Time series of shipboard observations in the southern Arafura Sea near
the Tiwi Islands indicated that the water column dynamics differed
between the east and west sides of the islands. On the west side, the
water column, characterized by temperature, salinity, and velocity, was
barotropic and tidal advection dominated. On the east side, the water
column was baroclinic and internal tides were present along with tidal
advection. These conditions affected the distribution of the turbidity
and fluorescence in the water column. Likewise, the influence of the
daily solar radiation cycle reached the bottom on the western side, but
was limited to the upper layer above the thermocline on the eastern
side. The fluorescence peaks also differed between the east and west
sides, with the eastern side dominated by the semidiurnal tides and the
western side by the daily solar cycle. Fluorescence integrated over the
water column was much higher on the eastern side than the western side.
Also on the eastern side, fluorescence was limited to the lower layer,
while on the western side, it encompassed the entire water column at
times and peaked below the warmer, higher oxygenated water generated by
solar radiation and surface mixing. These dynamics have distinct
implications for biological productivity and also may affect a proposed
tidal power system in the region.