New (and old) oceanographic tools 2012 Workshop DHP 2012 Tina Miller-Way

Properties of water of interest Parameters, units, significance –Temperature –Salinity –Dissolved oxygen –Turbidity –Light levels –Depth…

Tools to measure these properties - depth Sounding lines –Problems… Pressure sensor Sonar

Tools to measure these properties - temperature Thermometer - Hg-based how to do at depth? - reversing

Tools to measure these properties - salinity Direct or indirect measurement Refractometer Conductivity sensor

Tools to measure these properties - turbidity Secchi disk transmissometer

Tools to measure these properties - dissolved oxygen Methods - chemical, electrical, optical Optode Polarigraphic electrode Winkler

Dissolved oxygen Concentration vs saturation Saturation - –expected amount given temp, pressure, salinity (ideal gas law) = 100% saturation –Under, over or at saturation –Units = % Concetration - units = mg/l (or ppm, mmol)

Dissolved oxygen nomographs Use nomographs to determine expected DO levels (100% saturation)

Dissolved oxygen nomographs use to determine saturation level

Example O 2 data

Tools to measure these properties - light What wavelengths? –Photosynthetically active radiation (PAR) sensor How to account for changes in incident light? –Deck sensor

Other parameters Chlorophyll levels - fluorometer

But these properties vary with depth Typical open ocean profiles Called - a hydrocast

Monitoring units Hydrolab/YSI = brands

Combined units moored, deployed, mobile CTD Argo floats

Hydroloab hydrocast

CTD hydrocast See our CTD hydrocast

Other oceanographic tools Water samplers –Nansen / Niskin bottle –messengers