Offline absorbing aerosol height


The Absorbing Aerosol Height product provides information on the height of absorbing aerosol layers.


Offline. The products are available to users in two weeks from sensing. Usual delay is 2-3 days.

Theoretical basis

The AAH algorithm code derives the height of the absorbing aerosol layer using the oxygen-A absorption band. The method used is based on the FRESCO+ cloud information algorithm. The AAH algorithm uses the Absorbing Aerosol Index (AAI) product produced by the AC SAF for aerosol detection.


The AAH processor is integrated part of the AC SAF processing at the KNMI. This way, the algorithm has immediate access to absorbing aerosol information via the AAI product. The information from the oxygen-A absorption band is used to determine aerosol layer height in a similar way as is done for the FRESCO cloud algorithm.

Units and spatial resolution

Absorbing aerosol height is provided in km and absorbing aerosol pressure in hPa. The spatial resolution of the product is equal to the spatial resolution of the GOME-2 instrument: 40 km x 40 km for Metop-A and 80 km x 40 km for Metop-B and Metop-C.


This product is validated by RMI and AUTH. Validation is based on comparisons with CALIOP lidar observations (RMI) and on comparisons with EARLINET ground-based lidar observations (AUTH).

Archiving and dissemination

This product is archived at the FMI and available via offline data access page.

File format

This product is delivered in HDF5 format, each file containing one satellite orbit (sunlit portion). The size of a single product file is about 1.0 MB.

Algorithm version information

Time period GOME-2 / Metop-A GOME-2 / Metop-B GOME-2 / Metop-C
02.03.2020 - 14.09.2020 1.32 1.32 N.A.
14.09.2020 onwards 1.32 1.32 1.32


Composite image of offline absorbing aerosol index (Metop-C overpasses three days ago)