Difference in Temperature between Shallow and Deep Valleys of

Difference
in Temperature
of
between
the Bhutan
Shallow
and Deep
Valleys
Himalaya
Takashi ＥＧＵＣＨＩ＊ｌ
and Pema Ｍ/ＡＮＧＤＡ＊2
Abstract
The
differences
Lamperi,
in thermal
same
in temperature
located
condition
between
temperature,
are found
between
the shallow
the annual
between
丘ｏｍ the valley
diurnal range
to the valley wind
deep
bottom,
and Lumitsawa
valleys,
and
as the altitudinal difference
is found
of large
valley
that invades
the shallow
I. Introduction
and
Himalaya
falls along
the eastern Himalayas
climate is found
and
more
than 4,000
foothills, while,
basin located
about
causing
dry
between
vegetation
(Schweinfurth,
montane
along
70−80 km
foothills, it is found
bottom
the regional
(Ohsawa,
along the
is mainly
the intra-
between
The
contrasting
the
deep
Dochula
and
the
vegetation
ｗallichiana
deep
shallow
series and
valleys
of the
the dry
valley ecosystems
&
*ＩDepartment
shallow
observed
of
most
Ohsawa,
remarkable
2006).
Along
of Geography, Komazawa
＊２RNR-RDC-Yusipang,
valleys.
oxyodon,
Department
the
and
mal
east
while
humid
the
from
(2008)
moisture
and
uercus
east
Dochula
Fagaceae
of
west
Dochula
Himalayan
from
C?.
east
dry
slope
west
dry
of
Dochula
Himalayan
lanata)
Himalayan
at
ele-
the
lower
elements
((?.
C?. ｌａｍｅｌｌｏｓａ，
Ｃａｓtａｎｏｐｓiｓ
mid-altitudes
the
west
slopes
that
slope
of
(Wangda
clarifies
&
the
conditions
differentiates
Dochula
Ohsawa,
from
2006).
differences
along
the
and
the
University, Tokyo
of Forest and Park Services,Ministry of Agriculture and Forests, Thimphu
１ −
7?
ｓｅｍｅｃａｒｐｉｆｏｌｉａ
Punatsangchu valley. The altitudinal difference
shallow
shaldistin-
of
slope
to
the
most
m.
transition
both
(east
the
humid
west
ぶa
ぶα
The
valleys
slope
of
3000
as
dumo
尽力泌(?
mountain
and
the
dumo
from
Ｄｏｃｈｕla).Ｔｈｅ
ca.
C?･ glauca,
Eguchi
of
to
such
Γoxbu
vegetation
Himalaya
humid
pass.
deep
formation
showed
ｈｙｓtｒiｘ)ａt
characteristics
in the Bhutan
(/?
other
different
of
77
1 972)
ments
altitudes
series which
the
forest
the
Dochula
corresponds
to
valley)
is also
between
ｌａｎａtａ
into
totally
the
type
(deep
around
of
the
2200
(Stainton,
to
Punatsangchu-
Wangchu-Dochula
is one
(Wangda
vegetation
and
was
is
valley)
of vegetation
basinけhe
vegetation
between
of vegetation
-
different
forest
type
the valley
dominates
(?μｅｒｃμぶ lanata
-(?.
along
characteristic
(shallow
bottｏｍ｡
the intramontane
slope
on the up-
according
forest
transits
asl)
(west
Phj^to-geographically
from
the
is due
dry
ｗallichiana
m
are
valley)
type
largely
valleys
along
valley
into
further
foraied
(deep
The
the altitude or the relative height
P.
Dochula)
valley
mesic
1987).
mixed
dominated
while
deep
than
like phenomena.
changes
m)and
of
guishing
957). Along
fohn
in
is the rela-
and
valley
cause
which
types
slope
the valley
Lamperi
the shallow
(2800-3000
forest
to 800 mm,
along
and
in temperature
of differences
ｓｅｍｅｃａｒｐｉｆｏｌｉａ
-Ｐｉｃｅａｓｐｉｎｕloｓａ-Tsuga
forest
６００mm
on the slope of valley changes
In
forms
low
by xeric type at the valley bottom,
per slope of the valleyけhe
mm
annual
the intramontane
to occur
1 956,1
(?.
