Seven-year continuous measurement of CO2 and CH4 at Atlas Mohammed V atmospheric research station in Northwest Africa

Understanding greenhouse gases (GHG) dynamics and improving carbon cycle assessments, particularly in under-sampled regions such as North Africa, requires continuous atmospheric measurements of carbon dioxide (CO 2 ) and methane (CH 4 ). The study reports on the first long-term in situ analysis of CO 2 and CH 4 carried out by the Atlas Mohammed V (AMV) atmospheric research station, located at an altitude of 2,076 m in the Middle Atlas Mountains in Morocco (33.40° N, 5.10° W) between November 2018 and December 2024. The station, established in collaboration with the French atmospheric network, offers an important data source to support the regional atmospheric inversions. The annual growth rate of CO 2 and CH 4 was 2.84 ± 0.36 ppm·year -1 and 12.81 ± 2.95 ppb·year -1 , respectively, which corresponded to the regional trends. Cross-wavelet method illustrated strong coherence between CO 2 and CH 4 at seasonal timescales, through mutual anthropogenic and biospheric drivers. The seasonal ratios of ΔCH 4 /ΔCO 2 ranged from 12.7 ppb·ppm -1 in winter, to 24.9 ppb·ppm -1 in spring, and in autumn by 22.4 ppb·ppm -1 . We observed a negative correlation during summer (-40.9 ppb·ppm -1 , r=-0.36) exposing competing processes of photosynthetic uptake and photochemical oxidation. At AMV, the seasonal cycle amplitudes of CO 2 and CH 4 were 6.1 ppm and 30 ppb, respectively, compared to those at ASK (8.3 ppm; 17 ppb) and IZO (8.1 ppm; 33 ppb). These results underscore the necessity of persistent ground-based monitoring in Africa for lessening the uncertainties related to global carbon budget estimations, and better understanding of the regional emission patterns and atmospheric transport processes.