1. Section 3 Remote sensing of global change El niño Global Change Instructor: Dr. Cheng-Chien LiuCheng-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/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 video http://svs.gsfc.nasa.gov/vis/a000000/a00 0200/a000287/a000287.mpg http://svs.gsfc.nasa.gov/vis/a000000/a00 0200/a000287/a000287.mpg http://svs.gsfc.nasa.gov/vis/a000000/a00 0200/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.gifhttp://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.jpg and http://svs.gsfc.nasa.gov/stories/elnino_20030114/el_nino_3dm.jpghttp://svs.gsfc.nasa.gov/stories/elnino_20030114/norm_3dm.jpghttp://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 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 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.htmlhttp://svs.gsfc.nasa.gov/stories/elnino/index.html

8. Consequences (cont.)  The carbon connection - physical and biological processes Plankton bloom  biologic change  CO 2 change El Niño cut the amount of CO 2 released into the atmosphere by 700 million metric tons A short video 1  http://svs.gsfc.nasa.gov/stories/elnino/COphy.mov http://svs.gsfc.nasa.gov/stories/elnino/COphy.mov A short video 2  http://svs.gsfc.nasa.gov/stories/elnino/CObio.mov 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  m  Channel 2: 0.725-1.0  m  Channel 3: 3.55-3.93  m  Channel 4: 10.3-11.3  m  Channel 5: 11.4-12.4  m  Mission

10. Table 1 Continuous observation of SST by AVHRR on boarded NOAA polar-orbiting satellite series Source: http://edc.usgs.gov/products/satellite/avhrr.htmlhttp://edc.usgs.gov/products/satellite/avhrr.html Table 1 Satellite #DatesPass# of bands NOAA-66/79 - 11/86am4 NOAA-78/81 - 6/86pm5 NOAA-85/83 - 10/85am4 NOAA-92/85 - 11/88pm5 NOAA-1011/86 - 9/91am4 NOAA-1111/88 - 9/94pm5 NOAA-125/91 - 12/94am5 NOAA-13failedpmn/a NOAA-1412/94 - presentpm5 NOAA-155/98 - presentam5 NOAA-169/00 - presentpm6

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*T 4 + c*(T 4 -T 5 )*T surf + d*(sec([[theta]])-1)*(T 4 - T 5 ) + e*lifetime  T 4 and T 5 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.  T surf 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 (  0.5 0 C) 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 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 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/ http://podaac.jpl.nasa.gov/sst/ SST Measurement with the AVHRR  http://www.ae.utexas.edu/courses/ase389/midterm/duncan/duncan.html #channels 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 http://www.ngdc.noaa.gov/seg/globsys/avhrr2.shtml  Data AVHRR Stitched Orbits  http://edcdaacftp.cr.usgs.gov/html/avhrr_orbits.html http://edcdaacftp.cr.usgs.gov/html/avhrr_orbits.html NASA-Earth Observing System Data Gateway  http://edcimswww.cr.usgs.gov/pub/imswelcome/ 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 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 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 http://topex-www.jpl.nasa.gov/mission/topex.html Jason-1  http://topex-www.jpl.nasa.gov/mission/jason-1.html http://topex-www.jpl.nasa.gov/mission/jason-1.html GRACE  http://www.csr.utexas.edu/grace/ http://www.csr.utexas.edu/grace/

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