The Tropospheric Monitoring Instrument (TROPOMI) is a satellite borne spectrometer aboard the Copernicus Sentinel-5 Precursor (S5P) satellite. S5P, the first mission in the Copernicus atmospheric composition Sentinel series, was launched on 13 October 2017 and is designed for a minimum mission lifetime of seven years. A detailed description of the TROPOMI instrument is available on its dedicated website (see TROPOMI ).
S5P is a sun synchronous satellite; a full description of the mission is available from the European Space Agency Sentinel-5P website. The satellite overpasses the Hail Creek mine between 03:00 and 04:00 UTC, corresponding to approximately 1:00-2:00p.m. local time.
S5P data are distributed through the Copernicus Data Space Ecosystem and are hosted on cloud infrastructure based on Amazon S3 storage.
Estimation of the mixing ratio for each TROPOMI pixel is indirect (Level 2) and relies on complex post processing algorithms that have evolved over time. Multiple versions of the retrieval algorithm have been used, as documented in the Hasekamp, et. all ATBD . The Copernicus dataset includes products processed with versions 010202, 010300, 010301, 010302, 010400, 020200, 020301, 020400, and 020500, where, for example, version 010302 corresponds to major version 1, minor version 3, revision 2. At the time of writing, the most recent processor version is 020800.
Validation of the TROPOMI retrievals is an ongoing effort (see Hasekamp, et. all ATBD Lorente, et al., 2021 , Qu, et al., 2021 ). This validation is performed through comparisons with independent satellite observations (e.g. GOSAT) and ground based measurements from 19 Total Carbon Column Observing Network (TCCON) sites. Improvements identified through these comparisons are incorporated into successive updates of the processing algorithms. The TROPOMI products relevant to the April 2018 - December 2019 period were originally processed using algorithm versions 1.2.2, 1.3.0, 1.3.1, and 1.3.2. In 2022, these data were reprocessed using version 2.4.0, which introduced revisions to the treatment of surface albedo and added corrections for surface reflectance Hasekamp, et. all ATBD .
It should be noted that some TROPOMI data exhibit pronounced striping artefacts, a known issue acknowledged by SRON. The original study indicates that de-striping was applied using a fixed mask. According to the TROPOMI Algorithm Theoretical Basis Document (ATBD; H Hasekamp, et. all ATBD ), a formal de-striping procedure has been developed, and its application should be indicated by the metadata flag processing.perform_destriping in the METADATA/ALGORITHM section of the product files. This flag is not present in the datasets used in the present analysis, indicating that the de-striping algorithm was not applied.