GSICS-EP-15, 16-17 May 2014 (Guangzhou, China) 1 Intersatellite Calibration of infrared sensors onboard Indian Geostationary Satellites using LEO Hyperspectral Observations A S Kiran Kumar [email protected]P K Pal, C M Kishtawal, Pradeep Thapliyal, Munn Shukla Space Applications Centre Indian Space Research Organisation Ahmedabad (INDIA) Updates from GSICS members and Observers Indian Space Research Organisation (ISRO)
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Intersatellite Calibration of infrared sensors onboard ... Calibration of infrared sensors onboard Indian Geostationary Satellites using LEO Hyperspectral Observations A S Kiran Kumar
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GSICS-EP-15, 16-17 May 2014 (Guangzhou, China) 1
Intersatellite Calibration of infrared sensors onboard Indian Geostationary Satellites using
Data Source: IASI L1C through Eumetcast at SAC/ISRO in BUFR format
Methodology• Land/sea mask: Use only ocean pixels
• Temporal Collocation: 5, 15, 30 Minutes
• Spatial Collocation: – Within IASI IFOV (2x2 pixels)
• Zenith angle collocation:
| sec(βAIRS) – sec(βKalp) | < 0.01, and
βIASI & βKalpana < 10
• Spatial homogeneity test: Wang et al., JAOT 2009, vol.26,1843-1855
(SD of Kalpana Tb within one IASI IFOV) / (mean Tb of IASI FOR) < 0.01
GSICS-EP-15, 16-17 May 2014 (Guangzhou, China) 10
Daily (Daytime) BIAS/ Standard Deviation of Differences (IR) Time Diff: 30 min
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1-Ju
l
11-J
ul
21-J
ul
31-J
ul
10-A
ug
20-A
ug
30-A
ug
9-S
ep
19-S
ep
29-S
ep
9-O
ct
19-O
ct
29-O
ct
Date (2011)B
IAS
/ S
tdD
ev (K
)
BIASStdDev
(Morning) Mean StDev = 1.3 K
Daily (Nighttime) BIAS/ Standard Deviation of Differences (IR) Time Diff: 30 min
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1-Ju
l
11-J
ul
21-J
ul
31-J
ul
10-A
ug
20-A
ug
30-A
ug
9-S
ep
19-S
ep
29-S
ep
9-O
ct
19-O
ct
29-O
ct
Date (July 2011)
BIA
S /
Std
Dev
(K)
BIASStdDev
(Evening) Mean StDev = 1.3 K
TIR Channel Kalpana/IASI (Jul-Oct, 2011)
GSICS-EP-15, 16-17 May 2014 (Guangzhou, China) 11
Daily (Daytime) BIAS/ Standard deviation of difference (WV) Time Diff: 30 min
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1-Ju
l
6-Ju
l
11-J
ul
16-J
ul
21-J
ul
26-J
ul
31-J
ul
5-A
ug
10-A
ug
15-A
ug
20-A
ug
25-A
ug
30-A
ug
4-S
ep
9-S
ep
14-S
ep
19-S
ep
24-S
ep
29-S
ep
4-O
ct
9-O
ct
14-O
ct
19-O
ct
24-O
ct
29-O
ct
Date (2011)B
IAS
/ S
tdD
ev (K
)
biasStdDev
Daily (Nighttime) BIAS/ Standard deviation of difference (WV) Time Diff: 30 min
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1-Ju
l
6-Ju
l
11-J
ul
16-J
ul
21-J
ul
26-J
ul
31-J
ul
5-A
ug
10-A
ug
15-A
ug
20-A
ug
25-A
ug
30-A
ug
4-S
ep
9-S
ep
14-S
ep
19-S
ep
24-S
ep
29-S
ep
4-O
ct
9-O
ct
14-O
ct
19-O
ct
24-O
ct
29-O
ct
Date (2011)
BIA
S /
Std
Dev
(K)
BIASStdDev
(Morning) Mean StDev = 0.9K
(Evening) Mean StDev = 1.0 K
WV Channel Kalpana/IASI (Jul-Oct, 2011)
GSICS-EP-15, 16-17 May 2014 (Guangzhou, China) 12
Summary of Kalpana Intercalibration
• Kalpana TIR Channel intercalibrated with AIRS radiances for 2011 (clear sky conditions)– Std. Dev. of differences very small 0.3-0.4K– Bias smaller during daytime with seasonal variations– Bias higher during nightime
• Kalpana TIR and WV channel intercalibration with IASI radiances (all-sky conditions)– Std. Dev. of differences high (1.3K TIR and 0.9K WV)– TIR: bias smaller during daytime with seasonal variations during– TIR: higher bias during nighttime– WV: lower bias during daytime and higher bias during nighttime
GSICS-EP-15, 16-17 May 2014 (Guangzhou, China) 13
Data Source: IASI L1C (Eumetcast)Temporal Collocation: < 15 MinutesSpatial Collocation: within IASI pixel (12 km)
Zenith angle collocation:
maxzen = 0.1-0.4 depending upon the absorption
Spatial homogeneity test: Std. Dev. of INSAT-3D (7x7 pixel) and IASI (5x5) radiances within environment surrounding the target pixel
• Convolved radiance of broadband sensor using ‘n’ number of hyperspectral sounders channels may be computed using:
• Rconv is convolved broadband radiance, RIASI is radiance of hyper-spectral sounder, superscript ‘i’ is hyper-spectral channel index, SINSAT is the sensor response function of INSAT-3D channels at the central wavenumber of hyper-spectral channel ‘i’, and ‘n’ is the total number of hyper-spectral channels in broadband sensor’s SRF range.