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Global Navigation Satellite System (GNSS) based scatterometry offers breakthrough opportunities for wave, wind, ice,
and soil moisture remote sensing. Recent developments in electronics and nano-satellite technologies combined with
modeling techniques developed over the past 20 years are enabling a new class of remote sensing capabilities that
present more cost effective solutions to existing problems while opening new applications of Earth remote sensing. Key
information about the ocean and global climate is hidden from existing space borne observatories because of the
frequency band in which they operate. Using GNSS-based bi-static scatterometry performed by a constellation of microsatellites
offers remote sensing of ocean wave, wind, and ice data with unprecedented temporal resolution and spatial
coverage across the full dynamic range of ocean wind speeds in all precipitating conditions.
The NASA Cyclone Global Navigation Satellite System (CYGNSS) is a space borne mission being developed to study
tropical cyclone inner core processes. CYGNSS consists of 8 GPS bi-static radar receivers to be deployed on separate
micro-satellites in October 2016. CYGNSS will provide data to address what are thought to be the principle deficiencies
with current tropical cyclone intensity forecasts: inadequate observations and modeling of the inner core. The
inadequacy in observations results from two causes: 1) Much of the inner core ocean surface is obscured from
conventional remote sensing instruments by intense precipitation in the eye wall and inner rain bands. 2) The rapidly
evolving (genesis and intensification) stages of the tropical cyclone life cycle are poorly sampled in time by conventional
polar-orbiting, wide-swath surface wind imagers.
It is anticipated that numerous additional Earth science applications can also benefit from the cost effective high spatial
and temporal sampling capabilities of GNSS remote sensing. These applications include monitoring of rough and
dangerous sea states, global observations of sea ice cover and extent, meso-scale ocean circulation studies, and near
surface soil moisture observations. This presentation provides a primer for GNSS based scatterometry, an overview of
NASA's CYGNSS mission and its expected performance, as well as a summary of possible other GNSS based remote
sensing applications.
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