Weekly Ocean News

DATASTREME OCEAN SPRING BREAK WEEK: 5-9 March 2012

This is Break Week for the Spring 2012 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 -- As meteorological summer concluded in the Southern Hemisphere, two tropical cyclones formed in the South Indian Ocean last week. Tropical Storm Irina formed at midweek over the waters of the Mozambique Channel off the west coast of Madagascar and traveled to the south and then to the southwest. By this past weekend, Irina was approaching the southeast coast of Mozambique. For additional information and satellite imagery on Tropical Storm Irina, consult the NASA Hurricane Page.
Farther east, Tropical Storm 15 formed over the waters of the central tropical South Indian Ocean northeast of Port Louis, Mauritius. This minimal tropical storm weakened as it traveled to the southwest and dissipated in slightly more than one day. See the NASA Hurricane Page for satellite imagery and additional information on Tropical Storm 15.
Final restoration plan for Cosco Busan Oil Spill completed -- Officials with several federal agencies including NOAA, the US Fish and Wildlife Service, the National Park Service and the Bureau of Land Management, together with state agencies such as the California Department of Fish and Game and the California State Lands Commission recently produced a final restoration plan for the November 2007 Cosco Busan Oil Spill that addresses the impacts upon ecosystems of San Francisco Bay produced by the oil spill from the "ship that struck the Bay Bridge." [NOAA News]
Emissions of hydrogen sulfide off the African coast seen from space -- A natural-color image obtained last week from data collected by the MODIS sensor onboard NASA's Aqua satellite shows a pattern of pale green colors in the coastal waters along Africa's Namibian coast that appear to indicate high concentrations of sulfur and low levels of oxygen, which would be related to the release of hydrogen sulfide gas from the organic-rich sediments. [NASA Earth Observatory]
Tenth anniversary of the Envisat satellite observed -- Last week, the European Space Agency's Envisat satellite marked its tenth anniversary in space as what the agency claims to be the "largest Earth-observation satellite ever built." This 8-ton polar orbiting satellite that has ten onboard optical and radar sensors is in a sun-synchronous orbit around the planet. These sensors have been monitoring planetary land cover, surface topography, ocean color, stratospheric ozone concentrations and pollutant plumes along with land and ocean surface temperatures. [NASA Earth Observatory]
Thickest sections of Arctic ice melting faster than ice at the edge -- Using satellite data collected between 1980 and 2012, scientists at NASA's Goddard Space Flight Center have found that the oldest and thickest multi-year sea ice covering the Arctic Ocean has been decreasing at a faster rate than the younger and thinner seasonal ice found at the edge of the sea ice. [NASA GSFC]
Arctic air pollutants appear to be driven by sea ice -- An international science team from the United States, Canada, Germany and the United Kingdom led by a researcher from NASA's Jet Propulsion Laboratory has proposed that the increased chemical release of bromine gas (the "bromine explosion") into the atmosphere may be the result of drastic reductions In Arctic sea lice during the last decade. The increased bromine concentrations have resulted in ground-level ozone depletion and the deposition of toxic mercury into the Arctic. The team used data from six NASA, European Space Agency and Canadian Space Agency satellites; field observations and a numerical weather model. [NASA JPL]
Assessing impact of sea level rise on California beach towns -- Researchers from Duke University and five other research institutions recently reported on a study of 51 public beaches in the Los Angeles metropolitan in which they assessed how rising sea levels would impact the economies of coastal communities in Southern California during the 21st century. They found an uneven distribution of economic winners and losers for beach towns, based in part upon beach size. They considered both long-term changes due to rising global sea level associated with changing climate and on short term changes due to winter storms and high tides. Generally, the towns with wider beaches could become winners, while those with narrow beaches could lose tourist dollars. [Los Angeles Times]
Current rates of ocean acidification could be unprecedented -- Oceanographers with Columbia University's Lamont-Doherty Earth Observatory, the University of California, Santa Cruz and several other international institutions claim that their analysis of ocean sediment cores indicate that the world's oceans are currently becoming more acidic at a faster rate than they did during four major extinctions that occurred during the past 300 million years when both temperatures and atmospheric carbon increased dramatically. They used the Paleocene-Eocene Thermal Maximum (PETM) approximately 56 million years ago as an analog to current ocean changes [The Earth Institute – Columbia University]
Atmospheric dust linked to increased glacier melting and ocean productivity -- Researchers at the University of Miami's Rosenstiel School of Marine and Atmospheric Science and the United Kingdom's Loughborough University report that they have found a link between large dust storms on Iceland and glacial melting, with the dust serving to increase glacial melting and to contribute important nutrients to the waters of the North Atlantic Ocean surrounding the island. They claim their results show an important role of airborne dust on climate change and subpolar ocean ecosystems. [University of Miami Rosenstiel School of Marine and Atmospheric Science ]
Variations in winter storm tracks across Northern Hemisphere -- A climatology of the winter storm tracks and their variations across Asia and North America is described along with maps. [Earth Gauge]
"Google street view" available for the Great Barrier Reef -- A YouTube video was created to highlight a collaborate project between Queensland University and an insurance company that would create a "Google street view" version of Australia's Great Barrier Reef. This link is available through YouTube from the SciShow channel hosted by Hank Green. [YouTube] Editor's note: Special thanks go to Terri Kirby Hathaway, a LIT Leader and the Marine Education Specialist for North Carolina Sea Grant in Manteo, NC, for providing this link that she considered to be appropriate for an oceanography class. EJH
An All-Hazards Monitor -- This Web portal provides the user information from NOAA on current environmental events that may pose as hazards such as tropical weather, drought, floods, marine weather, tsunamis, rip currents, Harmful Algal Blooms (HABs) and coral bleaching. [NOAAWatch]
Global and US Hazards/Climate Extremes -- A review and analysis of the global impacts of various weather-related events, to include 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

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.
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)