Environmental science through orbiters. An example of Sentinel-5P on how the Covid-19 pandemic impacted the air quality

Due to the lockdown caused by the SARS-CoV-2 coronavirus disease (a.k.a. COVID-19) pandemic in 2020, most industrial and social activity drastically stopped. This drastic fall in human and industrial activity might have caused a drastic fall in the concentration of important atmospheric pollutants. This study investigates whether the atmospheric concentration of NO2, CO, HCOOH, CH4, SO2 and O3 changed during this extraordinary situ-ation. Secondly, this manuscript demonstrates how orbiter data can be freely used to endeavour any research question and the usefulness of multivariate data analysis in analyzing such data. The data used was the European Space Agency Copernicus Sentinel-5P satellite (SP5). Besides, the molecular concentration found with S5P was compared with the ground meteorological stations of the Basque Government, Spain. Concerning the individual evolution of the molecular concentrations found with SP5, no significant differences were obtained for the abovementioned molecules for the same period (from January until June) in different years (2019 and 2020) using ANOVA. The average concentration between years and their respective relative standard deviations were in the same range. Nevertheless, Principal Component Analysis applied to the time series demonstrated significant changes in the overall behaviour of the monitored pollutants.