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V i s i b i l i t y Laboratory-Un ive r s i t y of C a l i f o r n i a
Scr ipps I n s t i t u t i o n of Oceanography San Diego 52, C a l i f o r n i a
ATMOSPHERIC OFTICAL MEASUREMENTS IN WESTERN FLORIDA,
FLIGHT 112, P a r t I
Aimerian R. Boi leau
April I960 Indox. Number NS 714-100
810 REFERENCE 60-22
Bureau of Ships Contract M0bs~72092
Approved:
/ -'if Seibert Q. Duntley, Director V i s ib i l i t y Laboratory
or J
Approved for Distribution:
& /f^uli. RogeirRevelle, Director Scripps Institution of Oceanography
SIU KNFKFJKMCF. 6 0 - 2 2
TABLE OF CONTENTS
Page
INTRODUCTION AND SUMMAHY 1
PROCEDURE 2
Fl igh t P a t t e r n , Figure 1 3 Temperature P r o f i l e , Figure 2 5 Color Photographs of Sky, Figure 3 , e t . seq 7 Sun ' s Zenith and Azimuth Angles, Figure 10 15
PRESENTATION OF DA/A 16
Catalogue of Graphs 18 Data v s . A l t i t u d e , Figure.. 1.1, e t . seq . ?Q Data v s . Azimuthal Angle, Figure 26, e t ^ seq. 35
DISCUSSION 53
Preface 53 Notation and Insti-umentation 53 Filter-rhototube Spectral Response, Figure 44 54 Recorded Optical Quantities 56 Computed Optical Property 58 Operational Procedure 59 Cycling of Filters 61
REFERENCES
ACKNOWLEDGEMENTS
ATMOSPHERIC OPTICAL MEASUREMENTS IN WESTERN FLORIDA,
FLIGHT 112, Part I~"~
by
Almerian R0 Boileau
INTRODUCTION AND SUMMARY
The Visibility Laboratory of the University of California, La
Jolla Campus, is engaged in an on-going research program studying
optical image transmission through the atmosphere. In connection with
this work several data gathering flights were made in western Florida
in the vicinity of Eglin Air Force Base in the spring of 1957. Flight
112, the subject of this report, was one of these.
Part I of this report, presents the data as a catalogue of
the recorded optical measurements as they varied with altitude, time
of day, azinuthal angle with respect to the sun, and meteorological
conditions. Not included is the distribution of the sky's luminance
and radiance which will be presented as one or more additional parts
of this report.
•$:-
This report is a result of research which has been supported by the Geophysics Research Directorate, Air Force Cambridge Research Center, Bedford, Massachusetts, and the U. S. Navy Bureau of Ships.
SIO Ref. 60-22 - 2 -
PROCEDURE
U. S„ M r Force XB-29, No. 4224725 took off from Eglin Air Force
Base, Florida, at 0917 Eastern Standard Time, 16 May 1957 to begin
Flight 112. This airplane carried optical and meteorological instru
ments from the Visibility Laboratory of the University of California,
La Jolla Campus. At the time of the flight there were nine optical
instruments in operation plus one meteorological instrument, viz.,
a resistance type indicating vortex thermometer. The airplane arrived
at 20 000 feet altitude preparatory to data gathering at 1010.
Data were gathered from 20 000 feet to 1 000 feet as follows:
Eastern Standard Time
1010 - 1036
1042 - 1057
1057 - 1108
1108 - 1118
1119 - 1127
1200 - 1204
Altitudes Headings
At 20 000 feet 000°
20 000 to 10 000 feet 355
At 10 000 feet 175°
10 000 feet to 000° 1 000 feet
At 1 000 feet ' 180°
On Eglin A.F. Base 185° runway
The flight pattern was north and south between Eglin Air Force
Base and Crestview as shown in Figure 1.
SIO Ref. 60-22 - 3 -
O I
31 00
F L I G H T T R A C K
F I G U R E I F L I G H T I I 2 16 MAY 1957 C R E S T V I E W , F L O R I D A
SIO Ref. 60-22 - 4 -
The day was clear and xvarm. During ascent, from take-off to
20 000 fee t , the a i r temperature was recorded at each 100 feet of
a l t i t u d e . The temperature prof i le i s shown as Figure 2. Near the
p ro f i l e , at the appropriate a l t i t u d e s , are subjective notes made by
the project engineer during ascent. The smooth curves drawn near the
temperature prof i le represent pseudo-adiabats. Note that in general
the observed haze layers are at a l t i t udes where the temperature p rof i l e
has a g rea t e r slope than the pseudo-adiabats; the haze layer jus t below
10 000 feet and the lack of an observed haze layer between 16 500
feet and 17 500 feet are exceptions.
SIO Ref. 60-22 - 5 -20, i 2 0
.ti
IWg
m G j-tR: m m uSfe ssjeS LE^E^JTff l iSQi S l f l f f i f e
16
HF
UJ UJ u-l
;f£ EF
n;; CO Q
z" < 13 O X
rW
FF Sffl
m .
