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Sediment Trap
Sediment traps are instruments used in oceanography and limnology to measure the quantity of sinking particulate organic (and inorganic) material in aquatic systems, usually oceans, lakes, or reservoirs. This flux of material is the product of biological and ecological processes typically within the surface euphotic zone, and is of interest to scientists studying the role of the biological pump in the carbon cycle. Sediments traps normally consist of an upward-facing funnel that directs sinking particulate matter (e.g. marine snow) towards a mechanism for collection and preservation. Typically, traps operate over an extended period of time (weeks to months) and their collection mechanisms may consist of a series of sampling vessels that are cycled through to allow the trap to record the changes in sinking flux with time (for instance, across a seasonal cycle). Preservation of collected material is necessary because of these long deployments, and prevents sample decomposi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Season
A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's tilted orbit around the Sun. In temperate and polar regions, the seasons are marked by changes in the intensity of sunlight that reaches the Earth's surface, variations of which may cause animals to undergo hibernation or to migrate, and plants to be dormant. Various cultures define the number and nature of seasons based on regional variations, and as such there are a number of both modern and historical cultures whose number of seasons varies. The Northern Hemisphere experiences most direct sunlight during May, June, and July, as the hemisphere faces the Sun. The same is true of the Southern Hemisphere in November, December, and January. It is Earth's axial tilt that causes the Sun to be higher in the sky during the summer months, which increases the solar flux. However, due t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mooring (oceanography)
current_meter.html" ;"title="sediment traps and current meter">sediment traps and current meters --> A mooring in oceanography is a collection of devices connected to a wire and anchored on the sea floor. It is the ''Lagrangian and Eulerian specification of the flow field, Eulerian way'' of measuring ocean currents, since a mooring is stationary at a fixed location. In contrast to that, the ''Lagrangian way'' measures the motion of an oceanographic drifter, the Lagrangian drifter. Construction principle The mooring is held up in the water column with various forms of buoyancy such as glass balls and syntactic foam floats. The attached instrumentation is wide-ranging but often includes CTDs (conductivity, temperature depth sensors), current meters (e.g. acoustic Doppler current profilers or deprecated rotor current meters), and biological sensors to measure various parameters. Long-term moorings can be deployed for durations of two years or more, powered with alkaline or lit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marine Snow
In the deep ocean, marine snow (also known as "ocean dandruff") is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to the aphotic zone below, which is referred to as the biological pump. Export production is the amount of organic matter produced in the ocean by primary production that is not recycled ( remineralised) before it sinks into the aphotic zone. Because of the role of export production in the ocean's biological pump, it is typically measured in units of carbon (e.g. mg C m−2 d−1). The term was first coined by the explorer William Beebe as he observed it from his bathysphere. As the origin of marine snow lies in activities within the productive photic zone, the prevalence of marine snow changes with seasonal fluctuations in photosynthetic activity and ocean currents. Marine snow can be an important food source for organisms living in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-ratio (oceanography)
In oceanic biogeochemistry, the f-ratio is the fraction of total primary production fuelled by nitrate (as opposed to that fuelled by other nitrogen compounds such as ammonium). The ratio was originally defined by Richard Eppley and Bruce Peterson in one of the first papers estimating global oceanic production. This fraction was originally believed significant because it appeared to directly relate to the sinking (export) flux of organic marine snow from the surface ocean by the biological pump. However, this interpretation relied on the assumption of a strong depth-partitioning of a parallel process, nitrification, that more recent measurements has questioned. Overview Gravitational sinking of organisms (or the remains of organisms) transfers particulate organic carbon from the surface waters of the ocean to its deep interior. This process is known as the biological pump, and quantifying it is of interest to scientists because it is an important aspect of the Earth's c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Pump
The biological pump (or ocean carbon biological pump or marine biological carbon pump) is the ocean's biologically driven sequestration of carbon from the atmosphere and land runoff to the ocean interior and seafloor sediments.Sigman DM & GH Haug. 2006. The biological pump in the past. In: Treatise on Geochemistry; vol. 6, (ed.). Pergamon Press, pp. 491-528 In other words, it is a biologically mediated processes which result in the sequestering of carbon in the deep ocean away from the atmosphere and the land. The biological pump is the biological component of the "marine carbon pump" which contains both a physical and biological component. It is the part of the broader oceanic carbon cycle responsible for the cycling of organic matter formed mainly by phytoplankton during photosynthesis (soft-tissue pump), as well as the cycling of calcium carbonate (CaCO3) formed into shells by certain organisms such as plankton and mollusks (carbonate pump). Budget calculations of the bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellite
