Trishchenko, AP; Garand, L (2012). Observing polar regions from space: advantages of a satellite system on a highly elliptical orbit versus a constellation of low Earth polar orbiters. CANADIAN JOURNAL OF REMOTE SENSING, 38(1), 12-24.
Recent reports on Arctic climate change sparked an interest in the development of a new observing system for this region, specifically a satellite system making use of a highly elliptical orbit (HEO), an idea supported by the World Meteorological Organization. This paper attempts to quantify the advantages of such a system relative to a traditional constellation of Lower Earth Orbit (LEO) polar satellites. A realistic two-satellite HEO system is compared with currently operating two-, four-, and seven-satellite LEO constellations in terms of spatio-temporal coverage and capability to provide sequences of single, dual, and triplet images at a required temporal resolution. This is important to properly monitor dynamic events, such as volcanic ash transport, frontal systems, smoke from wild fires, and cloud motion from which wind vectors are derived. A two-satellite HEO system is 5-10 times more efficient for monitoring dynamic events from image pairs above 70 degrees N than a standard four-satellite morning-afternoon sun synchronous LEO constellation. An analytical model was developed to quantify the spatio-temporal coverage from a LEO constellation. Results demonstrate that a LEO constellation with orbital characteristics similar to the upcoming Joint Polar Satellite System should include as many as 23 (34) spacecrafts to achieve coverage with 15 (10) min refresh rate at 60 degrees N, i.e., the capability of a two-satellite HEO system. In addition, data reception issues and the need for complex image compositing affect the product latency of an LEO system, and further reduce its efficiency in comparison with an HEO system.