10 :~. i <-]:!::
H-
LiJ Q
I ' M
TPTr
8
4:
;+
;p-'
0 ±~i-
ii 4-~; Mr
j ± i t Hi ii 0 2 4 6 8
R A T U R E ( ° C ] FIGURE
S.IO Rcf. 60-22 - 6 -
Color p r in t s made from Kodachrome transparencies taken by the
project engineer in the bombardier's posit ion of the B-29 describe
the day much be t t e r than word3. These are shown in Figures 3 through
9 immediately following th i s page. These were taken through the glass
windows at the bombardier's pos i t ion . Reflection of objects inside
the airplane are seen in several of the p r i n t s .
SIO Ref. 60-22 (second printing) -7 to 13 -
Figures 3-9, included in the first printing of this report,
consisted of color prints from Kodachrome transparencies made during
data-gathering runs. These depict the appearance of the sky as seen
from 20,000, 10,000, and 1,000 feet and while they give the reader a
visual description of the atmosphere during flight, something highly
desirable, they are not necessary for using the data in Figures .11-4.3.
Accordingly, these Figures are not included in this second printing.
310 Ref. 60-22 l/; -
Azimuthal and zenith angles of the sun computed for 30.5 N.
Lat. and 86.5 W. Long., the approximate position of Eglin .d.r Fore-
Base, are shown in Figure 10 immediately following this page. Those
angles are plotted for the period 1 000 to 1 200 Eastern Standard Time.
The ordinates of the lower graph are shown as zenith angles on the
left and as elevation angles on the right, these angles being comple
mentary.
SIO Ref. 60-22 - 15
I b U — ^ / CO UJ UJ 1 50— <r o UJ
o 1 4 0 -
I (-3 1 3 0 -5 M < 12 0—
y> 2 3 1 1 0 -CO
1 0 0 -
I I i i i 1000 1030 1100 1130
E A S T E R N STANDARD
1200 1230
T I M E
UJ 6 0 - |
O UJ Q
UJ _ l
<
I
z UJ N
_C0
~z 3 CO
5 0 -
4 0 -
1000
r - 3 0
- 4 0
- 5 0
1030 1100 1130 EASTERN STANDARD T I M E
1200 1230
SUNS A Z I M U T H U L AND Z E N I T H ANGLES
DURING FL IGHT 112, COMPUTED FOR
POSITION 3 0 . 5 ° N. L A T . , 8 6 . 5 ° W . L O N G .
F I G U R E 10 F L I G H T 112 |6 MAY 1957
E G L I N A. F.
..'JiO Ref* 60-22 lfc -
PRESENTATION OF DATA
The- da t a recorded dur ing F l i gh t 112 are presented herewi th as
a ca t a logue of g raphs . Each measured q u a n t i t y i s shown as i t var ied
with a l t i t u d e and t i n e or as i t va r i ed with r e s p e c t to the s u n ' s
azimuth. The computed apparent a t t e n u a t i o n l eng th v a l u e s , L^ (z ) ,
a re s i m i l a r l y p re sen t ed .
The purpose-: of t h i s r e p o r t i s to make a v a i l a b l e the da t a which
were recorded and, in the case of t h e a t t e n u a t i o n l e n g t h , computed.
I n t e r p r e t a t i o n and d i s c u s s i o n of a p p l i c a t i o n s of t he se da t a arcs
rese rved for subsequent r e p o r t s .
The fol lowing no tes concern ing the graphs a r e p e r t i n e n t :
1. Each instrument measured a photometric quantity and i t s
radiometric counterpart . This was accomplished by successively i n t e r
posing four di f ferent opt ica l f i l t e r s in to the f lux path of each
instrument. The four measured quant i t ies were sampled once each f i l t e r
cycle. (See Figure 44 for f i l ter -phototube spec t ra l responses).
The f i l t e r cycling and r a t e of descent were such that data points were
recorded approximately three times per thousand feet of a l t i t u d e . The
graphs presented herein are faired cujrves based on the data po in t s .
2. Certain f igures, e . g . , Figures 17, 18, 19, and 20, have a
v e r t i c a l l ine drawn which represents the l imit ing high value of the
instrument 's response. This condition i s further indicated by the words
SIO Ref. 60-22 - 17-
"OFF' SCALE" printed to the right of the vertical line. At the conclu
sion of this field trip the sensitivity of each of those instruments
was adjusted to permit higher values to be recorded.
3. In Figures 18, 19, and 20, the two limiting graphs which enclose
the crosshatched area represent the range of values obtained by the
nadir telephotometer. This telephotometer has a 1 circular cone
acceptance angle. At 20 000 feet the area subtending this angle is a
disc 350 feet in diameter, at lower altitudes the diameter is less.
Hence areas of different reflectances, which are seen successively as
the airplane flies along a prescribed course, will cause the nadir
luminances, and radiances to fluctuate over a range of values.
