Detailed Reports on the Validationof the SGLI Products

4．Ocean Products

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4. Validation Results of Ocean Products
4.1 Evaluation Summary
Product

ReleasethresholdStandard
accuracy

Target accuracy

Normalized water
50% (<600nm)
30% (<600nm)
2
leaving radiance (incl. 60% (443~565nm) 0.5W/m /str/um 0.25W/m2/str/um(>600nm)(>600nm)cloud detection)
Atmospheric
80%
50%
30%
correction(AOT@865nm)(AOT@865nm)(AOT@865nm)
parameters
Photosynthetically20% (10km/month) 15% (10km/month) 10% (10km/month)available radiation−35~+50%
Chlorophyll-a−60~+150%(offshore),−60~+150%(offshore)concentration−50~+100% (coast)
Total suspended−60~+150%
matter concentration (offshore)
Colored dissolved
organic matterSea surface
temperature

Status*1

Evaluation Methods◎

Comparison with in-situ observation data.

○

Comparison with in-situ observation data.

◎

Comparison with in-situ observation data.

○

Comparison with in-situ observation data.
Comparison with other satellite data
(GOCI).

−60~+150%−50~+100%○−60~+150%(offshore)−60~+150%−50~+100%○Comparison with in-situ observation andother satellite data (MODIS).

0.8 K (daytime)

0.8 K (day & night 0.6 K (day & night
time)
time)

☆

Comparison with in-situ observation data.

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

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4. Validation Results of Ocean Products
4.2 (a) Normalized water leaving radiance (NWLR)

Validation Method:-

RMS errors are evaluated comparing SGLI-derived NWLR with in-situ optical measurements conducted during
simultaneous buoy (MOBY*1), tower (AERONET-OC: sky- and ocean-radiometer installed on oceanic towers)
and the campaigns of ship observations and also comparing with other satellite products.

Validation data and condition etc.:-

In-situ data acquired within 3 hours from SGLI observations were used for comparison.
SGLI data were extracted from 5 by 5 pixels near the in-situ observation sites to have one averaged value andthen the data were selected by the following criteria (Bailey, 2006);
1. Aerosol optical thickness (AOT) ≤ 0.3, solar zenith angle ≤ 70 deg., the atmospheric correction scheme
passed successfully, the target pixel is neither near the cloudy pixel nor within the region of the sun-glint
correction, and the number of valid pixels ≥ 13.
2. A coefficient of variation (CV) is computed for pixels which passed the 1st test (1.) for bands between 412
and 565 nm and for the AOT 865 nm using the arithmetic mean and standard deviation of the 5x5 pixels,
and the median CV is less than 0.15.

Validation period:-

Yoko-Maru: Feb. 2nd to Oct. 16th 2018
Shinsei-Maru: May 21st to 28th 2018
Nagasaki-Maru: Jul. 19th to 27th 2018
MOBY*: Jan. 1st to Jul. 9th 2018
AERONET-OC: Jan. 1st to Oct. 26th 2018

*1: MOBY data are provided from NOAA through the agreement (a memorandum of understanding (MoU)) between JAXA and NOAA.
Reference: Bailey, S.W., and Werdell, P.J. (2006). A multi-sensor approach for the on-orbit validation of ocean color satellite data products. Rem.
Sens. Environ. 102, 12-23.

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4. Validation Results of Ocean Products
4.2 (a) Normalized water leaving radiance (NWLR)

Validation Results:

RE:

RE :

RE :

RE :

14%

41%

32%

19%

RE :

RE :

RE :

21%

25%

0.38 W/m2/str/um

Estimated errors

Release threshold

14 ~ 41% (<=600nm)
0.38W/m2/str/um(>600nm)

60% (443 ~ 565 nm)

Standard accuracy

Target accuracy

30% (<600 nm),
50% (<600 nm),2
0.5W/m /str/um (>600nm) 0.25W/m2/str/um (>600nm)

Release threshold and Standard accuracy are achieved
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4. Validation Results of Ocean Products
4.2 (b) Atmospheric correction parameters (ACP)

Validation Method:-

RMS errors are evaluated comparing SGLI-derived aerosol optical thickness (AOT) with in-situ measurementsof AOT at the wavelength of 865 nm conducted during simultaneous tower (AERONET-OC: sky- and oceanradiometer installed on oceanic towers).

