Geostationary Interferometric Infrared Sounder (GIIRS)
Description
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 32×4 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 |
|---|---|
| Weight | 315kg |
| Dimension | 1353.5mm (length) × 2179.9mm (width) × 1549mm (height) |
| Bands | Long-wave: 700∼1130cm-1 (8.85∼14.29μm) Mid-wave: 1650∼2250cm-1 (4.44∼6.06μm) |
| Spectral resolution | 0.625cm-1 (actual measurement) |
| No. channels | 1650 (actual measurement) |
| Spatial resolution | 16km |
| Temporal resolution | 768km × 960km (30 min) 4480km × 5000km (60 min) |
| Radiation calibration accuracy | 1.5K |
| Spectral calibration accuracy | 10ppm |
Characteristics
| FY-4A (R&D) | FY-4B (Operational) | |||||||
|---|---|---|---|---|---|---|---|---|
| Spectral parameters (normal mode) | Range (cm-1) | Resolution | No. channels | Range (cm-1) | Resolution | No. channels | ||
| LWIR | 700∼1130 | 0.8 | 538 | LWIR | 700∼1130 | 0.625 | 688 | |
| S/MIR | 1650∼2250 | 1.6 | 375 | S/MIR | 1650∼2250 | 1.2 | 500 | |
| VIS | 0.55-0.75μm | 1 | VIS | 0.55-0.75μm | 1 | |||
| Spatial Resolution | L/S/MWIR | 16km | L/S/MWIR | 8km | ||||
| VIS | 2km | |||||||
| Area | China | 5000 × 5000 km2 | China | 5000 × 5000 km2 | ||||
| Mesoscale | 1000 × 1000 km2 | Mesoscale | 1000 × 1000 km2 | |||||
| Temporal resolution | China | <1 hour | China | <1 hour | ||||
| Mesoscale | <½ hour | Mesoscale | <½ hour | |||||
| Sensitivity (mW/m2sr⋅cm-1) | LWIR | 0.5∼1.1 | LWIR | 0.3 | ||||
| S/MIR | 0.1∼0.14 | S/MIR | 0.06 | |||||
| VIS | S/N>200(ρ=100%) | VIS | S/N>200 (ρ=100%) | |||||
| Calibration accuracy (radiation) | 1.5k (3σ) | 1.0k (3σ) | ||||||
| Calibration accuracy (spectrum) | 10 ppm (3σ) | 5 ppm (3σ) | ||||||
| Quantization (bits) | 13 | 13 | ||||||
Scan range of GIIRS (105°E)
Data and Products
| Satellite | Instrument | Datasets |
|---|---|---|
| FY-4B | GIIRS | L1 data, L2L3 product |
| FY-4A | GIIRS | L1 data, L2L3 product |
Calibration and Validation
GIIRS