SIO Ref. 60-22
CATALOGUE OF GRAPHS
Atmospheric Op t i ca l Measurements vs A l t i t ude and Time
Quant i ty Syjibol Figure
I l luminance , Downwelling V r 11
I r r a d i a n c e , Pcwuwel]ing K ( z , ~ ) 12-13
I l lvmir .ance, Upwelling E ( z , + ) 14
I rradn. anc e, Upwel l i n g H ( z , + ) 15
Luminance, Zenith B(z ,0 ,0 ) 16
Radiance, Zenith N(z ,0 ,0 ) 17
Luminance, Nadir B(z,180° ,0 ) 18
Radiance, Nadir N(z,180° ,0 ) 19-20
Luminance, Hor i zon ta l B(z ,90° , 0
113 ) 21
Radiance, Hor izon ta l N(z ,90° , o N
113 ) 22
Luminous Path Function Hor i zon ta l
B ( z , 9 0 ° 0
,113 ) 23
Radiant Path Function N^.(z,90° ,113°) 24 Hor izon ta l
Apparent At tenuat ion Length LA(z) 25
SJO Ref. 60-22 - 19 -
Atmospheric Optical Measurements by Azimuthal
Distr ibut ion a t Constant Altitude
Time iil-iiHI-L?. Zi&lJ!£ Page
1016 20 000 feet 26-31 35-40
1105 10 000 feet 32-37 41-46
1119 1 000 feet 38-43 47-52
The horizontal luminous path function, horizontal radiant path
function, horizontal luminance, and horizontal radiance were recorded
at each of the above a l t i tudes and from these recorded values apparent
at tenuation lengths for the photometric case and two radiometric cases
were computed. At each of the above a l t i tudes the upper and lower sky
luminance and radiance values were also measured; these quant i t ies w i l l
be the subject of addi t ional par ts of th is report .
SIO Ref. 60-22 20
- 20 -T O T A L a 1042 EST
\
JMIMAN 18
17
L L U M I MA MC
xm—sirr FTTJT;—jrurr
14 / '
ui UJ u.
O |2
CO o z < CO 3 o I
UJ Q 3
i 1057 EST
108 E S T
V
a
A
1118 EST -I r
D 0 W N W E L L ING F T " 2
i i i i i i
I.L L U M I N A N C E L U M E N S
E ( z , - )
O o
o o CM
o o o
o o m o o
o o o o o
O O o CD (T> Q
O o o r\J
FIGURE II FLIGHT NO. 112 MAY 16, 1957 C R S S T V I E V / , FLORIDA ,
O O O O o O O ro
O O
O O in
O O 10
O o o o CD
b o o
SIO Ref. 60-22 - 21 -
1042 EST TOTAL
IRRADI ANCE
FROM IRRADIA JCE
3KT FRO M SUN
1 1057 EST
1108 EST 7i
^
18 EST
I R R A D I A N C E , DOWNWE
WATTS F T " 2
LING H ( z , - )
( B L U E REC,ORp) £ i« in i t ;
FIGURE 12 FLIGHT NO. 112 MAY 16, 1957 CRSjSTVIEVy, FLORI.DA J i_
CM
6 d CO
d r- co o> o d d
CM ro if) CD r- 00 0> o
SIO Ref. 60--22 £4. -
o-
\
1042 EST
I R R A D I M C-O-A-M «H
MC E &H—
M TOTAL
9 -V IRR / DIANCE:
] F R O M SKY i 8 -
L_ \ ( •
\ 16-— )
15
14
\ . 13
\ ) 12
\ r
II
{ 10 57 EST. I 10 110 8 EST.
9 T 8 L 7
•fa
c
~i -t \ \
\ \ 1 \ \ •
/ i) 1 _ 1
I R R A D I A N C E , WATTS FT
DOWI^ - 2
1 JW E
(F
L L I NG IED R
i i
H ECOR
i i
. » ' FIGURE 13 U r 1 FLIGHT NO. 112 n \ MAY 16, 1957 D ', , CRE jSTVIEW. FLORI.DA ,
•>C )l CJ ro <T. m CD f*- CO CD _ CM ro <J- m CD r- 00 <Ji o
o o
SIO Ref. 60-22 - 23 -
2 0 1042 I : S T
18
17
16
14
i j
^ 13
? 12
r>
2 II st S> 3
£ IO
3
t 8
0 5 7 EST
1108 EST
EST
I L L U M I N A N C E . L U M E N S
U P W E L L I N G - 2 J I I I
E ( z , + ) FT
'O O
o o CM
o ro
O O
O O m
o o CD
o o
o o o o CD o
-6~ o o CM
FIGURE 14 FLIGHT NO. 112 MAY 16, 1957 CREjSTVIEty, FLORI,0A
O
8 lO
O O 2
O O s
O O o i n o 2
r>_ CD
6-6-i o o & °-CD ^-f
SIO Ref. 60-22
2 0
18
17
15
14
10
- 24 -
RED
1042 EST
1057 EST
BLUE
1108 EST
18 EST
IR R A D I A N C E , U P W E L L I N G WATTS F T " 2
— 1 — 1 • ' ' CM
d J_
H ( z . - r - )
J i i ro *r in co FT oo en
o" 6 d d o d 6 "" _i CM
FIGURE 15 FLIGHT NO. 112 MAY 16, 1957 C R E f f T V I E W , FLORI.DA
ro _i_ _L.
m CD co en o
STO Ref. 60-22 - 25 -
2 0
19
0 4 2 EST
17
16
15
14
ui w 13 u.
u. P 12
on Q
< CO | 3 P :X 10
0 5 T E:S
UJ
Q
b
I 3 E S T
L U M I N A N C E , Z E N I T H B ( Z , 0°, 0°)
FO,OT l .AM,BE RTS
FIGURE 16 FLIGHT NO. 112 MAY 16, 1957 CRESTVIEV^, FLI OR! DA ,
"8 88 o o o m m e-i
O O
o o o o o o o o o o o o o o o o o o CM rO 1 - m CD r CO en O
o o CM
O O
O O
o o in
O O O m
O O O s-
SIO Ref. 60-22 - 26 -
CM to r m CO N- CD O"1
d O O o o o o o
SIO Ref. 60-22
20
- 27 - •
UJ UJ
u.
