5Antarctic Ice Sheet‫ུש‬ȁࢼ෗ཤࡉࢥުఱ‫ڠ‬ാ࿐‫ٳ‬อࢥ‫شڠ‬
Sylviane Surdyk࣭ၛޭ౷ࡄ‫ݪ‬ਫ਼
Hiroyuki Enomoto
Department of Civil Engineering,Kitami Institute of Technology
Sylviane Surdyk
National Institute ofPolar Research5.1 ྚ౶͈ఱၘ͈ࡕ̱̞۪‫ିמ͂ޏ‬۷௶ͥ͢ͅͺίυȜΙSevere Environment of 㵰Uncharted㵱 Continent Necessitates Satellite Observation
AMSR͈3ch଼ْࣣ௨Ȫ89GHzȂ18GHzȂ10GHzȫͤ͢ͅȂධޭఱၘ̷͈͂ਔս͈٬ຕ͈အঊͬ۷௶̳̭̦ͥ͂੄ြ̳͘ȃධޭఱၘඤ
ၘ໐͉ດࣞ3000m಼̢ͬͥࣞࡔ̞͂̈́̽̀̀Ȃൃ‫͉ͅܢ‬Į80Ɏͅ‫ݞ‬͐೩‫͈أ‬ႀ֖̞̳͂̈́̽̀͘ȃൃ‫͉ܢ‬Ȃ඾ৣ̩̱̱̈́͊͊͜ήςΎȜΡͅਥͩͦͥ۷௶৪ͬ‫̞̫̈́ັ̵ܙ‬ୱ͂ຕ͈ଲ‫̳́ٮ‬ȃ൐ධޭ͈ຕ઄͈ΡȜθೀષ໐͈̜͌͂̾́ͥΡȜθF͉́Ȃ඾ུ͈۷௶‫ݶ‬ത̦୭̫ͣͦȂຕ઄͂‫಺͓ͥ಺ͬ߸۾͈࢓ܨ‬औ̦৘ঔ̯̞̳̦ͦ̀͘Ȃ՛ૄ࠯́͜ࢩํսͅ۷௶ͬ‫ڐ‬ఱ̧́ͥ਀༹̦‫̳̞̀ͦͣ͛͘ݥ‬ȃຕ઄͈‫׻‬༏໐͉ͅ౒ຕ͂ࡤ͊ͦͥ٬ષͅಫͤ੄̱̹ຕ‫̩ࢩ̦ع‬ంह̱̞̳̀͘ȃ̭͈‫܅״‬໐͉ධޭຕ઄͈ᙐူȆક࿍͈‫̀̽͂ͅࢹܥ‬ఱ̧̈́‫̳̜̦ͤ͘ޣג‬ȃ̭͈౒ຕ͈༲ٟͥ͢ͅධޭຕ઄̥͈ͣຕ͈ၠ੄͉Ȃධޭఱၘ͈ୱຕၾ͈հ೰଻ͬࣉ̢ͥષ́ਹါ̈́۷௶చય̞̳͂̈́̽̀͘ȃAMSR͈6GHzȂ10GHz͈ζͼ·υ෨۷௶͉́Ȃ೩̞ܵഽ‫أ‬ഽ͈౷֖࡛̤͂̈́̽̀ͦ̀ͤȂ஠ഛ࢓͈́۬ণ̦‫خ‬ෝ̳́ȃ

0qW

EA composite AMSR image of 89, 18 and 10GHz displays the Antarctic
snow and ice distribution. Antarctica has an inland plateau area with anelevation over 3,000m a.s.l. and a very cold climate with temperatures as
C. In winter, this area is closed to frequent observation due tolow as -80ɋ
darkness, strong winds, and blowing snow. On a peak of an Antarctic
dome, Dome Fuji, Japan maintains an observation site but seeks more
observation techniques to combat the severe conditions described above.
Shelf ice forms the coastal ice margin, and its fluctuations are animportant factor in the changing ice mass outlet from Antarctica. Microwave
observation by AMSR 6 and 10GHz channels will focus on these regions inall weather conditions since this area appears as a low brightness
temperature (Tb) area.

