1. LT Erica A Museler OC3570 16 September 2002
Operational Oceanography Project: comparison of in-situ and measured optical properties
LT Erica A Museler
OC3570
16 September 2002

2. Presentation Outline Guide to Ocean Optics Transmissometer
SeaWiFS/ Ocean Color
In-situ work
Leaps
Reference to Navy Operations

3. Quick Guide to Ocean Optics
Ocean optics: study of the propagation of light and it’s interactions with the materials in the ocean.
IOP’s and AOP’s
ctotal and Kd

4. Transmissometer *Instrument that measures a collimated beam of light
transmission with-in 25cm (z), using the 670nm wavelength.
*Range in water is 0-100% (0-5 VDC)
% Transmission = 20 x Volts
c = -ln (%Transmission)/[z] (1)
__________________________________________________
*For Diver Visibility take (1) and solve for z (call it R for
range of visibility and assume % transmission is constant):
R ~ 4.0/[c]
*Where did 4.0 come from?

5. CTD Transmissometer % Dive 1 Results c R 3.05 77.5 1.02 3.92 6.1 77.4
Depth % c R
3.05
77.5
1.02
3.92
6.1
77.4
9.14

6. CTD Transmissometer % Dive 2 Results c R 3.05 72.5 1.29 3.1 6.1 72.0
Depth % c R
3.05
72.5
1.29
3.1
6.1
72.0
1.31
9.14
75.8
1.11
3.6

7. CTD Transmissometer % Dive 4 Results (*) c R
Depth % c R
3.05
75.1
1.15
3.49
6.1
9.14
75.4
1.13
3.54
(*) Dive 3 was a hull dive

8. CTD Transmissometer % Dive 5 Results c R 3.05 90.0 .42 9.5 6.1 91.0
Depth % c R
3.05
90.0
.42
9.5
6.1
91.0
.38
10.5
9.14
90.5
.40
10.0

9. Transmissometer

10. In-situ work (the fun stuff.)
4 Dives for measurements (1,2,4,5)
Note: dive #3 was a hull dive and not counted for experimental measurements.
All dives with the exception of the last one showed greater visibility below ~4.6 m
The last dive had decreased visibility at the 9.14 m mark.

11. Dive Location Depths(m) Visibilities(m) 1 2 4 5 3.05 6.1 2.08 4.32
~ Monterey Bay
3.05
6.1
2.08
4.32 2
~ Port San Luis
9.14
4.57
4.7
6.15 4
7.36
7.62 5
~ Santa Barbara
6.25

12. SeaWiFS K532 (Diffuse Attenuation Coefficient at 532nm)
August 2002 monthly composite
DIVE 5:
K532~ 0.1 m-1
Light intensity will be reduced one
Natural log (1db) within 10 meters.
(ie: Visibility is 10 m deep)
The darker blue regions reveal an area
with greater visibility.

13. Observations
Visibility and Transmissivity values do not match exactly but do show the same trend for each station
This difference is associated with the different wavelengths viewed and how light is scattered
-- Transmissometer, well collimated beam of
red light
-- The human eye, un-collimated view of light in the green to blue spectrum

14. Leaps
Assumption that the eye attenuates like a narrow beam of light, ie: transmissometer
How accurate is the ‘transmissometer’?
No consideration for scattering and types of scatterers.
Assumed same contrasts
Lighting conditions and look directions are not addressed.

15. Reference to Navy Operations: Planning, Time, Operations, Money…
Salvage Ops: ‘Is it too turbid to send divers to recover this aircraft this week?’
EOD: ‘Should we send a diver (clear vis) or a dolphin (muddy waters) to ID/locate the threat?’
MIW: ‘Will our ROV camera’s see the target before physical contact is made?’
SPECOPS: ‘Will the beach insertion during the day be compromised by airborne visual contacts?’

16. End of Presentation References
National Research Counsel: Oceanography and Naval SPECWAR
National Research Counsel: Oceanography and Mine Warfare
www7240.nrlssc.navy.mil/ocolor/HOTEL
Sea Tech Transmissometer Manual
Light and Water Radiative Transfer in Natural Waters, Mobley, Curtis D. 1994
NRL: Kernal Blitz Report, April 5, 2001
DiVA Final Report, Maffione, Robert A. August 2002
Mr. Tarry Rago