Proceedings Article | 22 December 2004
Proc. SPIE. 5661, Remote Sensing Applications of the Global Positioning System
KEYWORDS: Microwave radiation, Unmanned aerial vehicles, Sensors, Spatial resolution, Stars, Antennas, Remote sensing, Satellites, Radiometry, Receivers
Improving the understanding of the Cryosphere and its impact on global hydrology is an important element of NASA’s Earth Science Enterprise (ESE). A Cold Land Processes Working Group (CLPWG) was formed by the NASA Terrestrial Hydrology Program to identify important science objectives necessary to address ESE priorities. These measurement objectives included Snow Water Equivalent (SWE), snow wetness, and freeze/thaw status of underlying soil. The spatial resolution requirement identified by the CLPWG was 100 m to 5000 m. Microwave sensors are well suited to measure these and other properties of interests to the study of the terrestrial cryosphere. It is well known that the EM properties of snow and soil at microwave frequencies are a strong function of the phase of water, i.e. ice/water. Further, both active and passive microwave sensors have demonstrated sensitivity to important properties of snowpack including, depth, density, wetness, crystal size, ice crust layer structure, and surface roughness. These sensors are also sensitive to the underlying soil state (frozen or thawed). Multiple microwave measurements including both active and passive sensors will likely be required to invert the effects of various snowpack characteristics, vegetation, and underlying soil properties to provide the desired characterization of the surface and meet the science needs required by the ESE. A major technology driver with respect to fully meeting these measurement needs is the 100 to 5000 m spatial resolution requirement. Meeting the threshold requirement of 5000 m at microwave frequencies from Low Earth Orbit is a technology challenge. The emerging capabilities of unmanned aircraft and particularly the system perspective of the Autonomous Aerial Observation Systems (AAOS) may provide high-fidelity/high-resolution measurements on regional scales or larger that could greatly improve our measurement capability. This paper explores a vehicle/sensor concept that could augment satellite measurements to enhance our understanding of the Cryosphere. The measurement performance and technology issues related to the sensor and aircraft will be assessed. Finally, specific technology needs and research necessary to enable this AAOS concept will be discussed.
