OCEANOGRAPHIC SENSORS AND INSTRUMENTATION

The following section describes various oceanographic sensors and instrumentation developed by Ukrainian and Russian institutes. Most of the instruments described were developed at the Marine Hydrophysical Institute (MHI), Ukrainian Academy of Sciences, in Sevastopol, Ukraine. The other major source of oceanographic instrumentation in the FSU is the Institute of Oceanology, Russian Academy of Sciences, Moscow. Instrument configurations allow for towed, profiling, and moored conditions. Basically the sensors and instrumentation can be grouped in current meters, CTDs, DO, pH, transmissometers, geomagnetic compasses, and various others.

Numerous design configurations for current meters have been developed by MHI, including rotating elements (propeller, impeller) and nonmoving parts (acoustic and electromagnetic). Most of these current meters record the time series measurements data internally for periods up to a year depending on the sampling, or in some cases vector averaging, interval. Depth capabilities range from 50 m to 6,000 m, depending on application. Several designs allow for data processing on an IBM-compatible personal computer (PC). MHI has concentrated on acoustic current sensors that measure small scale (10s of cm) velocities based on acoustic travel time instead of the acoustic Doppler current profilers that measure over a much longer scale (100s of m). It appears that this technology and the capabilities of the MHI acoustic current meters are similar to the NBIS ACM developed in the United States and at Christian Michelsen Institute, Bergen, Norway, in the 1970s. Electromagnetic current meters were introduced by Marsh and McBirney, Inc., in the 1970s, and have demonstrated applications in the marine environment and in other environments.

MHI has also developed various other instrumentation, such as those measuring conductivity, temperature, and depth for physical oceanographic studies. CTD designs include both towed and lowered (sounding) or profiling versions. One version, the MGI-1201, is capable of CTD measurements at speeds to 15 kt with depths to 1,500 m, allowing surveys over a large area. Another towed version, the MGI-9201, has control surfaces and can be maneuvered in three dimensions at towing speeds up to 12 kt. The shape of the vehicle is radically different from that of other towed vehicles, such as the Sea Soar or Batfish, which are used for similar ocean research (Dugan and Jendro 1993). In addition to the CTD capability, this unit measures light attenuation (transmissometer) at two wavelengths, and chlorophyll-a fluorescence. The towed body trajectory may be controlled by an operator or an onboard computer. This instrument was designed to study frontal boundary zones, internal waves, and fine structure of the upper ocean.

MHI has developed a series of profiling systems lowered by cable and utilized from ships of opportunity. Some of these instruments (MHI-4103, MG1-4116) have CTD, DO, pH, turbidity, sound speed, and light attenuation sensors and, in some versions, current measurement capability. Several designs incorporate sampling of up to 26 samples. Several models have 6,000 m depth capability. A deck unit provides readouts of sensor values, computation of secondary parameters, and data output into chart recorders, printers, and computers. There are also self-contained designs that record data on magnetic tape. Additional information on these miscellaneous oceanographic instruments may be found in the site report on MHI (Appendix C) and in MHI's specification catalog (Marine Hydrophysical Institute 1993).

Much of the instrumentation developed in Russia and Ukraine has had questionable data quality, and the accuracy and reliability has not been on a level with comparable Western ocean sensors (Dugan and Jendro 1993). Numerous cooperative intercalibration experiments, both in the laboratory and the field, have revealed measurement anomalies outside the reported accuracy bounds of the sensors. It is unclear if this can be attributed to instrument quality, calibration procedures, laboratory standards, or routine maintenance. Data of known quality is an important product from international global experiments.


Published: June 1994; WTEC Hyper-Librarian