Measurements of the absolute volume scattering function for green light in southern California ...

225 Pages·2014·3.74 MB·English

by  Tucker, Stevens Parrington

AN ABSTRACT OF THE THESIS OF
for the DOCTOR OF PHILOSOPHY
STEVENS PARRINGTON TUCKER
(Name) (Degree)
in General Science (Physical Science) presented on 26 May 1972
Title: MEASUREMENTS OF THE ABSOLUTE VOLUME SCATTERING FUNCTION FOR GREEN
LIGHT IN SOUTHFargalm'ORNIA COASTAL WATERS
Redacted for Privacy
Abstract approved:
VAurt, Professor of Oceanography
Wayne
In this work direct in situ measurements in deep water are
reported for the absolute volume scattering function [OM] for
scattering angles between 10 and 160 degrees from the forward
direction. The work entailed substantial modifications of the U. S.
Navy Electronics Laboratory's scattering meter (nephelometer)
described by Tyler and Austin [Applied Optics 3: 613-620 (1964)]
but heretofore unused.
Results are given for beam attenuation and absolute volume
scattering measurements of green light (dominant nm) in
sdominant
commercially distilled water, in various hydrosols containing poly-
styrene and divinylbenzine latex spheres of known sizes, in San
Diego harbor water for several runs at eight selected depths between
1 and 15 m, and in off-shore ocean waters west of San Diego,
California, at numerous depths from near the surface to more than
700 m. Data are reported for four separate off-shore cruises made
during July 1966 and August 1967.
The scattering data are presented graphically and in tabular form
and are interpreted in terms of temperature, beam attenuation, and,
for San Diego Bay, the tidal level and density structure of sea water.
Good agreement was found between scattering functions calculated
on the basis of Mie theory and laboratory tank observations with the
NEL meter. The observed scattering from 600-700 gallon batches of
commercially distilled water was in reasonable agreement with other
reported values for such easily contaminated large quantities of
water.
Comparisons are made between measurements made with the NEL
scattering meter operated in situ, on the one hand, and measurements
made with a Brice-Phoenix laboratory scattering meter on simul-
taneously collected Nansen samples. The dissymmetry ratio
[Z45 p(45)/(1 (135)] was consistently lower by an average factor
=
135
of more than two for the Brice-Phoenix as compared to the NEL
meter, for which the range was 12.0 Z 16.1 for San Diego Bay
water. These observed differences may be attributed in part, at
least, to settling of larger particles from the turbid harbor water
(beam attenuation coefficient ,^; 2 m-1), both in the Nansen bottles used
to collect water samples and in the scattering cuvette.
In off-shore waters Z was--in the ocean region investigated--seen
generally to decrease between a maximum of 9. 37 near the surface
(29 m) to a minimum of 1.98 at a relatively great depth (553 m). The
absolute volume scattering functions measured with the NEL scattering
meter are in reasonable agreement with other, less direct, observations
which have been reported.
Tentative calculations of the total scattering coefficient
[b = ffp(Q)d...a.] were made on the basis of Jerlov's [Reports of the
41r
Swedish Deep Sea Expedition 3: 73-97 (1953)] hypothesis that
b = k p(45), taking k = 30 sr. This value for k gives plausible
results for b and the absorption coefficient based on absolute
values of p(45) for offshore waters. This value for the "constant"
k appears, however, to be too high for San Diego Bay in which at
times c - 30/3(45) < 0 and k = 12 sr gives somewhat more
.,_
reasonable results.
Unfortunately, simultaneous scattering measurements were not
available in the near-forward range of angles, i.e.,
0 4. Q< 100
,
within which a major portion of the scattered light is directed, thus
making it impossible to carry out the integration of /(9) to obtain b
directly.
Measurements of the Absolute Volume Scattering
Function for Green Light in Southern California
Coastal Waters
by
Stevens Parrington Tucker
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Doctor of Philosophy
June 1973
APPROVED:
Redacted for Privacy
Wayne V. urt, Major Professor, Professor of Oceanography
Redacted for Privacy
David L. Willis, Chairman, General Science Department
Redacted for Privacy
Dean of Graduate School
Date thesis is presented 26 May 1972
Typed by J. B. Madler for Stevens Parrington Tucker
ACKNOWLEDGEMENT
I am deeply indebted, to the late Dr. George F. Beardsley, Jr, ,
whose support and encou ragen-ient made the completion of this work
possible, To Dr, Wayne V, Burt I owe thanks for his encouragement
to pursue this study in the first place,
I owe special thanks to Mr, Kenneth V, Mackenzie of the Naval
Undersea Research and Development Center and former head of the
NEL Deep Submergence Group, for his support while I was at the
Navy Electronics Laboratory. Thanks are due also to Mr. Robert
Seeley who designed and constructed the projector lamp current
regulator and helped at sea.
I am indebted also to Senior Chief Petty Officer Douglas Tarvin,
USN, Captain of the YFU-45 and his crew for their help during
