The NAMMA Carbon mOnoxide By Attenuated Laser Transmission (COBALT) dataset includes measurements of the carbon monoxide mixing ratio and derived carbon monoxide mixing ratio profiles in the upper troposphere/lower stratosphere using an in-situ laser absorption spectrometer. These data files were generated during support of the NASA African Monsoon Multidisciplinary Analyses (NAMMA) campaign, a field research investigation sponsored by the Science Mission Directorate of the National Aeronautics and Space Administration (NASA). This mission was based in the Cape Verde Islands, 350 miles off the coast of Senegal in west Africa. Commencing in August 2006, NASA scientists employed surface observation networks and aircraft to characterize the evolution and structure of African Easterly Waves (AEWs) and Mesoscale Convective Systems over continental western Africa, and their associated impacts on regional water and energy budgets.