diversity of
causes
minimum
，Ｐｉｎｕｓｗallichiana
asl)
(2500-2700
of
north of the southern
basin, the vegetation
dominates
part
to be significantly large. The
precipitation reaches
southern
the main
variation
along
slopes
m
and
is almost
and
the shallow
valley and
(2200
temperature
the shallow
of temperature
valley
Bhutan
between
Yusipang
maximum
Yusipang
to be larger along
diurnal range
mean
mean
of the main
and between
between
to clarify the dif!erence
the diurnal
valleys. One
Lumitsawa
annual
the annual
temperature
deep
and
are analyzed
valleys. The
However,
and
and
of temperature
of the deep
and
in monthly
the shallow
of the causes
different
valleys.
Khasadrupchu
varies. The
valley. One
deep
variation
tive height
deep
Khasadrupchu
the shallow
and
to differ between
temperature
between
at ａ similar altitude along
in
slope
therof
Regional Views Ｎ０. 25 2012
between
Bajo
qualifying
and
other hand,
along
dinal difference
around
The
Dochula
1000
condition
thermal
valley
the
the
altitu-
Dochula
is
valley･
focused
on
in
(Wangchu)
in the
temperature
and
western
the
part
Along
(1720
and
were
(3120
valley, five such
set at Bajo (1200
m), Lumitsawa
Dochula
set at hourly
(2180
m),
Lamperi
m).Ｔｈｅ automated
interval. The
is presented
automated
m), Mendigang
temperature
in Table l and
(2640
m)，
loggers
are
data for the
Figures
2 and
3.
the
III. Difference in Temperature between the
between
deep
the Punatsangchu
thermometers
year 2002
in the pres-
the slope of the Wangchu
difference
ley (Punatsangchu)
m
on the slope of the Wangchu
along
valley
2000
the valley ａ shallow
analysis is mainly
the
shallow
and
in detail. Therefore,
condition
and
than
valley. ０ｎ the
valley, the
Thimphu
m, making
thermal
as deep
the Wangchu
between
valley is not shown
ent paper,
is more
the Punatsangchu
Shallowand Deep
Valleys
val-
of Bhutan
Himalaya.
The
annual mean
temperature, seasonal change
in monthly temperature, and diurnal range of ternperature are analyzed to clarify the difference in
II. Data and Analysis Procedures
temperature between the shallow and deep valleys･
In particular,the differences in temperature
tween Khasadrupchu
clarify the difference in temperature between
Yusipang and Lamperi, located at the same altitude
the
shallow and
deep
valleys. Therefore, automated
thermometers
were
set in the shallow valley of
Wangchu,
and the deep
(Fig. 1). Along
valley of Punatsangchu
the Wangchu
valley, two
Onset
HOBO
Pro automated thermometers were set at
Khasadrapchu
(2205 m）ａｎｄ Yusipang （2700 m）.
-
Fig. 1. station map
and Lumitsawa
be-
Available temperature data was not sufficientto
and between
of differenttypes of valley,are analyzed.
1. Annual mean temperature
The annual mean temperatureis almost same
between Yusipang and Lamperi and between
Khasadrupchu and Lumitsawa, and is not differ-
(from
２−
Google earth)
Difference in Temperature between
Table
Stationname
1.
Shallow and Deep Valleys (Eguchi and Wangda)
Annual
mean
temperature
Bajo
Mendigang
Altitude (m)
1200
1720
2180
2640
3120
2700
2205
Average
18.3
16.0
13.5
9.9
6.6
10.2
13.2
Ｍａχimum
25.0
22.0
18.5
13.8
10.6
17.1
22.0
Minimum
13.3
12.2
10.5
7.0
3.7
5.1
7.2
Diurnal range
11.7
9.8
8.1
6.9
6.9
11.9
14.8
ent between
the
1). However,
minimum
and
shallow
valleys.
temperature
and
annual
mean
and
along
both
and
the shallow
daily
the
maximum
shallow
than
along
Lumitsawa).
daily minimum
along the shallow
Along
mean
Khasadrupchu)
valley (Lamperi
valleys (Table
daily maximum
differ between
Annual
is higher
(Yusipang
deep
mean
temperatures
deep
and
the annual
Lumitsawa
(2002)
On
valley
the deep
the contrary,
temperature
is lower
valley than along the deep
valleys, the
diurnal
valley.
range
of tern-
perature is larger at the valley bottom
and
smaller
annual
as the altitude increases.
diurnal range
along
of temperature
the shallow
ley. The
annual
at Yusipang
Lamperi
valley
mean
(2700
m)
is
the annual
temperature
at Khasadrupchu
Lumitsawa
(1200
the deep
val-
of temperature
as Bajo (1200
mean
diurnal
reaches
and
than
m).０ｎ
range
of
than
Bajo
m).
