AGRI

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	FY-4A: 14, FY-4B: 15
Spatial resolution	0.5~1 km (VIS/near IR), 2~4 km (IR)
Time for full-disc scanning	15 min
Time for sector scanning	1min (1000km × 1000km)
Sensitivity	S/N>3 @ 1% (reflection bands) NE∆T: 0.2K @ 300K (IR bands)

Characteristics (FY-4A)

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	Mid-wave Infrared	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	Water vapor	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