CO Q
z < CO 3 o X
UJ
Q
3
_J
<
o o O O O o o o o o o o o y o o o o CM rO xf in y r - co CD o
o o o CM
o o 8
o o o o o 8
o o o CD
o o o c o o o c N 00 O C
310 Ref. 60-22 - 28 -
R A D I A N C E
W A T T S Cl~
NA DIR
F T ' 2
N ( Z , 180, 0 )
( B L U E RECORD i i i J L
FIGURE 19 FLIGHT NO. 112 MAY 16, 1957 C R E g T V I E ^ , FLORI,0A
-dr O
d
CM ro xT in CO r*- co en O O o ' o o o o o — o o o o o o d o" o
CM
d ro
d o in O
CO
d I s - CO
o d d
SIO Ref. 60-22 - 29 -
1 342 E ST
r
< *z: n 2 2 .
r-r
4 ^ i / /
i
•
<?
10 57 ES T
/£ UJ _ i
-II 38 ES T
i % CO
' /
u. u. o
; / ^ %
£ / '£ —
< 5 —
< t t £//
.2/ £ "^T
%
1118 E :ST _
'// / s
/ : $ >
R A D I A N C E , N A D I R
W A T T S , £l~[ F T ^ 2 (
N ( Z , 180° 0°)
R E P RECORD)
FIGURE 20 FLIGHT NO. 112 MAY 16, 1957 CRE,STVIE\y , FL0RI,DA , , ,
o d
CM ro NT m CD N 00 0> O O O o O O o o — O O o o O o d d o
CM
d ro d
*r m co F- oo cr> d 6 o d d o'
SIO Ref. 60-22 - 30 -
2 0
19
18
17
15
14
j j
•u 13
2> 2 | | «t LO 3
° 10
00 0
iis.
1042 EST
1057 ES
0 8 ES
1118 EST
L U M I N A N C E , H O R I Z O N T A L B ( Z , 9 0 ° 113°)
FOOT L A M B E R T S O o
o o CM
o o ro
6—6-o o m
o o CD
O O r
o o CO
J L
FIGURE 21 FLIGHT NO. 112 MAY 16, 1957 CRSjSTVIEW. FLORIDA ,
O O O
O o o CM
o o o ro
O O O
O o o m
o o CD
O O O O o o o O o o o o N CO CO O
SIO Ref. 60-22
2 0
- 31 -
1042 EST
<>
s )
R.EC 1 1 B L l E
\ 1 1
3 5 5 ° < ,
1
I I
)
, (
/
1057 EST 1 / 1108 EST } 1
/
0 0 0 ° \ I
• \ \
t 1 \
I
1118 EST - .
RADI ANC E , HORI
W A T T S XT ' F T "
ZONT - 2
A L M ( Z , 9 0 ° 13°) F I 6 U 1 0 ' FLIG
MAY i CRE
RE 2 2 HT NO. 112
16, 1957 ? T V I E t y , FLORI DA
O d
CM O d
ro v(- i f i (D 1 - CO Cl O O o o o o Q —
d d o 6 ci o 6 °
CM ro xt; in CO r oo en d o O O O O o o
SIO Ref. 60-22 i
20
19
- 32 -
18
17
16
15
14
ui w 13 u.
u. o 12
CO Q
z <£ CO 3 O X
10
cu Q 3
0
LUMINOUS PATH FUNCTION B „ ( Z , 9 0 ° 113°)
FOOT L A M B E R T S / N A U T I C A L M I L E J I L J L
F I G U R E 2 3 F L I G H T NO. 112 MAY 16 , 1 9 5 7 C R E f t T V I E V y , F ORI.OA
o ^ O CM
o O O O O O o o ro xT in CD N co en o
o o CM
o o ro
O O xT
O m o
CD
O O
o o r>- co
o o o.o en O
SIO Ref. 60-22 - 33 -
104 2 ES T J. ^
{ RED
\ BLUE
3f > 5
\
IC 5" • EST * 1
1 10 3 EST
(
0 0 0 ° ... t
...