Validation data and condition etc.:-

In-situ data acquired within 3 hours from SGLI observations were used for comparison.
SGLI data were extracted from 5 by 5 pixels near the in-situ observation sites to have one averaged value andthen the data were selected by the following criteria (Bailey, 2006);
1. Aerosol optical thickness (AOT) ≤ 0.4, solar zenith angle ≤ 70 deg., the atmospheric correction scheme
passed successfully, the target pixel is neither near the cloudy pixel nor within the region of the sun-glint
correction, and the number of valid pixels ≥ 13.
2. A coefficient of variation (CV) is computed for pixels which passed the 1st test (1.) for bands between 412
and 565 nm and for the AOT 865 nm using the arithmetic mean and standard deviation of the 5x5 pixels,
and the median CV is less than 0.15.

Validation period:-

AERONET-OC: Jan. 1st to Oct. 26th 2018

Reference: Bailey, S.W., and Werdell, P.J. (2006). A multi-sensor approach for the on-orbit validation of ocean color satellite data products. Rem. Sens.
Environ. 102, 12-23.

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4. Validation Results of Ocean Products
4.2 (b) Atmospheric correction parameters (ACP)

Validation Results:

精度: 67.9%

Estimated errors

Release threshold

Standard accuracy

Target accuracy

68%(AOT@865nm)

80% (AOT@865nm)

50% (AOT@865nm)

30% (AOT@865nm)

Release threshold is achieved

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4. Validation Results of Ocean Products
4.2 (c) Photosynthetically available radiation (PAR)

Validation Method:-

RMS errors are evaluated comparing SGLI-derived monthly averaged PAR with those derived
from mooring buoys such as TAO/TRITON, PIRATA, RAMA.

Validation data and condition etc.:-

In-situ data acquired within 3 hours from SGLI observations were converted to daily PARs andthen averaged to monthly PARs for comparison with SGLI- PARs.
Daily SGLI-PARs within 10 km box at the center of in-situ observation sites were extracted andthen averaged to monthly PARs.

Validation period:-

TAO/TRITON、PIRATA、 RAMA : Jan. 1st to Oct. 31th 2018

Reference: National Center for Atmospheric Research Staff (Eds). Last modified 01 Nov 2013. "The Climate Data Guide: Tropical Moored Buoy System: TAO,TRITON, PIRATA, RAMA (TOGA)." Retrieved from https://climatedataguide.ucar.edu/climate-data/tropical-moored-buoy-system-tao-triton-pirata-rama-toga.

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4. Validation Results of Ocean Products
4.2 (c) Photosynthetically available radiation (PAR)

Validation Results:

RE: 15.2%

Estimated errors

Release threshold

Standard accuracy

Target accuracy

15% (10km/monthly ave.)20% (10km/monthly ave.)

15% (10km/monthly ave.)

10% (10km/monthly ave.)

Release threshold and Standard accuracy are achieved
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4. Validation Results of Ocean Products
4.2 (d) Chlorophyll-a concentration (CHLA)

Validation Method:-

RMS errors are evaluated comparing SGLI derived CHLA with those derived from in-situ sampled sea water byfluorescence method or HPLC analysis and also with other satellite products.

Validation data and condition etc.:--

In-situ data acquired within 3 hours from SGLI observations were used for comparison.
SGLI data were extracted from 5 by 5 pixels near the in-situ observation sites to have one averaged value andthen the SGLI data were selected by the following criteria (Bailey, 2006);
1. Aerosol optical thickness (AOT) ≤ 0.3, solar zenith angle ≤ 70 deg., the atmospheric correction scheme
passed successfully, the target pixel is neither near the cloudy pixel nor within the region of the sun-glint
correction, and the number of valid pixels ≥ 13.
2. A coefficient of variation (CV) is computed for pixels which passed the 1st test (1.) for bands between 412
and 565 nm and for the AOT 865 nm using the arithmetic mean and standard deviation of the 5x5 pixels,
and the median CV is less than 0.15.
Comparisons between SGLI and other satellite CHLA products were conducted for monthly averaged global
data projected on grids with 1/24 deg. Interval.

