GCOM-C SGLI Sensor Characterization

SGLI Sensor Characterization | link to post-launch cal

1. SGLI relative spectral response (RSR)

All-band/3-telescope RSR (fine resolution)
All-band/3-telescope RSR (low resolution)
All-band RSR (fine resolution)
All-band RSR (low resolution)
- In-band and out-band of VNIR are synthesized by EORC. (The out-band data is gradually used from both 1/4 of edges of in-band wing.)
- In-band and out-band of SWIR and TIR are synthesized by the GCOM-C project team.
- "All band/3-telescope" includes three VNR telescopes (L, N, R: Left (western side in the descending path), Nadir, and Right).
- "All band RSR" includes only VNR Nadir (N) telescope.
- Center-wavelength shift (Coefficients c0~c4 shown below) should be considered for algorithms sensitive to the wavelength.
Format:
"All band/3-telescope":
WL(nm) RSR_VL01(left)... WL(nm) RSR_VN01(nadir)... WL(nm) RSR_VR01(right)... WL(nm) RSR_P01... WL(nm) RSR_SW01... WL(nm) RSR_TI01...
...
"All band":
WL(nm) RSR_VN01... WL(nm) RSR_P01... WL(nm) RSR_SW01... WL(nm) RSR_TI01...
...

Table of Brightness temperature to Radiance conversion (TIR01 and TIR02)
130K-330K (update:20160728)
130K-350K (update:20160728)
130K-400K (update:20160728)
Format (csv):
BT[K], TIR01 Radiance[W/m^2/str/um], TIR02 Radiance[W/m^2/str/um]
..., ..., ...
Table of Radiance to Brightness temperature conversion (TIR01 and TIR02)
~350K 0.0-18.0 or 16.2 W/m^2/um/str (update:20160728),
~400K 0.0-29.7 or 25.2 W/m^2/um/str (update:20160728)
Format (csv):
TIR01 Radiance[W/m^2/str/um], TIR01 BT[K], TIR02 Radiance[W/m^2/str/um], TIR02 BT[K]
..., ..., ..., ...
Reference
- VNR: Uchikata T., K. Tanaka, Y. Okamura, S. Tsuida, and T. Amano (2014): Proto Flight Model (PFM) performance and development status of Visible and Near Infrared Radiometer (VNR) on the Second-generation Global Imager (SGLI) , Proceedings of SPIE, 9264, 92640Q (November 26, 2014); doi:10.1117/12.2068558.
- TIR: Tanaka, K., Y. Okamura, T. Amano, T. Hosokawa, and T. Uchikata (2014): The development status of Second Generation Global Imager (SGLI), Infrared Scanning Radiometer (SGLI-IRS), Proceedings of SPIE 9264, Earth Observing Missions and Sensors: Development, Implementation, and Characterization III, 92640G (November 19, 2014); doi:10.1117/12.2073597.

Liear scale figure

Log scale figure

Comparison with AHI and MODIS

Summary table of (average) center wavelength (WLc) and bandwidth (HW) [nm] (rev. 2014/10/20)

