GLI Cryosphere Products and Findings fromthe Validation Experiments
Teruo Aoki (MRI)
Masahiro Hori (JAXA/EORC)
Hiroki Motoyoshi (Space Service Co., Ltd.)Tomonori Tanikawa and Akihiro Hachikubo (Kitami Institute ofTechnology)
Konosuke Sugiura (JAMSTEC/IORGC)
Teppei J. Yasunari (Hokkaido University)
Yasuko Iizuka (Graduate Univ. of Advances Studies)
Yukinori Nakajima and Fumihoro Takahashi (RESTEC)
Knut Stamnes, Wei Li and Hans Eide (Stevens Institute ofTechnology)
Rune Storvold (NORUT Information Technology Ltd.)
andJens Nieke (University of Zurich)Goal
9Development of remote sensing technique to detect qualitativechange of cryosphere, the most sensitive area for global warming.
9To investigate the radiative properties of snow/ice surface.
9Improvement of land-surface model (LSM) in cryosphere ofGCM.

GLI Cryosphere products
9Cloud detection over snow/ice
9Snow/Ice extent
9Snow surface temperature
9Two types of snow grain sizes
9Mass concentration of snow impurities (water-insoluble solid
particles (soot-equivalence))Principles to retrieve snow grain size and impurities
9Near infrared albedo depends on snow grain size
9Visible albedo depends on mass concentration of impurities

Spectral albedos depending on (a) snow grain size and (b) impurities, wherespherical ice particles are assumed for snow grains and soot for impurities.

ADEOS-II/GLI RGB composite in 2003

AprMayJunJul

Aug

Sep

R: 0.678μm G: 0.865μm B: 0.460μm

ADEOS-II/GLI Snow/ice extent in 2003

ADEOS-II/GLI Snow surface temperature in 2003

ADEOS-II/GLI Snow grain size in 2003

ADEOS-II/GLI Snow impurities in 2003

Validation Experiments

Eastern Hokkaido, Japan:
Feb. or Mar. in 2001-2005
for MODISBarrow, Alaska:
Apr. in 2003
for GLI & MODIS

Spectral BRDF

Spectral albedo

FTIR

Snow pit work

Validation of snow surface temperature

Satellite

Snow pit work for snow surface
temperature in Barrow, Alaska

R=0.904
RMSE=1.1K

Ground truth
9Satellite-derived snow surface temperature well agreed withthe ground-based measurements with RMSE= 1.1K.

Validation of snow impurities
ChVIS=0.46µm, ChNIR=0.865µm

Satellite

Ground truth for massconcentration of snow impurities

RMSE=5.1 ppmw (85%)
R=0.598

Ground truth
9Satellite-derived mass concentrations of snow impurities werelower than the ground-based measurements. This is because
the snow impurities assumed in the algorithm was soot,whereas the main composition of in situ measured impurities
was mineral dust in our sites.

Validation of snow grain sizes

Satellite

ChVIS=0.46µm, ChNIR=0.865µm

0-5cm
R=0.851

ChNIR=1.64µm

Surface
R=0.507

Ground truth (r2=branch width)
9Retrieved grain size from ChVIS= 0.46µm and ChNIR= 0.865µm
comparatively agreed with ground truth data.
9Grain size from ChNIR=1.64µm was smaller than those fromsnow pit work, which means measured reflectance at λ=1.64µm
is higher than theoretically assumed one in the algorithm.

Sun glitter from sun crustand some possibilities at λ=1.64µm
9BRDF
9Sensor calibration
9Validation method

PVPH

Retrieved verticalinformation of snow
grain size
It was confirmed that
retrieved snow grain size
using 1.64µm-ch. contains
the information of shallower
snow layer than 0.865µmch., where the minimum
RMSEs and the highestcorrelations are observedat surface for 1.64µm and0-5cm layer for 0.865µm-ch.

Summary (1)9Comparatively good agreements were obtained for satellite
derived snow surface temperature and snow grain size using
0.865µm-ch. with in situ measurements.
9Accuracy of mass concentrations of snow impurities and snow
grain size from 1.64µm-ch. was insufficient. However, theiressential information were successfully retrieved.
-> Need algorithm improvements.
9Validations are still insufficient for all cryosphere products.
9-> Need more validations.

