Using near real-time satellite data for severe weather protection of remote telescope facilities

摘要

Remotely operated astronomical radio telescope facilities that are spread over a large geographical area demand a new kind of protection from severe weather phenomena such as wind gusts and lightning. Both of these factors pose a unique danger to dish shaped antennas which many radio telescopes are based on. Structural damage can be incurred by severe wind gusts if a dish antenna is not stowed into its minimum wind profile position, and lightning protection might not be at its optimal configuration if the dish is not stowed. Traditionally, anemometers have provided wind information to base stow decisions on. In the case of thunderstorms capable of triggering microburst events however, anemometers do not provide timely enough warning, and their spot measurements are too localised to provide safety for distributed antenna networks. We discuss our implementation of a near real-time satellite data based severe storm warning system built for the Australian Square Kilometre Array Pathfinder (ASKAP), the methods used to diagnose convective developments, and we will show on a number of examples how well such a satellite based system can work, despite the system inherent time lag. We conclude by discussing future developments and improvements that can be made to the system for deployment with extremely large projects such as the Square Kilometre Array (SKA) currently being planned and built in South Africa and Australia that will require monitoring of an area orders of magnitude larger even than we are monitoring today. Using data products derived from the Advanced Himawari Imager (AHI) deployed on the Japanese Meteorological Agency's (JMA) Himawari 8 satellite, we can obtain information on convective developments in the troposphere that are likely to result in dangerous wind gusts. This data is taken in 10 minute intervals and generally available no later than 8 minutes after the observation time, thus providing near real-time information on the weather situation. One additional challenge is the large area covered by the radio interferometers we are operating. In the case of the Australian Square Kilometre Pathfinder (ASKAP) telescope in remote West Australia's Murchison Radio Observatory (MRO), the landmass covers dozens of square kilometers featuring 36 dish antennas of 12m diameter each.