Band	WLc[nm]	HW[nm]	TranW[nm]	EX	F0[W/m^2/um](Thuillier)	F0[W/m^2/um](Kur)	F0[W/m^2/um](TSIS-1)
VNL01	379.853	10.7	3.0	4.1	1093.5379	1109.8123	1075.1551
VNL02	412.306	10.4	3.2	3.8	1711.2835	1755.5305	1760.7541
VNL03	443.433	10.2	3.0	3.9	1903.2471	1929.4749	1913.7742
VNL04	489.686	10.4	2.8	4.3	1937.9540	1964.0677	1951.0623
VNL05	529.638	19.7	5.0	4.6	1850.9682	1877.0691	1902.9754
VNL06	565.926	19.9	5.1	4.6	1797.4827	1822.6236	1854.0025
VNL07	672.002	22.3	5.2	5.0	1502.5522	1524.9353	1525.8050
VNL08	672.148	22.1	5.3	4.9	1502.1799	1524.5890	1525.4644
VNL09	762.917	11.4	3.8	3.6	1245.8937	1263.4791	1229.6826
VNL10	866.835	21.1	6.0	4.1	956.2896	1005.4531	950.4534
VNL11	867.023	21.3	5.9	4.3	956.5311	1005.5876	950.4993
VNN01	380.030	10.7	3.1	4.1	1092.1436	1108.4976	1074.7954
VNN02	412.514	10.4	3.2	3.8	1712.1531	1756.5108	1762.1595
VNN03	443.240	10.2	3.0	3.9	1898.3185	1924.4533	1908.7546
VNN04	489.849	10.4	2.8	4.3	1938.4602	1964.5807	1951.6327
VNN05	529.640	19.7	5.1	4.6	1850.9604	1877.0611	1902.9684
VNN06	566.155	20.1	5.0	4.7	1797.1344	1822.2721	1853.7614
VNN07	671.996	22.3	5.2	5.0	1502.5667	1524.9477	1525.8179
VNN08	672.098	22.1	5.2	4.9	1502.3177	1524.7151	1525.5930
VNN09	763.074	11.4	3.7	3.6	1245.3663	1262.9589	1229.2831
VNN10	866.765	21.1	6.1	4.1	956.2323	1005.5116	950.4500
VNN11	867.120	21.3	5.8	4.3	956.5352	1005.4458	950.4382
VNR01	380.212	10.7	3.1	4.1	1090.5931	1107.0316	1073.8359
VNR02	412.589	10.4	3.2	3.8	1712.4760	1756.8697	1762.5998
VNR03	443.051	10.2	3.0	3.9	1893.5879	1919.6334	1903.9212
VNR04	490.311	10.4	2.8	4.3	1941.0715	1967.3261	1955.5650
VNR05	529.664	19.7	5.0	4.6	1851.0657	1877.1674	1903.0540
VNR06	566.377	20.1	5.0	4.7	1796.8275	1821.9625	1853.5657
VNR07	671.950	22.3	5.2	5.0	1502.6962	1525.0681	1525.9371
VNR08	672.120	22.1	5.3	4.9	1502.2582	1524.6613	1525.5375
VNR09	763.234	11.4	3.8	3.6	1244.8290	1262.4288	1228.7940
VNR10	866.713	21.1	6.0	4.1	956.2577	1005.5964	950.5103
VNR11	867.086	21.3	5.8	4.3	956.5735	1005.5181	950.4974
VNP01	671.892	20.9	6.0	4.1	1503.6050	1525.9627	1526.8186
VNP02	866.180	20.3	5.6	4.2	956.8333	1007.5356	951.3730
SWI01	1054.994	21.4	10.4	2.5	646.5213	652.4925	648.3060
SWI02	1385.351	20.2	7.0	3.4	361.2250	354.9883	351.5705
SWI03	1634.506	195.8	18.8	12.1	237.5784	232.5702	229.4956
SWI04	2209.481	50.8	17.4	3.5	84.2413	81.3353	80.4421
TIR01	10793.5	763.2	210.6	4.3	0.0000	0.0000	0.0000
TIR02	11956.8	783.0	252.0	3.7	0.0000	0.0000	0.0000

Approximation: RSR(W) = exp( log(1/2) * ( abs(W - WLc)/(HW/2) )^EX )
W: wavelength [nm]
TransW: Transition width [nm] from 0.1 to 0.8
F0 is calculated by Thuiller (2003) (at 1.0AU): GCOM-C standard irradiance
F0(Kur) is calculated by Kurucz (1992) (at 1.0AU)
F0(TSIS-1) is "The TSIS-1 hybrid Solar Reference Spectrum" by Coddington et al., 2021 (at 1.0AU)

Center wavelength shift

Center wavelength of VNR-NP (telescope-L/N/R) and VNR-PL by normalized pixel number (-0.5 ~ +0.5) (rev. 2014/09/26, rev. 2014/10/23, rev. 2015/3/29 (POL), rev. 2015/12/25 (POL))

Coefficients c0~c4, regression error, Average, Min and Max of center wavelengths of VNL (VNR-NP telescope-Left), VNN (VNR-NP telescope-Nadir), VNR (VNR-NP telescope-Right) and VNR-PL (The coefficients were calculated by EORC using original measurements by SGLI sensor team) (rev. 2014/09/26, rev. 2014/10/23, rev. 2015/3/29 (POL), rev. 2015/12/25 (POL))

