines the feasibility of detecting and tracking tsunamis. Altimeters hold promise in meeting such requirements.

Although tsunami waves are detectable by space-borne altimeters, a single altimeter mission is less effective due to the poor spatial coverage. A large spatial coverage (equivalent snap-shot observation) can be obtained by a constellation of satellites.

This study further addresses a constellation design using a number of small altimeter satellites to coordinate large spatial coverage and repetivity to monitor tsunami waves. A judicious choice of number of satellites, number of orbits and orbital inclinations facilitates a near real-time observation possibility.

The present study focuses the oceanic region around the Indian subcontinent in the Bay of Bengal using a small satellite constellation. A coverage analysis for the targeted region is done for various simulated configurations using Satellite Tool Kit (STK) by optimizing the constellation to enhance repetivity.

Considering the altitude accuracy, the orbit determination capability using GPS-aided system is proposed. Further, radiometers at 22 and 31 GHz are augmented for atmospheric corrections.

The current research findings indicate that a set of three inclined orbits at 10, 15 and 20 degrees with at least 6 small satellites in each orbit would be able to adequately meet the requirements. Further optimisation in terms of more number of satellites and inclinations would indeed provide a more practical solution for tsunami observations.

tsunami, monitoring, small satellite constellation, microwave altimeter.