J
< /
1118 EST
R A D I A N T PATH FUNCT W A T T S ft"1 FT ~ 2
i /
ION NAl
N. (Z ,« J T I C A L
*0° Ml L
i
, ° FIGURE 2 4 ' ' 13 ) FLIGHT NO. 112 c MAY 16, 1957 c , C R E S T V I E \ y , FLORI.DA
o o
CM
O O
ro xf m CD 1"- co en _
O O o o o O O Q o ° o O o o o o O O Q o ° o
CM
o ro o
xf
o m o CD
O O oo en r o o -3
o o o o O O o o c •>
SIO Ref. 60-22 20
-34-
1042 E
T \
/ /
i )
' 1 j
\
<
J
/
BLUE / /
) P HOT. /
IC 5" r EST - ' / R ED
II Dc EST)
; /
- -- -
^
l i l t J ES T r
APPARENT t VTTENU/ N AUTK
XTION : A L
LE M I L
NGTH ES
I
L A ( Z
1
- N , O R B/' FIGURE 25 ) - / K I U K / D FLIGHT NO. 112
™* D * MAY 16, 1957 i CREiSTVIEty , FLORI.DA L ... \,
CM rO in to N co en o o CM
o ro
O xf
o o o d . p g m co r- co »• q
STO Ref. 60-22
310
300
2 9 0
2 6 0 - / -
270
2 6 0
2 50
240
2 30
L U M I N O U S PATH FUNCTION B*( 2 0 , 0 0 0 , 9 0 ° c/> )
FOOT L A M B E R T S / N A U T I C A L M I L E
PHOTOPIC RECORD 2 0 , 0 0 0 FT 1016 EST
F I G U R E 2 6
F L I G H T NO. 112
MAY 16, 1957
C R E S T V I E W , FLORIDA
SIO Ref. 60-22 - 36 -
200 190 180 170 160
i. L U M I N A N C ' E , H O R I Z O N T A L B ( 2 0 , 0 0 0 , 90°, c/> )
FOOT L A M B E R T S
PHOTOPIC RECORD 2 0 , 0 0 0 FT 1016 EST
F I G U R E 2 7 F L I G H T NO. 112
M AY 16, 1 9 5 7 CR E S T V I E W , F L O R I D A
SIO Ref. 60-22 © 9 0
- 37 -
A P P A R E N T A T T E N U A T I O N LENGTH L A ( 2 0 , 0 0 0 )
N A U T I C A L M I L E S
PHOTOPIC RECORD 2 0 , 0 0 0 FT 1016 EST
F I G U R E . 2 8 FLIGHT'- NO. 112-
MAY 16 , 1 9 5 7 .
CR E S T V I E W, FLOR I DA
SIO Ref. 60-22 <D - 38 -
< •
200 190 180
R A D I A N T P A T H F U N C T I O N N ^ ( 2 0 , 0 0 0 , 90°, c/> )
WATTS fl,"1 FT " 2 PER N A U T I C A L M I L E
B L U E AND RED RECORDS 2 0 , 0 0 0 FT 1016 EST
F IGURE 2 9 F L I G H T NO. 112
MAY 1 6 , 1957
C R E S T V I E W , F L O R I D A
SIO Ref. 60-22
200 190 180 170 160
F I G U R E 3 0 F L I G H T NO. 112 R A D I A N C E , H O R I Z O N T A L N ( 2 0 , 0 0 0 , 9 0 , c/> )
W A T T S £l~l F T " 2 MAY 16,1957
BLUE AND RED RECORDS 2 0 , 0 0 0 FT 1016 EST CR E STVi E W, FLOR I DA
SIO Ref. 60-22 - 40 -
200 190 180 170 160
A P P A R E N T A T T E N U A T I O N L E N G T H L A ( 2 0 , 0 0 0 ) ' F L I G H T NO. 112
N A U T I C A L M I L E S M A Y ,6,1957
B L U E AND RED R E C O R D S 2 0 , 0 0 0 FT 1016 EST C R E S T V I E W , F L O R I D A
STO Ref. 60-22
200 190 180 170
O
160
LUMINOUS PATH FUNCTION B„( I 0, 000 , 90° <f>)
FOOT L A M B E R T S / N A U T I C A L M I L E
PHOTOPIC RECORD 10,000 FT 1105 EST
F I G U R E 3 2
F L I G H T NO. 112
MAY 16, 1957
C R E S T V I E W , F L O R I D A
+•. SIO Ref. 60-22 t§) • 6 0 0 0
- 42 -
- 9 0
200 190 180 170
L U M I N A N C E , HORIZONTAL B( 10 ,000 , 90? c/> )
FOOT L A M B E R T S
PHOTOPIC RECORD 10,000 FT 1105 EST
160
F I G U R E 3 3 F L I G H T NO. 112
MAY 16, 1957
C R E S T V I E W , FLORIDA
SIO Ref. 60-22
310
300
2 9 0
280 - f -
270
2 6 0
2 50
240-1
230
- 100
120
130
200 190 180 170
A P P A R E N T A T T E N U A T I O N LENGTH L A ( ( 0 , 0 0 0 )
NAUTICAL MILES
PHOTOPIC RECORD 10,000 FT 1 1 0 5 EST
160
F I G U R E 3 4 F L I G H T NO. 112
MAY 16, 1 9 5 7
C R E S T V I E W , F L O R I D A
SIO Ref. 60-22
310
300
290
280
270
2 6 0
250
240
230
R A D I A N T PATH FUNCTION N*( 10,000 , 90 , t/> ) >-l
WATTS &~' FT . " 2 PER N A U T I C A L M I L E
B L U E AND RED RECORDS 10,000 FT 1105 EST
F IGURE 3 5 F L I G H T NO. 112
MAY 16, 1 9 5 7
C R E S T V I E W , F L O R I D A
310 Ref. 60-22
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F IGURE 3 6 F L I G H T NO. 112
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F IGURE 3 7
F L I G H T NO. 112
MAY 16, 1957
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MAY 16 , 1957
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MAY 16, 1957
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A D I A N T PATH FUNCTION N*( 1000 , 9 0 ° , $ ) »- l - , ~ 2 W A T T S £l~ FT PER N A U T I C A L M I L E
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F I G U R E 41 F L I G H T NO. 112
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F I G U R E 4 2 F L I G H T NO. 112
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F I G U R E 4 3 F L I G H T NO. 112
MAY 16, 1957
C R E S T V I E W , F L O R I D A
SIO Ref. 60-22 - 53 -
DISCUSSION
Preface
The V i s i b i l i t y Laboratory of the Un ive r s i t y of C a l i f o r n i a , La
J o l l a Campus, has been engaged for s e v e r a l yea r s in an on-going research
program concerning image t r ansmiss ion through the atmosphere. This program
• j- 1
is discussed in "Image Transmission by the Troposphere I." In this
article;, of special interest in connection with this report, are notation,
discussion of path functions, attenuation length, and the concept of
equilibrium radiance (and luminance).
