This article reports on the usefulness of bilateral comparison of chemosens
ory information to an animal or agent tracking an odor to its source. Insta
ntaneous concentration fields of a chemical plume diffusing in a fully deve
loped, turbulent. open channel flow are measured using planar laser-induced
fluorescence. The plume is released isokinetically 25 mm above the smooth
bed (z(+) = 90), thus transport is mainly due to advection and ambient turb
ulence. A spatial cross-correlation function in the spanwise direction give
s a strong indication of the relative position of the centerline and distan
ce from the source. The relative direction of the plume centerline can be e
stimated from the instantaneous concentration. provided the sensors are sep
arated by a distance larger than the spanwise integral length scale of the
concentration field.