2-(Ｃ)).ln
The
monthly
in January
the mean
mean
temperature
temperature
the middle
and
the monthly
mean
contrary, in
reaches
(Bajo)
upper
valley is higher
maximum
of shallow
than that of the deep
winter,
valley
the
tends
mean
to be lower
be almost
The
mean
maximum
of the
that of the
minimum
in January
However,
the monthly
reaches
maximiim
(Bajo,
Mendigang,
in August
Yusipang).
mean
in June
maximum
monthly
mean
maximum
of Khasadrupchu
the same
monthly
as Dochula
mean
minimum
season
range
the
and
m) is found
(3120
m)｡
to
of temperature
the summer
mon-
in monthly
mean
the shallow
diurnal
and
deep
small. ０ｎ the contrary, in winter,
mean
diurnal
range
shallow
of temperature
valley
valley. In particular, it reaches
KI!asadrupchu
(2120
difference
temperature
on
minimum
(2120
in winter (Fig. 2-(Ｄ))･
between
larger in the
The
as
that of deep
mean
during
maximum
becomes
monthly
deep
than
diurnal range
in July
of temperature
becomes
in the
m)｡
in
annual
between
the
than
nearly ２００Ｃat
mean
relatively
during
diurnal
Khasadrupchu
the
range
and
Bajo
high
temperature
of
dajîme
throughout
the
temperature
at Khasadrupchu
the winter night.
3. Diurnal
and
along
Lumitsawa)
in temperature
diurnal
the
range
shallow
than
of
and
valley (Lamperi
and
the deep
the night, the tern-
in the shallow
valley
valley. ０ｎ the contrary, during
temperature
is found
than in
the deep
shallow
and
deep
higher
than in the
the dajîme,
in the shallow
valley. Temperature
valleys is found
10−11 o'clock in the morning
temperature
valley (Yusipang
(Fig. 3-(A)). During
perature is lower
and
between
almost
18-19
the
valley
the
same
at
o'clock in
the evening｡
In
tempera-
(Yusipang
the year.
the
Khasadrupchu)
Dochula,
than that of the
variation
January,
is larger
altitudes
Khasadrupchu)
altitudes (Lamperi,
valley is higher
valley throughout
temperature
at the lower
Lumitsawa,
ture of the shallow
reaches
in all the stations (Fig. 2-(Ｂ))･
at the higher
The
temperature
lower
In siraimer, the difference
deep
monthly
minimum
is the same
particular, the monthly
temperature
In
valley. ０ｎ the
than
mean
valley
at
on
the shallow
temperature
monthly
valley becomes
valley. In
during
parts of the slope. In summer,
along
reaches
in July (Fig･
valley. ０ｎ the contrary, in winter, that
year and relatively low
in June
temperature
maximum
that of deep
However,
and in July or August
temperature
the
minimum
valley｡
The
deep
reaches
and
Khasadrupchu
of the shallow
ＫＩ!asadrupchu
July, the diurnal range
and
ley (Lamperi
the
-
deep
temperature
in all the stations (Fig. 2-(A)).
the valley bottom
shallow
in monthly
minimum
January
summer,
depends
change
Yusipang
temperature
of
2. Annual
mean
in
valleys
14.8°C, 6.7°C
３°c larger
monthly
minimum
soon
to be larger
along
The
reaches
mean
1 1.９０Ｃ，
5°C larger
the same
larger
than
is found
than
diurnal range
and almost
the other hand,
The
becomes
Dochula
Lamperi
３−
temperature
Khasadrapchu)
and
of temperature
Lumitsawa)
is almost
is larger
than in the deep
(Fig.
the
same
3-(B)).
