In October 2026, the Laboratory of Atmospheric Physics of Aristotle University of Thessaloniki (AUTH) was selected to organise the international annual 8th ESA–ECMWF–EUMETSAT Joint Training on Atmospheric Composition. The Training School was hosted in the Conference Room of the Department of Mathematics and was held under the auspices of the Department of Physics, the Dean’s Office of the School of Sciences, and the Research Committee of Aristotle University of Thessaloniki (ELKE AUTH). Faculty members, laboratory teaching staff, postdoctoral researchers and doctoral candidates from the Laboratory of Atmospheric Physics contributed to the activities of the Training School, under the organisation and coordination of MariLiza Koukouli, Assistant Professor at the Laboratory of Atmospheric Physics. The week-long programme included scientific training, the development and presentation of collaborative group projects, and familiarisation with open and reproducible science practices in the field of atmospheric monitoring using satellite- and ground-based observations. It also provided participants with opportunities for direct interaction and networking with scientists from ESA, EUMETSAT and ECMWF. The Training School was made possible with the financial support of ESA, the Dean’s Office of the School of Sciences, and ELKE AUTH.