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Instrument: HRDI : High Resolution Doppler Imager
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Associated Platforms

Spectral/Frequency Information
Wavelength Keyword: VISIBLE
Spectral/Frequency Coverage/Range: 550 to 770 nanometers
Spectral/Frequency Resolution: 0.001 nanometers

Related Data Sets
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[Source: HRDI/UARS project home page, ]

The High Resolution Doppler Imager (HRDI) was one of the instruments on board the Upper Atmospheric Research Satellite (UARS). The satellite was launched on 12 September 1991 as a part of NASA's effort to study the Earth's stratosphere and mesosphere. UARS was the first satellite in NASA's Mission to Planet Earth. HRDI observed the emission and absorption lines of molecular oxygen (and other atmospheric components) in small volumes (4 km in height by 50 km in width) above the limb of the Earth. From the Doppler shift of the lines, the horizontal winds can be determined to an accuracy of ~5 m s-1, while the line shapes and strengths yield information about the temperature and atmospheric species, such as mesospheric ozone. The HRDI instrument conducted scientific measurements from November 1991 until April 2005. The UARS spacecraft was deactivated on 14 December 2005 at 17:16:37z, completing 78084 orbits over 5208 mission days. The UARS spacecraft is expected to re-enter the atmosphere sometime in 2009 or 2010.

Wind measurements from the TIDI instrument on the TIMED satellite provide overlapping measurements with HRDI from early 2002 through the end of the UARS mission. TIDI observations continue to the current time.

The primary purpose of this site is to make HRDI data available to the scientific community. A secondary goal is to provide information about the instrument technical

Online Resources

Instrument Logistics
Data Rate: 4.750 kbps.
Instrument Start Date: 1991-11-01
Instrument Stop Date: 2005-04-01
Instrument Owner: NASA