AC SAF NRT and Offline products

Near Real Time data

GOME-2 NRT data are Level 2 products, that are disseminated as hdf5 format. NRT products are available to users in 3 hours from sensing. The GOME-2 NRT trace gas files are provided separately for Metop A and B. The files contain observations of all parameters listed below in one file. Observations are available for past two months. 


NRT trace gas parameter Units      
NOTropospheric column molec. /cm2
NOTotal column molec/cm2

O3  Total column

SOTotal column DU
HCHO  Total column molec./cm2


The quicklook maps are available at (Select instrument as GOME-2):


Offline data

Offline data are either Level 2 or Level 3 data (depending on the parameter) that are updated regularly to extent the temporal coverage up to date. A typical delay for offline products is 2-3 days.  For this course the relevant offline data products are trace gases, absorbing aerosol index, and tropical tropospheric ozone. 

The offline trace gas files contain parameters listed below in one hdf5 file.  Metop A and B files are provided separately, A since 2007 and B since 2012 (near) up to date. 


Offline trace gas parameter          Units           
NO2 Tropospheric column molec./cm2
NO2 Total column molec./cm2
H2O Total column kg/m2
O3 Total column DU
SO2 Total column DU
HCHO Total column molec./cm2
BrO Total column molec./cm2


Absorbing aerosol index (AAI) is also provided as offline Level 2 data in hdf5 format.  Different products are provided in separate files.  The main difference between the products is spatial resolution. AAI from  Polarisation Measurement Detectors (PMDs) have somewhat higher resolution than AAI. 


Offline aerosol parameter Units
Absorbing aerosol index Unitless
Absorbing aerosol index from PMDs Unitless

The quicklook maps are available at:


Tropical Tropospheric Ozone is provided as Offline monthly Level 3 data in netCDF format.  The data are limited to the tropical region that ranges between 20°S and 20°N, and gridded to a regular grid. The GOME-2  tropospheric ozone product is based on the CCD method where the tropospheric column is retrieved by subtracting the stratospheric ozone column from the total column for cloud free observations. The stratospheric ozone column is estimated as the column above high reaching convective clouds.


Offline Tropospheric Ozone Units
Tropical tropospheric ozone DU

Last modified: Monday, 21 October 2019, 1:33 PM