Band	c0	c1	c2	c3	c4	RgErr[nm]	Ave[nm]	Min[nm]	Max[nm]
VNL01	3.7983E+02	-2.0654E-01	4.0953E-01	7.6962E-01	-7.5110E-01	0.005	379.85	379.80	379.91
VNL02	4.1235E+02	1.1515E-01	-7.2607E-02	5.3384E-01	-2.0197E+00	0.005	412.31	412.11	412.38
VNL03	4.4337E+02	9.0581E-02	6.3376E-01	5.5982E-02	7.0385E-02	0.004	443.43	443.37	443.57
VNL04	4.8966E+02	-3.0622E-01	3.3672E-01	4.5020E-01	-3.9824E-01	0.005	489.69	489.60	489.81
VNL05	5.2952E+02	-3.5294E-01	9.6784E-01	-3.1234E-01	1.9387E+00	0.011	529.62	529.47	530.08
VNL06	5.6589E+02	2.4046E-01	8.7851E-01	6.2411E-01	-2.7019E+00	0.008	565.93	565.76	566.12
VNL07	6.7184E+02	-3.4264E-01	7.7027E-01	-6.1871E-01	5.8120E+00	0.020	671.98	671.81	672.61
VNL08	6.7201E+02	-4.1357E-01	6.0967E-01	1.8496E-01	5.3048E+00	0.018	672.13	671.96	672.65
VNL09	7.6327E+02	3.1900E-01	-2.6370E+00	-1.6204E+00	-4.7683E+00	0.008	762.96	762.35	763.28
VNL10	8.6738E+02	1.8538E+00	-1.3750E+01	-1.2301E+01	4.8520E+01	0.046	866.83	866.23	867.48
VNL11	8.6759E+02	1.8948E+00	-1.3941E+01	-1.2742E+01	4.8163E+01	0.042	867.02	866.40	867.70
VNN01	3.8001E+02	1.7104E-01	2.9402E-01	-6.5029E-01	-6.9351E-01	0.005	380.03	379.99	380.08
VNN02	4.1257E+02	1.6869E-01	-2.2033E-01	4.3098E-01	-1.9828E+00	0.008	412.52	412.28	412.60
VNN03	4.4316E+02	-9.9156E-02	7.1108E-01	-1.6487E-02	4.1156E-01	0.005	443.23	443.16	443.40
VNN04	4.8983E+02	2.8187E-01	2.9698E-01	-3.6911E-01	-5.8977E-01	0.005	489.85	489.77	489.97
VNN05	5.2952E+02	3.9348E-01	8.8587E-01	2.7552E-01	2.0914E+00	0.010	529.63	529.48	530.09
VNN06	5.6613E+02	2.9743E-01	7.9222E-01	4.1063E-01	-2.9697E+00	0.007	566.16	565.96	566.34
VNN07	6.7182E+02	3.8590E-01	1.2226E+00	-2.3696E-02	3.8871E+00	0.022	671.97	671.76	672.55
VNN08	6.7194E+02	4.3907E-01	7.5132E-01	2.2127E-02	5.3565E+00	0.018	672.08	671.89	672.66
VNN09	7.6342E+02	-3.1793E-01	-2.5845E+00	1.6389E+00	-4.8441E+00	0.008	763.12	762.51	763.43
VNN10	8.6730E+02	-1.7540E+00	-1.3713E+01	1.2056E+01	4.8410E+01	0.045	866.76	866.18	867.43
VNN11	8.6767E+02	-1.8758E+00	-1.3568E+01	1.2824E+01	4.7018E+01	0.032	867.12	866.50	867.81
VNR01	3.8020E+02	-1.4418E-01	2.5644E-01	6.5340E-01	-9.4438E-01	0.006	380.21	380.18	380.24
VNR02	4.1265E+02	2.0817E-01	-3.2323E-01	3.4006E-01	-1.7034E+00	0.006	412.60	412.34	412.68
VNR03	4.4296E+02	1.0681E-01	8.1284E-01	-3.6629E-02	7.1595E-01	0.004	443.04	442.96	443.24
VNR04	4.9032E+02	-2.2237E-01	1.0639E-02	2.1432E-01	-5.0950E-01	0.007	490.31	490.21	490.39
VNR05	5.2955E+02	-4.1437E-01	9.1150E-01	-1.2109E-01	1.6420E+00	0.011	529.65	529.50	530.09
VNR06	5.6636E+02	3.4432E-01	7.4963E-01	2.2421E-01	-3.3094E+00	0.006	566.38	566.16	566.56
VNR07	6.7177E+02	-4.0534E-01	1.1152E+00	-1.8236E-01	4.7486E+00	0.018	671.93	671.73	672.55
VNR08	6.7198E+02	-5.0520E-01	6.5910E-01	2.4386E-01	5.1359E+00	0.017	672.10	671.91	672.67
VNR09	7.6357E+02	3.0504E-01	-2.5451E+00	-1.5900E+00	-4.8479E+00	0.007	763.28	762.68	763.58
VNR10	8.6725E+02	1.7793E+00	-1.3803E+01	-1.2226E+01	4.9354E+01	0.048	866.71	866.11	867.44
VNR11	8.6760E+02	2.0163E+00	-1.3424E+01	-1.4051E+01	4.8480E+01	0.034	867.08	866.46	867.90
VNP01	6.7191e+02	-3.3244e-01	1.2376e+01	1.2811e+00	-3.2838e+01	0.023	672.54	671.89	673.10
VNP02	8.6620e+02	-1.7438e+00	1.0498e+00	5.1759e+00	-5.6396e+00	0.007	866.22	865.85	866.63