between
val-
While
the
Regional Views Ｎ０. 25 2012
q"
25.0 .−一一、 (A)Mean
¥2o'o <≫
――^.'^こ、 Bajo
§:: 説j‘''ﾔ'f? ｀｀j
ヽごこ …―
a' 1.'‘' ゛‘･ ………Lumitsawa
5
Mend“g'ロg
Lamperi
0.0 ●/ ＼ F ･ -Dochula
-5.0 ―
1 2 3 4 5 6 7 8 9
10 11 12 −一一Yusipang
Month Khasadrupchu
35.0
β30.0 .−＾ヽ一一ヽ、、 (B)Maximum
｀i″25.0 − 、 −一一Baio
120.0 /F……….‘ぷ‘‘’｀ぶ゜゛∼４’｀こ｀S、 Mendigang
ir 15.0 /ｺﾞ．べ゛ ’＼. χ ………Lumitsawa
O- 10.0 /゛ Lamperi
Q 5.0 ’
F 0.0 ￣・￣Dochula
1 2 3 4 5 6 7 8 9 10
11 12 ミミーYusipang
Month Khasadrupchu
25.0
͡ 20.0 ’ (C)Minimum
X
――――、 −
已15.0 七
、￣￣￣Bajo
110.0 4.y’｀‘’§.‘ ゛、S゛’゛･･y、 Mendigang
巴 5.0 ・.’’ 岬゛‘ ………Lumitsawa
1 0.0 >>' Lam
peri
β! -5.0 −
●− Dochula
-10.0 1 2 3 4 5 6 7 8 9
1o 11 12 ’’゜Yusipang
Month Khasadrupchu
25.0
range
P
20.0 (D)Diurnal
ヽi● Bajo
3
15.0 ’ 、 Mendigang
S10.0 ダこ云今‘誂｀ﾐﾌ、 j乙｀1 ………Lumitsawa
□. -･9 ’●.−,ぷ〃一,J .−
Lam peri
E
5o ……｀’’……… β ゛’ −一一Dochula
0.0
1 2 3 4 5 6 7 8 9 10
11 12
一一-Yusipang
Month Khasadrupchu
Fig.
shallow
valley and the deep
the temperature
is found
than in the deep
ture between
2. Monthly
mean
temperature
temperature, (Ｂ)Ｍａｘimｕｍtemperature, (C) Minimum
valley during
valley during
the shallow
the night,
higher in the shallow
the day. The
and deep
valley
same
of 2002
temperature, (D) Diumal
tempera-
４ −
range of temperature
at 8 o'clock in the morning and ｌ o'clock in
the midnight.
valleys is almost
-
(A) Mean
Difference in Temperature between
Shallow and Deep Valleys (Eguchi and Wangda)
20.0
(A) January
15.0
０ｑ０︵ハ︶゜︶Ｑ﹄コ︶ｅｊ３ｄｉｕ３ｉ
−一一Bajo
一一一一Mendigan
………Lumitsawa
０
０ Lamperi
−・-Dochula
-5.0
”-Yusipang
Khasadrupchu
10.0
１ 2 3 4
5 6 7 8 9 10111213 141516171819
202122 23 24
Hour
30.0
(B)July
25.0
００一一一｀ノ﹄１１
︵Ｏ︶ａｊｎｊｅｊ３ｄｉｕ８ｉ
一一-Bajo
-"― Mendigan
………Lumitsawa
０一一一
０ Lamperi
−・-Dochula
一一-Yusipang
０．０
１ 2 3
4
5 6
7
8
9 101112
13 14 15 16 17 1819
2021
Khasadrupchu
22 23 24
Hour
Fig. 3.
