OClO column data record


OClO column data record provides long-term information about slant column densities of chlorine dioxide in the atmosphere. It has been reprocessed with the latest algorithm version (see below).


Data record

Satellites and instruments

GOME-2/Metop-A and GOME-2/Metop-B

Algorithm version

GDP 4.8

Time period

  • 23/01/2007 - 16/11/2016 (GOME-2/Metop-A)
  • 13/12/2012 - 16/11/2016 (GOME-2/Metop-B)

Theoretical basis

The retrieval of the product is based on GOME-2 (ir)radiance measurements in the wavelength region of 345-389 nm.


DLR generates trace gas column products with Universal Processor for UV/VIS Atmospheric Spectrometers (UPAS), inside which the GOME Data Processor (GDP) operational algorithm is the baseline algorithm for the trace gas column retrievals from GOME-2. The latest GDP 4.8 uses an optimised DOAS (Differential Optical Absorption Spectroscopy) algorithm to determine the OClO slant column. Since enhanced OClO can only be observed over the polar regions at large solar zenith angles, the OClO data record only contains slant columns (no conversion to vertical column).

Units and spatial resolution

OClO columns are given as slant column densities (molecules/cm2).

GOME-2/Metop-A has 24 forward-scan pixels with a nominal resolution of 40 km x 40 km, and 8 back-scan pixels with a nominal resolution of 120 km x 40 km.

GOME-2/Metop-B has 24 forward-scan pixels with a nominal resolution of 80 km x 40 km, and 8 back-scan pixels with a nominal resolution of 240 km x 40 km.

Both forward- and back-scan pixels are processed and written to the product.


This product has been validated by Belgian Institute for Space Aeronomy (BIRA-IASB). The validation is based on an end-to-end approach, that has been developed to evaluate independently all critical components of the level-1-to-2 retrieval chain, using correlative observations performed by ground-based and satellite instruments.

Archiving and dissemination

This product is archived at the DLR and available via data record access page.

File format

The product is delivered in HDF5 format, each file containing one satellite orbit (sunlit portion).


GOME-2 pages at DLR: ATMOS