WLc[nm]=c0 +c1*X +c2*X^2 +c3*X^3 +c4* X^4
X (= -0.5 ~ +0.5): (pixels - center_pixel)/pixel_length
pixels: 1~pixel_length at a telescope
pixel_length=1500 (VNR-NP 250m), pixel_length=857 (VNR-PL)
c0: center wavelength at the telescope center (X=0)

SGLI TIR Sensor Plank Function

[these equations or the above conversion tables are recommended] (optimized for 130K~400K)
From SGLI-band Radiance (RD) to SGLI-band Brightness temperature (BT) by SGLI center wavelength (WL): BT0 =c2 /WL /log(c1/RD/WL^5 +1);
BT[K] =cr2t(1) +cr2t(2)*BT0 +cr2t(3)*BT0^2;
From SGLI-band Brightness temperature (BT) to SGLI-band Radiance (RD) by SGLI center wavelength (WL): RD0 =c1 /WL^5 /(exp(c2/WL/BT) -1);
RD[W/m^2/str/um] =ct2r(1) +ct2r(2)*RD0 +ct2r(3)*RD0^2;; Constants (same as Himawari-8):
c =299792458;
h =6.62606957E-34;
k =1.38064880E-23;
c1=2*h*c^2 *1.0E+24;
c2=(h*c)/(k *1.0E-6);
TIR01:: WL[um]=10.7935
cr2t=[-3.6658555409e-01, 1.0032838274e+00, -6.0965021334e-06];
ct2r=[-2.7185709007e-04, 9.9843659844e-01, 6.1836121620e-05];
TIR02:: WL[um]=11.9568
cr2t=[-3.2302206075e-01, 1.0031652102e+00, -6.3965619878e-06];
ct2r=[-4.9968999113e-04, 9.9866962896e-01, 8.0654962709e-05];

Approximation by the center wavelength
[not recommended for precise calculations]

(BT->Radiance or Radiance->BT table should be used for precise calculations; see aboves)

Upper panel shows brightness temperature (BT) and Radiance relation: Light blue: TIR01 (10.7935 um), Red: TIR02 (11.9568 um)
Lower panel shows BT error due to monochromatic approximation:
Radiance[W/m^2/str/um] = 119104286.8142 / WL[um]^5 / ( exp( 14387.7696 / WL[um] / BT[K] ) - 1);: WL: center wavelength [um] (= wavelength [nm] *0.001); BT: Brightness Temperature [K]
- TIR01 center wavelength (white weight): 10.7935um, RMSE=0.0522[K]
- TIR02 center wavelength (white weight): 11.9568um, RMSE=0.0497[K]
-- TIR01 minimum error wavelength: 10.7939um, RMSE=0.0521[K]
-- TIR02 minimum error wavelength: 11.9555um, RMSE=0.0485[K]

