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Article Dans Une Revue Tellus B - Chemical and Physical Meteorology Année : 2021

Analysis of the temporal variability of CO 2 , CH 4 and CO concentrations at Lamto, West Africa

Résumé

The 10-year observations of the atmospheric molar fractions of CO2, CH4 and CO in West Africa were analyzed using a high precision measurement of the Lamto (LTO) station (6°31 N and 5°02 W) in Côte d’Ivoire. At daily scale, high concentrations appear at night with significant peaks around 7 a.m. local time and minimum concentrations in the afternoon for CO2 and CH4. The CO concentrations show two peaks around 8 h and 20 h corresponding to the maximum in road traffic of a northern motorway located 14 km from the station. The long-term increase rates of CH4 (∼7 ppb year−1) and CO2 (∼2.24 ppm year−1) at Lamto are very close to global trends. The variations of the concentrations of the three gases show strong seasonality with a peak in January for all gases and minima in September for CO2 and CH4, and in June for CO. The CO variation suggests a significant impact of fires on the CO, CO2 and CH4 anomalies in the Lamto region during the dry season (December to February). CO and CH4 show strong correlations (at synoptic-scale and monthly based) in January (r = 0.84), February (r = 0.90), April (r = 0.74), November (r = 0.79) and December (r = 0.72) reflecting similar sources of emission for both gases. The trajectories of polluted air masses at LTO, also indicate continental sources of emission associated with Harmattan winds.
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hal-03104651 , version 1 (19-01-2021)

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Toure Dro Tiemoko, Michel Ramonet, Fidele Yoroba, Kobenan Benjamin Kouassi, Kouakou Kouadio, et al.. Analysis of the temporal variability of CO 2 , CH 4 and CO concentrations at Lamto, West Africa. Tellus B - Chemical and Physical Meteorology, 2021, 73 (1), pp.1-24. ⟨10.1080/16000889.2020.1863707⟩. ⟨hal-03104651⟩
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