Remote Sensing. Aerosol: detection and tracing. System science. Global warming. Health

Transcription

1 Remote Sensing Aerosol: detection and tracing. Global warming. Health System science Global features - floods. Surface temperature. Surface moisture, etc.

2 Remote Sensing Applications: State/Local Planning Radarsat image from Canadian Center for Remote Sensing showing flood-stage levels of Po River (light blue) vs normal flow conditions (dark blue). Image Source:

3 Aerosols

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5 Remote Sensing Application: Resource Evaluation Image Source: Web Exercise posted by Marlon Vinson: Using Remote Sensing Techniques to Find Gold in the Canadian Shield. Image manipulations are used to highlight areas containing hydroxide-bearing minerals (pink) as an indicator for the presence of gold. Gold mining areas are in yellow. course_projects/geog432/2002/vinsonm/

6 SeaWifs Successful for African Dust SeaWiFS-measured reflectance image after Rayleigh correction, in the Northeast United States on July 16, 1999.

7 Electromagnetic Radiation radio microwave IR UV X-rays rays meters visible Reflected energy can be modeled using wave theory or as photons. Waves have set wavelengths as indicated by the colored indicator scale Note: 10^-6 m = 1 micron extending from the very short 1 micron = 1000 nanometers gamma ray region to radio waves.

8 Subdividing Visible Range UV blue green red NIR Light in filter Light out Blue, green and red divide the visible region into subsections. Most satellite sensors record one or more visible subsections, and other portions of the spectrum (IR, microwave, etc.). Blue bandpass filter blocks UV and green.

9 Crooksville Petri Dish Mag 20,000 Mag 10,000 Size of bacterial cell 0.1x0.5 micron at most

10 A Black Body A black body is one that completely absorbs all radiation. Graphite as an example absorbs all but 3% of incoming radiation. Conversely, a black body perfectly emits radiation as a smooth function of temperature; at absolute zero, no energy is emitted. Stars absorb and emit radiation freely.

11 Blackbody at 6000K Using Planck Radiation Formula Radiation Visible 5000K Wavelength of Radiation (nm) The electromagnetic radiation source for remote sensing is the sun. Assuming a temperature of 6000K, and using the Planck formula, the sun emits white light, e.g. emits strongly across the range 500 to 700 nm.

12 Blackbody Radiation: Hmwk 1. Play with the spectrum posted at the web site listed below. What temperature is a star that radiates yellow light? What temperature for blue? Which is hotter?

13 Reflect I Transparency: Clear Glass/Air: Electromagnetic oscillations cause oscillations within electron cloud of atoms but oscillations are not of a frequency that creates strong absorption electrons anchored to atoms. Colored Glass: - resonance takes place and certain frequencies that absorb energy (wavelengths absorbed). Metallic Reflection: Electromagnetic oscillations cause displacement of electrons from atoms electrons not anchored. Absorbed energy is reemitted at same wavelength, e.g. reflected.

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15 Leaves Non-Metallic Reflection Electron oscillations do not propagate from the surface inward; rather, energy is absorbed, held briefly and then re-emitted at a wavelength that reflects the energy of the oscillating electrons. Chlorophyl a and b strongly absorb blue ( nm) and red ( nm); carotonids & riboflavin absorb blue; phytochromes absorb blue and UV. As a result the leaf surface reflects green.

16 Leaf Structure Palisade Parenchyma Mesophyll Cell Spongy Parenchyma Mesophyll Cells

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18 Chlorophyll a and b Chlorophyll a and b have similar absorption bands dominate and mask other compounds. Disappearance of chlorophyll in the Fall exposes other underlying pigments

19 B- Carotene Beta carotene is also strongly absorbing, but is masked by chlorophyll. Unlike chlorophyll, B- carotene does not absorb in the red region; senescence causes leaves to turn yellow in the Fall. Fall production of anthocyanin produces red coloration.

20 Tristan

21 Measured Leaf Colors Percent reflectance: energy reflected from the surface relative to a Spectralon reference standard.