Ocean Conveyor Belt

Thermohaline circulation of the ocean corresponds to the change of density in flowing water. It is created through global density gradients constructed by surface heat and freshwater fluxes through the large scale ocean circulation. It is based on deep water currents that make up 90% of the ocean. Water moves around areas found under sea, ocean basins, since density is caused by forces and gravity. The amount of salt in the water and the temperature of the water changes the density. Salinity and cold temperatures make the water more dense which causes deep waters, which form when air temperatures are cold and the salinity of the surface of waters is high, to sink into deep ocean basins at high latitudes where temperatures are cold enough for the density to decrease. In other terms, it is known as part of the ocean circulation created through the differences in densities.The density of the water is dependent on the salinity and temperature which changes from the surface of the water either heating up or cooling down as freshwater flows as said before. Thermohaline circulation moves a massive current around the world not to

The Bay’s salinity varies widely from season to season and from year to year, depending on the amount of fresh water flowing from its rivers. The Bay tends to be fresher in spring, when snow melts and heavy rainstorms frequently fall. During the drier months, the Bay is usually saltier. Salinity also increases with depth. Fresh water remains at the surface because it is less dense than salt water. The water on the Bay’s eastern shore tends to be saltier than the water on the western side. This is due to two factors; most fresh water enters the Bay from its northern and western tributaries, and The Coriolis Force, a phenomenon caused by the earth’s rotation, pushes flowing water in the Northern Hemisphere to the right, causing saltier water to move up the Bay veers toward the eastern shore.

(Salton Sea Symposium, 1998) However , the condition of the Sea has drastically changed and so has the amount of healthy living organisms in the Sea. By the 1980�s the water level rose greatly and gave way to abandoned businesses, deteriorating structures and empty beaches. The above was due to the fact that evaporation is the only outlet to the Salton Sea , in fact 1.35 million acre feet of water is lost each year , thus increasing its salinity even more. The salinity of the Salton Sea has increased to 45,000 parts per thousand or 45 PPT; the Pacific Ocean is currently 35 PPT.

4) The salinity of the position mid-ocean surface water changes with latitude due to its position regarding the equator and high precipitation produces these changes.

As fresh water drains from land, it mixes with salt water from an ocean, and this water is called an

As well as being an area where nutrients are recycled and released into the water, the Polar Front region in the North Atlantic plays a fundamental role in the driving of ocean currents. At the front near the Greenland, Iceland and Norwegian (GIN) seas and the Labrador Sea, warm salty water from the North Atlantic is cooled by Arctic waters and by intense heat loss to the atmosphere; it becomes denser and sinks to deeper layers of the ocean. Salt rejected as sea ice forms also increases the density and contributes to the process. Although a slow process, this sinking takes place over a wide area and each winter several million cubic kilometers of water sink and begin moving slowly south along the bottom of the Atlantic Ocean. It is known as thermohaline circulation because it is driven in part by temperature and partly by salinity differences.

Consider the potential for complexity of salinity and circulation within an estuarine system, a partially enclosed coastal body of brackish water that has freshwater input by rivers and salt water input by marine processes. The circulation of an estuary can vary substantially across a range of time scales such as daily, seasonally, or annually. Changes in freshwater input during periods of heavy rain, fluctuations in tides, or changes in the direction that the wind is blowing can all contribute toward how water moves around within the estuarine system. During periods of heavy rain fall, freshwater input may result in a much lowered salinity in the estuary, whereas during periods of drought and strong onshore winds salty water can be pushed

The maritime polar air mass is a very moist eastward bound airmass. This system is charterised as an oceanic air mass with high mosture levels and modest sesonal temperature changes.

This movement of the deep water forms a giant conveyor belt that covers a large part of the open ocean (figure 1). The Gulf Stream, for example, which is largely driven by thermohaline circulation, transports warm water from the Caribbean northwards.

Because there is a particular salinity defining brackish water, such salinity is subject to increase due to evaporation and stagnation of water. This

The average temperature of the upper layer (0-700 meters below sea level) has increased more than three times as much as the lower (700-2000 meters below sea level). This is because the ocean is heated from above and it takes time for the heat to penetrate deeper. Satellite and direct temperature measurements indicate that the abyssal layer, below 2000 meters, has not warmed measurably. (12)

These oceans contain around 3% sodium chloride, meaning for every gallon of water in the ocean there is about one cup of salt. This may seem like a lot of salt but the plants and animals of the marine biome are adapted to this part of their environment (KDE 1). They are also adapted to the various temperatures of their specific area. The average temperature of the saltwater biome is 39 degrees Farenheit, although it is much colder in deeper areas of the ocean (KDE 2). While the organisms living in the oceans are adapted to these conditions they could be seriously harmed by changes in their environment caused by pollution such as chemicals and decreases in oxygen

Rahmstorf (2003) defined thermohaline circulation as deep ocean currents which are carried by density and the gradient of temperature. Rahmstorf (2003) defines salinity as the measure of dissolved salt in water salt. Rahmstorf further explained thermohaline circulation is the direct and largest circulation of water on planet earth occurs, as a result of changes in temperature as well as salinity ( thermo= heat and haline =salt). Similarly Ganachaud and Wunsch (2000) concurs that thermohaline can also be referred to as thermohaline conveyor belt. These currents are formed by differences in water mass density, that are caused by variations both in salinity and temperature, these different currents move water masses through the

The course the developed lesson comes from is marine ecology. Any student who has taken the pre-requisite course (biology) may take the class. It consists of mostly juniors and seniors; however, a handful of students take the class during their sophomore year. During the first unit of study (oceanography) of the class, we discuss the physical properties of water and how they affect living organisms. One topic covered is salinity and temperature. The essential questions for understanding in this lesson are (1) how temperature and salinity of water affect density and (2) how do those factors, in turn, affect how heat moves around the world.

Marine currents are masses of salt water, which distribute differently from adjacent masses. They may be superficial, usually warmer and deeper, which are cooler. In general, they are generated by a difference in temperature, winds and salinity (Kampel, 1998). In Polar Regions, these currents lose heat to the atmosphere, generating large masses of polar air, or the "cold fronts", becoming extremely cold and dense. When the ocean freezes, the salt is adhered to the denser and cooler mass of water, and this new pool migrates to the bottom carrying nutrients and carbon dioxide. The water that is immediately below rises, and begins a cycle, which generates the main route of transportation and redistribution of global energy, which takes a thousand years to go around the globe. This process is crucial for the terrestrial climate system, as well as for nutrient loading (resurgence phenomena) and CO2 balance.