Validation period:-

Yoko-Maru: Feb. 2nd to Oct. 16th 2018
Shinsei-Maru: May 21st to 28th 2018
Nagasaki-Maru: Jul. 19th to 27th 2018
Hokko-Maru: Jun. 1st to 8th 2018
Aqua/MODIS: Oct. 1st to 31st 2018

Reference: Bailey, S.W., and Werdell, P.J. (2006). A multi-sensor approach for the on-orbit validation of ocean color satellite data products. Rem. Sens.
Environ. 102, 12-23.

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4. Validation Results of Ocean Products
4.2 (d) Chlorophyll-a concentration (CHLA)

Validation Results:
VS. In-situ data (open sea)

VS. Aqua/MODIS (open sea)

RE:

RE:

-58.0%

147.3%

Monthly (Oct.) ave. Chl-a

Estimated errors

Release threshold

Standard accuracy

Target accuracy-58% (in-situ, open sea)
147% (Aqua/MODIS, open sea)

−60~+150% (open sea)

−60~+150%−35~+50% (open sea),−50~+100% (coastal)

Release threshold is achieved
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4. Validation Results of Ocean Products
4.2 (e) Total suspended matter concentration (TSM)

Validation Method:-

RMS errors are evaluated comparing SGLI derived TSM with those derived from in-situ sampled
sea water by filtration method (weighting the dried filters before and after the filtration toestimate the mass of suspended matter) and also with other satellite products.

Validation data and condition etc.:-

Comparisons only with other satellite products were conducted because there are no in-situ
data available at the moment of evaluation 1-year after the GCOM-C launch.
Korean’s geostationary satellite “GOCI”-derived TSM was used for the comparison with SGLI for
the TSM range of 0.1 to 65 g/m3 (*1). The comparison was made on the spatial grids of 1 km.

Validation period:-

GOCI: Oct. 31, 2018.

*1: The definition of GOCI’s TSM is different from that of SGLI. That is, GOCI’s TSM is the amount of floating inorganic matte in seawater, whereas
SGLI’s TSM is the sum of floating inorganic and organic matter in seawater. Thus, SGLI’s TSM is considered to be larger than that of GOCI.

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4. Validation Results of Ocean Products
4.2 (e) Total suspended matter concentration (TSM)

Validation Results:

Comparison with GOCI(> 1g/m3)

RE:

47 %

RE::

126 %

※The definition of GOCI’s TSM: ”The amount of floating inorganic matte in seawater”*1)*1) http://kosc.kiost.ac.kr/eng/p30/kosc_p33.html

Estimated errors

Release threshold

126% (vs. GOCI)−60~+150% (open sea)
-53% (vs. GOCI, > 1g/m3)

Standard accuracy

Target accuracy−60~+150%−50~+100%

Release threshold is achieved
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4. Validation Results of Ocean Products
4.2 (e) Total suspended matter concentration (TSM)

Validation Results (Cont.):--

SGLI-derived TSMs tend to be higher than those of GOCI for the TSM range higher than 1 g/m3
which is considered due to the difference of the TSM definition between SGLI and GOCI as
described before.
In addition, SGLI-derived TSMs become significantly higher than those of GOCI at the lower TSM
range less than 1 g/m3 which can be considered due to an overestimation of NWLR at 670 nm asshown in the figure below. The overestimation of TSM could be reduced after the improvementof the SGLI NWLR product by next update.
• NWLR(670) error of 0.4 W/m2/sr/μm is theestimated accuracy in this evaluation (within
the standard accuracy).
• nLw(670) error of 0.2 W/m2/sr/μm is theestimate using in-situ data from MOBY*1(within the target accuracy).
*1: MOBY data are provided from NOAA through the agreement (amemorandum of understanding (MoU)) between JAXA and NOAA.

