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Passive Microwave Rain Rate Remote Sensing. Christopher D. Elvidge, Ph.D. NOAA-NESDIS National Geophysical Data Center E/GC2 325 Broadway, Boulder, Colorado 80305 USA Tel. 1-303-497-6121 Fax. 1-303-497-6513 Email: chris.elvidge@noaa.gov http://dmsp.ngdc.noaa.gov/ http://sabr.ngdc.noaa.gov/.
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Passive Microwave Rain Rate Remote Sensing Christopher D. Elvidge, Ph.D. NOAA-NESDIS National Geophysical Data Center E/GC2 325 Broadway, Boulder, Colorado 80305 USA Tel. 1-303-497-6121 Fax. 1-303-497-6513 Email: chris.elvidge@noaa.govhttp://dmsp.ngdc.noaa.gov/http://sabr.ngdc.noaa.gov/
Outline • Why do we need microwave sensors? • Evolution of passive microwave sensor • History • Future • Rain rate retrieval • Physical bases • Algorithm performance • Examples • Application to disaster warning
Microwave Remote Sensing from Space Advantages Disadvantages • Penetration through non-precipitating clouds. • Highly stable instrument calibration. • Radiance is linearly related to temperature (i.e. the retrieval is nearly linear). • O2 is uniformly mixed gas throughout the atmosphere. • Larger field of views (10-50 km) compared to vis/IR. • Variable emissivity over land. • Polar orbiting satellites provide discontinuous temporal coverage.
Why do We Need Observations in Lower Troposphere? The planetary boundary layer contains the for weather Convective events in well mixed layer during daytime heating Fog and low clouds under nocturnal inversion Layer of air containing the roots of summertime convection Low-level jet Depth of cold air in winter to tops of stratocumulus
History and Future of Passive Microwave Earth Observation • NASA 1970-1987 Nimbus satellite ESMR-1, ESMR-2, SMMR • NOAA 1978-1999 POES MSU, 1999-present POES AMSU • DMSP 1982-present SSM/T 1987-present SSM/I, 1991-present SSM/T2, 2004-2015? SSMIS • NASDA 1997-present TRMM TMI & PR, 2002-present Aqua AMSR, 2003-present ADEOS-2 AMSR • NPOESS 2007-2030? CMIS
Abbreviation Frequency (GHz) Resolution(km) 19V 19.35 70x45 19H 19.35 70x45 22V 22.235 60x40 37V 37.0 38x30 37H 37.0 38x30 85V 85.5 16x14 85H 85.5 16x14 DMSP SSM/I Sensor • Flown on DMSP F8 - F15 • It is a conical scan sensor.
NOAA AMSU Sensor • Flown on NOAA-15 (May 1998) and NOAA-16 (Sept. 2000) satellites • Contains 20 channels: • AMSU-A • 15 channels • 23 – 89 GHz • AMSU-B • 5 channels • 89 – 183 GHz • 6-hour temporal sampling: • 130, 730, 1330, 1930 LST
AMSU-A and –B Scan Pattern • Cross-track scan geometry • AMSU-A (30 FOV/scan; 48 km @ nadir) • AMSU-B (90 FOV/scan; 16 km @ nadir) • 2200 km swath width
Precipitation MonitoringTornadic Storm on Sept 24 2001 AMSU NEXTRAD
AMSR image of Typhoon 6 June 17, 2003
Conclusion • Passive microwave remote sensing has a unique capability to detect rain and estimate rain rates from orbit. • This complements ground based weather radar and precipitation measurements. • Algorithms work over water, may extend to land with more advanced sensors. • Satellite data from multiple systems can be used to get greater integration time, provide a more complete depiction of rain rate through the day and prediction of severe rain events.