Notation and Instrumentation
The notation used in this report follows the notation given in
detail in the aforesaid article. The radiometric quantities irradiancc and
radiance are designated by H and N, respectively; the photometric counter
parts illuminance and luminance are designated by E and B, respectively..
In the parentheses following the basic symbols, z specified altitude
in feet, the minus sign - indicates downwelling flux, the plus sign +
indicates upwelling flux, 0 specifies the zenith angle of the line of
sight of the photometer, and 0 specifies the azimuthal angle of the photo
meter. In this report the azimuthal angle 0 is with respect to the
-•Dun's bearing.
The phototubes in the optical equipments are filtered to provide certain
spectral responses. The photometric quantities are those recorded with
phototube-filter combination that has the spectral sensitivity of the
standard luminosity curve for the daylight-adapted human eye. This is
designated as the "photopic" response and is shown as the upper curve of
Figure 44.
S. 0. Duntley, A.R. Boileau, and R.W. Preisendorfer, "Image Transmission by the Troposphere I, "Journal of the Optical Society of America, 47, pp. 499-506, (1957). ' ~~
SIO Ref. 60-22 - 54 -
4i00 i ; . !,• • - T ' T T .
_.LLL:.-.._LU F I G U R E 4 4
STO Ref. 60-22 - 55 -
At the time of Flight 112 the phototubes were also filtered to
respond to radiant energy in the blue end of the spectrum in accordance
with the blue spectral sensitivity curve in Figure 44. Similarly, they
were also filtered to respond to the radiant energy in the middle part
?nd the red end of the spectrum in accordance with the green and red
spectral sensitivity curves in the same Figure. In this report these
three sensitivities and responses to radiant energy recorded through
these three filters are referred to as "blue" "green" and "red" sensiti
vities .and responses.
In each instrument the filters uned to provide the four filtered
phototube spectral sensitivities are interposed successively in the flux
path by the action of a ratchet solenoid which drives a wheel in which
the filters are mounted. The ratchet solenoids are controlled from the
project engineer's station so that all instruments have the same filter
in position at any one time.
At the time of Flight 112 the normal order of interposition of
filters was photopic, blue, green, and red. Subsequent reduction of
data showed that the photopic and green data (when reduced to the same
dimensional units) were so similar that it was decided to limit the
data reduction and presentation to the photopic, blue, and red.
The phototubes are believed to measure the total radiant flux
incident upon their cathodes independent of the degree of polarization.
A test of several of the phototubes which are used in the optical instruments
showed no rtiscvrnjble effect when polarized light with the direction of
polarization undergoing a continuous change of 360 was incident on the
phototube's cathodes.
SIO Ref. 60-22 5 6 -
Recorded O p t i c a l Quan t i t i e s
The fo l lowing opti c.n~\ qnant. i t . ics w^i-o recorded during F l i g h t 112:
Quant i ty Symbol Cns trumen t a t i o n
I l l uminance , Dovvnwe?ling
I r r a d i a n c e , ~.cw.a-relling
I l luminanc e , Upwel1 j ng
I r r a d i a n c e , Upwelling
E(z,-)
H(z,-)
E(s,+)
Measured on a horizontal flat plate collec- tor,,v A rotating device shadows the collector plate from the 3r.n:s rays twice each revolution thus giving a measure of illuminance fcoa the diffuse sky light.
Measured on a horizontal flat plate collector'""
Luminance, Zenith
Radiance,, Zenith
Luminance, Nadir
Radiance, Nadir
B(z,0,0)
N(z,0,0)
Measured by zenith telephotometer. Instrument is mounted so that when airplane is level it measures integrated luminance (or radiance) of a 1° circular cone of zenith sky.
N(z,180 ,0) Measured by nadir telephotometer. Instrument is duplicate of zenith
N(z,180°,0) telephotometer and is mounted to measure the integrated luminance (or radiance) of a 1° circular cone of nadir sky.
The flat plate collectors are made from translucent opal plastic. The exposed side of the plate is ground to a fine mat surface until the incident radiation is accepted nearly proportional to the cosine of the angle of incidence.
sro nof. ^-22 - 57
Quantity Symbol Instrumentation
Luminance, Horizontal
Radiance, Horizontal
B(z,90 ,0) Measured by equilibrium radiance 0 telephotometer of attenuation
N(z,90 ,0) meter.1 This telephotometer measures average luminance (or radiance) of g° circular cone of sky directly in front of ai rplane.
Horizontal.Luminoue Path Function
Horizontal Radiant Path Function
B„(z,90 ,0)
N (z,90 ,0)
Measured by path function telephotometer of attenuation meter.
