2. 2 Remote sensing applications in Oceanography: How much we can see using ocean color? Adapted from lectures by: Martin A Montes Rutgers University Institute of Marine and Coastal Sciences

3. 3 Main topics  Introduction: definitions, sensor characteristics  Model development: IOP’s, AOP’s, Forward and Inversion approach  Applications: chl, phytoplankton size structure

4. 4 Ocean color sensors  Definition:  Types: Passive vs Active  Sensor characteristics: swath, footprint, revisiting time, spectral resolution

5. 5 Ocean color sensors: characteristics First sensors: B&W Temporal resolution: revisiting time? Spectral resolution: number of channels?, bandwidth?

6. Differences between measuring SST and ocean color: Infrared radiometers (like AVHRR) measure radiation emitted from the ocean surface Assumes ocean is like a black-body emitter with T B related to actual temperature Measures skin temperature only Ocean color sensors do not measure emission – they measure reflectance How do we know we’re measuring reflectance, not emission?

7. Emission by the Earth in the visible is zero. Reflectance of the ocean in the thermal infrared is almost zero Reflectance of the ocean is not only a “skin” phenomenon. Its signal is more complex because the optical depth is much greater and depends on wavelength.

8. Ocean color sensors: characteristics http://www.ioccg.org/reports_ioccg.html

9. Ocean color sensors: characteristics

10. 10 Ocean color sensors: characteristics

11. Hyperion hyperspectral sensor on EO-1 220 channels

12. 12 Inherent and Apparent Optical properties IOP’s: not influenced by the light field (e.g., absorption coefficients) AOP’s: influenced by the light field (e.g., reflectance, backscattering)

13. 13 IOP’S & biogeochemical parameters AbsorptionBackscattering PhytoplanktonCDOMPOCSPM VSF??

14. 14 Forward vs. Inversion models Forward: IOP’s R rs (Hydrolight or non-commercial code) Given what we know is in the water, what do we expect it to look like? Inversion: R rs (Empirical, analytical, statistical) Given what we see, what can we tell about what is in the water? IOP’s

16. Rrs(412)/Rrs(555) band ratio yields a reasonably consistent relationship with in situ observations of CDOM absorption across several regions in the Mid-Atlantic continental shelf Can also derive empirical relationship between backscatter and particulate matter in the water. This allows estimation, by satelite, or Particulate Organic Carbon (POC) in the ocean.

21. CZCS image of the Gulf Stream obtained on April 1, 1982, showing a prominent warm-core ring. http://disc.sci.gsfc.nasa.gov/oceancolor/additional/science-focus/classic_scenes

24. 24 MODIS Sea Surface Temperature, 2000 December 6, 17:05 and MODIS Surface Chlorophyll Concentration

25. 25 Phytoplankton Bloom in the Arabian Sea