A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope thermoelectric generators (RTGs). Most satellites also have a method of communication to ground stations, called transponders. Many satellites use a standardized bus to save cost and work, the most popular of which is small CubeSats. Similar satellites can work together as a group, forming constellations. Because of the high launch cost to space, satellites are designed to be as lightweight and robust as possible. Most communication satellites are radio relay stations in orbit and carry dozens of transponders, each with a bandwidth of tens of megahertz. Satellites are placed from the surface to orbit by launch vehicles, high enough to avoid orbital decay by the atmosphere. Satellites can then change or maintain the orbit by p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ocean Current
An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, shoreline configurations, and interactions with other currents influence a current's direction and strength. Ocean currents are primarily horizontal water movements. An ocean current flows for great distances and together they create the global conveyor belt, which plays a dominant role in determining the climate of many of Earth’s regions. More specifically, ocean currents influence the temperature of the regions through which they travel. For example, warm currents traveling along more temperate coasts increase the temperature of the area by warming the sea breezes that blow over them. Perhaps the most striking example is the Gulf Stream, which makes northwest Europe much more temperate for its high latitude compared to other are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mixed Layer
The oceanic or limnological mixed layer is a layer in which active turbulence has homogenized some range of depths. The surface mixed layer is a layer where this turbulence is generated by winds, surface heat fluxes, or processes such as evaporation or sea ice formation which result in an increase in salinity. The atmospheric mixed layer is a zone having nearly constant potential temperature and specific humidity with height. The depth of the atmospheric mixed layer is known as the mixing height. Turbulence typically plays a role in the formation of fluid mixed layers. Oceanic mixed layer Importance of the mixed layer The mixed layer plays an important role in the physical climate. Because the specific heat of ocean water is much larger than that of air, the top 2.5 m of the ocean holds as much heat as the entire atmosphere above it. Thus the heat required to change a mixed layer of 2.5 m by 1 °C would be sufficient to raise the temperature of the atmosphere by 1&nb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelagic Zone
The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the surface of the sea and the bottom. Conditions in the water column change with depth: pressure increases; temperature and light decrease; salinity, oxygen, micronutrients (such as iron, magnesium and calcium) all change. Marine life is affected by bathymetry (underwater topography) such as the seafloor, shoreline, or a submarine seamount, as well as by proximity to the boundary between the ocean and the atmosphere at the ocean surface, which brings light for photosynthesis, predation from above, and wind stirring up waves and setting currents in motion. The pelagic zone refers to the open, free waters away from the shore, where marine life can swim freely in any direction unhindered by topographical constraints. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mooring (watercraft)
A mooring is any permanent structure to which a vessel may be secured. Examples include quays, wharfs, Jetty, jetties, piers, anchor buoys, and mooring buoys. A ship is secured to a mooring to forestall free movement of the ship on the water. An ''anchor mooring'' fixes a vessel's position relative to a point on the bottom of a waterway without connecting the vessel to shore. As a verb, ''mooring'' refers to the act of attaching a vessel to a mooring. The term likely stems from the Dutch language, Dutch verb ''meren'' (to ''moor''), used in English since the end of the 15th century. Permanent anchor mooring These moorings are used instead of temporary anchors because they have considerably more holding power, for example because of lesser damage to the marine environment, and are convenient. Where there is a row of moorings they are termed a tier. They are also occasionally used to hold floating docks in place. There are several kinds of moorings: Swing moorings Swin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sediment Trap Thermaikos 2
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently sediment transport, transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension (chemistry), suspension in river water and on reaching the sea bed deposited by sedimentation; if buried, they may eventually become sandstone and siltstone (sedimentary rocks) through lithification. Sediments are most often transported by water (fluvial, fluvial processes), but also wind (aeolian processes) and glaciers. Beach sands and stream channel, river channel deposits are examples of fluvial transport and deposition (geology), deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of aeolian transport and deposition. Glacial moraine deposits and till are ice-transported sediments. Clas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
