Healy
U.S. Coast Guard Cutter Healy

Conductivity, Temperature, and Depth (CTD) sensors are in situ instruments used to measure water depth, pressure, salinity, temperature, and density in the ocean. CTD sensors can be deployed on various water-based platforms such as autonomous underwater vehicles (AUVs), buoys, gliders, or research vessels. When mounted on a vessel, CTD sensors are usually attached to a rosette and then lowered to the seafloor to record water properties. These sensors typically sample at 30 Hz and can provide accurate measurements at specific water depths according to the researcher's needs.

Generic-Atmospheric State (Gen-AtmsState) refers to non-specific instruments on a platform used for measurements of atmospheric state parameters. These are typically in situ sensors that measure temperature, pressure, humidity, and wind speed/direction. Types of atmospheric state instruments include thermometers, hygrometers, barometers, and anemometers.

Generic-Chemistry Related Sensors (Gen-Chemistry) refers to non-specific instruments on a platform used for atmospheric chemistry measurements. These are typically in situ analyzers that measure various chemical compounds such as trace gases, halocarbons, volatile organic compounds, nitrates, aerosols, and other chemical species. Measurements can include mixing ratio, composition, particle size, optical properties, and particle size distribution.

The Acoustic Doppler Current Profiler (ADCP) is an in situ acoustic sensor used to measure ocean currents. ADCP utilizes the Doppler effect to detect sound waves, providing measurements of the speed and direction of currents throughout the water column. It can be easily mounted on various water platforms such as ships, buoys, and autonomous underwater vehicles (AUVs). Additionally, it can be deployed on the seafloor to deliver profile measurements of ocean currents.

The PRR-800 High Resolution Profiling Reflectance Radiometer is a water-based profiling radiometer manufactured by Biospherical Instruments, Inc. It collects profile measurements of underwater radiance and irradiance for ocean color research. It operates across the 340-900 nm spectral range at a bandwidth of 10 nm. The PRR-800 has a depth range of 350 m and a maximum data rate of 15 Hz.

Fluorometers are water-based sensors that measure patterns of fluorescence. They provide measurements of chlorophyll-a fluorescence, optical backscatter, and colored dissolved organic matter (CDOM) in seawater. They are typical used to asses chlorophyll concentrations to determine phytoplankton concentrations in the ocean. Fluorometers can be deployed on research vessels, buoys, autonomous underwater vehicles, and other water-based platforms.

The LISST Submersible Particle Size Analyzer is a water-based in situ particle analyzer manufactured by Sequoia Scientific. It is a laser-diffraction-based particle size analyzer that measures suspended particle size and concentration in aquatic environments, such as the ocean, rivers, lakes, and streams. It provides particle size distribution from 1 μm to 500 μm in 36 size ranges. It has a maximum operating depth of 600 m at a resolution of 0.01 m and a typical sampling rate of 1 Hz. The laser within the instrument operates at 670 nm and has an optical path of 25 mm.

Photosynthetically Active Radiation (PAR) Sensors are in situ optical devices used to study photosynthesis and plant physiology. They detect light between 400 and 700 nm and convert it into signals for PAR measurement. PAR sensors can be mounted on ground-based or water-based platforms or be portable and handheld. They are primarily used in agriculture, such as monitoring crop growth and analyzing light distribution in plant canopies, but they are also employed to study phytoplankton and aquatic productivity.

Spectrophotometers are passive photometers that measure the light intensity of the sample solution as a function of the wavelength of the electromagnetic radiation. Spectrophotometers are typically used for ground-based or shipborne observations. They can operate either in the ultraviolet to visible (185-700 nm) spectral range or the infrared (700-15000 nm) range. They are typically used in vegetation studies, air pollution monitoring, and water and soil quality analysis.

The Submersible Biospherical Optical Profiling System (SuBOPS) is a water-based in situ sensor used to measure water's apparent optical properties (AOPs). The optical profiler is mounted on a kite-like free-fall backplane and descends into water at speeds less than 20 cm per second to measure AOPs. It operates across 19 channels in the 320 to 860 nm spectral range with a 10 nm full-width at half maximum bandwidth. SuBOPS has a vertical resolution of less than 1 cm and a data acquisition rate of 12 Hz. It has collected vertical profiles in temperate and arctic waters at depths of less than 3 m.