Luminance, Upper Sky
Radiance, Upper Sky
Luminance, Lower Sky
Radiance, Lower Sky
B(z,9,0)
N(z,9,0)
03- 9<£90''
B(z,9,0)
N(z,9,0)
90- - 9 ..180°
Measured by upper hemisphere scanning telephotometer. This instrument measures the integrated luminance (or radiance) of a 5 circular cone of the sky as it sweeps from horizon to horizon through the zenith, making 10° steps in azimuth between each elevation sweep. A complete map of the upper sky is made in 18 sweeps in 90 seconds.
Measured by lower hemisphere scanning telephotometer. This instrument is similar to upper hemisphere scanning telephotometer in that it has a 5° acceptance angle and makes a complete lower sky map in 90 seconds; it is dissimilar to the upper scanning telephotometer in that its elevation sweep and azimuth movement are combined, the scanner swinging in a zimuth at a constant rate of ten degrees for each 180° elevation sweep.
otv..- Figure 4, p. 503 of reference 1.
..510 Ref. 60-22 - 58 -
Computed Optical Property
The following opt ica l property i s commuted .frun two r-.e.-vsured
quan t i t i e s :
Apparent Attenuation Length'' L,(s) Computed from path function, * photometric or radiant , and
horizontal luminance or horizontal radiance as follows:
L ; (z) - 13 (%,9Q°,0) or N (z,9O°,0) B.»(z,9O°,0) %(z,9Ou ,0)
2. The measured horizontal radiance, N(z,90 ,0),±f t n e atmosphere i s suf f ic ient ly c lear , wi l l have a l esse r numerical value than the horizontal equilibrium radiance, Nq(z,9O°,0). This i s due to the curvature of the earth and i t s atmosphere. This causes the r a t io of measured horizontal radiance to radiant path function.. N(z,9O°,0)/ N!c.(z,9O°;0)-to be l ess than the ra t io of horizontal equilibrium radiance to radiant path function Nq(z,9O°,0) / % ( B , 9 0 , 0 ) . This second ra t io i s defined as attenuation iength.
L(z) = Nq(z,9O°,0) / N,,(z,9O°,0)
Tlw first ratio is d'.fined as apparent attenuation length,
L,(z).= N(z,9O°,0) /N,(z,9O°,0)
Because N(z,90 ,0) on a clear day is less than Nq(z,90 ,0), the apparent attenuation length is/less than attenuation length, i.e., L (z) ,«f„. L(z).
The report "Theory of Attenuation Measurements in Planetary Atmospheres," R. V. jPreisendorfer, Scripps Institution of Oceanography, University of California, La Jo11a Campus, SIO Ref. 58-81, of 24 November 1958 discusses this in detail.
Subsequent to Flight 120 a scanning device was installed on the horizontal radiance telephotometer by which the differences between measured horizonLai radiances and horizontal equilibrium radiances could be determined by means of equations developed in the above mentioned report (SIO Ref. 58-81). Only one test flight using this technique was possible pri.or to the decommissioning of the airplane. The differences were found to be negligible for the blue response, and not over % for the photopic -tad red responses and this only at altitudes of 10 000 to 20 000 feet.
SIO Ref. 60-22 - 59 -
Operational Procedure
To record the measurements of the various optical quantities
three different flight patterns are normally used. In sky mapping the
airplane is maintained in straight and level flight for 90 seconds;
during this time the filters are not changed. Path function measurements
o ~ °
for 36<"> -t" azimuth require a left hand circular flight path at 30
bank; during this time the filters are cycled to permit recording of
comparable photometric and radiometric data. To record data as a
function of altitude the airplane is held in a level attitude and by
use of reduced power and extended flaps is allowed to descent. The
flight procedure must be a composite of the different flight patterns to
get the greatest amount of reliable data in the shortest elapsed time.
The three types of flight patterns are described in greater detail
as follows:
"A" run. Airplane maintained level, at constant altitude and constant heading for duration of sky mapping. Usually two "A" runs are made in succession, 90 seconds each, with filters changed between runs. Another "A" run on reverse course with third filter selection completes sky map in photopic, blue, and red spectral sensitivities and returns airplane to starting point vicinity. During the run all other optical instruments are recording,
o ° "B" run Airplane i s flown in a l e f t handed, 30 bank, 360
turn during which horizontal path function and horizontal luminance (and radiance) are recorded. Each cardinal and in te r -ca rd ina l compass heading i s ident i f ied by the co-pi lot and indicated e l e c t r i c a l l y on instrument records. F i l t e r s are cycled by hand from project engineer 's posi t ion. At conclusion of "B" run airplane i s kept in l e f t handed turn during which time project engineer
SIO Ref. 60-22 - 60 -
photographs sky at cardinal compass headings. When conditions warrant it, i.e., to get a more complete coverage, photographs are also made at inter-cardinal compass headings.
"L" r u n Airplane is maintained in level attitude, cr. constant heading, but with altitude decreasing approximately 1000 feet per minute. (This is accomplished by lowering landing gear, extending flaps, and reducing power, the flap extension and power reduction being adjusted to give a suitable descent rate at level attitude.) All optical instruments are recording during this run except upper and lower sky scanning telephotometers. Filters are cjrcled by hand from project engineer's position.
