Offline GOME-2 monthly averaged (level 3) trace gas columns

Example composite images of monthly (Jan 2020) products


The monthly averaged (level 3) trace gas column products from GOME-2 provide information about the vertical column densities of O3, NO2 (total and tropospheric), HCHO, BrO, SO2 and H2O (TCWV) in the atmosphere.


Offline. Based on the product requirements, the data for previous month must be available to the users on the 15th day of the current month. Typical delay is 2-3 days.

Satellites and instruments

GOME-2/Metop-B and GOME-2/Metop-C

Algorithm version

Level 3 gridding algorithm version 1.0 (based on GDP 4.8/4.9 GOME-2 Level 2 trace gas column products)

Theoretical basis

Level 3 gridding algorithm using area-weighted tessellation and cloud screening.


DLR produces monthly gridded (averaged) O3, NO2 (total and tropospheric), HCHO, BrO, SO2 and H2O (TCWV) products based on the corresponding level 2 products generated with the GOME Data Processor (GDP) operational algorithm (only forward-scan pixels are used).

Units and spatial resolution

The trace gas column data are provided as vertical column densities with the following units: total O3 and SO2 columns in Dobson Units (DU), NO2, HCHO and BrO columns in molecules/cm2, and H2O columns in kg/m2. The spatial resolution is 0.25° x 0.25° (global coverage) and the temporal resolution is monthly (calendar).


The level 3 GOME-2 trace gas column products have been validated by RAL Space (RAL) in the framework of an AC SAF Associated Scientist project. The validation focused on the following aspects: (1) to verify the consistency between level 2 and 3 products, (2) to examine the consistency among the three GOME-2 sensors, and (3) to validate the level 3 products by comparing to ground-based observations.

Archiving and dissemination

These products are archived at the DLR and available via offline data access page.

File format

The products are delivered in NetCDF-4 format, each file containing monthly averaged trace gas column data including error estimates (one trace gas per file), and additional cloud parameters and surface properties data.