Oceanography

Wave erosion occurs when waves wear down rock in the ocean floor and turn them into sand. This is how some beaches' sand is made. The waves will also pick up rocks and throw them down or just split them open. Waves cause erosion by the force of the wave onto the ground below it and it picks up sand and rocks. It is like when a river causes erosion but waves do it more aggressively. If the waves are strong and hit rocks and cliffs hard enough, the rock breaks into smaller particles. This is a form of mechanical erosion. Another way is when the water can sometimes get between the cracks in a rock. When it cools down, the water freezes, thus expanding the cracks and breaking it. Beach erosion is caused by:

* wind

* rain

* ocean waves

* water runoff

* human and animal activity

* plant growth and decay

* rivers
Wave is erosion is caused by the influx of large amounts of water on a shoreline. The wave action can remove large amounts of sand and rock over time.

South Atlantic tropical cyclones are unusual weather events that occur in the southern hemisphere. Strong wind shear (which disrupts cyclone formation) and a lack of weather disturbances favorable for tropical cyclone development make any hurricane-strength cyclones extremely rare. If a "hurricane season" were to be demarcated in the South Atlantic, it would most likely be the opposite of the North Atlantic season, from November to the end of April with mid-March being the peak when the oceans are warmest in the Southern Hemisphere. These tropical cyclones would be given identifiers starting with SL in the future.

According to a study published in 2008, there were 92 subtropical cyclones in the Southern Atlantic between 1957 and 2008. Below is a list of notable South Atlantic tropical and subtropical cyclones.

On April 10, 1991, a weak tropical storm formed in the eastern South Atlantic, recorded by weather satellites off the coast of Angola. It formed on April 10, and dissipated two days later, drifting west-southwestward from where it formed. Of the few South Atlantic tropical cyclones that have been recorded, this was the only one in the eastern portion of the South Atlantic.

A small area of convection developed on a trough of low pressure in mid January off Brazil. It organized and appeared to become a tropical depression on January 18. The next morning, it had a small CDO and well-defined bands, and the system, either a weak tropical storm or a strong tropical depression, likely reached its peak. Located 150 nautical miles (280 km) southeast of Salvador, Brazil, it weakened as upper level shear, typical for the basin, prevailed. The depression moved inland on the 20th as a circulation devoid of convection, and dissipated the next day over Brazil, where it caused heavy rains and flooding.

Cyclone Catarina was an extraordinarily rare tropical cyclone, forming in the southern Atlantic Ocean in March 2004. Just after becoming a hurricane, it hit the southern coast of Brazil in the state of Santa Catarina on the evening of March 28, with winds estimated near 155 kilometres per hour (96 mph), making it a Category 2-equivalent on the Saffir-Simpson Hurricane Scale. The cyclone killed 3 to 10 people and caused millions of dollars in damage in Brazil.

At the time, the Brazilians were taken completely by surprise, and were at first in utter disbelief that an actual cyclone could have formed in the South Atlantic despite the insistence of the Miami Hurricane Center otherwise. Later, they were convinced, and adopted the name "Catarina" for the storm, after Santa Catarina state. This event is considered by some meteorologists to be a nearly once-in-a-lifetime occurrence.

A small area of convection 600 miles southeast of Rio de Janeiro was tracked into an area of relatively low shear and marginal 26°C waters on February 23, 2006. The wave had deep convection, was able to form a closed LLC and had 35 mi/h (56 km/h) winds as measured by Quikscat on February 24, 2006. These characteristics were operationally recognized for three hours before high shear began to tear the system apart, just short of the six hours required to be officially declared a tropical depression. The storm was estimated at have peaked in intensity with winds of 65 mph (100 km/h), equivalent to a strong tropical storm, early on February 23. While under study, the system was referred to as 90L Invest. The shear would eventually cause the system to dissipate later that night.

A cold-core mid to upper-level trough in phase with a low-level warm-core low formed a system over Uruguay and Rio Grande do Sul state in Brazil and moved eastward into the South Atlantic. Winds exceeded 54 knots on the coast of Uruguay and extreme southern Rio Grande do Sul. The storm produced rainfall in 24 hours of 300 mm or more in some locations of Rocha (Uruguay) and southern Rio Grande do Sul. The weather station owned by MetSul Weather Center in Morro Redondo, Southern Brazil, recorded 278.2 mm in a 24-hour period. Fourteen deaths and thousands of evacuees are attributed to the storm with an emergency declared in four cities.

On March 8 2010, a previously extratropical cyclone developed tropical characteristics and was classified as a subtropical cyclone off the coast of southern Brazil. The following day, the United States Naval Research Laboratory began monitoring the system as a system of interest under the designation of 90Q. The National Hurricane Center also began monitoring the system as Low SL90. During the afternoon of March 9, the system had attained an intensity of 55 km/h (35 mph) and a barometric pressure of 1000 hPa (mbar). It was declared a tropical storm on March 10 and became extratropical late on March 12. Anita's accumulated cyclone energy was estimated at 2.0525 by the Florida State University. There was no damage associated to the storm, except high sea in the coasts of Rio Grande do Sul and Santa Catarina. Post mortem, the cyclone was given the name "Anita" by private and public weather centers from Southern Brazil.

