Prof. Christofer S. Ruf Profile

Prof. Christofer S. Ruf

Professor at Univ of Michigan

SPIE Involvement:

Author

Proceedings Article | 20 August 2020 Poster + Presentation

The NASA CYGNSS microsat constellation

Chris Ruf, Clara Chew, Darren McKague, Shakeel Asharaf, Mahta Moghaddam

Proceedings Volume 11505, 1150503 (2020) https://doi.org/10.1117/12.2570153

KEYWORDS: Satellites, Radar, Global Positioning System, Heat flux, Soil science, Floods, Data modeling, Receivers, Surface roughness, Scatter measurement

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Proceedings Article | 21 October 2014 Paper

CYGNSS: NASA Earth Venture Tropical Cyclone Mission

Christopher Ruf, Paul Chang, Maria Paola Clarizia, Zorana Jelenak, Aaron Ridley, Randall Rose

Proceedings Volume 9241, 924109 (2014) https://doi.org/10.1117/12.2071404

KEYWORDS: Observatories, Antennas, Global Positioning System, Scattering, Calibration, Satellite navigation systems, Satellites, Doppler effect, Scatterometry, Radar

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Proceedings Article | 14 October 2014 Paper

The NASA CYGNSS mission: a pathfinder for GNSS scatterometry remote sensing applications

Randy Rose, Scott Gleason, Chris Ruf

Proceedings Volume 9240, 924005 (2014) https://doi.org/10.1117/12.2068378

KEYWORDS: Satellite navigation systems, Remote sensing, Observatories, Scatterometry, Global Positioning System, Receivers, Signal detection, Scattering, Doppler effect, Antennas

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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.

Proceedings Article | 9 November 2012 Paper

Ocean altimetry and wind applications of a GNSS nanosatellite constellation

Randall Rose, Christopher Ruf, Haruo Seki

Proceedings Volume 8528, 85280G (2012) https://doi.org/10.1117/12.977595

KEYWORDS: Satellite navigation systems, Observatories, Neodymium, Scatterometry, Receivers, Antennas, Temporal resolution, Ions, Climatology, Remote sensing

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Proceedings Article | 8 December 2006 Paper

Millimeter-wave array receivers for remote sensing

Todd Gaier, Pekka Kangaslahti, Alan Tanner, Bjorn Lambrigtsen, Shannon Brown, Michael Seiffert, Douglas Dawson, Sander Weinreb, William Wilson, Boon Lim, Christofer Ruf, Jeffrey Piepmeier

Proceedings Volume 6410, 64100G (2006) https://doi.org/10.1117/12.697830

KEYWORDS: Receivers, Radiometry, Calibration, Microwave radiation, Staring arrays, Remote sensing, Amplifiers, Prototyping, Atmospheric sensing, Polarimetry

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Proceedings Article | 3 October 2006 Paper

GeoSTAR: a microwave sounder for geostationary applications

B. Lambrigtsen, S. Brown, S. Dinardo, T. Gaier, P. Kangaslahti, A. Tanner, J. Piepmeier, C. Ruf, S. Gross, S. Musko, S. Rogacki

Proceedings Volume 6361, 63610K (2006) https://doi.org/10.1117/12.689121

KEYWORDS: Antennas, Prototyping, Receivers, Satellites, Optical correlators, Microwave radiation, Meteorological satellites, Calibration, Phase shifts, Space operations

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The Geostationary Synthetic Thinned Aperture Radiometer, GeoSTAR, is a new concept for a microwave atmospheric sounder intended for geostationary satellites such as the GOES weather satellites operated by NOAA. A small but fully functional prototype has recently been developed at the Jet Propulsion Laboratory to demonstrate the feasibility of using aperture synthesis in lieu of the large solid parabolic dish antenna that is required with the conventional approach. Spatial resolution requirements dictate such a large aperture in GEO that the conventional approach has not been feasible, and it is only now, with the GeoSTAR approach, that a GEO microwave sounder can be contemplated. Others have proposed GEO microwave radiometers that would operate at sub-millimeter wavelengths to circumvent the large-aperture problem, but GeoSTAR is the only viable approach that can provide full sounding capabilities equal to or exceeding those of the AMSU systems now operating on LEO weather satellites and which have had tremendous impact on numerical weather forecasting. GeoSTAR will satisfy a number of important measurement objectives, many of them identified by NOAA as unmet needs in their GOES-R pre-planned product improvements (P3I) lists and others by NASA in their research roadmaps and as discussed in a white paper submitted to the NRC Decadal Survey. The performance of the prototype has been outstanding, and this proof of concept represents a major breakthrough in remote sensing capabilities. The GeoSTAR concept is now at a stage of development where an infusion into space systems can be initiated, either on a NASA sponsored research mission or on a NOAA sponsored operational mission. GeoSTAR is an ideal candidate for a joint "research to operations" mission, and that may be the most likely scenario. Additional GeoSTAR related technology development and other risk reduction activities are under way, and a GeoSTAR mission is feasible in the GOES-R/S time frame, 2012-2014.

Showing 5 of 6 publications

Conference Committee Involvement (2)

Microwave Remote Sensing of the Atmosphere and Environment IV

9 November 2004 | Honolulu, Hawai'i, United States

Microwave Remote Sensing of the Atmosphere and Environment III

24 October 2002 | Hangzhou, China

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