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Section 3 Remote sensing of global change

Section 3 Remote sensing of global change. El niño Global Change Instructor: Dr. Cheng-Chien Liu Department of Earth Sciences National Cheng Kung University Office: Building of Earth Sciences, room 30206 Voice: +886-6-2757575 ext. 65422 E-mail: ccliu88@mail.ncku.edu.tw

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Section 3 Remote sensing of global change

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  1. Section 3 Remote sensing of global change El niño Global Change Instructor: Dr. Cheng-Chien Liu Department of Earth Sciences National Cheng Kung University Office: Building of Earth Sciences, room 30206 Voice: +886-6-2757575 ext. 65422 E-mail: ccliu88@mail.ncku.edu.tw Office hours: Monday 14:00 – 17:00, Wednesday 9:00 – 12:00 URL: http://mail.ncku.edu.tw./~ccliu88/ Last updated: 25 April 2005

  2. Introduction • El Niño • El Niño was named by people who fish off the western coast of Central America to refer to the warm current that invades their coastal waters around Christmas time • Significance • Air-sea interaction  climate change • El Niño  a typical example of air-sea interaction  short term climate change • El Niño  disrupt fisheries and bring severe weather events worldwide

  3. Mechanism of El Niño • Conditions of atmosphere and ocean during the normal year and El Niño (Fig. 1, 2) • A short videohttp://svs.gsfc.nasa.gov/vis/a000000/a000200/a000287/a000287.mpg

  4. Fig. 3.1.1 Fig. 1 Conditions of atmosphere and ocean during the normal year and El Niño. Source: http://140.115.123.30/gis/globalc/fig/06-10.gif

  5. Fig. 3.1.2 Fig. 2 Conditions of atmosphere and ocean during the normal year and El Niño. Source: http://svs.gsfc.nasa.gov/stories/elnino_20030114/norm_3dm.jpgand http://svs.gsfc.nasa.gov/stories/elnino_20030114/el_nino_3dm.jpg

  6. Consequences • An immense pacific bloom • Along the equatorial Pacific • During El Niño  nearly a complete lack of plankton • During La Niña  enormous plankton bloom • A short video 1 (12 Month Sequence) • http://svs.gsfc.nasa.gov/stories/biosphere/movies/Bio_Globe_Pacific_1.mov • A short video 2 (22 Month Sequence) • http://svs.gsfc.nasa.gov/stories/biosphere/movies/Bio_Pacific_1.mov

  7. Fig 3 Fig. 3 Along the equatorial Pacific during El Niño and La Niña. Source: http://svs.gsfc.nasa.gov/stories/elnino/index.html

  8. Consequences (cont.) • The carbon connection - physical and biological processes • Plankton bloom  biologic change  CO2 change • El Niño cut the amount of CO2 released into the atmosphere by 700 million metric tons • A short video 1 • http://svs.gsfc.nasa.gov/stories/elnino/COphy.mov • A short video 2 • http://svs.gsfc.nasa.gov/stories/elnino/CObio.mov

  9. Remote sensing techniques for studying El Niño – SST • Sensor • Advanced Very High Resolution Radiometer (AVHRR) • Channel 1: 0.58-0.68 mm • Channel 2: 0.725-1.0 mm • Channel 3: 3.55-3.93 mm • Channel 4: 10.3-11.3 mm • Channel 5: 11.4-12.4 mm • Mission

  10. Table 1 Satellite # Dates Pass # of bands NOAA-6 6/79 - 11/86 am 4 NOAA-7 8/81 - 6/86 pm 5 NOAA-8 5/83 - 10/85 am 4 NOAA-9 2/85 - 11/88 pm 5 NOAA-10 11/86 - 9/91 am 4 NOAA-11 11/88 - 9/94 pm 5 NOAA-12 5/91 - 12/94 am 5 NOAA-13 failed pm n/a NOAA-14 12/94 - present pm 5 NOAA-15 5/98 - present am 5 NOAA-16 9/00 - present pm 6 Table 1 Continuous observation of SST by AVHRR on boarded NOAApolar-orbiting satellite seriesSource: http://edc.usgs.gov/products/satellite/avhrr.html

