L2 data from the SEMPAS instrument in Zeebrugge, Belgium

L2 data (multiple species, differ per data type) from the SEMPAS instrument during its on-shore test campaign in the port of Zeebrugge, Belgium. This data is used to infer the results presented in Mettepenningen et al., SEMPAS: A UV-visible Spectroscopy Instrument for Monitoring Shipping Emissions and Atmospheric Composition on the North Sea, in prep.

The dataset contains three data types:
- Shipping emission measurements: L2a slant column densities of NO$_2$, SO$_2$ and O$_4$ for a selection of measured ships that passed the instrument throughout the campaign period. The selection is based on the cases as described in the paper. Additional static and dynamic shipping information is given in the same file as the measurements, taken from an AIS receiver on the instrument.
- Atmospheric measurements: L2a slant column densities for NO$_2$, SO$_2$, HCHO and O$_4$ as processed through the QDOAS software, provided for the full campaign period.
- FRM4DOAS data: the L1 data has been directly processed through the operational FRM4DOAS framework. This creates L2b vertical column densities and concentration profiles of NO$_2$ and HCHO, provided for the full campaign period.