The author has identified the following significant results. LANDSAT MSS data of a three year time lapse indicate change of sea surface condition in Seto Inland Sea and coastal region. The red tide which formerly concentrated in the bay or inland sea now extends into an open sea. A small ocean vortex similar to mesoscale atmospheric vortex is revealed by the band 4 image of the satellite data. A manual photographic method applied to a single band image of MSS is effective in detecting sea surface pollution

Maruyasu, T.

Ochiai, H.

Takeda, K.

Tsuchiya, K.

English

NASA Technical Reports Server

"Nad* availabt der NfTA s worsh!7P7 
Inth Interest of earry and wide dis-
NQ seminatron of Earth Resources Survey8 Program information a d without liability 
ITr any Use made therent" 
Application of Landsat MSS Data to the Study of Oceanographical Environment 
Kiyoshi Tsuchiya (National Space Development Agency of Japan, 2-4-1,
 
Hamamatsu-cho, Minato-ku, Tokyo, 105, Japan)
 
Hiroaki Ochiai (Toba National Merchant Marine College, Toba-city, Mie­
ken, 517, Japan)
 
.... Kaname Takeda (Science and Technology Agency, 2-2-1, Kasumigaseki,
 
I Chiyoda-ku, Tokyo, 100, Japan)
 
r-1 
u CN ABSTRACT 
I Based on Landsat MSS data of three years time lapse, the change of
 
'Ul sea surface condition in Seto Inland Sea and coastal region is studied.
 
ED
' It is found that red tide popularly called after its apparent color expanded.
 
E4 E 00 It is also found that red tide which used to concentrate in the bay or inland 
M sea extends into an open sea- A small ocean vortex similar to nesoscale
 
z U. 
')0 En'. atmospheric vortex is revealed-by the Band 4 image of Landsat MSS data.
 
EH A simple manual photographic method, "Bqui Density Slicing Method. is
 
inmW applied to a single band image of MSS which indicates this method is effective 
9 ,4 to detect sea surface pollution. 
,g 1. Introduction
 
'0 CD
 
HOU
 
.4 Recently the coastal region is suffering from red tide popularly called 
H after its apparent color. Red tide is caused by unusually abundant generation
'0oM
 
I1C4 -
MA,, of plankton which is caused by nutrification of water. When red tide appears,
 
fish is Killed resulting in damage to coastal fishing industry.
 
Z M)_HMaruyasu and Ochiai (1976) pointed out that Bands 4 and 6 data of Landsat 
o~cn MSS are useful for the detection of red tide. Although visual analysis 
'P m can distinguish polluted sea surface from clean area it is hard to distinguish 
0 slick. 

apply numerical analysis for the detection of red tide. 

r red tide from other pollutants such as oil An attempt is made to 
In addition a
 
simple photographical method which is useful for the study of sea surface
 
pollution detection will be stated.
 
Original photograhy .may be purchased from:1 
EROS Data Center' 
Sioux Falls, SO sit $&I1 
-1­
https://ntrs.nasa.gov/search.jsp?R=19770026615 2020-03-22T08:09:40+00:00Z
2
 
2. Occurrence of red tide in Seto Inland Sea
 
The name of red tide has become Very popular recently, however this
 
phenomenon is not recent finding. In Table I is shown annual frequency
 
of red tide in Seto Inland Sea which the authors have collected from all
 
available sauces at present. Seto Inland Sea, located between western
 
mainland of Japan and Shikoku has been noted for its beautiful scenery
 
and clean water. This Inland Sea is also very important place for coastal
 
fishing industry ( as to the location see Fig.,]).
 
Table 1 	Annual occurrence of red tide in Seto Inland Sea
 
Year 	 NuMber of appear- Number of- daiaged 
ance case case 
1967 48 8
 
1968 61 12
 
1969 67 	 18
 
1970 79 35
 
1971 136 39
 
1972 164 23
 
1973 210 18
 
1974 298 17
 
1975 300 29
 
1976 326 18
 
It can be seen that the number of observation increased from 48 in 1967
 
to 326 in 1976 or 7 times as many as that in 1967.. In spite of rapid increase
 
of occurrence, the increase of damaged cases is not so large as the total
 
occurrence case.
 
In order to see 6n effect of season on the occurrence; monthly- frequency
 
of recent two years is plotted and shown in Fig. 2, which clearly indicates
 
seasonal effect on its occurrence. High frequency of occurrence is limited
 
in the warm season between April and September.
 
