The SLSTR Aerosol Optical Depth (AOD) is a global product provided by the SL_2_AOD package in one measurement data file NRT_AOD.nc file.
The products will be generated in NRT only and will include all retrieved and derived aerosol parameters associated with the SLSTR solar channels, except 1375 nm dedicated to cloud detection.
It is based upon the acquisition grid of SLSTR nadir images, but the SLSTR L1b grid is then binned to super-pixels (9x9 pixels) with a resolution of 4.5km. The position and time of the centre pixel of each super-pixel, in addition to the position of the corner pixel are included in this measurement file.
Note1: the product will be available to the users during the course of 2018.
Note2: an AOD product will be generated in NTC timeliness only by the Level-2 synergy processor, exploiting the synergy between OLCI and SLSTR.
| Descriptive Name | Aerosol Optical Depth |
| Variable Name | AOD |
| Product Level | 2 |
| Description | Retrieved and derived aerosol parameters associated with the SLSTR solar channels. |
| Product Parameters | |
| Coverage | Global (over land and water) |
| Timeliness and Packaging | NRT: 3 min frame |
| Units | -- |
| Format | 16-byte unsigned integer |
| Appended Data |
Aerosol optical thickness and related uncertainty at the selected SLSTR channels, fine-mode aerosol optical depth at 550 nm, Aerosol Angstrom exponent between 550 and 865 nm, Dust aerosol optical thickness at 550 nm, Aerosol absorption optical thickness at 550 nm Aerosol single scattering albedo at the selected SLSTR channels, Surface directional reflectance (BRF) at the selected SLSTR channels, Associated time and geographical coordinates … plus other parameter provided at the corners of the super-pixel |
| Additional Information | |
| Input Bands | channels S1, S2, S3, S5, S6 for AOD calculation |
| Ancillary and Auxiliary Data | No ADS |
| Flag mask | Flag meaning | Description |
| 1 | land | Super pixel is ocean (0) or land (1) |
| 2 | oblq_missing | oblique view not present |
| 4 | cloudy_n | Nadir retrieval rejected due to cloud cover (cloud fraction of majority surface type exceeds 50 %) |
| 8 | cloudy_o | Oblique retrieval rejected due to cloud cover (cloud fraction of majority surface type exceeds 50 %) |
| 16 | dual_view | single (0) / dual (1) view retrieval |
| 32 | glint_n | glint detected nadir |
| 64 | glint_o | glint detected oblique |
| 128 | sdr_neg | at least one surface reflectance (SDR) value negative |
| 256 | aod_zero | retrieval failed to AOD zero (<5e3) |
| 512 | fm_clim | fine mode retrieval failed, value taken from climatology |
| 1024 | unc_failed | uncertainty estimate failed |
| 2048, …, 32768 | spare | |