2. Signal to Noise Ratio (SNR)

Reference
- Sakashita, T., S.Tsuida, T. Amano, K. Shiratama and K. Tanaka (2016): "Proto Flight Model (PFM) development status of visible and near-infrared radiometer (VNR) on the Second-generation Global Imager (SGLI) ", Proc. SPIE 9881, Earth Observing Missions and Sensors: Development, Implementation, and Characterization IV, 98810S (May 2, 2016); doi:10.1117/12.2222504.
- Tanaka, K., T Amano, T. Uchikata and T. Sakashita (2016): "Early test results of proto-flight test of Second Generation Global Imager (SGLI) Infrared Scanning Radiometer (IRS) ", Proc. SPIE 9881, Earth Observing Missions and Sensors: Development, Implementation, and Characterization IV, 98810M (May 2, 2016); doi:10.1117/12.2224732.
- Hashiguchi, T., Y. Okamura, K. Tanaka, Y. Nakajima, K. Suzuki, T. Sakashita and T. Amano (2016): "Radiometric performance of Second-generation Global Imager (SGLI) using integrating spheres ", Proc. SPIE 10000, Sensors, Systems, and Next-Generation Satellites XX, 1000007 (October 19, 2016); doi:10.1117/12.2241955.

SNR at Lstd (VN09:1km, others:250m)

Band	NPL	NPN	NPR	Lstd(W/m2/sr/um)	Lmax(W/m2/sr/um)
VN01	659	675	692	60	240-241
VN02	826	786	789	75	305-318
VN03	487	531	532	64	457-467
VN04	858	870	868	53	147-150
VN05	468	522	457	41	361-364
VN06	1064	1038	1017	33	95-96
VN07	1006	1013	988	23	69-70
VN08	537	564	546	25	213-217
VN09	1746	1592	1600	40	351-359
VN10	510	470	493	8	37-38
VN11	504	511	478	30	305-306

SNR at Lstd (1km)

Pol	60	0	-60	Lstd(W/m2/sr/um)	Lmax(W/m2/sr/um)
PL01	643	707	614	25	293-315
PL02	646	763	760	30	396-424

SNR at Lstd (SW03:250m, others:1km)

Band	SRU-A	SRU-B	Lstd(W/m2/sr/um)	Lmax(W/m2/sr/um)
SW01	951	937	57	289.2
SW02	346	337	8	118.9
SW03	100	103	3	50.6
SW04	379	381	1.9	21.7

NEdT(K) (500m)

Band	SRU-A	SRU-B	NEdT(K)	Tmax(K)
TIR1	0.039	0.038	300	340
TIR2	0.069	0.065	300	340

3. Polarization sensitivity

Reference
- Sakashita, T., S.Tsuida, T. Amano, K. Shiratama and K. Tanaka (2016): "Proto Flight Model (PFM) development status of visible and near-infrared radiometer (VNR) on the Second-generation Global Imager (SGLI) ", Proc. SPIE 9881, Earth Observing Missions and Sensors: Development, Implementation, and Characterization IV, 98810S (May 2, 2016); doi:10.1117/12.2222504.
- Tanaka, K., T Amano, T. Uchikata and T. Sakashita (2016): "Early test results of proto-flight test of Second Generation Global Imager (SGLI) Infrared Scanning Radiometer (IRS) ", Proc. SPIE 9881, Earth Observing Missions and Sensors: Development, Implementation, and Characterization IV, 98810M (May 2, 2016); doi:10.1117/12.2224732.
- Hashiguchi, T., Y. Okamura, K. Tanaka, Y. Nakajima, K. Suzuki, T. Sakashita and T. Amano (2016): "Radiometric performance of Second-generation Global Imager (SGLI) using integrating spheres ", Proc. SPIE 10000, Sensors, Systems, and Next-Generation Satellites XX, 1000007 (October 19, 2016); doi:10.1117/12.2241955.

VNR-NP polarization sensitivity table
Q=(-row_c+row_l.*cos(2*shita))./(1-row_c.*row_l.*cos(2*shita));
U=((1-row_c).*row_l.*sin(2*shita))./(1-row_c.*row_l.*cos(2*shita));
sample matlab/octave code

4. Stray light (TBD)