The usual sequence of data-gathering runs is:
"A" runs at maximum altitude for sky maps, using successively the
three optical filters.
"B" runs for path function and horizontal luminance and radiance
measurement.
"B" run for photographing sky.
"L" run from maximum to middle altitude.
Repeat "A" and "B" runs at middle altitude followed by "L" run
from middle to minimum altitude.
Repeat "A" and "B" runs at minimum altitude.
The "L" runs vary in length, usually because of meteorological
conditions. If there are no pronounced haze layers seen during ascent,
or, if no temperature inversion is apparent, the procedure would be as
outlined above. In the case of Flight 112 the "L" run was from 20 000
feet to 10 000 feet, and from 10 000 feet to 1 000 feet.
SIO Ref. 60-22 - 61 -
Cycling of F i l t e r s
The operation of the op t ica l f i l t e r select ion mechanism i s different
for the three typos of runs. In the "A" runs each f i l t e r remains in
the flux path u n t i l a complete sky map i s obtained. In the "B" and "L"
runs the f i l t e r s are cycled, but at different r a t e s . This discussion
covers f i l t e r cycling during :|B" and "L" r rn s .
In making "B" runs ei ther of two modes of f i l t e r operation can be o
used. One i s to cycle the f i l t e r s during the 360 turn, the other i s to o
make three 360 turns with the filters changed at the end of each turn.
The advantage of the first method is that the data obtained in the three
spectral ranges apply to the same air parcel. Additionally, this is
accomplished in one turn of four minute duration. The main disadvantage
of the method is that the data plotted as three separate curves are
incomplete and missing portions of the curves must be constructed; and this
has proven to be more difficult than expected.
In the second method the data recorded in each turn for each filter
are complete and the data so recorded and plotted are more reliable than
that obtained by the first method. There are three disadvantages, however.
First, the airplane does net necessarily retain its flight path end a
different sample of air is measured, secondly, at four minutes per turn
the time utilized in "B" runs is extended, and thirdly, if the same
flight path is followed successive turns are in air contaminated with
engine exhaust products. Both of these methods have been tried and from
the results obtained the decision was made to use the first method, that
L/:-, the one turn method with filters cycled during turn,. during Flight 112,
::U0 Ref. 60-22 - 62 -
The cycling of filters during the "B" run;; u h& done on a nominal
ten-second period. To identify the record by spectral response the
photopic filter was used for four seconds, followed by blue for two
seconds, green for two seconds, and red for two seconds.
The cycling of the filters for the '!I" run? is a. must if comparable
spectral data are to be recorded. The method of making several "L"
runs with one filter for each run introduces relatively large time
variations with changes of sun's elevation, and air movement taking place-
such that the instrument probes during two successive runs cannot
possibly be sampling the same air. The period of cycling during the
"L" runs is dictated by the rotation of the shadowing device on the
upper hemisphere illuminometer, it being very desirable to get one
shadowed reading during each filter positioning. This established the
filter cycling period of about sixteen seconds, i.e., seven seconds on
photopic response, and three seconds each for the blue, green, and red
responses, but since fifteen seconds are easier to see on a watch dial
this was used as the basis for the cycling period.
Because the atmosphere is stratified the data recorded by the
various measurements do not plot as simple curves but show considerable
structure. In the cases of the instruments looking upward or downward
and those receiving illuminance or irradiance the effect of the
stratification is to show gradual changes. In these instruments cycling
of filters can be tolerated. In the case of the instruments with a
» r'
SIO Ref. 60-22 li^-*^-^63 -
horizontal line of sight, specifically the path function meter and the
equilibrium luminance telephotometer, the stratification has a pro
nounced effect as the instruments are moved vertically. The measurement'
made through the filter which is in the flux path as the stratum is
entered 13 the accurate one; the other two filtered quantities arc
measured before and after entering the stratum. To plot graphs of these
two quantities it has been necessary to accept the shape of the graph
of the recorded quantity.
To overcome the disadvantages of cycling the filters in the
horizontally seeing instruments the path function meter and equilibrium
telephotometer? are being redesigned to record simultaneously the three
spectral quantities through beam-splitting prisms and three separate
filter-phototube combinations.
SIO Ref. 6 0 - 2 2
REFERENCES
1 . Duntley, S. Q., A. R. Boi leau , and R. W. P r e i s e n d o r f e r , "Image
Transmission by the Troposphere I , " Jou rna l of the O p t i c a l Soc ie ty
of America, 47, pp. 499-506, (1957) .
2 . P r e i s e n d o r f e r , R. W., "Theory of At tenua t ion Measurements i n
P l a n e t a r y Atmospheres," 310 Ref. 58-81 , Scr ipps I n s t i t u t i o n of
Oceanography, Un ive r s i t y of C a l i f o r n i a , La J o l l a Campus, 24 November 1958.
SIO Ref. 60-22
ACKNOWLEDGEMENTS
While the assistance of all who have helped in this work is very
much appreciated special mention i3 made of the crew of the B-29,
No. 4224725, Captain Robert Baron, USAF, Aircraft Commander, 1st Lieu
tenant Donald Crandall, USAF, and Air Force Cambridge Research Center
Test Support Group. Thanks are also due to Mr. H. C. Schepler and
Mr. Fritz Mantey of Air Force Armament Center, Eglin M r Force Base,
for their assistance during the period of operations at that base.
