Chemical Aeronomy in the Mesosphere and Ozone in the Stratosphere (CHAMOS) is an on-going science collaboration focusing on energetic particle precipitation and related atmospheric effects. Originally, it was started by scientist from Finnish Meteorological Institute (FMI) and Sodankylä Geophysical Observatory (SGO) back in 1998 as an response to European Space Agency's Announcement of Opportunity related to the Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument on board the Envisat satellite.
The collaboration has now continued for 20 years and produced over 80 peer-reviewed scientific publications. Today there are 25 people in the CHAMOS group, and five more institutes have joined CHAMOS: British Antarctic Survey, University of Otago, EISCAT Scientific Association, Institute for Space-Earth Environmental Research, University Centre in Svalbard, and University of Helsinki.
Over the years, CHAMOS work has been funded by the Academy of Finland, the European Union, New Zealand Marsden Fund, National Environmental Research Council (UK), and University of Oulu (FI).