3. 	Landsat MSS images showing the sea surface pollution
 
In Fig. 2 is shown Landsat MSS images of Seto Inland Sea taken
 
-2­
3 
I(a) 0, , , ,-
KOREA..
 
THE SEA OF-JAPAN
 
'
 
:H fro"hinaH. S /. S ... Nagoya t.okyo 
* 5 . ..._s~>o .:Yokk oS A"o 
--. '"SHIKOKU ich( T'-o-s.-

YUSHU; 
 // .:* -00 3..IINEN -. ,THE PACIFIC OCEAN 
---..- ... . .... . ..... 
.... '""' "" "''' '"'""'" ". .....:.......i 5V '" .9 .--- 
""2 N ' , "''' .. - ­
;-:- -.-.-.:.-1 -:--:- H .o s U .. ... /--.-'1 : - .'':::
. .. ... .
 
.0 NH UI 1 A I N" L A N 
.- ......... .. .... ........ ......
 
--'-:."..S~ ~ .Y-'-,,.-.." ------~ ~ ."I ~ ".. ... :b 
.............
 
F .-..a) NpfJaan.howiga pr.oxiat posio o. .iie 
- ~ ~ ~ .. . .. ,.,, ..............

Fig. I (a) Map of Japan showing approximate position of cities,
 
(b) Map of Seto Inland Sea.
 
- 3 ­
4
 
Feb. " 	 " 
 -- .. -- 975­-	 .....]94 

July 
--
Aug.
 
-Oct. .... -
b....I].-	 I­
- .. 0 .. .. : 20 ":30 ..-..40--:--- 50".-..-
Fig. 2 	Monthly frequency of red tideTn Seto Inland Sea in
 
1974 and 1975.
 
three years time lapse.. In Fig. 3 are shown Landsat MSS images of Seto
 
Inland Sea taken on Nov. 
12 1972, Jan.*23 1973 and Dec. 30 ]975"respectively.
 
Comparing the last 
image with those taken nearly three years before,
 
one spectacular difference is recognized in the area 
to the east'of Shodo
 
Island where a fairly large white area 
is recognized. 
-There is no sea
 
truth information in this area and it is hard to know the 
source of this
 
high reflectance. There was an 
report of red tide.observation at the mouth
 
of Kojima Bay (A in Fig. 4) in Seto'Inland Sea. Making use of this area
 
as sea 
truth, an analysis of similarity to red tide is made and the result
 
of which is shown in Fig. 4 in 5 categories ranging from I to 5. 
The­
number 5 means similarity to red tide at the mouth of-Kojima Bay 
is 100*,
 
while number I means the probability of red tide is 
zero. Generally ­
speaking the area with the values bbove 4 has very high probability of red
 
ti-de. Since sea 
surface 	condition is influenced by various factors and
 
- 4 ­
ORIGINAL PAGE IS5
 
OF POOR QUAI j
 
(a) NOV. 12 1972 (b) JAN. 23 1973
 
(c) DEC.30 1975
 
Fig. 3 Landsat MSS images. (a) Nov. 12 1972, (b) Jan. 23 1973,
 
-4 :
 
(c) Dec. 30 1975. All the images and.Band
 
- 5 ­
6 
the speed of variation is rather fast, it does not 
mean that red tide
 
exists always in the same place, however the result of the analysis
 
indicates that the surface of Seto Inland Sea to the east of Shodo
 
Island has chnaged during the past three years.
 
12 NOV. 1972 	 30 DEC 1975
 
.
R ( ... .............................. 

. .
 
.- .. 10
-'*~J E::K 	 .*3...... .....20  
-'_34 
 :*:: 	 1o H 0 .3K5:E 
Fig. 4 Similarity to red tide in eastern Seto Inland Sea around
Shodo Island. The degree of similarity is shown in5 cate­
gories ranging from 1 to 5 with 
5 the highest similarity.
 
