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SeaWinds Scatterometer

SeaWinds Scatterometer. James Tianchen Li. Remote Sensing of Ocean Surface Winds. Oceans cover 70 per cent of the Earth's surface Remote sensing allows measurements to be made of vast areas of ocean repeated at intervals in time.

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SeaWinds Scatterometer

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  1. SeaWindsScatterometer James Tianchen Li

  2. Remote Sensing of Ocean Surface Winds Oceans cover 70 per cent of the Earth's surface Remote sensing allows measurements to be made of vast areas of ocean repeated at intervals in time. The interaction between the atmosphere and the ocean establishes and maintains both global and regional climates. In the United States alone, hurricanes have been responsible for at least 17,000 deaths since 1900 and hundreds of millions of dollars in damage annually.

  3. Introduction to SeaWinds • OnQuikSCAT(1999~2009) • On ADEOS II (2002~2003)(Advanced Earth Observing Satellite) • Specialized microwave radar • Measures near-surface wind velocity (both speed and direction) • A rotating dish antenna with two beams • Part of NASA’s Earth Observing System (EOS)

  4. SeaWinds on QuikSCAT QuikSCAT was launched in 1999 and was already operating 7 years beyond its design life. The QuikSCAT nominal mission ended on November 23, 2009. Artist's concept of QuikScat. Image credit: NASA/JPL Artist's impression

  5. SeaWinds on ADEOS II Launched from Tanegashima Space Center pad YLP-1 on 14 December 2002, aboard H-2A-202. On 23 October 2003, the solar panel failed. At 2349 UTC, the satellite switched to "light load" operation due to an unknown error

  6. Mission (QuikSCAT) • Launch Vehicle: Titan II • Mission Life: 2 years (+7) • Orbit: Sun-synchronous, 803 km,98.6° inclination orbit • The only remote-sensing system to provide • Accurate • Frequent • High-resolution • All weather conditions

  7. Measurements • 1,800 km swath during each orbit • provides approximately 90% coverage of Earth's oceans every day • Wind-speed measurements of 3 m/s to 20 m/swith 2 m/s accuracy • Direction, with an accuracy of 20 degrees. • Wind vector resolution of 25 km • The Ku-band SeaWindsscatterometer estimates near-surface ocean wind vectors by relating measured backscatter to a geophysical model function for the near-surface vector wind.

  8. Science Objectives • Acquire all-weather, high-resolution measurements of near-surface winds over global oceans. • Determine atmospheric forcing, ocean response, and air-sea interaction mechanisms on various spatial and temporal scales. • Combine wind data with measurements from scientific instruments in other disciplines to help us better understand the mechanisms of global climate change and weather patterns. • Study both annual and semi-annual rain forest vegetation changes. • Study daily/seasonal sea ice edge movement and Arctic/Antarctic ice pack changes.

  9. Operational Objectives • Fill the gap in data until such time as the originally planned SeaWinds instrument could be launched on ADEOS-II. • Improve weather forecasts near coastlines by using wind data in numerical weather- and wave-prediction models. • Improve storm warning and monitoring.

  10. Spacecraft • ADCS approach: 3-axis stabilized, Star Tracker/IRU/Reaction Wheels, C/A Code GPS • Pointing Acc.: < 0.1° absolute per axis • Pointing Knowl.: < 0.05° per axis • Telecom: (Science) 2 Mbps S-band P/L(Hskp) 5, 16, 256 Kbps S-Band, 2 Kbps S-Band uplink • Propulsion: N2H4 Blowdown • Mass: 970 Kg • Orbital Avg Power: 874 W • Data Capacity: 8 Gbits

  11. Ground Systems • Tracking by Earth Polar Ground stations Svalbard, Norway; Poker Flats, Alaska; Wallops Island, Virginia; and McMurdo, Antarctica; Hatoyama, Japan (contingency station). • High-quality research data products produced at JPL and distributed to science community within 2 weeks of receipt. • Scatterometer science data products are distributed through the JPL Physical Oceanography Distributed Active Archive Center (PO.DAAC), a scientific data distribution site: http://podaac.jpl.nasa.gov. • Operational data products produced at National Oceanic & Atmospheric Administration (NOAA) for international meteorological community within 3 hours of data collection.

  12. Instrument Description • Radar: 13.4 GHz; 110 W pulse at 189 Hz PRF • Antenna: 1-meter-diameter rotating dish producing 2 spot beams sweeping in a circular pattern • Mass: 200 kg • Power: 220 W • Average Data Rate: 40 kbit/s

  13. Block Diagram of SeaWinds

  14. SeaWindsMeasurementGeometry 250 to 800 km swath contains data that meet wind accuracy requirements when averaged over all wind directions

  15. Data from QuikSCAT/SeaWindsScatterometer 25 kmRes http://manati.star.nesdis.noaa.gov/datasets/QuikSCATData.php

  16. 25 kmRes Hurricane Katrina (August 23, 2005 – August 30, 2005)

  17. Detail from last slide

  18. 12.5 kmRes

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