Snow grain size and impurities from two-week-data(TERRA/MODIS, Sep.27–Oct.11, 2000)

0.0(mm)Snow grain size

1.00.0(ppmw)
Mass concentration ofsnow impurities

3.0

Snow crystals at DomeFuji (77°19’S, 39°42’E,3810m) in Antarctica
9Snow pit works with 2-3 times
a week from Oct., ‘03 - Jan., ‘04.
9Surface snow were covered
with diamond dust and the grain
size increased in summer.

Surface

500µm

500µm

Satellite retrieved snow grain radius using 1.64µm channel

Syowa

Dome-FMawson(Motoyoshi et al.
2006, to be submitted)
9Snow grain size was large in summer and over plateau.
¾It would be very sensitive to global warming.

Observations forradiation budget, snow,and aerosolsz1999-2001 at Kitami, Hokkaido
z2001-2003 at Shinjyo, Yamagata
z2004-2006 at Sapporo, Hokkaido

RB: Radiation Budget
SPW: Snow Pit Work
MNR: Multi-channel Radiometer
OPC: Optical Particle Counter
SSR: Snow-Sky Radiometer
AWS: Automatic Weather StationAWS

Kitami
Sapporo

SSR

RB, MNR

SPWShinjyo

SnowOPC

Observations forradiation budget, snow,and aerosols

RadiationbudgetSnow-sky-radiometer

Particlecounter

Diffuse radiation

Snow pit work and radiation budgetEffects of snow physicalparameters on albedo
9Measured visible and nearinfrared albedos fall withintheoretically inferred ranges
from snow grain size and snow
impurities with RTM.
-> These data could be usedfor validations of empiricalsnow albedo model of LSM in
GCM and/or development ofphysically-based snow albedo
model.
(Aoki et al. 2003, JGR,
doi:10.1029/2003JD003506)

Satellite-retrieved snow
parameters andvalidation data on theground

Satellite

9Ts and reff
9Ts and cs
9reff and cs
9Albedo and reff
9Albedo and cs-> These data also could be
used for validations of snow
albedo models of LSM in GCM.

GroundDaily variations of snow
impurities and albedo
9Mass concentration was low
in accumulation season andhigh in melting season.
9Remarkable albedo reduction
was observed at heavy dust
event on 11-12 March 2004.
Sapporo2003/2004(Aoki et al. 2006, SOLA in press)

Relationshipbetween snow
impurities andvisible albedo
Snow RTM model:9One snow layer
9Mineral dust model
as snow impurities
9Several snow grain
sizes
9Even in accumulation season (high albedo period), measured
snow albedos were lower than theoretically calculated one with‘mineral dust (MD) only’ model and fall in the range of theoreticallycalculated one for ‘MD+soot (ST) 0.50 ppmw’ model.
-> This suggests the snow would be polluted with the absorptive
aerosols such as black carbon (soot).

March-April

May-June

Simulated 1880-2002 snow albedo change due to BC.

(AfterHansenandNazarenko,2003)
Simulated 1880-2002 Ts change for the transient BC snow/ice albedo forcing

In-situ measured spectral
directional emissivity ofsnow/ice in the atmosphericwindow
0°
15°
30°

45°

60°

75°

88

9 10 11 12 13

9 10 11 12 13
Wavelength (µm)(Hori et al.
2006, RSEin press)

Summary (2)9Radiation properties of snow/ice were clarified with validation
experiments using radiometers, spectrometers and FTIR.
9Spatial-time variations of snow grain size in the Antarctic wereobtained.
9Snow contamination with soot was confirmed in Japan.
- > For the northern hemisphere?
9Those data could be used for validations of empirical snow
albedo model of LSM in GCM and/or development of physicallybased snow albedo model.

Snow grain sizes using 0.865- and 1.64µm-channels
9In melting (wet) snow areas, retrieved snow grain size from
1.64µm is expected to be the same as that by 0.865µm.
9However, snow grain size by 1.64µm is smaller than 0.865µm.
(a) 0.865 µm(b) 1.64 µm

Snow grain size retrieved ADEOS-II/GLI data in April, 2003 using (a) 0.87µmchannel and (b) 1.64µm-channel.