Correlation radiometer measurements of carbon monoxide in Southern Africa during the 2000 dry season

MOPITT-A (Measurements Of Pollution In The Troposphere-Airborne) is a new correlation radiometer that operates from the superpod of an ER-2 aircraft. The instrument is equipped with four channels, three of which are sensitive to tropospheric carbon monoxide. The fourth channel is sensitive to methane. In 2000, the instrument participated in the SAFARI 2000 field campaign in southern Africa, whose goal was to quantify atmospheric and land changes associated with biomass burning processes. Case study retrievals were performed for the September 7th flight, using radiances from a single CO channel. The method employed is a regression scheme that relies on the fact that radiances are mainly a function of the surface temperature and the CO column. The product of the retrieval is a tropospheric CO column based on a constant vertical profile. The instrument is able to distinguish between clean air and polluted air belonging to the so called 'river of smoke', laden with biomass burning material. The results compare favorably with two CO products independently derived from spectra recorded by the Scanning High Resolution Interferometer Sounder (S-HIS) on the ER-2. The precision of the retrievals is of the order of 5 ppbv.