Divided by observation water area

Marine hydrological observationDivided by observation water areaThere are two main categories for seaside observation and offshore observation:

Seaside observation refers to observations conducted along the coast, on islands, and on platforms. Coastal observation can be mainly divided into three methods: ① single element observation. Long term continuous observation stations (such as tide level observation stations and wave observation stations) established to observe a single hydrological element, mainly built along or near the coast, using automatic instruments that are easy to maintain and have stable performance as observation equipment for observation. ② Comprehensive observation. Long term continuous observation stations established to simultaneously observe multiple hydrological elements are usually built along the coast or using observation buoys, and multiple automatic instruments are used as observation equipment for observation. ③ Temporary station observation. Observation activities that provide basic hydrological data for marine engineering research, design, and construction, with actual observation projects determined by the survey tasks. Using ships, buoys, submersible markers, etc. as carriers, use appropriate observation instruments to complete representative single or multiple station synchronous observations in the designated sea area within the planned time, and conduct continuous observations for more than one day and night each time. general choice3Continuous observations on Sundays that meet favorable astronomical conditions.

Marine observation refers to observations conducted in sea areas far from the coast, often used for marine survey projects. Can be divided into3Method: ① Large scale observation or cross-sectional observation conducted by following the survey, that is, setting up several observation stations or several representative observation stations in the surveyed sea area, and forming a cross-section at regular intervals(One month or one quarter)Observe once at each observation station or section. ② Continuous observation and synchronous observation refer to setting up several representative observation stations in the surveyed sea area, and conducting continuous observations for more than one day and night at each observation station or at multiple observation stations according to task requirements. ③ Comprehensive three-dimensional monitoring, using carriers located underwater, on the water surface, and in the air, equipped with observation instruments to observe relevant hydrological elements.

Classified by observation method

According to the observation methodIt can be divided into two categories: direct observation and remote sensing observation:

Direct observation is the use of instruments and equipment to directly measure the characteristics of hydrological elements. The observation principle refers to the corresponding changes in physical and chemical properties of the sensing elements in the instrument when hydrological elements change, and the conversion into a directly measurable form using the relationship between the two changes and technical means. Direct observation instruments are classified according to their structural principles5Class. ① Acoustic style. Such as acoustic depth measurement equipmentAcoustic Doppler Current ProfilerAcoustic wave meter, sound velocity meter, etc. ② Optical type. Such as optical wave meters, turbidity meters, etc. ③electronic typeSuch as electromagnetic current meters, abandoned depth thermometers, abandoned temperature and salinity depth meters, etc. ④ Mechanical. Such as rotor type ocean current meters, float type tide gauges, etc. ⑤ Other forms. Wave gauges and accelerometers used for wave observation, plug disks used for seawater transparency observation, pressure type tide gauges and pressure type tide gauges used for tidal and wave observation, and instruments that integrate multiple observation functions (such as temperature salt depth turbidity profiling instruments). The installation or operation methods of direct observation instruments are divided into fixed, suspended, towed, self returning, and abandoned types. Fixed observation is the process of installing observation instruments onto an observation platform and collecting observation data according to pre-set parameters. The observation platforms include shore based platforms (such as marine environmental monitoring stations, tide gauge stations, ocean stations, etc.), sea surface platforms (such as offshore oil platforms, offshore wind power towers, etc.), and seabed based observation platforms. Hanging observation is the use of tools such as winches and suspension rods on observation platforms to place observation instruments into water and observe hydrological elements while anchored or sailing. The observation platform is a surface vessel or buoy. Dragged observation is a method of using a surface vessel as an observation platform and towing observation instruments into the water using a towing cable at the stern for navigation observation. Self return observation is based on underwater equipment as an observation platform, which dives into the water during observation and automatically surfaces upon completion of the observation. Abandoned type is an observation platform that uses a surface vessel as an observation platform. During observation, the sensor part is thrown into the sea, and the measured data is transmitted to the vessel through wires or radio waves. The sensor is not recovered after use.

Remote sensing observation is the use of instruments to detect and record electromagnetic radiation information of the ocean in a non-contact and long-distance manner. By analyzing the detected electromagnetic radiation information, the spatiotemporal distribution of oceanic hydrological elements can be obtained. The observation principle is that the instrument emits and receives electromagnetic waves, and uses the inherent relationship between electromagnetic radiation information and marine hydrological elements and environmental conditions to extract or invert the characteristics of marine hydrological elements. Remote sensing observation system platforms are divided into shore based platforms, space-based platforms, and space-based platforms. A shore based platform is a radar station established on a coastal or offshore platform. The radar station emits electromagnetic waves in the working band, which are reflected by the sea surface and receive their echo signals. After analysis and processing, observation data is obtained. Commonly used for observing hydrological elements such as surface currents, waves, tides, etc. in the target sea area in the medium and long term. Air based platforms are carried by aircraft, airships, and hot air balloons, carrying remote sensing detection instruments to receive reflected electromagnetic radiation information from the ocean to the sun. After analysis and processing, they obtain image or observation data. Commonly used for one-time or regular observation of hydrological elements such as seabed topography, seawater temperature, water color, and sea ice. Space based platforms areArtificial earth satelliteSpacecraft such as space stations are used as carriers, and remote sensing detection methods are the same as those of space-based platforms, except that they have a larger detectable area and a wider range of applications.