Monthly
mean
diurnal variation in temperature
of 2002
(A) January, (B) July･
rv. Discussions
deep
valley during
along
the shallow
the deep
The differences in temperature between
temperature
Thereforeけhe
and
low
but along
a different aspect, are mainly
located
at ａ similar altitude
clarify the difference in thermal
The
and deep
annual
shallow
and
nual
mean
maximum
the
annual
temperature
deep
valleys.
and
variation
in
ture between
monthly
the shallow
and
to be lower
the shallow
the night and
day than along the deep
temperature
is found
valley
the deep
than
perature along
temperature,
and
differ between
valley. The
during
diurnal range
of
the shallow
siraimer, the
valley is higher
Yusipang
than
the
to Dochula
Yusipang
On
(the
the altitudinal differto Dochula
m, it is ca. 2000
deep
are located
of temperature
(2008)
(the
m
shal-
between
valley). Khasadrupchu
near
the
shallow
the contrary, Lumitsawa
on the middle
and be-
is the relative height
While
Khasadrupchu
valley. Eguchi
５−
temperature
lower
and Lumitsawa
Lamperi
valley) is ｃα.1000
are located
than the
and
between
bottom.
tern-
the shal-
of differences in the tempera-
the valley bottom.
and
to be larger along the shallow
valley. In
along
of
winter.
valley throughout
becomes
Khasadrupchu
ence
Bajo
the
valley
from
low
valley is found
higher
shallow
of the causes
tween
valleys. Particularly in winter,
along
during
an-
temperature
temperature
in
valley in winter.
One
variation in temperature
deep
the
However,
the diurnal
the temperature
along
is similar between
minimum
than
valley is higher than the deep
deep
the
in summer
dajîme
similar to
diurnal range
the year. ０ｎ the contrary, the nighttime
valleys｡
mean
the
to
between
-
the shallow
analyzed
condition
to be
night. The
is smaller
Yusipang
and, the temperature
valley is found
valley during
Khasadrapchu and Lumitsawa and between
Lamperi,
the dajîme
or upper
and
valley
Lamperi
slope of the deep
clarifies that the diurnal range
is large
at the
valley
bottom
and
Regional Views Ｎ０. 25 2012
becomes
along
smaller
at the valley
high
during
temperature
the night,
radiative
cooling
and low
valley
Lumitsawa
becomes
(2008)
valley. Wangda
m
and becomes
(2006)
the difference
culation and
also make
the
(1250
the area humid
from
species. Contrastingly,
m
the Wangchu
parts of
Lauraceae
on the ridge top, which
makes
the lower
in the
interesting
diurnal
bottom.
The
the shallow
time
altitudes dry. Thus
deep
range
of temperature
valley than in the deep
of the shallow
than that of deep
becomes
lower
dry
is larger in
valley. The
day-
valley is relatively
the year
of the shallow
than that of the deep
valley
valley only in
winter.
The
becomes
strong
fine weather.
accumulates
The
temperature
is caused
the
comes
dry
ridge
valley. The
higher
the dajîme,
or passes
temperature
We
would
of subsid-
phenomena
the dajîme.
often flows
so
the night
temperature
relatively lower
In Yusipang
from
Dochula
and
shallow
valley to
further observation
Mr. Karma
Director, Council
research of Bhutan, for their full sup-
port and valuable comments
the Renewable
on
this study. At
Natural Resources
Development
Center-Yusipang,
thank the former Program
Norbu
Dukpa,
Research
we
would
Director, Dr. Lungten
and the present Program Director Dr. Kinley
Tenzin, who
always
supported
our collaborative
study.We would alsolike to thank the research team
Kuenzang
Dhendup,
Chu
basin,
becomes
cloud
Ｔ･， 2008.
7? eports
often
Therefore,
99−106.
valley be-
Ohsawa,
valley
of
Ｍ。
Himalaya.
Regional
conditions
represented
by
the
versity.
６−
differences
on
the
in
slope
thermal
of
Tsang
Bhutan Himalaya. Ｇｅｏｇｒaphical
乃砂aj面なりμ
1987.
Vegetation
olitan
ひdiversity,
zones
in
the
In Ｌｉｆｅｚｏｎｅ
ｅｃｏｌｏｇｙ
ｏｆ the
Ｈｉｍａｌａｙａ, ｅ
ｄＭ.
temperature,
Norbu,
Ghemiray)
References
moisture
that of the deep
Kumar
valley
皿d
and
Damber
who always helped with our study･
Eguchi,
time.
and
like to
and
-
dajîme
and
of Forests and Park
Services and Dr. Tashi Samdup,
for RNR
valley
of the shallow
than
in
occurs in
there is not enough
like to thank
valley. ０ｎ the
the radiative cooling
during
often
and in-
as the altitude is lower
wind
this hjmothesis,
develops
day, and
Acknowledgement
only in winter.