The effects of NWLR (670) errors on TSM

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4. Validation Results of Ocean Products
4.2 (f) Colored dissolved organic matter (CDOM)

Validation Method:-

RMS error is evaluated comparing SGLI derived CDOM with those derived from in-situ sampled sea water by
optical measurements and also with other satellite products.

Validation data and condition etc.:--

In-situ data acquired within 3 hours from SGLI observations were used for comparison.
SGLI data were extracted from 5 by 5 pixels near the in-situ observation sites to have one averaged value andthen the SGLI data were selected by the following criteria (Bailey, 2006);
1. Aerosol optical thickness (AOT) ≤ 0.3, solar zenith angle ≤ 70 deg., the atmospheric correction scheme
passed successfully, the target pixel is neither near the cloudy pixel nor within the region of the sun-glint
correction, and the number of valid pixels ≥ 13.
2. A coefficient of variation (CV) is computed for pixels which passed the 1st test (1.) for bands between 412
and 565 nm and for the AOT 865 nm using the arithmetic mean and standard deviation of the 5x5 pixels,
and the median CV is less than 0.15.
Comparisons between SGLI and other satellite CDOM products were conducted for monthly averaged global
data projected on grids with 1/24 deg. Interval.

Validation period:-

Yoko-Maru: Feb. 2nd to Oct. 16th 2018
Shinsei-Maru: May 21st to 28th 2018
Nagasaki-Maru: Jul. 19th to 27th 2018
Hokko-Maru: Jun. 1st to 8th 2018
Aqua/MODIS: Oct. 1st to 31st 2018

Reference: Bailey, S.W., and Werdell, P.J. (2006). A multi-sensor approach for the on-orbit validation of ocean color satellite data products. Rem. Sens.
Environ. 102, 12-23.

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4. Validation Results of Ocean Products
4.2 (f) Colored dissolved organic matter (CDOM)

Validation Results:
VS. In-situ data (open sea)

VS. Aqua/MODIS (open sea)

RE:
49%

RE:
122.8%

Monthly (Oct.) ave. CDOM

Estimated errors

Release threshold

Standard accuracy

Target accuracy-51% (in-situ, open sea)
123% (Aqua/MODIS, open sea)

−60~+150% (open sea)

−60~+150%−50~+100%

Release threshold is achieved
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4. Validation Results of Ocean Products
4.2 (g) Sea surface temperature (SST)

Validation Method:-

Overall RMS errors are evaluated comparing SGLI derived SST with those derived from buoymeasurements obtained from iQuam.

Validation data and condition etc.:--

In-situ buoy data acquired within the spatial difference of 10 km and time difference of 2 hours from SGLI
observations were used for comparison. In addition, before the comparison, the SGLI SSTs that meet thefollowing conditions were selected;
1. Standard deviation of SGLI SST within 5 x 5 pixels around the buoy location is less than 1.0 ℃.
2. The difference between maximum and minimum of SGLI SSTs within the 5x5 pixel box is less than 3.0 ℃.
3. The difference between SGLI SST and iQuam SST is less than 5 ℃.
SGLI SSTs at the spatial resolution of 1 km with the quality flag of “good” or “acceptable” were used forcomparison (same as the input for Level-3 processing).
The buoy data with the quality assurance flag of iquam_flag=0 and quality_level=5 were obtained from NOAA
iQuam site and used for the comparison.

Location of buoy data

Validation period:-

Oct. 1st to 31st 2018.

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4. Validation Results of Ocean Products
4.2 (g) Sea surface temperature (SST)

Validation Results:
DaytimeJapan

Nighttime

RMSE :

RMSE:

0.50℃

0.41℃

2018.10.02 01:01(UTC) SST
Spatial distribution of SGLI SST (thewestern North Pacific Ocean off Japan)

Estimated errors

Release threshold

Standard accuracy

Target accuracy

0.4℃ (day)0.5℃ (night)

0.8℃ (day)

0.8℃

0.6℃

Release threshold, Standard and Target accuracies are achieved
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