  11. Remote sensing techniques for studying El Niño – SST (cont.) • Principle • Compute actual scene radiance from satellite counts • E=S*C + I • Find scene "temperature" (uncorrected) from radiance • T=temperature in degrees Kelvin • E=scene radiance as computed above • nu=central wave number of the channel (cm^-1, listed in the NOAA Polar Orbiter Data Users Guide) • C1=2*pi*Planck's Constant* c(speed of light)^2 • C2=c * Planck's Constant / Boltzmann Constant

  12. Remote sensing techniques for studying El Niño – SST (cont.) • Principle (cont.) • Correct for atmospheric effects and sensor artifacts • SST = a + b*T4 + c*(T4-T5)*Tsurf + d*(sec([[theta]])-1)*(T4-T5) + e*lifetime • T4 and T5 are the temperature measurements for channels 4 and 5 respectively • a,b,c,d, and e predetermined by comparing AVHRR radiance values to in situ temperature measurements taken from buoys. • Tsurf is an a priori estimate of the actual SST made from a precompiled composite SST map of the same area. • theta is the satellite zenith angle • lifetime is the number of days since the launch of the satellite, used to calibrate drift of the sensor response over time.

  13. Remote sensing techniques for studying El Niño – SST (cont.) • Measurements (0.50C) • NEW Rotating Globe Animation showing El Niño and La Niña events (1996-1999) using TOPEX/POSEIDON and Pathfinder SST Data Sets • http://podaac.jpl.nasa.gov/sst/movies/rotating_globe.mov • Animation showing El Niño and La Niña events (1996-1999) using AVHRR Oceans Pathfinder and TOPEX/ Poseidon Data Sets • http://podaac.jpl.nasa.gov/sst/movies/epacific_75q.mov

  14. Remote sensing techniques for studying El Niño – SST (cont.) • Useful links • Pathfinder SST • http://podaac.jpl.nasa.gov/sst/ • SST Measurement with the AVHRR • http://www.ae.utexas.edu/courses/ase389/midterm/duncan/duncan.html#channels • AVHRR: A Brief Reference Guide • http://www.ngdc.noaa.gov/seg/globsys/avhrr2.shtml • Data • AVHRR Stitched Orbits • http://edcdaacftp.cr.usgs.gov/html/avhrr_orbits.html • NASA-Earth Observing System Data Gateway • http://edcimswww.cr.usgs.gov/pub/imswelcome/

  15. Remote sensing techniques for studying El Niño – SSH • Sensor: Altimeter • An instrument that measures altimetry • Aneroid altimeters measure air pressure • Radar or laser altimeters time returning microwaves or light

  16. Remote sensing techniques for studying El Niño – SSH (cont.) • Mission: • TOPEX/Poseidon (August 10, 1992 – present) • Jason-1 (December 07, 2001 – present) • The Tandem Mission Flash animation • http://topex-www.jpl.nasa.gov/mission/gary-interview3.mov • GRACE (March 17, 2002) • Gravity Recovery and Climate Experiment, is flying two identical spacecraft about 220 kilometers apart in a 500-kilometer polar orbit, and over its 5-year lifetime will produce an accurate map of the geoid. The geoid, the manifestation of the Earth's gravity field, is the basic figure on which all altimetry data is based. • OSTM (Proposed Launch: 2005) • OSTM - Ocean Surface Topography Mission, is a follow-on to Jason-1. (operational mode)

  17. Remote sensing techniques for studying El Niño – SSH (cont.) • Principle • TOPEX/Poseidon Instruments • http://topex-www.jpl.nasa.gov/gallery/tiffs/videos/topomeas.mov • Measurements

  18. Remote sensing techniques for studying El Niño – SSH (cont.) • Useful links • TOPEX/Poseidon • http://topex-www.jpl.nasa.gov/mission/topex.html • Jason-1 • http://topex-www.jpl.nasa.gov/mission/jason-1.html • GRACE • http://www.csr.utexas.edu/grace/

  19. Questions • What are the abnormal events of climate during 1982/83 El Niño around the world?

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