1. Light Attenuation along the California Coast
By: LT Lars Lone
Completed for OC3570

2. Overview Reason for research Attenuation revisited Data used Results
Conclusions
Follow on studies

3. Reason for Research Thesis research
Use of hyperspectral imagery in visible to near IR range
Understand more why visibility so limited
Not really discussed in my other OC classes and wanted to look at it more

4. Attenuation Beer’s Law: Iz = Io*exp(-k*z) So: k = -ln(Iz/ Io)/z
Where Iz = PAR, Io = SPAR, k = attenuation, z = depth
So: k = -ln(Iz/ Io)/z

5. Data Used
Sites Used
2,12,23
Sites Used
40,45,46,69

6. Data Used Data sets taken from local apparent noon
Mitigates need for use of Snell’s Law and refraction issues
Looked at:
SPAR
PAR (photosynthetic active radiation)
Transmissivity
Fluorometer

7. Results: Station 2 Attenuation and Par have similar curve shape
No extreme changes in any of the data sets looked at

8. Results: Station 12 Largest variation of attenuation
Water depth greater here
Similar Transmissivity and Fluorometer as before
Interesting values for PAR sensor

9. Results: Station 23 Abnormal attenuation curve
And lowest variation in attenuation
Transmissivity and Fluorometer look fairly normal
Par sensor off by factor of 10 compared to previous 2 stations.

10. Results: Station 40 Attenuation Similar to station 12
Fluorometer readings remain constant longer
Interesting spikes in SPAR at same depth
Note surface PAR as well

11. Results: Station 45 Interesting attenuation shift
Very short attenuation range
Large PAR values near surface similar to Station 23

12. Results: Station 46 Less variation in attenuation
Interesting PAR results as well
No significant changes in Fluorometer or Transmissivity

13. Results: Station 69 Again, abnormal attenuation results
PAR sensor has a factor of 10 greater than normal once again
No significant value difference for Fluorometer or Transmissivity

14. Conclusions: Deep water had greater overall attenuation values
Typical ocean values range from .02-2
My results agree with this
Unsure of cause for spike in PAR values at half of the sites
More research needs to be done

15. Future Studies: Attenuation at times other than local apparent noon
Nearshore vs. offshore
Attenuation loss due to reflectance vs. absorption