From January 19th to February 7th, 2008, we installed a Fourier
transform infrared spectrometer (FTIR) at Praia Airport on the island
of Santiago, Cape Verde. Our goal was to measure the combined
radiative effect of biomass burning aerosol and mineral dust usually
observed there during that time of the year, when mineral dust
emerging from the Sahara mixes with biomass burning aerosol
transported north-westwards from the Sahelian region. Our measurements
were part of the emph{Sa}haran emph{M}ineral Demph{u}st
Experiemph{m}ent 2 (SAMUM 2) funded by the German Research Foundation
(DFG) as continuation of the SAMUM field experiment in Morocco in
2006. SAMUM 2 is a joint venture of several German research institutes
and universities and included both ground based as well as airborne
measurements with the DLR Falcon research aircraft. The ground based
instrumentation included spectrometers for visible and thermal
infrared downwelling radiation, sun photometers, LIDAR and particle
impactors while the Falcon was equipped with LIDAR and several
instruments for aerosol analysis and sample return. A comparison of the
FTIR measurements with radiative transfer simulations yields the
expected aerosol forcing in the atmospheric window region after application of a suitable calibration
method
