Description
A multiple channel radiation imager, one of the primary instruments onboard FY-4. Technically featured by precisely designed two-mirror structure, capable of accurate and flexible sensing in two dimensions, and minute-level fast sector scanning. Frequent earth imaging over 14 bands with off-axis three reflections of primary optic system. On-board black body available for IR calibrations at very short time intervals.
| Satellite |
FY-4A
|
FY-4B
|
| Weight |
306kg |
|
| Number of channels |
14 |
15 |
| Spatial resolution |
0.5~1 km (VIS/near-IR bands)
2~4 km (IR bands) |
0.5~1 km (VIS/near-IR bands)
2~4 km (IR bands) |
| Time for full-disc scanning |
15 min |
15 min |
| Sensitivity |
S/N=200@ρ=100% (reflection bands)
NE∆T=0.2K@300K (IR bands) |
S/N=200@ρ=100% (reflection bands)
NE∆T=0.2K@300K (IR bands) |
| Calibration accuracy |
3~5% (VIS/near-IR bands)
1K (IR bands) |
3~5% (VIS/near-IR bands)
0.7K (IR bands) |
Characteristics
| Channel |
Type |
Central wavelength |
Band |
SNR or NEΔT @ specified input |
Spatial resolution |
Main purpose |
| 1 |
Visible & Near-Infrared |
0.47µm |
0.45～0.49µm |
S/N≥90 @ ρ=100% |
1km |
Aerosol |
| 2 |
0.65µm |
0.55～0.75µm |
S/N≥200 @ ρ=100% |
0.5~1km |
Fog, cloud |
| 3 |
0.825µm |
0.75～0.90µm |
S/N≥200 @ ρ=100% |
1km |
Vegetation |
| 4 |
Short-wave Infrared |
1.375µm |
1.36～1.39µm |
S/N≥90 @ ρ=100% |
2km |
Cirrus |
| 5 |
1.61µm |
1.58～1.64µm |
S/N≥200 @ ρ=100% |
2km |
Cloud, snow |
| 6 |
2.25µm |
2.1～2.35µm |
S/N≥200 @ ρ=100% |
2~4km |
Cirrus, aerosol |
| 7 |
Mid-wave Infrared |
3.75µm |
3.5～4.0µm (high) |
NEΔT≤0.7K @ 300K |
2km |
Fire |
| 8 |
3.75µm |
3.5～4.0µm (low) |
NEΔT≤0.2K @ 300K |
4km |
Land surface |
| 9 |
Water vapor |
6.25µm |
5.8～6.7µm |
NEΔT≤0.3K @ 260K |
4km |
High level water vapor |
| 10 |
7.1µm |
6.9～7.3µm |
NEΔT≤0.3K @ 260K |
4km |
Middle level water vapor |
| 11 |
Long-wave Infrared |
8.5µm |
8.0～9.0µm |
NEΔT≤0.2K @ 300K |
4km |
Water vapor, cloud |
| 12 |
10.7µm |
10.3～11.3µm |
NEΔT≤0.2K @ 300K |
4km |
Surface temperature |
| 13 |
12.0µm |
11.5～12.5µm |
NEΔT≤0.2K @ 300K |
4km |
Surface temperature |
| 14 |
13.5µm |
13.2～13.8µm |
NEΔT≤0.5K @ 300K |
4km |
Cloud thickness |
| Band |
Center wave length (μm) |
Band width (μm) |
Spatial resolution(km) |
Sensitivity/SNR |
Main purpose |
| 1 |
0.47 |
0.45~0.49 |
1 |
S/N≥90(ρ=100%) |
|
Aerosol |
| 2 |
0.65 |
0.55~0.75 |
0.5 |
S/N≥150(ρ=100%)@0.5km |
S/N≥3(ρ=1%)@1km |
Fog, cloud |
| 3 |
0.825 |
0.75~0.90 |
1 |
S/N≥200(ρ=100%) |
S/N≥3(ρ=1%) |
Vegetation |
| 4 |
1.379 |
1.371~1.386 |
2 |
S/N≥120(ρ=100%) |
S/N≥2(ρ=1%) |
Cirrus |
| 5 |
1.61 |
1.58~1.64 |
2 |
S/N≥200(ρ=100%) |
S/N≥3(ρ=1%) |
Cloud, snow |
| 6 |
2.25 |
2.10~2.35 |
2 |
S/N≥200(ρ=100%) |
S/N≥2(ρ=1%) |
Cirrus, aerosol |
| 7 |
3.75 |
3.50~4.00(high) |
2 |
≤0.7K(315K) |
|
Fire |
| 8 |
3.75 |
3.50~4.00(low) |
4 |
0.2K(300K) |
2K(240K) |
Land surface |
| 9 |
6.25 |
5.80~6.70 |
4 |
0.2K(300K) |
0.9K(240K) |
High level water vapor |
| 10 |
6.95 |
6.75~7.15 |
4 |
0.25K(300K) |
0.9K(240K) |
Mid level water vapor |
| 11 |
7.42 |
7.24~7.60 |
4 |
0.25K(300K) |
0.9K(240K) |
Low level water vapor |
| 12 |
8.55 |
8.3~8.8 |
4 |
0.2K(300K) |
0.4K(240K) |
Cloud |
| 13 |
10.80 |
10.30~11.30 |
4 |
0.2K(300K) |
0.4K(240K) |
Surface temperature |
| 14 |
12.00 |
11.50~12.50 |
4 |
0.2K(300K) |
0.4K(240K) |
Surface temperature |
| 15 |
13.3 |
13.00~13.60 |
4 |
0.5K(300K) |
0.9K(240K) |
Cloud and water vapor |
FY-4A AGRI transmittance over wavelength
FY-4A AGRI scan range (104.7°E)
FY-4A AGRI scan range (133°E)
Data and Products
Calibration and Validation
AGRI calibration and validation
FY-4B AGRI SRF (ZIP)
FY-4A AGRI SRF (PDF)
