ORCA Data
Currently, ORCA measures the physical parameters of temperature (degrees C) and salinity to obtain density. The density of
seawater is affected by both temperature and salinity; decreases in temperature and increases in salinity both cause density
to increase. The combination of these changes produces density stratification. ORCA also measures the biological parameters
of dissolved oxygen (umol/kg), phytoplankton chlorophyll fluorescence (ug/l), and nutrient concentrations (Nitrate). The chemical and
biological parameters can have complex variability and frequently show strong correlations to each other. Oxygen is often supersaturated
in the surface as phytoplankton photosynthesize but can decrease dramatically subsurface as organic material is respired. Nitrate is
primarily limited in the surface waters, and upwelling events of nutrient-rich deep water are often followed by chlorophyll blooms during
the growing season.