WEEKLY OCEAN NEWS

DATASTREME OCEAN WEEK SIX: 1-5 March 2004

• Atmospheric water clusters may play role in global warming -- Researchers at Hamilton College suggest that groups of two or more water molecules form clusters in the atmosphere could absorb upwelling infrared radiation from the earth's surface, thereby enhancing a warming of the atmosphere. [EurekAlert!]
• Aquatic ecosystems may cause faster carbon turnover than terrestrial counterparts -- A scientist suggests that aquatic ecosystems may play an important role in global carbon cycling and climatic change since they turn over carbon through the basal levels of the food chain at a more than ten times faster rate than do terrestrial ecosystems. [EurekAlert!]
• Sea level changes due to ancient ice sheets may modify idea of the Late Cretaceous climate -- Cores obtained from the New Jersey Coastal Plain have led scientists from Rutgers University to believe that ice sheets may have been responsible for major and rapid changes in sea level during the Late Cretaceous Period (99 to 65 million years ago), a time previously thought to have been ice-free because temperatures were assumed to have been higher than at present. [EurekAlert!]
• Marine sponges provide a model for nanotechnology research -- A research group at the University of California, Santa Barbara has been studying how marine organisms can build tiny structures on the nanoscale that possess properties that are desired in commercially made products. [EurekAlert!]
• New coral discovery causes rethinking -- Using DNA analysis techniques, an international team of scientists discovered a family of corals found only in the Atlantic Ocean, thereby revealing flaws in the widely used means of identifying and classifying coral in both the Atlantic and Pacific Oceans. [EurekAlert!]
• Initiative to protect marine habitats -- Four Latin American countries along with several international agencies have undertaken an ambitious marine conservation project known as the Eastern Tropical Pacific Seascape that extends from Costa Rica's Cocos Island National Park to Ecuador's Galapagos Island National Park and Marine Reserve and helps safeguard some of the world's richest marine habitats and dozens of endangered species. [EurekAlert!]
• A new manual on coastal management released --NOAA officials recently released a manual that offers coastal resource managers, the public and others a consolidated set of science-based tools for planning and conducting monitoring associated with restoration in habitats throughout U.S. coastal waters habitats. This manual is entitled "Science-Based Restoration Monitoring of Coastal Habitats, Volume One: A Framework for Monitoring Plans Under the Estuaries and Clean Waters Act of 2000 (Public Law 160-457)" [NOAA News]
• A cool picture -- The NOAA Photo Library has more than 30,000 photos taken by scientists and others affiliated with the various agencies in NOAA of the earth's oceans and atmosphere, including this photo of a drifting iceberg in the Ross Sea off Antarctica. [NOAA Photo Library]
• Proposed changes used to lessen fishing impacts -- Following a three-year experiment, NOAA Fisheries officials have proposed mandatory changes in fishing practice to reduce the inadvertent catching of sea turtles so that U.S. fishermen would regain access to prime swordfish fishing grounds in the Grand Banks. [NOAA News] However, Duke University researchers report that the incidental catch of approximately 250,000 loggerhead and leatherback turtles in the global pelagic longline fishery in 2000. [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.

Concept of the Week: Abyssal Storms

Until recently, ocean scientists thought of the deep ocean abyss as a dark, cold but serene place where 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) like the Gulf Stream 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 an atmospheric storm.

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 119, in your DataStreme Oceanography 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, 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

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

• 1 March 1498...Vasco de Gama landed at what is now Mozambique on his way to India.
• 1 March 1854...The SS City of Glasgow left Liverpool harbor for Philadelphia and was never seen again with 480 people on board.
• 1 March 1902...The first regular light stations in Alaska were established at Southeast Five Finger Island and at Sentinel Island. Both on the main inside passage between Wrangell Strait and Skagway. (USCG Historian's Office)
• 1 March 1905...The first regular light stations in Alaska were established. (USCG Historian's Office)
• 1 March 1927...A system of broadcasting weather reports by radio on four lightships on the Pacific Coast was put into effect. (USCG Historian's Office)
• 1 March 1970...US commercial whale hunting was ended.
• 1 March 1977...The United States extended its territorial waters to 200 miles.
• 1 March 1983...A ferocious storm battered the Pacific coast. The storm produced heavy rain and gale force winds resulting in flooding and beach erosion and in the mountains produced up to seven feet of snow in five days. An F2 tornado hit Los Angeles. Thirty people were injured and 100 homes were damaged. (The Weather Channel) (Intellicast)
• 3 March 1873...US Army Signal Corps established storm signal service for benefit of seafaring men, at several life-saving stations and constructed telegraph lines as original means of communication. (USCG Historian's Office)
• 3 March 1960...The submarine USS Sargo returned to Hawaii from an arctic cruise of 11,000 miles, of which 6,003 miles were under the polar ice, reaching the North Pole on 9 February. This cruise marked the first time that a submarine explored the Arctic in winter. (Naval Historical Center)
• 4-5 March 1899...Tropical cyclone Mahina (the Bathurst Bay Hurricane) crossed the Great Barrier Reef and generated a 48-ft storm surge across Barrow Point, Queensland, Australia. The Australian pearling fleet was destroyed, over 100 shipwrecks reported and 307 people killed. Barometric pressure fell to an unofficial reading of 915 millibars (27 inches of mercury). (Accord's Weather Calendar) (The Weather Doctor)
• 5 March 1914...The Spanish ship the Principe de Asturias that was enroute from Barcelona to Buenos Aires sank with the loss of 445 of the 588 passengers and crew members when it struck the jagged reefs along the Brazilian coast at Ponta Boi in dense fog.
• 5-6 March 1962...The Great Atlantic Coast Storm of 1962 caused more than $200 million in property damage from Florida to New England. Winds along the Middle Atlantic Coast reached 70 mph raising 40-ft waves, and 42 inches of snow fell at Big Meadows, in the mountains of Virginia--a state record. The storm caused greater alteration of the coastline from Cape Hatteras, NC to Long Island than any previous storm, including hurricanes. A new inlet was cut through Hatteras Island and more than 10 miles of Outer Banks barrier dunes were obliterated. The Virginia shoreline was rearranged by historic tidal flooding caused by the combination of the long stretch of strong onshore winds and the "Spring Tides." A 3-mile long boardwalk in Ocean City, MD was wiped out. (David Ludlum) (Intellicast)
• 6 March 1521...Ferdinand Magellan reached Guam in his around the world voyage.
• 6 March 1987...The British ferry Herald of Free Enterprise capsized in the English Channel off the coast of Belgium with the loss of 189 people.
• 7 March 1778...Captain James Cook first sighted the Oregon coast, at Yaquina Bay near present day Newport.
• 7 March 1932...A severe coastal storm set barometric pressure records from Virginia to New England. Block Island, RI reported a barometric pressure reading of 955.0 millibars (28.20 inches of mercury). (David Ludlum)

Return to DataStreme Ocean Homepage

URL: DSOcean:/news.html
Prepared by AMS DSOcean Central Staff and Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2004, The American Meteorological Society.