180q଎ġġġ5.1.1 2003ා7࠮27඾͈AMSR 3ch଼ْࣣ௨Ȫ89GHzȂ18GHzȂ10GHzȫFig. 5.1.1 Composite AMSR image from July 27, 2003 using 89, 18, and 10GHz channels

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5.2 ධޭ͈ୱຕ̥͈ͣζͼ·υ෨ΏΈ΢σ
Microwave Signals from the Antarctic Snow and Ice250

ධޭఱၘඤၘ໐̤̫ͥͅා‫͈أܨ͈ۼ‬ଔ֊͂ζͼ·υ෨ΟȜΗ͈๤‫ͬڛ‬া̱̳͘ȃ
଎5.2.1͉ΡȜθF̤̫ͥͅAMSR-E͈6͈̾ΙλϋΥσ͈ܵഽ‫أ‬ഽ͂ু൲‫ܨ‬ય۷௶௡౾ͥ͢ͅ2003ා͈ා‫أܨ͈ۼ‬ΟȜΗ͈๤‫ͬڛ‬া̱̞̳̀͘ȃ‫أܨ‬ΟȜΗͬࡉͥ͂Ȃ4࠮̥ͣ9࠮̥̫̀ͅȂड೩‫͈أܨ‬শ‫̦ܢ‬ࡐಠ̞̈́ͣ̈́ͅȂ̞ͩͥ͠Ȧcoreless winterȧ͈ΩΗȜϋ̦ࡉ̳ͣͦ͘ȃධޭ͈‫أܨ‬་‫͈ا‬අಭ̜̭͈́ͥΩΗȜϋ͉Ȃාਔ‫͂ܢ‬฼ාਔ‫͈ܢ‬΍ͼ·σ̦ਹ̈́̽̀୆̲̞̳̀͘ȃܵഽ‫أ‬ഽ͉‫أܨ‬་൲ͅ؊൞̱̞̳̦̀͘Ȃਔ෨ତ̦೩̩̈́ͥ̾ͦ̀ͅ૦໙͉઀̯̩̈́ͤȂ؊൞শ‫͜ۼ‬ಁ̧̳ͦ̀͘ȃպ௖͈ಁ͉ͦȂ89GHź͉͕͂ͭ̓ࡉ̵̦ͣͦͭ͘Ȃ36.5GHź15඾Ȃ23.8GHź24඾Ȃ
18.7GHź28඾̞͂̈́̽̀̀Ȃ6.295GHz͂10.65GHź͉30඾ոષ̞̳̈́̽̀͘ͅȃպ௖͈ಁ͉ͦୟୱಎ͈෎ഥ൵͂ζͼ·υ෨අ଻̽̀͢ͅࠨ̳ͤ͘͘ȃζͼ·υ෨ͤ͢ͅ૫൫̳ͥ૬̯̦։̹̈́ͥ͛Ȃպ௖͈ಁ̦ͦ։̧̳̈́̽̀͘ȃ230

Air Temperature

220

210

200

210
6V

Comparing the annual (2003) pattern of air temperatures from the200

10V

Automatic Weather Station (AWS) and six AMSR-E Tb at Dome Fuji,
18V

the air temperature indicates a very clear 㵰coreless winter㵱 pattern of190

pattern is due to the combination of the semi-annual and annual
oscillations. All the Tb follow the seasonal trend found in the AWS,

Tb (K)

no clear winter minimum from April to September. This particular

23V
36V

180

although the amplitudes decrease and delays of the maxima increase
with decreasing frequency. This phase delay is nearly non-existent at89V
17089GHz; approximately 15 days at 36.5GHz; 24 days at 23.8GHz; and28 days at 18.7GHz. The delays for 6.925GHz and 10.65GHz aregreater than 30 days. The phase delay depends on thermal diffusivity

160

and the microwave properties of the snow. The phase delay differs
among frequencies due to the differing penetration depths of themicrowave signal.

150
01/01

01/31

03/02

04/01

05/01

05/31

06/30
07/30
Date (2003)

08/29

଎ġġġ5.2.1 ΡȜθF͈‫͂أܨ‬AMSR-Eܵഽ‫أ‬ഽ
Fig. 5.2.1 Air temperature and AMSR-E Tb at Dome Fuji

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09/28

10/28

11/27

12/27

Air temperature (K)240ນġġġġġġ5.2.1 AMSRΙλϋΥσ͈ධޭୟୱ֖͈́૫൫૬̯
Table 5.2.1 Penetration depth of AMSR channels in Antarctic snowਔ෨ତΙλϋΥσFrequency Channels (GHz)

6.925

10.65

18.7

23.8

36.5

89

૫൫૬̯Ηͼί1
Penetration depth Type1

42.

