Data plot showing measurements of hydrogen chloride in the atmosphere of Mars, as collected by the Atmospheric Chemistry Suite (ACS) onboard the ESA-Roscosmos ExoMars Trace Gas orbiter. The detections were also confirmed by the complementary instrument, Nadir and Occultation for MArs Discovery (NOMAD). The global dust storm of 2018 is indicated by the brown/orange gradient. The plot shows the locations of the measurements over time (solar longitude) and planetary latitude.