.6
 
3. 	A small ocean vortex as revealed by Landsat MSS image

In the image of September 11 1975 covering the coastal area of
 
central Japan, a small ocean vortex is found off the tip of Kii 
Penin­
sula in the periphery of the Kuroshio, one of the largest warm ocean
 
current in the iiorld which 
is flowing along Japanese Islands. The whole
image of which is shown in Fig. 5. An attempt is made to interpret the
 
phenomenon.
 
i) A synoptic-oceanographical condition
 
Detailed analysis of all available data indicates the existence offa­
ORIGINAL PAGE 1 7
 
OF POOR QUAIXII 
136-5E <137E 137.5E 138E
 
7r % 
35N
I 4N 
3335N 
33N 
-135'.5E 136E 136.5E " 13'7E 
Fig.5 The-image of Landsat-2 showing turbid coastal 
water and
 
small ocean vortex. 0048 GMT September 11 1975
 
- 7 ­
8
 
fairly large scale cold water mass to the south-eastern tip of Kii Penin­
sula where a large meandering of the Kuroshio was taking place as is indi­
cated in Fig. 6. The large meandering of the Kuroshio -was first found by
 
Japanese Navy in 1934 during the maneuver. Through their large scale
 
survey, they found a large jold water mass blocking the Kuroshio. The
 
Kuroshio was detouring the cold water mass 'resulting in a large meandering.
 
Later it was found that the cold water mass influences fishing grounds
 
a great deal. Since then this cold water mass has been observed five times
 
as is indicated in Table 2.
 
Table 2 Observation of cold water mass to the south-east
 
of Kli Peninsula
 
Year of first obs. Duration
 
1934 9-5 years
 
1953 2.5
 
1959 4
 
1969 1 
1975 Sti-ll existing
 
I4Q

• 135 140E
 
Mik
-35N 
Fig. 6 Schematic representation of the synoptic condition of the
 
Kuroshiocoastal current and cold water mass on September
 
IB 1975.
 
- 8­
9
 
The present cold water mass was first observed in August 1975. Its
 
spatial dimension is oscillating. At its maximum size, the major and
 
minor axes were as large as 280 and 220 kms respextively while at its
 
minimum it shrinked to a circular shape of approximately 90 kms diameter.
 
The cold water mass split into two parts in May 1977 and the meandering
 
of the Kuroshio stoped for a while then again the meandering has started
 
due to reformation of large cold water mass in the previous place.
 
At the time of observation by Landsat on September II 1975 it is
 
considered that the axis of the Kuroshlo was slowly moving toward north
 
or approacing Ki Peninsula. There were south-west and south-south­
east ward coastal current to the east and west of Kii Peninsula respec­
tively. It is considered~that the present vortex was formed in the place
 
where turbid coastal flows on both sides of the peninsula and the Kuroshio
 
converge. The strong cyclonic shear may have triggered its formation and
 
maintained it. It has a certain similarity to the plume like pattern of
 
suspended sediments in Calorina's continental shelf revealed-by Apollo
 
pictures and studied by Hairs (1971). Both phenomena were formed on the
 
left hand periphery of large warm ocean currents. 
91 V1. similar analysis to the one made in the Seto Inland Sea is applied 
/to the small ocean vortex using the red tide observed in Mikawa Bay (as 
to location see Fig. 6) the result of which is shown in Fig. 7 (a). It 
was found that the spiral part of the vortex has a high degree of similarity
 
to the red tide of Mikawa Bay. Using CCT of MSS data the classification
 
is also made with the red tide of Hi.kawa Bay, the water at the mouth of
 
River Yahagi flowing into the western edge of Mikawa Bay and the water of
 
the open sea as the sea truth. The result of analysis is shown in Fig. 7
 
(b).
 
(a)I fRed tide 
Water at mouth
 
_folf Riv. Yahagi 
Water of open
 
FIg. 7 (a) Similarity analysis applied to the small ocean vortex. Symbols
 
are same as those in Fig. 'I. (b) Classification of water involved
 
in the small ocean vortex.
 
10
 
It is interesting to notice that the radiation characteristics of the
 
water involved in the vortex have strong similarity to that-of r&d tide in
 
the spiral part and the-'rest of the part to the water in the mouth of the
 
River Yahagi. There are no enough data to discuss the mechanism of the
 
formation of the vortex in detail, however, the-result of the present
 
analysis indicates that the ottex is revealed by :the water drawn into the
 
vortex. -if there is an upward motion in-the spiral part like an atmospheric
 
vortex, an upwelling nutricious water may have contributed to the generat,on
 
of plankton with the-result of contribution of-the formation of the red tide
 
in the spiral part.
 
