Ver.3 Cryosphere Products

1

Evaluation SummaryProduct

Snow and Ice
covered area (incl.
cloud detection)
Okhotsk sea-ice
distribution

ReleasethresholdStandard
accuracy

Targetaccuracy

10%

7%

10%

5%

Status*1

Evaluation Methods

5%

○⇒◎

Comparison with other satellites data (e.g.
MODIS, VIIRS, Sentinel-3…).

3%

○⇒◎

Comparison with other satellites data (e.g.
MODIS, VIIRS, Sensinel-3…).

Snow and ice
surfaceTemperature

5K

2K

1K

◎

Comparison with in-situ observation(Automatic weather station thermal
radiometer data) and other satellites data(e.g. MODIS, VIIRS Sentinel-3…).

Snow grain sizeof
shallow layer

100%

50%

30%

◎Comparison with in-situ data for thestandard and target accuracy thresholds.

*1 Symbols denote as follows; 〇: the release threshold achieved, ◎: the standard accuracy achieved, ☆: the target accuracy achieved.

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Validation results of Cryosphere products – SICE/OKID- Version 3 Major changes and validation details
C1AB/SICE - Snow and Ice cover area algorithm- Revised cloud detection/surface classification training data set using Neural network machinelearning method- All training data were simulated by DISORT radiative transfer model
C1C/OKID - Okhotsk sea-ice distribution algorithm- Revised cloud detection/surface classification training data set using Neural network machinelearning method – communalize with C1AB
- All training data were simulated by DISORT radiative transfer model
Validation data for the C1AB/ SICE
- Snow area:
MOD10C2 Snow Cover Extent Product- Sea ice area*:
MOD29E1D Sea Ice Product

Validation data for the C1C/OKID- Sea ice area* :MOD29E1D Sea Ice Product*NSIDC defines sea ice exists in case of the ice fraction/ice concentration more than 15%.

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Validation results of Cryosphere products - SICE
- Snow and Ice cover extent product validation results using other satellite products
Ver.3 sample image
2019.05.09 – 2019.05.24

Validation result of Ver. 3

Validation result of Ver. 2
2018.03.22 - 2019.12.31
16 days composite

2018.03.22 - 2021.06.09
16 days composite

N = 40r = 0.99 (p < 0.01)
Rel. Err. = 8.5 %Bias = 462,283 km2

N = 71r = 0.99 (p < 0.01)
Rel. Err. = 6.5 %Bias = -663.057 km2

Validation period was expanded: 1.5 year to 3 year.
Validation result

Release accuracyStandard accuracy

Target accuracy

Ver.2: 8.5 % (Mar. 2018 - Dec. 2019)Ver.3: 6.5 % (Mar. 2018 - Jun. 2021)

10 %7%5%Accuracy improved and SICE product is achieved the standard accuracy
4Validation results of Cryosphere products - OKID-Okhotsk sea-ice distribution product validation results using other satellite products
Validation result of Ver. 2

Ver.3 sample image
2021.02.27
False Color ImageOKID classification
snowValidation result of Ver. 3

Ice Fraction > 15 %2018.02.10 - 2020.03.05
8 days composite

Ice Fraction > 15 %2018.03.06 - 2021.05.17
8 days composite

cloudsea iceland

N = 73r = 0.99 (p < 0.01)
Rel. Err. = 4.99 %Bias = -5,345 km2

N = 30r = 0.99 (p < 0.01)
Rel. Err. = 9.0 %Bias = -5,986 km2

ocean

1. Validation period was expanded: 2 season to 4 season.
2. Surface classification was improved from visual evaluation compared with False color image.
Validation result

Release accuracyStandard accuracy

Target accuracy

Ver.2: 9.0 % (Feb. 2018 - Mar. 2018)
Ver.3: 5.0 % (Feb. 2018 - May. 2021)

