Conductivity/Salinity: Conductivity is a key parameter for the in-situ determination of salinity, density, and speed of sound. The Aanderaa Conductivity Sensors are based on an inductive principle that provides stable measurement without electrodes. The sensors are 132 points calibrated and automatically switch between lower, below ten psu, and higher salinities at which different methods to calculate salinity are used. Experiences from factory re-calibrations reveal that these sensors have a minimal field drift, less than 0.008 mS/cm-year. For field verification of the sensor functioning, a multi-resistor loop is used.
Oxygen Optodes: Most chemical and biological processes are influenced by changes in dissolved oxygen. Consequently, oxygen is a prime parameter to measure in aquatic studies. Aanderaa revolutionized natural water oxygen measurements with the introduction of oxygen optodes in 2002. These sensors' proven long-term stability (years) and reliability have opened new possibilities in coastal and open ocean water monitoring, described in more than 150 scientific publications. The latest developments include new ultra-stable and trace foils. The opcodes are forty-point calibrated with an absolute accuracy better than ±2 % over the whole range of oxygen concentrations and temperatures. Different sensor versions are rated from 100 to 12 000 m depth.
Pressure/Wave/Tide: In 2006, we introduced a new series of compact Pressure/Wave/Tide sensors based on silicon sensing elements, using a piezoresistive measuring principle. These sensors are 20 points calibrated and have demonstrated excellent accuracy (0.01 %), resolution (0.1 mm), and stability (drift less than 0.01 % per year). Also, they consume little energy, can handle shock and can withstand 50% overpressure without damage and the need for re-calibration. These sensors have outperformed quartz pressure sensors in several studies. They are selected in applications ranging from coastal wave measurements to mm movements of the seafloor in seismic areas and off-shore oil and gas applications.
Turbidity: Turbidity is a proxy for water suspended mineralogenic particles like sand, silt, and clay. The combination of turbidity measurements with acoustic backscatter from the Doppler Current Profiling sensor is useful. It gives high-resolution information on the origins and distribution of Particles in the water column.
Currents: Aanderaa offers Acoustic Doppler Current Profiler (ADCP) and Single Point instruments and Stand-alone sensors used in a wide range of applications, from surface buoys to the deepest trenches, to measure currents, waves, and particles.
Waves: At Aanderaa, we have focused on three different methods for spot measurements of waves, including:
Integration of sensors from other manufacturers: For parameters that we do not offer, we integrate sensors from different manufacturers to our systems, including EXO units from YSI for shallow water applications with sensors, e.g., pH, Algae, CDOM, ORP/Redox, Blue-green algae, Salinity, Temperature, Oxygen and with a wiper for anti-fouling. For deeper waters, we integrate sensors from other manufacturers.