The
the shallow
air becomes
the
ｄｃ･，
is considered
analysis are necessary･
cooling
the shallow
than the deep
cool-
season
radiative
it is the rainy season
sky
the nighttime
air from
valley because
and narrower
because
of
eflficientlyin the shallow
contrary, in summer,
covers
because
cool
more
than in the deep
is smaller
weak
vegetation
of Yusipang (Dorji Gyaltshen, Tshewang
difference in nighttime
by the radiative cooling. In winter, radiative
ing
the mountain
valley
factors, for
valley wind
during
circulation data in the deep
be-
at the valley
valley throughout
temperature
The
valley
Director General, Department
valleys is the difference
diurnal range of temperature
and the nighttime
cool
valley.
difference in temperature
and
temperature
higher
top and
only
on along the Wangchu
the shallow
of the causes.
or the eastern ridge. However,
verify
1.5, 1.2,
valley is much
are usually
tween
soil moisture,
valley during
clouds
Another
complex
the shallow
to the mountain
species appear
the Wangchu
by
cir-
drier due to its short range
formed
in
valley. Fohn-like
as ａ result of
and
temperature
the shallow
during
is around
to be caused
well in the deep
vades
and
Khasadrupchu
local circulation system
over
is 5-8°C
Dochula
and
Bajo
the
tern-
is 9-14°C.
rate between
and
air humidity,
to be one
in
respectively. While the relatively
dajîme
example
Yusipang
Dochula
asl)
the valley bottom
for Fagaceae
high
lapse
Dochula
is considered
ence
of vegetation
are formed
between
and
and Khasadrapchu
between
0.８０Ｃ/100m,
crosses
Wangchu
０ｎ the upper
valley winds
is
as the
report that the albetween
皿d
Dochula
temperature
Yusipang,
becomes
is lower
difference in maximum
Dochula
the connected
of mountain-valley
valley, clouds
laden
with
higher
the difference
aspects of Dochula.
Punatsangchu
making
during
the Punatsangchu
of ｃα.1000 m
valley make
moisture
val-
valley.
asl) valley and Punatsangchu
in the two
Therefore,
to be high
Ohsawa
&
titudinal difference
(2200
bottom.
along
between
The
by
of the shallow
increases
perature
temperature,
altitudinal range
valley. The
during
reveals that the relative humidity
altitudinal range
Wangchu
maximum
the
contrary,
of the deep
at the valley bottom
as
皿d between
large in comparison
and Lamperi
mean
higher
causes
air accumulates
Yusipang
is found
of
monthly
wind
during the night, and the diurnal range
of temperature
Eguchi
the subsidence
cool
at the
and
that,
is relatively
valley
to rise. ０ｎ the
ley, the temperature
low
because
the strong
the relatively
at Khasadrapchu
day
the temperature
the dajîme
with
increases
valley. This indicates
bottom,
air associated
the
as the altitudinal range
the Punatsangchu
Ohsawa:
1 85-206,
Chiba
43:
Bhutan
Bhｕtａｎ
Uni-
Difference in Temperature between
Schweinfurth,
entalter
U.,
im
Schweinfurth,
U.,
vertikale
lava.
1956.
Himalaya.
Uber
klimatische
Ｅｒdkｕｎｄｅ，
1957.
Verbreitung
10:
Shallow and Deep Valleys (Eguchi and Wangda)
Trock-
Murray,
297-302･
Wangda,
Die horizontale und
der
Vegetation
ＢｏｎｎｅｒＧｅｏｇｒaphiｓｃｈｅ
im
Hima-
Ａｈｈａｎｄｌｕｎｇｅｎ， l0:
along
gradient
of the
western
the
dry
Ｍ。
2006.
topographical
west
Bhutan.
and
humid
Forest
and
east
Ｄ.
Ａ･，
1972.
Forests
of
Nepal.
John
７−
pattern
climatic
slopes
of
Ｊｏｕｒｎａｌ
ｏｆＲｅｎｅｗable
TV ａtｕｒalＲｅｓｏｕｒｃｅｓ
Bhｕtａｎ. 1(1):1−17.
J.
-
Stainton,
Ohsawa,
analysis
Dochula,
1-373.
Ｌｏｎｄｏｎ･
Ｐ･， &

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