Oceanography

Multiple water sample devices

Multiple water sample devices allow the use of Niskin bottles on electically conducting wire. Different manufacturers have different names for their products, such as rosette or carouel. In all products the Niskin bottles are arranged on a circular frame, with a CTD usually mounted underneath or in the centre.

The advantages of multi-sample devices over the use of a hydrographic wire with messengers is that the water bottles can be closed by remote control. This means that the sample depths do not have to be set before the bottles are lowered. As the device is lowered and data are received from the CTD, the bottle can be closed by remote control. As the device is lowered and data are received from the CTD, the operator can look for layers of particular interest and take water samples at the most interesting depth levels.

Thermosalinographs

Continuous readings of temperature and salinity at the surface can be foundout through CTDs. Water from the cooling water intake of the ship’s engines is pumped through a tank in which a temperature and a conductivity sensor are installed. Such a system is called a thermosalinograph. In which the parameters are observed and are graphically represented called thermosalinograph.

Remote sensors

Most oceanographic measurements from space or aircraft are based on the use of radiometers, instruments that measure the electro-magnetic energy radiating from a surface. This radiation occurs over a wide range of wavelengths, including the emission of light in the visible range of heat in the infrared range, and at shorter wavelengths such as Radar and X-rays. Most oceanographic radio meters operate in several wavelength bands.

Radiometers that operate in the infrared are used to measure sea surface temperature. Their resolution has steadily increased over the years; the AVHRS ( Advanced Very High Resolution Radiometer ) has a resolution that comes close to 0.2⁰C.

Multi-spectral radiometers measure in several wavelength bands. By comparing the radiation signal received at different wavelengths it is possible to measure ice coverage and ice age, chlorophyll content, sediment load, particulate matter and other quantities of interest to marine biology.