|Hudson Riverkeeper Monthly CTD Surveys|
|Caption: Summary of all CTD transects, where colors indicate date, while years are shown alongside each colored line. Lines show the range of conditions from the first to last day spent on each transect, in terms of the semi-diurnal (D2) tidal range and mean flow past Poughkeepsie. The mean Poughkeepsie flow for the period 2001-present is shown with a dotted line.|
Since 2001, monthly along channel CTD transects have been run during ice-free months from The Battery to
Individual transect plots are available following the link below. There are also "climatology" figures summarizing how the Hudson's salinity, temperature, density and stratification vary over differing tidal and riverflow forcing. Spring tides have the largest range in water level, because the gravitational effects of the sun and moon act constructively, whereas neap tides have the smallest range because their gravitational effects act in opposition. Riverflow forcing is highly variable for the Hudson; flow past Green Island dam averages 400 m3 s-1, but in a typical year varies over a factor of 25, with 1980-2004 means for annual minimum and maximum riverflow of 90 m3 s-1 and 2340 m3 s-1.