Tropospheric ozone column from Limb-Nadir matching of SCIAMACHY and OMPS observations, merged to cover the 2003-2023 period.

This dataset is called SCIA+OMPS as it merges two tropospheric ozone column (TrOC) time series, independently retrieved for SCIAMACHY and OMPS measurements. The merging is on a monthly 5°x5° latitude-longitude gridded basis. The retrieval of OMPS (Orfanoz-Cheuquelaf et al., 2023) and SCIAMACHY (Ebojie et al., 2016) TrOC data employs a specific methodology called limb-nadir matching (LNM), which consists in combining two observations, in limb and in nadir, of nearly the same air mass performed by the same instrument (SCIAMACHY) or from two instruments on the same platform (OMPS). This technique has the advantage of minimizing instrument-related biases. The merging of the recently re-processed SCIAMACHY with LNM OMPS TrOC was performed on de-seasonalized anomalies of the two time series by using OMI-MLS as a transfer function: the bias between SCIAMACHY and OMI-MLS anomalies in the period 2007-2012 and between OMPS and OMI-MLS over 2012-2017 was removed to merge them. OMPS TrOC seasonal cycle was then added back to get a dataset in DU covering 2003-2023.