In offshore and

coastal engineering Coastal engineering is a branch of civil engineering concerned with the specific demands posed by constructing at or near the coast, as well as the development of the coast itself. The hydrodynamic impact of especially waves, tides, storm surges ...

, metocean refers to the

syllabic abbreviation An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters or words taken from the full version of the word or phrase; for example, the word ''abbrevia ...

meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...

and (physical) oceanography.

Metocean study

In various stages of an offshore or coastal engineering project a metocean study will be undertaken. This, in order to estimate the environmental conditions of direct influence on the choices to be made during the project phase at hand, and to arrive at an effective and efficient solution for the problems/goals stated. In later phases of a project, more detailed and thorough metocean studies may be needed, depending on whether there is an expected additional gain with respect to the successful and efficient completion of the project.

Metocean conditions

Metocean conditions refer to the combined

wind Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ...

wave In physics, mathematics, and related fields, a wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities. Waves can be periodic, in which case those quantities oscillate repeatedly about an equilibrium (re ...

and

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...

(etc.) conditions as found on a certain location. They are most often presented as statistics, including seasonal variations, scatter tables,

wind rose A wind rose is a graphic tool used by meteorologists to give a succinct view of how wind speed and direction are typically distributed at a particular location. Historically, wind roses were predecessors of the compass rose (found on charts) ...

s and probability of exceedance. The metocean conditions may include, depending on the project and its location, statistics on: ;Meteorology: *

wind speed In meteorology, wind speed, or wind flow speed, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in temperature. Wind speed is now commonly measured with an anemometer. Wind speed ...

, direction, gustiness,

and wind spectrum *

air temperature Atmospheric temperature is a measure of temperature at different levels of the Earth's atmosphere. It is governed by many factors, including incoming solar radiation, humidity and altitude. When discussing surface air temperature, the annual ...

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...

* occurrence and strength of

typhoon A typhoon is a mature tropical cyclone that develops between 180° and 100°E in the Northern Hemisphere. This region is referred to as the Northwestern Pacific Basin, and is the most active tropical cyclone basin on Earth, accounting for a ...

hurricane A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dep ...

s and (other)

cyclone In meteorology, a cyclone () is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above (opposite to an an ...

;Physical oceanography * water level fluctuations ** historical, expected and seasonal

sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardis ...

changes **

storm surge A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the ...

s **

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

s **

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater exp ...

s **

seiche A seiche ( ) is a standing wave in an enclosed or partially enclosed body of water. Seiches and seiche-related phenomena have been observed on lakes, reservoirs, swimming pools, bays, harbors, caves and seas. The key requirement for formation of ...

s **

wind wave In fluid dynamics, a wind wave, water wave, or wind-generated water wave, is a surface wave that occurs on the free surface of bodies of water as a result from the wind blowing over the water surface. The contact distance in the direction of ...

s – wind seas and swells – characterised by statistics like:

significant wave height In physical oceanography, the significant wave height (SWH, HTSGW or ''H''s) is defined traditionally as the mean ''wave height'' ( trough to crest) of the highest third of the waves (''H''1/3). Nowadays it is usually defined as four times the ...

s and periods, propagation directions and (directional) spectra *

bathymetry Bathymetry (; ) is the study of underwater depth of ocean floors ('' seabed topography''), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water ...

salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...

, temperature and other constituents * stratification, density-driven currents and internal waves * ice occurrence, extent, thickness, strength and seabed gouging

Metocean data

The metocean conditions are preferably based on metocean data, which can come from

measuring instrument A measuring instrument is a device to measure a physical quantity. In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Est ...

s deployed in or near the project area, global (re-analysis) models and

remote sensing Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Ear ...

(often by satellites). For estimating probabilities of exceedance – for relevant physical quantities – data of extreme events during more than one year is needed. By use of validated

numerical model Computer simulation is the process of mathematical modelling, performed on a computer, which is designed to predict the behaviour of, or the outcome of, a real-world or physical system. The reliability of some mathematical models can be dete ...

s, the availability of metocean data can be extended. For instance, consider the case of a coastal location where no wave measurements are available. If there is long-term wave data available in a nearby offshore location (e.g. from satellites), a wind wave model can be employed to transform the offshore wave statistics to the nearshore location (provided the bathymetry is known). Often, long-term local measurements of wave conditions due to extreme events (e.g. hurricanes) are missing. By using estimates for the wind fields during past extreme events, the corresponding wave conditions can be computed through wave hindcasts.

Notes

References

* {{ref end Offshore engineering Coastal engineering Physical oceanography Climate and weather statistics