Inhaltsbereich
EnMAP - Requirements and Technical Outline
multispectral versus hyperspectral
Identification - Quantification -> Diagnosis
Multi- versus Hyperspectral / Potentials
Every material is formed by chemical bonds, and as such can be characterised by spectral absorption features in the electromagnetic spectrum. EnMAP has the capability to detect individual absorption features in the spectra of many materials, solids, liquids, or gases. Actual detection depends on the instrument´s spectral coverage, spectral resolution, spectral sampling, signal-to-noise ratio, the abundance of the material and the strength of the materials absorption features in the wavelength region measured.
Identification – Quantification => Diagnosis
- Each material on the Earth‘s surface has a unique spectral characteristic
- Pigments, Minerals, Man Made Objects
Spectral Requirements
| Spectral sampling interval |
Spectral bandwidth (FWHM) |
Number of bands (total of ~ 244) |
|
| VNIR-range | |||
| 420 nm - 1000 nm | 6.5 nm | 8.1 ± 1.0 nm | ~ 89 |
| SWIR-range | |||
| 900 nm - 2450 nm | 10 nm | 12.5 ± 1.5 nm | ~ 155 |
The Number of bands may vary due to overlap at 900-1000nm and non-linearities of prism design.
Sensor Parameters
| Signal-to-noise ratio (SNR) at 30% reflectance; 30° sun zenith angle; visibility 21 km; target 500 m a.s.l. |
VNIR: > 450:1 (at 495 nm) SWIR: > 150:1 (at 2200 nm) |
| Spectral calibration accuracy | VNIR: 0.5 nm SWIR: 1 nm |
| Spectral stabilit | 0.5 nm |
| Radiometric calibration accuracy | < 5 % |
| Quantification / Radiometric stability | 14 bit / < 2.5 % |
| Spectral smile/keystone effect | < 20 % of detector element |
| Ground sampling distance (GSD) | 30 m x 30 m (at nadir; sea level) |
| Swath width | 30 km |
| Swath length | 1000 km/orbit - 5000 km/day |
| Geometric co-registration | ≤ 0.2 x GSD |
| Target revisit time | 23 days (VZA ≤ 5°) 4 days (VZA ≤ 30°) |
| Data rate | 860 Mbit/s |
| Downlink (X-band) / compression factor | 300 Mbit/s / Loss Less 2:1 |
| Mass memory | 512 Gbit |
| Weight | 325 kg (890 kg incl. bus) |