  The new generation of solar instruments provides better spectral, spatial,
and temporal resolution for a better understanding of the physical processes
that take place on the Sun. Multiple-component profiles are more commonly
observed with these instruments. Particularly, the He I 10830 \r{A} triplet
presents such peculiar spectral profiles, which give information on the
velocity and magnetic fine structure of the upper chromosphere. The purpose of
this investigation is to describe a technique to efficiently fit the two
blended components of the He I 10830 \r{A} triplet, which are commonly observed
when two atmospheric components are located within the same resolution element.
The observations used in this study were taken on 2015 April 17 with the very
fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS) attached to
the 1.5-meter GREGOR solar telescope, located at the Observatorio del Teide,
Tenerife, Spain. We apply a double-Lorentzian fitting technique using
Levenberg-Marquardt least-squares minimization. This technique is very simple
and much faster than inversion codes. Line-of-sight Doppler velocities can be
inferred for a whole map of pixels within just a few minutes. Our results show
sub- and supersonic downflow velocities of up to 32 km/s for the fast component
in the vicinity of footpoints of filamentary structures. The slow component
presents velocities close to rest.
