[1] Measurements of velocity and density profiles were made to describe the transverse structure of flow in Chacao Channel, Southern Chile (41.75°S), where typical tidal velocities are $4 m/s. Current profiles were obtained with a 307.2 kHz Acoustic Doppler Current Profiler (ADCP) over 25 repetitions of a cross-channel transect during one semidiurnal tidal cycle. The 2.2 km long transect ran northeast/southwest across the channel. A northern channel (120 m deep) and a southern channel (85 m deep) were separated by Remolinos Rock, a pinnacle that rises to 20 m depth at $0.7 km from the southern side. Density measurements to depths of $50 m were obtained with a Conductivity, Temperature, and Depth (CTD) recorder at the north and south ends of each transect repetition. One CTD profile was also taken in the middle of the northern channel. The mean flow exhibited weak vertical structure because of strong vertical mixing. The predominant lateral structure consisted of mean outflow (toward the ocean) in the channels and mean inflow (toward Gulf of Ancud) over the pinnacle and the sides of the channel. This lateral structure pattern was consistent with the mean flow pattern expected from tidal rectification, as robust overtides were generated throughout the transect. The contributions to flow divergence and vorticity by the lateral variations of the lateral flow (@v/@y) and by the lateral shears of the along-channel flow (@u/@y), respectively, were both of the order of 10 À3 s À1 . This caused advective and frictional forces (both horizontal and vertical) to be dominant in the across-channel momentum balance, as they were more than twenty times the Coriolis acceleration. The present work then represents one of the few examples reported where lateral friction (proportional to @ 2 v/@y 2 ) appears relevant to the transverse momentum balance.

Abstract. Seasonal data on temperature, salinity, dissolved oxygen (DO) and chlorophyll, combined with meteorological and river discharge time series, were used to describe the oceanographic conditions of the Reloncaví fjord (41 • 35 S, 72 • 20 W). The winds in the fjord valley mainly blow downfjord during the winter, reinforcing the upper layer outflow, whereas the winds blow predominantly up-fjord during the spring and summer, contrary to the upper layer outflow. The fjord, with a deep sill at the mouth, was well stratified yearround and featured a thin surface layer of brackish water with mean salinities between 10.4 ± 1.4 (spring) and 13.2 ± 2.5 (autumn). The depth of the upper layer changed slightly among the different studied seasons but remained at 4.5 m near the mouth. This upper layer presented a mean outflow (Q 1 ) of 3185 ± 223 m 3 s −1 , which implies a flushing time of 3 days for this layer. The vertical salt flux was ∼ 37 tons of salt per second, similar to the horizontal salt flux observed in the upper layer. These estimates will contribute to better management of the aquaculture in this region.

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