Tropospheric BrO column data record


Tropospheric BrO column data record provides long-term information about the vertical column densities of bromine monoxide (BrO) in the troposphere


Data record

Satellites and instruments

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

Algorithm version

G2_L2_tropBrO version 1.0

Time period

  • 23/01/2007 - 31/12/2018 (GOME-2/Metop-A)
  • 01/01/2013 - 30/06/2020 (GOME-2/Metop-B)

Theoretical basis

The retrieval of the product is based on the DOAS method (Differential Optical Absorption Spectroscopy) using GOME-2 radiance measurements in the wavelength region of 332-359 nm.


The tropospheric BrO processor is part of the AC SAF processing at DLR. First, an optimised DOAS algorithm is used to determine the total BrO slant column. Then a daily normalization procedure based on measurements in tropics is applied. The stratospheric column is subtracted based on climatological Bry to ozone relation and the BrO to Bry partitioning is estimated via the stratospheric NO2 columns. Both O3 and NO2 are observed by GOME-2 as well. In the final step, the tropospheric vertical BrO column is determined by Air Mass Factor (AMF) conversion, using the LIDORT RTM and a fixed tropospheric priori BrO profiles depending on the surface albedo.

Units and spatial resolution

Tropospheric BrO columns are given as vertical 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.

Only the high-resolution forward scans are written in 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 NetCDF-4 format, each file containing one satellite orbit (sunlit portion).


GOME-2 pages at DLR: ATMOS