Weekly Ocean News

DATASTREME OCEAN SPRING BREAK WEEK: 9-13 March 2009

This is Break Week for the Spring 2009 offering of the DataStreme Ocean course. This Weekly Ocean News contains new information items and historical data, but the Concept of the Week is repeated from Week 6.

Ocean in the News

Eye on the tropics -- The western South Pacific Ocean and the southern Indian Ocean remained active during the past week.
Tropical Cyclone Hamish developed late last week over the western South Pacific Ocean off the northeast Australian coast and moved southward and then southeastward off the coast. By late Saturday (local time) Hamish had become a major category 4 tropical cyclone (on the Saffir-Simpson Scale). Additional information and satellite imagery on Tropical Cyclone Hamish are available on the NASA Hurricane Page.
In the South Indian Ocean, Tropical Cyclone Gabrielle developed early in the week. After taking a somewhat erratic path, this marginal tropical storm weakened and dissipated by late in the week. For satellite images and additional information of Gabrielle, please consult the NASA Hurricane Page.
Deep-sea coral discovered by submersible -- Scientists operating the Pisces V submersible in the deep waters of Hawaii's Papahnaumokukea Marine National Monument discovered and identified seven new species of bamboo coral. [NOAA News]
Dolphin SMART Program welcomes new partner -- A tour operator in the Florida Keys was recently recognized as a new Dolphin SMART operator that will meet the standards designed by NOAA’s Florida Keys National Marine Sanctuary, NOAA Fisheries Service and other partners to responsibly view dolphins in the wild. [NOAA News]
Watch out for whales in San Francisco Bay -- Officials with NOAA’s Gulf of the Farallones National Marine Sanctuary have advised boaters who sail the waters of the San Francisco Bay area to be alert for whales and steer clear of them, as many gray whales migrate along the coast and into the Bay during this time of year. [NOAA News]
A shipwreck makes historical registry list -- Based upon documentation supplied by scientists from NOAA and the National Undersea Research Center at the University of Connecticut, the wreck of the early 20th century fishing vessel, Joffre, resting below the waters of NOAA’s Stellwagen Bank National Marine Sanctuary has been added to the National Register of Historic Places. This 105-foot long ship is in sanctuary waters off Gloucester, MA and represents the technological changes that occurred in the fishery industry of New England. [NOAA News]
Money from Recovery Act to help NOAA's mission -- Officials with NOAA recently announced that the $830 million the agency would receive as part of the recently enacted American Recovery and Reinvestment Act of 2009 would be used for a variety of projects aimed at fulfilling NOAA's mission to protect life and property and to conserve and protect natural resources. Approximately 28% of the funds would be used to help in habitat restoration and navigation projects, 52% would be used for construction of NOAA infrastructure, including ships, satellites and improvement for weather forecasting, while the remaining 20% would be used for climate modeling activities. [NOAA News]
Public participation invited on marine sanctuary advisory council boards -- Officials at two of NOAA's National Marine Sanctuaries are seeking applications to fill seats on their sanctuary advisory council boards, thereby ensuring public participation and counsel on sanctuary management. One advisory council seat is to be filled for the Monitor National Marine Sanctuary off North Carolina [NOAA News], while another seat and several alternate seats need to be filled on the Florida Keys National Marine Sanctuary [NOAA News]
Connecting old tectonic plates in Oceania -- Geoscientists from Australia and the Netherlands have reconstructed sequence of events between 50 and 20 million years ago where a tectonic plate between New Zealand and Australia was subducted approximately 1100 km into the earth's crust below the Tasman Sea forming a long chain of volcanic islands. This discovery shows a geographical connection between New Zealand and New Caledonia. [EurekAlert!]
Global and US Hazards/Climate Extremes -- A review and analysis of the global impacts of various weather-related events, including drought, floods, and storms during the current month. [NCDC]
Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

This Concept of the Week is repeated from Week 6.

Concept of the Week: Abyssal Storms

Until recently, ocean scientists thought of the deep ocean abyss as a dark and cold, but serene place where small particles rained gently onto the ocean floor. However, instruments lowered to the sea floor to measure ocean motion or currents and resulting mobilization of bottom sediments detected a much more active environment. Scientists found that bottom currents and abyssal storms occasionally scour the ocean bottom, generating moving clouds of suspended sediment. A surface current of 5 knots (250 cm/sec) is considered relatively strong. A bottom current of 1 knot (50 cm/sec) is ripping. Although this may be called an abyssal storm, the water motion pales by comparison to wind speeds in atmospheric storms.