8.0

1.2

0.55

0.15

0.03

૫൫૬̯Ηͼί2
Penetration depth Type2

34.

11.5

3.3

2.50

0.90

0.20

ນ5.2.1͉ȂAMSR͈6͈̾ΙλϋΥσ͈૫൫૬̯̞̾̀ͅা̱̞̳̀͘ȃධޭຕ઄͈‫ۋ‬ୱ͈ζͼ·υ෨૫൫૬̯͉ਔ෨ତͅջం̱̳̦͘Ȃ̯ͣͅୱ‫أ‬ȂࠫએၥࠂȂྟഽȂ௄ࢹ௮͜ͅ‫ͬޣג‬਋̫̳͘ȃਔ෨ତ̦̞ࣞ͂Ȃ૫൫૬̯͉઀̯̩̳̈́ͤ͘ȃ10GHzո‫͈ئ‬ਔ෨ତ͉́Ȃ૫൫૬̯͉ୱ‫͂أ‬௄ࢹ௮̽̀͢ͅఱ̧̩ऒֲ̯̳ͦ͘ȃ20GHzոષ͈ਔ෨ତ͉́ࠫ
એၥࠂ͈‫̦ޣג‬ड͜‫̦̳̞́ޑ‬Ȃྟഽ͂‫أ‬ഽ͜ͅ‫ͬޣג‬਋̫̳͘ȃ̭̭͉́2͈̾ୱৗͬ
ே೰̱̱̹͘ȃୱΗͼί1͉Ȃඤၘ໐͈೩‫ࣛ́أ‬ୱ͈ઁ̞̈́౷֖͈ୱ́Ȃ೩‫أ‬Ȫ-60Ɏȫ́ல̞ၥঊȂ೩ྟഽȂ೩ᙐူ௸ഽ͈͈̳́́͜ȃୱΗͼί2͉‫͈܅״‬๤‫ڛ‬എ‫أ‬౰́ࣛୱ͜ఉ̞
̭͂ͧ́Ȃ‫أ‬ഽȪ-20ɎȫȂळ̥̈́ၥঊȂ೩ྟഽȂࣞᙐူ௸ഽͬே೰̱̞̳̀͘ȃ̭͈ાࣣȂ
6GHzͬੰ̞̀‫܅״‬໐͈ୱΗͼί2͈૫൫૬̯̦ఱ̧̩̳̈́ͤ͘ȃ

Table 5.2.1 presents penetration depth ranges on six AMSR frequency channels, and penetration
depth for two types of snow, assuming observation at a 50 degree incidence angle. Penetration depth
over the ice sheet (dry snow) depends on the frequency, but also on the snow's temperature, density,layering, and crystal size and type. As the frequency increases, penetration depth decreases. For
penetration depth below 10GHz, the snow cover temperature and layering are determinant factors.
Above 20GHz, crystal size has the greatest influence, although density and temperature also have aneffect. In the following example, snow type 1 is a cold (-60㫦C) snow cover with coarse grain, lowdensity, and low accumulation rate. Snow type 2 is a warmer (-20㫦C) snow cover with fine grain, lowdensity, and high accumulation rate. Penetration depths are greater for snow type 2 than for snow
type 1 except at 6.925GHz, where the snow temperature was the determinant factor.

