ACE Class Report – Oceanography 3
Title: Oceanography 3
Instructor: Professor Harold J Tobin
University of Wisconsin – Madison
Why I chose this class:
The class teaches us how the ocean of the worldeffects our climates and the mysteries that is beneath the waves. Ocean science is an adventure because there is so much that is still unexplored. This class will improve my general knowledge of the Ocean.
What I learned from this class:
Coastal Erosion – Beaches and Sea Cliff:
Human has extensively modifying the natural deposition and erosion process on coastlines, and combined with gradual sea-level rise is causing loss of beaches and natural barrier in many areas. Construction of breakwaters and jetties interferes with natural longshore drift and caused wholesale changes in Atlantic coast shorelines. Seawalls and other structures designed to protect buildings can make beach erosion worse. Loss of sediment supply and protective vegetation leaves many coastal areas more susceptible to storm damage. Private property rights, insurance and public interest often collide over these issues.
Tidal Life – Sea Forest, and Coral Reefs:
The ocean floor host the most complex and varied ecosystems in the sea, which vary based on the type of substrate, access to light, and wave energy. The intertidal zones includes sea weeds and mangroves and other organism. Sandy and rocky beaches are relative deserts, dominated by surrounding organisms. Coral reefs and atolls are built up in the photic zone by colonies of coral polyps. The reef-structure Host a teeming community of organism in complex predator prey relationships.
Deep Bottom Life and Hydrothermal Vents:
The deep sea floor is vast and populated by scavenger communities. the most fascinating of all deep Benthic communities are those of the deep sea vents, where hey symbiotic relationships feed ecosystems that may be the key to origin of life on earth. Hydrothermal vents at the mid ocean ridges fuel an entire ecosystem based on on sunlight but on Chemosynthesis. Unique symbiotic relationships between bacteria that Chemosynthesis and larger fauna such as tubeworm, crabs and clams are the basic of these strange vent communities.
Trade Winds – The circulation of Heat and Wind:
The atmosphere and oceans are linked in their motions, driven by the uneven distribution of heat modified by the Coriolis effect on all movement as earth rotates on its axis. Uneven heating by the Sun from the equator to the poles cause density difference in the air masses, which rise and fall accordingly, creating pressure differences that in turn drive the winds. Winds in general blows due to pressure differences in air, some wind patterns are persistent year after year. Mariners depended on knowledge of the wind bands and calm regions for centuries of navigation.
The Coriolis Effect: The tendency of any object in motion on earth to deviate from a straight – line course due to the rotation of the planet.
Trade Winds: Prevailing Easterly winds centered on 15 Degrees latitude North and South.
Heavy Weather – Storms and Hurricanes:
Differences in pressure between air masses and differences in heat energy between ocean and atmosphere cause major storms. Extratropical cyclones form at the boundary between Ferrel and Polar cells. Tropical cyclones form within one air mass, fueled by the storage and release of latent heat by evaporation and condensation. Hurricanes build in intensity over warm ocean water, dissipate over cooler water and land, and move in predictable ways. The destructive power of hurricanes is in the force of the wind, the intensity of rainfall, and the storm surges that raises local sea level in front of the storm. Hurricanes in Atlantic oceans and Typhoons in the Pacific ocean.
The Gulf Stream to Gyres – Vast Surface Currents:
The major ocean currents move vast quantities of water and are driven by persistent Westerly and trade winds of the atmospheric cells. The phenomenon of Ekman Transport induces rotary current system in each ocean basin called Gyres. Western boundary currents ( eg. Gulfstream and Kuroshio) are the deepest and largest; they move warm tropical water poleward in both hemispheres. Eastern boundary currents (eg. Canary and California) are wider and shallower and move cold water towards the Equator. Gyres currents affect only the uppermost few hundred meters of the ocean.
Upwelling, Downwelling, and El Nino:
Vertical movement of near surface waters driven by the wind, called upwelling or downwelling, is important in oceanic biological productivity and also plays a key role in the global climate phenomenon known as El Nino. The upwelling brings deeper, nutrient rich water to the surface along the Equator and many coastal areas, supporting major fisheries. Downwelling cause surface water to sink, pushing the thermocline downward, which reduces productivity. El Nino is cyclical climatic effect in which the trade winds slacken, Equatorial current reverse and downwelling replaces up welling off the coast of Peru with climatic effects felt around the world.
The Deepest, Slowest River – Polar Bottom Water:
Most of the volume of the ocean participates in very slow Deepwater circulation driven by density differences called Thermohaline circulation, which depends on temperature and salinity variations. Cold, salty water formed in the Northern and Southern Polar regions sinks to form Deepwater masses and spread throughout the entire ocean. Flow is very slow relative to the surface currents but involves enormous masses of water and is responsible for the global-scale mixing of the ocean surface currents and deep circulation together make-up the global movements for water and heat in the ocean.
The Ocean and Global Climate:
Earth’s climate is a balance among solar radiation. The redistribution of heat by ocean and atmosphere and the natural greenhouse effect that traps heat due to the chemical composition of the atmosphere. Most of the heat in the climate system is stored in the ocean. Water vapor, Carbon Dioxide and Methane are the main heat-trapping gases in the atmosphere responsible for the greenhouse effect. Without them, earth would be a frozen wasteland. Ice and sediment cores are records of the past climate and show how rapidly earth’s climate has changed through time.
The Warming, Rising Sea:
The global warning phenomenon is a modification of the natural greenhouse system due to the rapid addition of Carbon compound to the atmosphere over the past 150 years, primary from the burning of fossil fuels. The link between Carbon Dioxide, Methane and Greenhouse warming has been known for over a century. About 80%of the extra heat retained through greenhouse warming is stored in the ocean. Effects that are already in existence include sea-level rise, changes in ocean acidity, and loss of sea-ice especially in the Artic region.
Marine Pollution – The Impact of Toxins:
Human activity is so pervasive that it increasingly has impacts that can be seen all over the world oceans.Oil spills can be locally devastating but tend to be of limited extend and are now much less frequent. Plastic garbage in the sea has become pervasive and can be disruptive to marine life. Ocean acidification from Carbon Dioxide human add to the atmosphere is a form of pollution that has the potential to greatly alter marine ecosystem. Heavy metals and chemical pollution are increasingly problems from industrial runoff, and bioaccumulation cause a health risk to humans.
The Future Oceans:
The ocean is constantly changing and human activity is accelerating those changes. Recognition of human impacts has led to important steps to maintain the chemical, physical balance, stability and ecosystem health in the ocean, but challenges abound. Marine conservation areas permit refugia for fish to spawn and population to recover. International agreement on what should be done in open ocean may help achieving sustainable yield levels. Heat input from global warming, rising sea levels and acidification from Carbon Dioxide will modify the ocean environment, presenting challenge for societal interaction with the global ocean.
How will this class contribute to my success upon release:
This class has taught me a lot about the ocean and its affect on the climate and the ecosystem and pollution that are happening. I would like to volunteer my services in oceans, bays or aqua conservation upon my release. To do my part in preserving the oceans.