A finite-difference numerical model is used to investigate seasonal-scale l
agoon-shelf exchanges and transport within Indian River, a multi-inlet lago
on on the Atlantic coast of Florida, U.S.A. Meteorological, hydrologic and
hydrographic data quantify forcing by seasonally-varying wind stress, coast
al sea level and the net freshwater gain. The along-axis component of the w
ind stress reverses seasonally. North-westward wind stress stores water in
the northern part of the lagoon in summer months, then south-westward wind
stress removes it in winter months. The seasonal rise and fall in water lev
el at opposite ends of the lagoon differ by +/- 0.1 - 0.2m, primarily as a
result of seasonal variations in wind forcing. The rise and fall of coastal
sea level forces water into the lagoon during summer months, then draws it
out during late fall and winter months. Net freshwater gain forces water o
ut of the inlets during summer months, when rainfall rates are highest, and
to a lesser extent during mid winter, when evaporation is relatively low.
When forcing is by shelf tides only, simulations suggest that the northern
and southern inlets are flood-dominant, while the central inlet is ebb-domi
nant. With the addition of seasonal-scale forcing, the northern inlet becom
es flood-dominant from late fall through early spring, then ebb-dominant du
ring the rest of the year. The central and southern inlets are ebb-dominant
throughout the year but seasonal variations differ.. The central inlet has
strongest outflow during summer months, while the southern inlet has stron
gest outflow during fall and winter months. Convergent and divergent patter
ns of transport within the lagoon are a complex response to both local and
remote forcing. Simulations suggest chat transport in the dredged part of a
navigation channel opposes transport outside the channel. (C) 2001 Academi
c Press.