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5.3 ‫͂࢓ܨ‬ධޭຕ઄ȇ་൲͈ಣ̢̱ͬ͂ͣͥClimate and the Antarctic Ice Sheet : Detecting Signs of Changeධޭఱၘ‫܅״‬໐͉́߃ා‫أ‬ഽષઌܱͬ჏̱̞̭̦̜̳̀ͥ͂ͧͤ͘ȃ̹͘Ȃ౒ຕ̦༲ٟ̱̞̀ͥ႕͜༭̯̞̳࣬ͦ̀͘ȃ೩ਔ෨͈ζͼ·υ෨ΙλϋΥσ̷͉͈ͦͣ۷௶ͅঀ̠̭̦͂੄ြ̳͘ȃ6Ȃ10GHz͉Ȃ߃ා‫࢓ܨ‬་൲͂ຕ઄་൲͈۷ത̥ͣȂະհ೰‫̦ا‬࿚ఴ̞͂̈́̽̀ͥ౒ຕ͈κΣΗȜ͜ͅ၌ဥ̯̳ͦ͘ȃ
଎5.3.1͈ი͈ಎ͉౒ຕ֖ͬা̱̞̳̀͘ȃ౒ຕ͈ୱຕ̥͈ͣඅခ͈ζͼ·υ෨༶ৣͬ۷௶̱̞̭̦̥̀ͥ͂ͩͤȂ౒ຕ͈۬ণ̦‫خ‬ෝ̳́ȃධޭఱၘ͈ਔս͉́٬ຕ་൲ͥ͢ͅζͼ·υ෨༶ৣ͈་‫̦ا‬ࡉ̳ͣͦ͘ȃධޭఱၘષ͉́Ȃ10m૬͈ୟୱ‫أ‬ഽ̦ා‫ۼ‬໹޳‫ܨ‬‫̩߃ͅأ‬Ȃාಎ͕͖֚೰͈౵ͬা̱̳̦͘ȂAMSR͈6GHz͈ΟȜΗ͉̭͈ୟୱ௄૬໐̥͈ͣ༶ৣͬ௴̢̤̀ͤȂ͕͖ා‫ۼ‬໹޳‫ܨ‬‫͈أ‬໦ືͅచ؊̱̹ΩΗȜϋͬা̱̞̳̀͘ȃດ͈̞ࣞࣞ൐ධޭ͉́ා‫ۼ‬໹޳‫̦أܨ‬೩̩̞̳̈́̽̀͘ȃ౒ຕ͂໹޳‫͈أܨ‬۷௶ͤ͢ͅȂධޭຕ઄͈་൲͈ಣ̱ͬࡉಫ̭̦ͥ͂੄ြ̳͘ȃ300

In some areas of the Antarctic, where recorded temperatures have280

risen and shelf ice has collapsed, observation data are available from260

low frequency channels of AMSR. AMSR 6GHz and 10GHz channels
focus on the shelf ice area, where instabilities are of great concern in240

the relationship between climate and ice sheet.

220

There is great change in Tb in the surrounding oceans as the sea ice

200changes, but little change over the ice sheet. This is because the 6GHz
signal indicates the temperature from the deep snow layer where the180

annual mean air temperature of the site can be determined. It remains

160

low in the inland areas.
140

By observing the shelf ice and mean temperature, sensors can120

monitor the signs of change in ice sheet conditions.

଎ġġġ5.3.1ȁAMSR 6GHz ͥ͢ͅ‫܅״‬໐͈౒ຕ͈฻༆ඤၘ֖͉́໹޳‫ͬأܨ‬฽‫̹̱ד‬ΩΗȜῧ̈́ͥȃ
Fig. 5.3.1ȁAMSR 6GHz indicating shelf ice along the coast
Tb reflects the annual mean temperature pattern inland.

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100[K]

5.4 ධޭຕ઄͂ఱ‫ܨ‬੏۪ȇ‫ݢ‬ષઌ̳ͥຕ઄‫أ‬ഽ
Ice Sheet and Atmosphere : Sudden Rise in Ice Sheet Temperatureઌ‫أ‬ஜ
Ȫ2003ා10࠮28඾ȫ
Before rise of ice sheet temperature (Oct. 28, 2003)ઌ‫ࢃأ‬Ȫ2003ා11࠮7඾ȫAfter rise of ice sheet temperature (Nov. 7, 2003)ήυΛ΅ϋΈΩΗȜῧઌ‫֖أ‬
Blocking pattern and the area where rise of ice sheet temperature

300
280
260
240
220
200
180
160
140
120
100
[K]

଎ġġġ5.4.1 ධޭఱၘષ͈́‫̈́ݢ‬ઌ‫࠿͈أ‬౶ȪAMSR-E 36GHzȫ
Fig. 5.4.1 Detection of sudden rise in ice sheet temperature (AMSR-E 36GHz)

