Mr. Donald Chu Profile

Donald Chu

at Northrop Grumman Systems Corp

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Publications (5)

Proceedings Article | 8 December 2006 Paper

Latest developments of geostationary microwave sounder technologies for NOAA's mission

Shyam Bajpai, Michael Madden, Donald Chu, Martin Yapur

Proceedings Volume 6410, 64100F (2006) https://doi.org/10.1117/12.697946

KEYWORDS: Microwave radiation, Antennas, Satellites, Clouds, Spatial resolution, Radiometry, Earth's atmosphere, Infrared radiation, Sensors, Atmospheric sensing

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Proceedings Article | 29 August 2005 Paper

GOES-R microwave sounder status

Michael Madden, Shyam Bajpai, Donald Chu

Proceedings Volume 5890, 58900I (2005) https://doi.org/10.1117/12.615149

KEYWORDS: Microwave radiation, Satellites, Antennas, Clouds, Spatial resolution, Sensors, Infrared radiation, Infrared imaging, Earth's atmosphere, Radiometry

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The National Oceanographic and Atmospheric Administration (NOAA) is now considering a microwave radiometer for the new series of Geostationary Operational Environmental Satellites (GOES) to be launched starting in 2012. GOES-R is expected to begin operations around 2014 and will provide significant advances in Earth coverage, environmental data, and prediction capabilities. GOES' unique vantage point in fixed geostationary orbit provides continuous, near-real-time updates (observations) of weather and environmental conditions for the Americas and large portions of the Atlantic and Pacific Oceans. In general, GOES-R sensor improvements arise from more frequent updates, finer spatial/spectral resolution, and an expanded field of view. Infrared (IR) atmospheric sounders are designed to provide excellent observations in clear conditions. Critical information within clouds and under cloud cover, however, is not available in the IR spectrum. Microwave sounders can provide synergistic coverage by their ability to observe energy through clouds. NASA's Earth Observing System (EOS) AQUA with the Advanced Microwave Sounder Unit (AMSU) and Atmospheric IR Sounder (AIRS) has illustrated the benefits of combining infrared and microwave sounder data. The benefits provided by polar microwave sounders can be extended to geostationary satellites. The combination of the Hyperspectral Environmental Suite (HES) IR sounder and Geostationary Microwave Sounder (GMS) can likewise provide complete geostationary sounder coverage and precipitation measurements.through our hemisphere. Three different sounders designs have been proposed for the GOES-R Geostationary Microwave Sounder (GMS); these designs would all use similar frequency bands to those of the AMSU A and B and therefore benefit from existing retrieval algorithms. Two designs use mechanically steered solid dish antennae, while a third design utilizes a sparse aperture antenna technology. All three GMS designs take advantage of the latest developments in sensor technology, algorithms, and antenna design. The joint NOAA/NASA GOES-R Program Office (GPO) is evaluating the various GMS designs for GOES-R. This paper will address the design, status, and advantages and limitations of these GMS approaches in reference to unmet meteorological requirements as part of Pre-Planned Product Improvement (P³I) on the GOES-R series of satellites.

Proceedings Article | 22 December 2004 Paper

Geostationary microwave sounder requirements

Donald Chu, Norman Grody, Michael Madden, Joel Susskind, William Blackwell

Proceedings Volume 5654, (2004) https://doi.org/10.1117/12.579020

KEYWORDS: Microwave radiation, Radiometry, Antennas, Clouds, Temperature metrology, Satellites, Humidity, Infrared radiation, Liquids, Oxygen

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Proceedings Article | 4 November 2004 Paper

GEO sounding using microwave instruments

Sergey Krimchansky, Joel Susskind, Alexander Krimchansky, Donald Chu, Robert Lambeck, Martin Davis

Proceedings Volume 5570, (2004) https://doi.org/10.1117/12.565283

KEYWORDS: Microwave radiation, Clouds, Antennas, Receivers, Signal processing, Satellites, Space operations, Video processing, Calibration, Knowledge management

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There are several microwave instruments in low Earth orbit (LEO) that are used for atmospheric temperature and humidity sounding by themselves and in conjunction with companion IR sounders. These instruments have achieved a certain degree of maturity and are undergoing a redesign to minimize their size, mass, and power requirements from the previous generation instruments. An example of these instruments is the AMSU-A series, now flying on POES and Aqua spacecraft, with the IR sounders HIRS3 and AIRS respectively. These older microwave instruments are going to be replaced by the ATMS instruments that will fly on NPP and NPOESS satellites with the CrIS IR sounder. A number of enabling technologies acquired from the ATMS instrument hardware design and data processing are directly applicable to performing similar microwave sounding on a geostationary platform. Because these technologies are already in place, they are readily available for the development of a geostationary orbit (GEO) microwave instrument, thereby avoiding costly technology development and minimizing the risk of not achieving the scientific requirements. In fact, the MMIC microwave components that were developed by ATMS for size and volume reduction are directly applicable to a GEO microwave sounder. The benefits of microwave sounders are well known. They penetrate non-precipitating cloud cover and allow for accurate soundings obtained with a collocated high spectral resolution IR sounder in up to 80% cloud cover. The key advantages of a microwave instrument in GEO will be its ability to provide high temporal resolution and uniform spatial resolution, and it will expand the utility of a collocated advanced IR sounder to cases in which partial cloud cover exists. A footprint in the order of 100 km by 100 km resolution with hemispherical coverage within one hour can be easily achieved for sounding channels in the 50 to 57 GHz range. A GEO microwave sounder will also allow mesoscale sampling of select regions.

Proceedings Article | 10 November 2003 Paper

GOES imager visible-to-infrared channel registration using star observations

Donald Chu, Jeanette Baucom, Perry Baltimore, James Bremer

Proceedings Volume 5151, (2003) https://doi.org/10.1117/12.505668

KEYWORDS: Stars, Sensors, Imaging systems, Infrared radiation, Mirrors, Infrared imaging, Signal detection, Visible radiation, Image registration, Beam splitters

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