44
J. Gower and S. King
Fig. 2.8 Level 1 radiance
spectra at points indicated by
arrows (A) in Fig. 2.7. The
red spectrum is of water
containing Trichodesmium;
the green spectrum of nearby
“clear” water; the blue
spectrum is the difference,
showing the added radiance
from the surface slick of
Trichodesmium (right axis on
expanded scale). The points
indicate MERIS bands where
radiances are measured
Fig. 2.9 As for Fig. 2.8, but
for location B showing a
similar Trichodesmium
signature, here with relatively
more detached trichomes
causing a relatively larger
peak at 500–620 nm
2.7 Trichodesmium Off Zanzibar
An intense bloom of Trichodesmium was reported in the channel between Zanzibar
and mainland Tanzania, in the period from 3 to 15 January 2011. The monthly MERIS
MCI time series for the area showed a significant MCI event in December 2010, but
nothing in January 2011 (Fig. 2.12). There are extensive coral reefs in the area, but
data for Fig. 2.12 were chosen to exclude these. Maximum bloom activity as shown