10 %5%3%Accuracy improved and OKID product is achieved the standard accuracy
5Validation results of Cryosphere products - SIPR
- Version 3 Major changes and validation details
SGSL - Snow grain size of shallow layer-

Revised snow grain size estimation algorithm using Neural network machine learning method- Revised the training data set (BRDF data set) using Neural-net: improved inversion accuracy

SIST - Snow and Ice surface temperature-Revised the emissivity table

SALB - Broadband blue sky Snow ALBedo-Add the direct retrieval of broadband blue sky snow albedo product as a research product
Snow albedo estimation using Neural network machine learning algorithm same as snow grain size

Validation data for the SGSL--Field campaign carried out on the Greenland Ice Sheet East-GRIP site (Jul. 2018), Japan/Hokkaido Nakasatsunai
site (Feb. 2020), and JARE observation data (2019) on the Antarctic Ice Sheet Dome Fuji Site
Surface Specific Area (SSA) measured by IceCube and HISSGraS and converted to optical equivalent snow grainsize
All data match-up conditions are in 10 minutes and 250 meters from nearest point of satellites

Validation data for the SIST
-Ground surface temperature was converted from Longwave radiation Flux observation by Automatic weatherstation (PROMICE)
All data match-up conditions are in 10 minutes and 250 meters from nearest point of satellites

Validation data for the SALB
-Surface albedo was calculated from Downward and Upward shortwave radiation flux observation by Automaticweather station (PROMICE)
All data match-up conditions are in 10 minutes and 250 meters from nearest point of satellites
6Validation results of Cryosphere products - SIPR
Snow grain size of shallow layer product validation results using in-situ observation data
Ver.3 sample image
2019.05.09 - 2019.05.24
500

2000

Ver.2 EGRIP★

100%400

Ver.3 EGRIP

Ver.2 NSN

Ver.3 NSN

50%

50%

300

100%
200

N = 11r = 0.50
Rel. Er. = 34.1%
bias = -19.1 µm

100

0050%

Ver.3 JARE

100
200
300
400
In-situ Snow Grain Size (µm)

500

SGLI Snow Grain Size (µm)★
SGLI Snow Grain Size (µm)

-1500

100%50%1000

100%500

N = 20r = 0.97
Rel. Er. = 50.3%
bias = 56.5 µm

00500
1000
1500
In-situ Snow Grain Size (µm)

2000

Validation sites were added: around Dome Fuji site by JARE.
Validation result

Release accuracyStandard accuracy

Target accuracy

Ver.2: 34 % (Greenland and Japan)
Ver.3: 50 % (Added the Antarctica)

100 %

50 %

30 %

Retrieval became stable on wide region and SGSL product achieved the standard accuracy
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Validation results of Cryosphere products - SIPR
-Snow and Ice surface temperature product validation results using AWS observation data
Ver.3 sample image
2019.05.09 - 2019.05.24

★
★ ★★
★
★★ ★

N = 135
r = 0.93 ( p < 0.01)
RMSE = 1.98 K
bias = 0.9 K

N = 551
r = 0.98 ( p < 0.01)
RMSE = 1.62 K
bias = 0.95 K

Validation period was expanded: 2 years to 3 years.
Validation result

Release accuracyStandard accuracy

Target accuracy

Ver.2: 2 K (GrIS: 2018 - 2019)Ver.3: 1.6 K (GrIS: 2018 - 2020)

5K

2K

1K

Accuracy improved and SIST product achieved the standard accuracy
8Validation results of Cryosphere products - SIPR-Snow and Ice surface albedo product validation results using AWS observation data
Sample image
2020.05.09 - 2020.05.24

Sample image
2020.11.17 - 2020.12.02

★
★ ★★
★
★★ ★

N = 744r = 0.80 ( p < 0.01)
RMSE = 0.087
bias = 0.03

Validation result

Release accuracyStandard accuracy

Target accuracy

0.087 (13 %)--7%

SALB product needs more in-situ data & quality control
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