ION
ION
ING
leAL
AND
AVHRR DATA \Ill
I
I
I
Kazuhi
Okuyama, Takafumi Konno,
Kunio Akatsu, and Rikuyo Morimoto
Japan
Association
i,
4-5,
Sei-i
Sai
102
Japan
Commission VII
I
ION
timation
snow distri
ion is import
ess
ial for
utili
water resources. In order to estimate snowmeltrunoff in
snow melting season, it is necessary to know
amount
ain regions. The past
snow cover in
snow cover is earring
snow survey wi
fort in field operations. In
study, using NOAA
Very Hi
Resol ion Radiometer (AVHRR) data, we focus
lop
est lish a
for esti
ing
snow cover
in the snow melting season. This study will promise to advance
for accuracy of prediction of runoff in the period.
PROCESS!
ing NOAA
sociation (JWA)
dis i
floppy di
digital images
is since November
on daily
We attempt to estimate snow cover with difinition
1984.
distinction condition
ination NOAA AVHRR data with snow
ta by
Meteorological Agency ( JMA) . The
ion
procedure
is study is shown in Fig. 1 •
Study area is
en from heavy snowfall region in Japan (Fig.
2). This area is surrounded by mountains of medeum height from
1500m to 2000m from
three direction with east, south, and
north.
e are 19 snow
ervation stations in
is s
area. It is also possible
ain snow
a.
Study peri
is
peri ,we could
ermined in
il
May, 19
In
is
five could free AVHRR images as follows:
il 2, 1984
April 14, 1984
il 24, 1984
May 7, 1984
May 19, 1984
To difine
2,
May 7,
e
ttion, we us
ee
discrimi
relationship
May 19. By useing
i1
two
channels
stations
Radicance
3 columns
of AVHRRI to AVHRR4.
Location of snow observation
is fitting to the position in the AVHRR images.
and temperature in the images is averaged by 3 lines
with consideration of the error in 1
ion.
RESULTS AND VERIFICATION
Relationships between AVHRRI and AVHRR2,
between AVHRR3
AVHRR4 is shown in Fig. 3. The difinition of distinction
ition is summerized in Table 1.
In the relationship
Fig.
(a), correl ion is 0.97 in only snow coverd poi
0.95 in
Ie points.
il 14 and April 24 is appli
AVHRR data set
verification using
ion data
resul
verifi
ion
e 2. From this resul , it is possible to
is summeri
in T
ion ratio(AR) by following expression:
cal cuI
an
AR : :
11 + 7 + 12 + 4
37
AR is calculated as 92%. This is enough to apply the result
estimate snow covered area.
The condition
snow cover is shown in Fig. 4 using verified
distinction condition as 3-Dimentional display. It is clear to
grasp the
ing
snow cover
area.
example, the
trend of the decreasing of snow cover
Mt. As i with 1600
square kilometer is shown in Fig. 5. Between April 14 and April
24, decreasing ratio is maximum in
study period.
REMARKS
This is first step to develop a method of estimation of snow
cover with application NOAA AVHRR
a. We must consider an
fect of incidence angle of s ar lays in slope. In this study,
we used only cloud free images, but cloud contermination problem
must
considered when using various data.
REFERENCES
1.
itson L., Nelson G.J.,
to F.W., NOAA
Techical
Memorandom NESS 107(1979), 83pp.
2. Tozawa Y., Iisaka J., Saitoh S., Muneyama K.,
Sasaki Y.,
Tokyo Scientific Center Report G318-1556(1981), IBM Japan,
14pp.
Table
Distinction condition of snow covered area
ion
l-AVHRR2
Distinction condition
AVHRRI - 1 .2
-11> AVHRRI - 1 . 2
-20 > AVHRRI - 1 .2
AVHRR3 > 10°C
AVHRR3 > 10°C
AVHRR3 < 10°C
AVHRR3 < 10°C
AVHRR3 < 10°C
Table 2
*
*
*
Points
AVHRR2 > -11
AVHRR2 > -20
AVHRR2
and
AVHRR4 > 5°C
and
AVHRR4 < 5°C
and
AVHRR4 > 5°C
and 5°C> AVHRR4 > ooC
AND
AVHRR4 < o °C
ults of verification
lculation
Observation
Total
Snow
No snow
11
2
13
Snow in part
7
12
19
No snow
1
4
5
19
18
37
Snow
Total
2
1
0
-2
0
1
3
5
ION OF
G
NOAA AVHRR IMAGES
SNOW OBSERVATION D
R GIS(lKM MESH
OF
3X 3
SNOW 0
19
MESH DA
I NCLUD I NG
ERVATION
IONS
ION
DIFINE
CONDI
TIONS)
ION ON SN
COVER
VERIFICATION
3-D
DISPLAY
Fig. 1
Flow chart
the procedure of this study.
1
141 E
140
~------------~~------~-----r--139
I
III
SENDAI
I
YONEZAWA
)
STUDY
AREA
r
III CITY
•
Fig. 2
SNOW SURVEY
Map of study area. There are 19 snow observation st ions
(el. Shadded area indicates
area which is calculated
on
snow covering area.
0
0
«)
200t
0
0
«)
v
c:::
c:::
0
J: 10
0
a::::
a::::
~o
x
•
>
«
0
«
,
•
'V"'"
o
0
.-
0
0
0
0
&0
0
0
0
00
>
0
150r
0
0
0
0
60
~60
6-6-
$
$Ll.
$
100~
•
0
00
0
0
0
o
ell)
$
0
0
0
0
00 0
0
0
o~OLl.O
50f-
l-------·
e
0°0
Fi g. 3
50
100
CCT
150
COUNTS
AVHRR2
a
200
0
1
-A
•
0
•
TE
RATURE
)
Relationship between
channels.
(alAVHRRl-AVHRR2. (b)
•
snow.
D.: snow in par
o:no snow
Ap r i I 2, 1984
April
Fig. 4
14, 1984
Results of snow cover mapping with 3-D display.
snow
snow in part
no snow
1.... 390
a y 1 , 19
Fi g. 4
continued.
1
(krJ)
2,000
c:::
w
>
1,500
•
0
()
o3:
1,000
Z
en
500
o
~4
0/7
APRI L
~9
MAY
1984
TIM E
Fig. 5
Trend of decreasing of snow cover around Mt. Asahi.
VII ... 392