Weekly Ocean News

DATASTREME OCEAN SPRING BREAK WEEK: 3-7 March 2008

This is Break Week for the Spring 2008 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.

**Welcome to participants at the 2008 Ocean Sciences Meeting in Orlando, FL on 2-7 March 2008!**

The theme of this meeting is "From the Watershed to the Global Ocean."

Ocean in the News

Eye on the tropics -- A tropical cyclone formed in the eastern South Indian Ocean off the Australian coast over the weekend. Tropical Cyclone 21S became a category 1 cyclone on the Saffir-Simpson Scale and was identified as Tropical Cyclone Ophelia. As of late Sunday (local time), this cyclone was continuing to travel to the west-southwest offshore of Australia.
A tropical storm briefly formed over the western South Pacific east of Australia at the end of last week. This system, identified as Tropical Cyclone 20P, traveled to the southeast and quickly became an extratropical low pressure system.
Tropical cyclone death toll mounts -- The disaster agency on Madagascar reported that near the end of last week, the death total from Tropical Cyclone Ivan had risen to 83, while 117 people remained missing. Some locals called "Ivan the Terrible", which made landfall on the island nation two weeks ago, the largest cyclone in living memory. [USA Today]
"Hurricane hunter" aircraft to have specialized surface wind instruments -- NOAA officials recently announced that the entire fleet of NOAA and US Air Force Reserve "hurricane hunter" aircraft will be equipped with a special wind sensing radar instrument called a stepped frequency microwave radiometer that will permit a more accurate determination of the surface wind speeds as the aircraft penetrate hurricanes and tropical storms. [NOAA News]
Resiliency of coast communities to disaster studied -- Researchers at Louisiana State University have been considering the economic and environmental factors as part of their study as to how coastal communities in Louisiana have responded to the recovery from disaster. [EurekAlert!]
A new seafood facts website is launched -- NOAA officials with the Agency's National Marine Fisheries Service recently unveiled a new website entitled "FishWatch" (http://www.fishwatch.noaa.gov) that is designed to provide the public with national seafood facts and assist the consumer with the necessary information needed concerning the types of seafood that are sustainable, safe and healthy. [NOAA News]
An update on the humpback whale count -- Humpback whales counted off Hawaii -- More than 700 volunteers at 57 sites across the Aloha State participated in the second of three scheduled survey dates held as part of the annual Hawaiian Islands Humpback Whale National Marine Sanctuary Ocean Count on the last Saturday in February. Because of better weather, they sighted a higher number of humpback whale sightings per count period than during the January survey, which had been plagued by unfavorable weather. The third survey will be held on the last Saturday in March. [NOAA News]
Citizen stewards sought for a California beach watch program -- The staff at NOAA's Gulf of the Farallones National Marine Sanctuary off California's Golden Gate is now recruiting volunteers for its Beach Watch shoreline monitoring program at several orientation meetings that will be held during March at several San Francisco Bay Area locations. [NOAA News]
Laboratory grown coral efforts get a boost -- The National Coral Reef Institute at the Nova Southeastern University Oceanographic Center near Ft. Lauderdale, FL has recently received financial assistance to grow more than 400 corals from the larval stage for eventual restoration of damaged coral reefs. [NOAA News]
Help for management of Latin American water and coastal resources -- Officials from NOAA and the World Bank recently announced that they had signed an agreement that entails a partnership designed to help developing nations such as those in Latin America manage their water and coastal resources and combat drought. Measurement of changes in climate would also be part of the project's effort to improve climate models designed to adapt to extreme climate conditions. [NOAA News]
A mega-iceberg monitored from space -- Photographs taken by the astronauts onboard the International Space Station in mid-January show detail of the large iceberg identified as A53a floating in the South Atlantic Ocean southwest of the South Georgia Islands off South America. [NASA Earth Observatory]
Harnessing the wind for desalination -- Researchers at Delft University of Technology in The Netherlands have employed a traditional windmill to drive a high pressure pump that forces seawater through a reverse osmosis membrane to produce fresh water. [Delft University of Technology]
Origins of Antarctic ice sheet probed -- Scientists from the United Kingdom's Cardiff University and the National Museum in Whales claim that they have found new evidence of cooling of the oceans from foraminifera remains in the ancient seafloor mud from near Tanzania, East Africa, which could help explain the mysterious appearance of the Antarctic ice sheet. [EurekAlert!]
West Antarctic glacial thinning studied -- Scientists from the British Antarctic Survey, the United Kingdom's Durham University and Germany's Alfred Wegener Institute for Polar and Marine Research have collected soccer ball-sized boulders from the glaciers in Antarctica's Amundsen Sea Embayment that could help in the prediction of the contribution of the West Antarctic Ice Sheet to projected rises in sea level. [EurekAlert!]
Ocean cores shows links between dust and climate variations -- Researchers from Lamont-Doherty Earth Observatory who have been analyzing seafloor sediment cores using radioisotopes across the equatorial Pacific Ocean can document peaks in the dust accumulation from Asia and South America corresponding to the periodic ice ages within the last 500,000 years. [EurekAlert!]
Spread of complex life may have been sparked by two events -- An international scientific team from Virginia Tech, the University of Maryland, University of Nevada at Las Vegas, and the Chinese Academy of Sciences claim that ancient marine sediments from the Yangtze Gorges area of South China indicate two events between 636 and 551 million years ago could have been responsible for the rise of oxygen and the spread of complex life forms, including animals. [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 131, in your DataStreme Ocean 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 dee p-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

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 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...The Portuguese explorer Ferdinand Magellan reached Guam in his around the world voyage. (Wikipedia)
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)
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.