ධޭఱၘඤၘ໐͉̱̱́͊͊‫̈́ݢ‬ઌ‫̦أ‬۷௶̯̳ͦ͘ȃ଎5.4.1͈ऒ଎͂ಎ؇଎͉ઌ‫أ‬ոஜ͈2003ා10࠮28඾͂ઌ‫͈ࢃأ‬11࠮7඾͈ܵഽ໦ືͬ๤‫̦̳͈̹̱́͜ڛ‬Ȃඤၘ໐͈೩‫أ‬֖͈ક৐ͬࡉ̭̦ͥ͂੄ြ̳͘ȃତ඾‫́ۼ‬30Ɏ͜ͅ‫ࡐ͐ݞ‬ಠ̈́‫أܨ‬ષઌฺ̞ͅȂୟୱນ௄̦౰͛ͣͦȂຕ઄ນ௄̥͈ͣζͼ·υ෨༶ৣ̦௩‫̳̹̹̱́͛ح‬ȃ‫ͬޣג͈׌‬਋̴̫ͅຕ઄ນ࿂͈‫أ‬ഽ͈۷௶̦‫خ‬ෝ̈́ζͼ·υ෨۷௶̦ခ̳࢘̈́ͤ͘ͅȃֲ͈଎͉ઌ‫֖͂أ‬500hPa࿂ࣞഽા଼͈ࣣ଎̳́ȃධޭຕ઄ષߗ࡛̹ͦͅήυΛ΅ϋΈͥࣞ͢ͅգાͤ͢ͅȂ౰‫̦ܨ‬ၠව̳ͥအঊ̦ࡉ̵̞̺̳͘ȃຽ౲͉ޭ‫̀̽͢ͅ־‬೩գા̞̹̈́̽̀ͅධޭඤၘ໐ષߗ͈ఱ‫̦̳́ܨ‬Ȃ̭͈̠࡛̈́͢યͤ͢ͅఱ‫̭̤̦ͤ۟࢐͈ܨ‬Ȃ౰‫͞ܨ‬କ૊‫̦ܨ‬ຕષͅ‫ͦ͊׋‬Ȃຕ઄‫أ‬ഽ͞ຕ઄ષ͈ࣛୱͅ‫̳̱͘ޣג‬ȃධޭ͈‫أ‬ഽ͂ୟୱͬࣉ̢ͥષ́ఱ୨࡛̈́ય͂ࣉ̢̳ͣͦ͘ȃ
AMSR͈۷௶ਔ෨ତ͈֑̞ͤ͢ͅȂୟୱນ௄ȡ૬௄͈‫أ‬ഽࢹ௮̦ଔ೰̯ͦȂౣ‫ܢ‬་൲̜́ͥઌ‫࡛أ‬ય͞Ȃಿ‫ે͈ܢ‬ఠͬ฽‫̹̱ד‬ා໹޳‫͈̓̈́أܨ‬ΏΈ΢σͬ৾ͤ੄̳̭̦͂੄ြ
̳͘ȃ̭͈ͦͣζͼ·υ෨ͥ͢ͅධޭຕ઄۷௶ͤ͢ͅȂ౷ષ۷௶͈ߗฒ֖̤̫۪ͥͅ‫ޏ‬۷௶̦ૺ̳͛ͣͦ͘ȃAn abrupt rise of air temperature has been recorded in Antarctica. The left and center figures
illustrate the 36GHz Tb patterns on October 28 and November 7, 2003. The inland cold area wasdiminished. A sudden temperature rise of 30ɋ
C in a few days heated the surface snow layer,increasing the microwave emission. Microwave sensors can observe the ice-sheet temperature, as it
is not affected by clouds.
The composite map with a 500hPa height chart (right) displays the associated blocking patternover Antarctica. The pressure field is usually low because the polar vortex is located over theAntarctic. However, in the blocking pattern, the circulation brings heat and moisture over the icesheet. This phenomenon significantly influences temperature and snow accumulation on the icesheet.
Using multiple-frequency observations with AMSR, we see thermal fluctuations between surface
and deep snow layers on the ice sheet, and then a short-term temperature rise and a long-term
temperature trend. Through microwave observation of the ice sheet, we can detect the environmentof this 㵰uncharted㵱 continent.

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