GIIRS

An infrared hyper-spectral vertical sounder, also the first space-borne interferometer that flies in geostationary orbit to take measurements of three dimensional atmospheric structure from interference of split light beams. Technically featured by a sensor array plane, a Michelson interferometer working over different infrared bands for large-area, continuous, fast, and accurate vertical air soundings of temperature and humidity.

Satellite	FY-4A	FY-4B	FY-4C
Weight	315kg
Dimension	1353.5mm (length) × 2179.9mm (width) × 1549mm (height)
Bands	Long-wave: 700∼1130cm^-1 Mid-wave: 1650∼2250cm^-1 Visible: 0.55∼0.90μm	Long-wave: 680∼1130cm^-1 Mid-wave: 1650∼2250cm^-1 Visible: 0.55∼0.75μm	Long-wave: 650∼1130cm^-1 Mid-wave: 1650∼2250cm^-1 Visible: 0.55∼0.75μm
Spectral resolution	Long-wave: 0.8cm^-1 Mid-wave: 1.6cm^-1	0.8cm^-1	0.625cm^-1
Spatial resolution	Infrared: 16km SSP Visible: 2km SSP	Infrared: 12km SSP Visible: 1km SSP	Infrared: 4∼8km SSP Visible: 0.5∼1km SSP
Temporal resolution	60 min	45 min	45 min
Radiation calibration accuracy	1.5K	0.7K	0.5K
Spectral calibration accuracy	10ppm	better than 10ppm	5ppm (with newly added ability of in-orbit spectral calibration)

Satellite

FY-4A

FY-4B

FY-4C

Weight

315kg

Dimension

1353.5mm (length) × 2179.9mm (width) × 1549mm (height)

Bands

Long-wave: 700∼1130cm^-1
Mid-wave: 1650∼2250cm^-1
Visible: 0.55∼0.90μm

Long-wave: 680∼1130cm^-1
Mid-wave: 1650∼2250cm^-1
Visible: 0.55∼0.75μm

Long-wave: 650∼1130cm^-1
Mid-wave: 1650∼2250cm^-1
Visible: 0.55∼0.75μm

Spectral resolution

Long-wave: 0.8cm^-1
Mid-wave: 1.6cm^-1

0.8cm^-1

0.625cm^-1

Spatial resolution

Infrared: 16km SSP
Visible: 2km SSP

Infrared: 12km SSP
Visible: 1km SSP

Infrared: 4∼8km SSP
Visible: 0.5∼1km SSP

Temporal resolution

60 min

45 min

Radiation calibration accuracy

1.5K

0.7K

0.5K

Spectral calibration accuracy

10ppm

better than 10ppm

5ppm (with newly added ability of in-orbit spectral calibration)

Band	Range	Sensitivity	Calibration accuracy
LWIR	700∼1130 cm^-1	0.5∼1.1 mW/(m²sr cm^-2)	1 K
MWIR	1650∼2250 cm^-1	0.1∼0.14 mW/(m²sr cm^-2)	1 K

VIS band

○ SNR: S/N ≥ 200 (ρ=100%)

IR bands:

Band	Range	Sensitivity	Calibration accuracy
LWIR	680∼1130 cm^-1	0.5 mW/(m²sr cm^-2)	0.7 K
MWIR	1650∼2250 cm^-1	0.1 mW/(m²sr cm^-2)	0.7 K

VIS band:

○ SNR: S/N ≥ 200 (ρ=100%)

IR bands:

Band	Range	Sensitivity	Calibration accuracy
LWIR	650∼1130 cm^-1	0.3 mW/(m²sr cm^-2)	0.5 K
MWIR	1650∼2250 cm^-1	0.06 mW/(m²sr cm^-2)	0.5 K

VIS band:

○ SNR: S/N ≥ 200 (ρ=100%)

Satellite	Instrument	Datasets
FY-4B	GIIRS	Search
FY-4A	GIIRS	Search

Satellite

Instrument

Datasets

FY-4B

GIIRS

FY-4A

GIIRS

Geostationary Interferometric Infrared Sounder (GIIRS)

Description

Characteristics

Data and Products

Calibration and Validation