A study of cloud cover over multiple sites within Australia for satellite/ground atmospheric optical communication links

Abstract

Australia is known to be the most arid continent on Earth. Given the link between aridity and the lack of clouds, Australia should be well-placed to have favourable conditions for space-related optical communications. There are many investigations in the literature that focus on identification of the preferred site(s) in those countries for locating satellite-to-ground optical communications infrastructure. On this matter, there are several observations about Australia that are of relevance. Firstly, the country is large and very geologically old and has been subjected over time to significant erosion. Apart from the high terrain in the SE of the continent, the country is relatively flat, which implies the selection of sites with low atmospheric scintillation may be a limiting factor. Changes in cloud cover due to climate change appears to be regional but variable on the decadal scale. Finally, much of the continental interior is inhospitable rangeland and desert with low population density and consequently little in the way of high bandwidth communications infrastructure. We reported previously on an analysis of a 40-year data set of satellite-derived cloud cover statistics to assess cloud cover change. In the present study we investigate, using the most recent decade of that data set, the ranking of six widely distributed sites across the Australian continent. Additionally, we explore multi-site selections to provide a statistically-based ranking of combinations of sites: any combination of three sites of the six sites analysed will achieve an average clear-sky probability greater than 0.90 with some combinations as high as 0.98. The large distances between sites (~500 - 2000 km) supports the assumption of statistically independent cloud cover.