CTD data from Rhode Island Sound collected from R/V Hope Hudner in 2009-2010 in support of Rhode Island Ocean Special Area Management Plan (NODC Accession 0109929)

The dataset consists of 173 CTD casts in Rhode Island and Block Island Sounds obtained during 4 surveys. The surveys were performed during 22-24 September 2009, 7-8 December 2009, 9-11 March 2010, and 16-18 June 2010. The casts cover the nearly the entire watercolumn from the surface to approximately 2 m above the bottom. The data were obtained with a SeaBird SBE19plus, which measures temperature, conductivity, pressure, optical backscatter, chlorophyll fluorescence, oxygen, and photosynthetically active radiation (PAR). All sensors were sampled at 4 Hz. The data were processed using the SeaBird data processing software suite, SBEDataProcessing-Win32. A low pass filter, with time constant of 1 s, was applied to the pressure record. Temperature and conductivity were low pass filtered with a 0.5 s filter time constant. To account for the relatively slower response of the temperature sensor, the temperature was advanced in time by 0.5 seconds relative to pressure. The oxygen voltage was advanced relative to pressure by 2 seconds for the September, December, and June survey casts and 5 seconds for the March survey casts. A correction for conductivity cell thermal mass effects was applied to the conductivity signal using the parameters recommended by SeaBird (alpha=0.04, 1/beta=8.0). A loop edit step was then applied, whereby portions of the cast in which the pressure was not changing sufficiently fast (0.1 dbar/s) were removed. This was followed by computation of salinity, sigma-t, and oxygen concentration. Finally, the data from the downcast were averaged into 1 dbar bins. Further details of the CTD data processing can be found in the header portion of the individual cast files. The final data files contain raw sensor values (1 dbar bin averages) plus a number of derived variables (e.g. salinity, sigma-t, oxygen). A full list of the output variables is contained in the header portion of the cast files.