Abyssal currents and storms apparently derive their energy from surface ocean currents. Wind-driven surface ocean currents flow about the margins of the ocean basins as gyres centered near 30 degrees latitude. (Refer to Figure 6.6, page 152, in your textbook.) Viewed from above, these subtropical gyres rotate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. For reasons given in Chapter 6 of your textbook and this week's Supplemental Information, surface currents flow faster, are narrower, and extend to greater depths on the western arm of the gyres. These are known as western boundary currents and include, for example, the Gulf Stream of the North Atlantic basin. Abyssal currents are also most vigorous on the western side of the ocean basins, moving along the base of the continental rise, which is on the order of several kilometers deep.

Abyssal storms may be linked to or may actually be eddies (rings) that occasionally break off from the main current of the Gulf Stream (and other western boundary currents). During an abyssal storm, the eddy or ring may actually reach to the bottom of the ocean where the velocity of a bottom current increases ten-fold to about 1.5 km (1 mi) per hr. While that is an unimpressive wind speed, water is much denser than air so that its erosive and sediment-transport capacity is significant even at 1.5 km per hr. At this higher speed, the suspended sediment load in the bottom current increases by a factor of ten. Abyssal storms scour the sea floor leaving behind long furrows in the sediment. After a few days to a few weeks, the current weakens or the eddy (ring) is reabsorbed into the main surface circulation and the suspended load settles to the ocean floor. In this way, abyssal storms can transport tons of sediment long distances, disrupting the orderly sequence of layers of deep-sea sediments. Scientists must take this disruption into account when interpreting the environmental significance of deep-sea sediment cores.

Concept of the Week: Questions

In the subtropical ocean gyres, boundary currents flow faster on the [(western)(eastern)] side of an ocean basin.
Currents in an abyssal storm erode, transport, and redeposit sediments that have accumulated on the [(continental shelf)(deep ocean bottom)].

Historical Events

9 March 1454...Amerigo Vespucci, the Italian navigator, was born in Florence, Italy. The North and South American continents were named in his honor by Matthias Ringmann, a German mapmaker.
9 March 1995...The Canadian Navy arrested a Spanish trawler for illegally fishing off Newfoundland.
10 March 1496...Christopher Columbus concluded his second visit to the Western Hemisphere when he left Hispaniola for Spain. (Wikipedia)
10 March 1849...Abraham Lincoln applied for a patent for a device to lift vessels over shoals by means of inflated cylinders.
11 March 2002...The National Ice Center reported that satellite images indicated that an iceberg with an area larger than the state of Delaware had calved from the Thwaites Ice Tongue, a region of snow and glacial ice extending from the Antarctic mainland into the South Amundsen Sea (Accord's Weather Guide Calendar)
13-15 March 1952...The world's 5-day rainfall record was set when a tropical cyclone produced 151.73 inches rain at Cilos, Reunion Island in the Indian Ocean. The 73.62 inches that fell in a 24-hour period (15^th-16^th) set the world's 24-hour rainfall record. (Accord's Weather Calendar)
14 March 1891...The submarine Monarch laid telephone cable along the bottom of the English Channel to prepare for the first telephone links across the Channel.
14 March 1903...President Theodore Roosevelt issued an executive order making Pelican Island near Sebastian Florida a "preserve and breeding ground for native birds," including pelicans and herons, marking the birth of the National Wildlife Refuge System. (Wikipedia)
14 March 1918...The first US concrete seagoing ship was launched at Redwood City, CA. (Today in Science)
15 March 1493...Christopher Columbus returned to Spain after his first voyage to the New World. (Wikipedia)
15 March 1778...Nootka Sound, Vancouver Island was discovered by Captain James Cook.
15 March 1946...For the first time, U.S. Coast Guard aircraft supplemented the work of the Coast Guard patrol vessels of the International Ice Patrol, scouting for ice and determining the limits of the ice fields from the air. (USCG Historian's Office)
15 March 1960...Key Largo Coral Reef Preserve in the Florida Keys was established as the nation's first underwater park. This preserve currently includes John Pennekamp Coral Reef State Park and the adjacent Florida Keys National Marine Sanctuary.