This data product covers geo-located, radiometrically and spectrally calibrated limb and nadir radiance spectra for Nadir, Limb, and Occultation measurements with additional monitoring and calibration measurements. The Level 1b product is the lowest level of SCIAMACHY data delivered to the users.
The instrument Instantaneous Field of View (IFoV) is approximately 0.045 deg (scan direction) x 1.8 deg (flight direction). This corresponds to a ground pixel size of 25 Km x 0.6 km at the sub-satellite point (nadir) and of 103 km x 2.6 km at the Earth's horizon (limb).
Nadir measurements have a maximum swath width of 960 km (in scan direction) and a typical footprint of 30 km (along track) x 60 km (across track).
Limb measurements have a tangent height range spanning from 0 to 100 km with 3 km vertical resolution. Azimuth scans are performed for constant elevation angle, typically 34 elevation steps per limb scan.
Maximum azimuth range is +/- 44 deg relative to S/C velocity (Note that the azimuth range is adjusted to observe the same atmospheric volume as for nadir measurements within five minutes).
The radiometric resolution is 16 bits, with a spectral resolution of 0.24 nm to 1.5 nm, depending on the spectral range. The Sun normalized radiometric accuracy is 2 to 3% in unpolarized light, and 3 to 4% in polarized light. The relative radiometric accuracy is less than 1% and the spectral accuracy spans form 0.005 nm to 0.035 nm.
Individual measurements from dedicated monitoring states include:
- Sun over diffuser
- Subsolar calibration
- Spectral lamp measurements
- White light source measurements
- Elevation mirror monitoring (Sun/Moon)
- ADC calibration
Level 1b products are corrected for degradation applying a scan mirror model and m-factors.The latest Level 1b dataset is version 8.0X.