On November 16, a cold-core mid to upper-level trough in phase with a low-level warm-core low formed a system over Uruguay and Rio Grande do Sul state in Brazil and moved southeastward into the South Atlantic, where it slightly deepened. The system brought locally heavy rains in southern Brazil and northeast of Uruguay that exceeded 200 milimeters in a few hours in some locations of Southern Rio Grande do Sul northwest of Pelotas. Damages and flooding were observed in Cerrito, São Lourenço do Sul and Pedro Osório. Bañado de Pajas, departament of Cerro Largo in Uruguay, recorded 240 mm of rain. Then, it started to drift southeastward, over open waters of the South Atlantic, where it gradually weakened.[ The subtropical cyclone became a weak trough on November 19, according to the CPTEC. The low pressure system that originated the subtropical cyclone favored hail storms that affected dozens of cities in Southern Brazil, mainly in Rio Grande do Sul state, on November 15. Over a dozen towns declared emergency due to the damages. In some places, the hail accumulated 30 cm (one foot) and could be seen in the fields even four days after the storm.

Early on March 14 2011, the Navy Hydrographic Center-Brazilian Navy (SMM), in coordination with the National Institute of Meteorology, were monitoring an organizing area of convection near the southeast coast of Brazil.[14] Later that day a low pressure area developed just east of Vitória, Espírito Santo,[15] and by 1200 UTC, the system organized into a subtropical depression, located about 140 km (90 mi) east of Campos dos Goytacazes.[16]

Guided by a trough and a weak ridge to its north, the system moved slowly southeastward over an area of warm waters,[17][18] intensifying into Subtropical Cyclone Arani on March 15,[19] as named by the Brazilian Navy Hydrographic Center.[20] The storm was classified subtropical, due to the convection being located east of the center. On March 16, Arani began experiencing 25 knots of wind shear due to the another frontal system bumping it from behind.

Geologists commonly us the term STREAM for any body of water that flows in a channel.

TOTAL LOAD

Rivers move not only water but also a tremendous amount of material. This material, called the total load, consists of bed load, suspended load and dissolved load. Bed loadcomprises particles of sand and gravel that slide, roll, and bounce along the channel bottom in rapidly moving water. Suspended load comprises mainly silt and clay particles carried in suspension above the riverbed. Dissolved load comprises electrically charged atoms or molecules, called ions, that are carried in solution in the water

Platforms: VesselsThe waters covering our planet are vast, extending over 70 percent of its surface. Beyond the coastlines of Earth's major continents, however, the ocean remains virtually unexplored, due in part to the sheer size of the ocean and the potentially deadly conditions that await ocean travelers.

Vessels are arguably the most critical element in any ocean-going venture. Once a ship leaves the safety of its dock, it is an island unto itself on the open seas, its crew at the mercy of the waves. Any ship, from a 15-foot sailboat to a 1,500-foot tanker, must carry all of the food, water, fuel, and equipment that its crew will need to live safely for the duration of the journey.

In the case of research vessels, such as those highlighted here, the ships must also be equipped with special tools and technology that allow scientists to explore ocean environments. Research vessels are highly advanced mobile research stations, providing stable platforms from which explorers can deploy equipment, divers, and submersibles. In addition, these vessels carry state-of- the-art electronics, computers, and navigational and communications systems.

Platforms: SubmersiblesOver the last few decades, engineers have developed submersible technologies capable of meeting the many challenges that the deep sea imposes upon explorers. Using advanced submersible technologies, remarkable new deep-water ecosystems have been discovered. Many of these communities were believed not to exist in harsh environments devoid of light and under crushing pressure. One such community was found in an area surrounding a hydrothermal vent, where water temperatures reach hundreds of degrees Centigrade and the water is bathed in caustic sulfur. After preliminary studies, which discovered many new species and raised even more questions about these organisms, researchers declared these communities to be as complex as many found on land.

As much as we may learn about our planet's underwater habitats through the use of satellites, shipboard sensors and divers, these technologies scratch only the surface of the oceans. Submersibles alone enable us to explore the abyssal depths. This section of the site highlights some of the major advancements in submersible technology. These submersibles allow us to travel deeper and with a greater degree of freedom than ever before, so that we can observe, describe and ultimately explain the phenomena of life in the deep ocean realm.

Observing Systems and SensorsThe exploration of any ecosystem requires detailed study and observation. Even on land exploration can be a challenge. In the ocean, however, the obstacles are even greater. The ocean is the most complex, challenging, and harsh environment on Earth and accessing it requires specially designed tools and technology. It has only been within the last 50 years that technology has advanced to the point that we can examine the ocean in a systematic, scientific, and noninvasive way.

Our ability to observe the ocean environment and its resident creatures has finally caught up with our imaginations.

Certain tools, such as sondes, CTDs, and drifters, provide specific information about the ocean environment. Other instruments, such as satellites, provide generalized data from which a wide range of observations can be made. The information gathered from the instruments deployed in the oceans and the sky will help us answer many fundamental questions about our world.

If we are truly fortunate, we will also gain a better understanding of ourselves and the role we play in the complex web of life on Earth.

Communication TechnologiesTechnologies that allow scientists to collaborate and transmit data more quickly and to a greater number of users are changing the way that we explore. From telepresence to shipboard computers, these technologies are increasing the pace, efficiency, and scope of ocean exploration.

When depths are not too great or conditions are not too unsafe, divers can descend into the water to explore the ocean realm firsthand. However, we are creatures evolved to live on land. Unaided by technology, people are about as helpless underwater as, well, a fish on grass.

It is only through relatively recent advances in technology that exploration via diving has been possible. Even with these advancements, severe restrictions remain on the depth and length of time that divers can spend underwater.