numerous cruises in 1965 and 1966; and to Lieutenant J. M. Rodgers,
USN, Captain of the USS REXBURG, and his crew for their assistance
during our several cruises in
1967.
Finally, and most especially, I am indebted to Mr. James Reese
of the Naval Undersea Research and Development Center, whose help
in all aspects of this work proved invaluable, including work at sea,
data reduction, and writing both the Mie scattering and data reduction
programs.
TABLE OF CONTENTS
Page
I. INTRODUCTION 1
II. NEL SCATTERING METER 16
A. Introduction 16
B. Mechanical Modifications 20
1. Suspension Frame 20
2. Cable 22
3. Batteries 23
4. Battery Boxes 23
5. Power Supply Case 25
C. Electrical Circuit ry 27
1. Introduction 27
2. Deck Control Box 27
3. Motor Housing Circuitry 28
4. Detector 30
5. Projector 31
6. High Voltage Supply and Projector Servo 31
III. CALIBRATION OF THE NEL SCATTERING METER . 38
IV. MEASUREMENT PROGRAM 51
A. Introduction 51
B. Distilled Water 51
C. Scattering from Artificial Spheres 54
Laboratory Measurements on Samples of
D.
San Diego Bay Water 58
E. IN,leasure:-.1i':s of Sari Diego Bay
Water at t]-1e. NEL 59
F. Measurements in Coastal Waters off San Diego . . . 76
V. SUMMARY 105
VI. BIBLIOGRAPHY 107
APPENDIX A FORTRAN program used to reduce NEL
scattering meter data on the NEL CDC
1604 computer 112
APPENDIX B FORTRAN program used to reduce Brice-
Phoenix scattering meter data on the OSU
CDC 330 digital computer 114
APPENDIX C FORTRAN program used to make Mie
scattering calculations on the NEL CDC
1604 computer 117
APPENDIX D Graphs of absolute volume scattering
functions measured with the NEL
scattering meter 121
APPENDIX E Tables of absolute volume scattering
functions measured with the NEL
scattering meter 136
APPENDIX F Tables of absolute volume scattering
functions measured with the Brice-
Phoenix scattering meter, 204
APPENDIX G Graphs of the total beam attenuation
coefficient (c) as a function of depth
measured with the NOTS null-balance
transmissometer, USS REXBURG,
21-24 August 1967 210
LIST OF FIGURES
Figure Page
Schematic diagram to show the basic
1. 6
instrumental geometry used in the measure-
ment of p(g)
2. Photograph of the NEL scattering meter before 19
modification. The projector housing is at the
left while the detector is on the right. The
black box in front of the projector is a light
trap. The black cylinders in front of the
detector and projector are light shields
3. NEL scattering meter support frame (a) and 21
cable termination (b)
4. Type 30H battery (12 V, 100 AH) modified for 24
use in high pressure oil bath (a). Battery box
schematic (b)
5. Block diagram showing the principal components 26
of the scattering meter and the necessary con-
necting cables
6. Motor housing switching circuitry 29
7. Block diagram of solid state servo illumination 32
control unit
8. Schematic diagram of solid state servo 33
illumination control unit
9. Photograph of the assembled instrument 37
package. Battery boxes are at each corner,
while the Marine Advisers alpha-meter is
to the left of the NEL scattering meter. A
thermistor probe is shown strapped to the
black cylinder immediately beneath the pro-
jector housing. The high voltage power
supply and photometer circuitry are in the
case at the far right-hand side. (The small
cylinder between the battery boxes on the
left contains a CO2 sensor. )
10. Volume calibration schematic: I./ = r = 48. 3 39
cm. The photo-tube was normal 10 th2e cali-
bration plate.
atic 42
Figure Page
12. Volume ratio by Tyler's procedure (1963). 46
The solid line is a least-squares fit of
V 1(0)/A
13. Cross section of a diverging projector beam 48
14. Examples of raw data from several NEL 50
scattering meter runs. Distilled water in
laboratory tank (a), San Diego Bay water at
the NEL barge (b). Offshore deep water (c)
15. Chart showing the locations of the ocean 52
stations at which scattering measurements
were made off San Diego
16. Chart showing the locations of the NEL barge 53
and the near-shore station in San Diego Bay
17. Scattering functions for distilled water 55
18. Scattering functions measured for latex 57
spheres. Solid lines are best fits calculated
by Mie theory; dotted lines are measured
s catte ring. Ordinates: relative scatte ring
coefficient. Abscissas: scattering angles in
degrees. a = radius of spheres, m = relative
refractive index, and k = wave number
19. Volume scattering coefficient as a function 60
of scattering angle for San Diego Bay water
in NEL tank, 18 May 1967. Vertical bars
indicate probable uncertainties in the abso-
lute values of p(Q)
20. Comparison between NEL and Brice-Phoenix 61
scattering meters for San Diego Bay water,
18 May 1967
21. Tidal level in San Diego Bay as a function of 65
time during scattering meter lowerings A, B,
and C from the NEL barge
22. Beam attenuation, absorption, and total 67
scattering coefficients, salinity, and
al,
temperature as functions of depth for
lowerings A (a), B (b), and C (c) at the
NEL barge, 29-30 June 1967
23. Water density (C/t. ) plotted as a function of 68
beam transmission (c) for each of the three
casts made at the NEL barge in San Diego
Bay, 29-30 June 1967