4. A simple method of photographic processing for equi-density-extraction
 
Recently it has become easy to use false-color representation method by
 
specially made apparatus, however it is not al-I who can use it. The method
 
described below may be of use who are trying to analyze a single MSS band
 
image using only photographic processing facilities. Fig. 8 is a schematic
 
representation bf the-method.the detail of which will be dxpaained below.
 
i) From an original positive film make proper number of negative films
 
giving different exposure time for simplicity make it'four in this case.
 
Assume the density of the films are: Nl(N2,/N3 <N4.
 
ii) Make four positive films from the four previously made negative
 
films and name them as P], P2, P3 and P4 respectively(same exposure time).
 
iii) Superpose the negative films on the positive films in such a manner:
 
PI+N2, P2+N3 and P3+N4 then due to the difference in density of each film,
 
equi-density partwappears. In the figure, the white part conrresponds to
 
this equi-density region.
 
iv) Make positive films out of the superposed films. Name them as
 
equi-density positive films; Q, Q2 and Q3 respectively. Stippled areas
 
in the figure correspond to them. It should be understood that three
 
different densities are extracted.
 
v) Make negative films out of the- previously made three positive films
 
and call them Qi', Q2' and Q3'. respectively. Using
 
vi) Using the three negative films make positive color film in such a
 
manner: first take Q' and expose it on a color pper through a-blue filter,
 
then take Q2' and expose -itthrough a green filter on the same paper and
 
finally taking Q3' expose it through a red filter on the same paper then
 
- 10 ­
Ortg pos. 
IN2 	 N3 4 
PI1 [P 	 4 $P5 . , $P4_ 
N2 N3 N4 
), 	 Q2 
 PQ3 
. 
Eq Dl. 
Pos. PUl 
(V 
...... ..
.. .
 
-] /I]I­
(vi) 
Q 
-VA4'
M 
; 
Fig. 8 	 Scbematl c representation of equh density extraction method
 
through manual photographic processing.
 
12 
ORIGINAL PAGE 18 
OF POOR QUALIT 
a colorpositive print is completed. It is not necessary to follow
 
the combination of the color filters described above. The positive
 
color print thus made is shown in Fig. 9 in which the turbid sea surface
 
is well indicated.
 
.... ....... 
~~~~. ...... 6 1 t .- *~. ­
s.. * 
-4 - Nil W E T 
-......-... 
_* -. -. v.. . ., 	 . 
X.:. 
. . . . . . . . . . . . . . . . . . . . 
Fig. 9 	A color positive print made out of Band-4 of Landsat Miss
 
image alone through manual photographic pcocessing method.
 
Dec. 30 1975.
 
The above described method is a standard procedure. Generally
 
speaking a certain amount of information is lost in going through one
 
processing therefore if it is possible less processing step is desirable.
 
In this sense the step (v) may be omitted in certain field such as in the
 
study of oceanography in which a small difference of reflectance must be
 
treated. Fig. 10 is an example of the image made through omitting the
 
step (v) in which a small density difference is better indicated than
 
I-ig 	 2.
 
- 1.2 ­
13
 
4!Iit~z,° % ..• ° • .::.-.... 
--. O x. 
-,=- -- -__ 
..............-- ­
.. :°....:..:. o. .. -.. -- /­
:.--A:--:: 	 ; ___. 
......	 N 4K 
Fig. 10 	 A color negative print made out of Band-4 of Landsat MSS image
 
alone through manual photographic processing method. Dec. 30 '75..
 
'5. Concluding-remark
 
Landsat MSS data are especially useful to get a most-up-tot date infor­
mation on the se surface condition. In spite of a great effort to keep the
 
sea gurface clean, it seems that the polluti6n is still going on. Red tide
 
in the Seto Inland Sea is becoming a great problem in a fishing industry
 
there. The spatial extension as revealed by Landsat image is of great use
 
in the study of the mechanism of this phenomenon.
 
Just like atmospheric vortices of various scales have been found.by
 
meteorological satellites, vortices of various scales of the ocean will be
 
found if a proper observation tool is invented. Equi-density extraction
 
method developed by the present authors will be of help to those who have
 
only photographic facilities.
 
References
 
Mairs, R. L., 1971: Oceanographic interpretation of Apollo photographs.
 
Int. Workshop on Earth Res. Survey Systems, 553-579.
 
Maruyasu, T. and H. Ochiai, 1976: Investigation of environmental change
 
pattern in Japan. Application of Landsat-l data to marine
 
environment in central Japan. NASA-CR-146155, 16 pp.
 
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Application of LANDSAT MSS data to the study of oceanographical environment

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