This computation involves the Level 1b processing algorithm applied to raw TROPOspheric Monitoring Instrument (TROPOMI) data.

The Earth radiance measurements form the bulk of the measurements. Apart from the optical properties of the instrument, there is some flexibility in the electronics that determine the Earth's radiance ground pixel size. The co-addition period determines the ground pixel size in the along-track direction. Row binning (which is possible for UVN-DEMs only) determines the ground pixel size across track. The parameter space is limited, however, as choosing a smaller ground pixel size will increase the data rate and will decrease the signal-to-noise ratio for the individual ground pixels. The data rate is limited by both internal interfaces within the instrument as well as by the platform’s on-board storage and down-link capabilities.
For the Earth's radiance measurements, the co-addition period can be set to either 1080ms or 840ms. This
effectively results in a ground pixel size of approximately 7km or 5.5km along-track. The co-addition period is set in the instrument configuration, initially, the nominal operations phase was started with 1080ms. For the SWIR-DEM, which contains a CMOS detector, row binning is not supported. This means that, effectively, the binning factor is 1 for the SWIR bands (Band 7 and Band 8), resulting in a ground pixel size across-track between 7km at the center and 34km at the edges of the across-track field of view. The ground pixel size varies across-track since the spatial dispersion (degrees/pixel) is constant, resulting in a ground pixel size that becomes larger towards the edges of the across-track field of view due to the Earth’s curvature.
Apart from the binning factor and the co-addition period, the remaining configuration parameters for
the Earth radiance measurements, including exposure time and gains, have been optimized during in-flight
commissioning for the best signal-to-noise ratio while minimizing the saturation of the detector or electronics. This optimization was based on scenes with the highest radiance levels, typically clouded scenes. Since the highest radiance level changes as a function of latitude, a total of five different settings for different latitude zones are created. For bands 4 and 6 saturation, it has not been possible to exclude saturation completely due to instrument limitations.

For more information please see the ATBD document linked in the docs tab.