Weekly Ocean News

DATASTREME OCEAN SPRING BREAK WEEK: 5-9 March 2007

This is Break Week for the Spring 2007 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

Five-year coral reef research plan is released -- NOAA officials recently released the NOAA Coral Reef Ecosystem Research Plan that identifies the nation's plan for coral reef research through the year 2011. [NOAA News]
"Hurricane hunter" aircraft used to verify satellite wind measurements -- A NOAA WP-3D Orion "hurricane hunter" aircraft recently completed a month-long mission to collect in-situ wind and precipitation data during winter storms over the North Atlantic as part of the NOAA 2007 Ocean Winds Winter Experiment that would be used to validate remotely sensed data collected by orbiting satellites. Ultimately, this mission should help improve marine weather forecasts. [NOAA News]
A possible transition from El Niño to La Niña conditions foreseen -- Scientists at the NOAA Climate Prediction Center recently reported that the anomalous atmospheric and oceanic weather conditions identified as an El Niño event, such as above-average water temperatures in the eastern equatorial Pacific Ocean, approximately four months ago have now faded as cooler than average water has been observed, resulting in what could lead to a La Niña event. [NOAA News] New sea-level height data collected by NASA's Jason altimetric satellite in early February 2007 also indicate that the waters in the tropical Pacific Ocean have undergone the change from warm (El Niño) to a cool (La Niña) event. An oceanographer at the NASA Jet Propulsion Laboratory is concerned that this transition into a La Niña event could cause a continuation of the drought across the West. [NASA Earth Observatory]
- Indonesian wildfires linked to recent El Niño event -- Scientists have used rainfall data and atmospheric carbon monoxide data collected by the Measurements of Pollution in the Troposphere (MOPITT) instrument aboard NASA's Terra satellite to track wildfire pollution plumes that spread from the Indonesian islands over the Indian Ocean during three months in late 2006. They have linked the increased wildfire activity in Indonesia with the recent El Niño event. [NASA Earth Observatory] Images and charts are available. [NASA] [NASA Earth Observatory]
Another tropical cyclone detected -- A MODIS instrument on one of NASA's satellites shows Tropical Cyclone Gamede traveling across the western South Indian Ocean near Madagascar last week. [Editor's note: The clouds associated with the feeder bands surrounding the system's eye appear as a clockwise swirl, opposite to Northern Hemisphere counterparts. EJH] [NOAA OSEI]
Coastal Virginia receives help in preparation for tsunami and storm-surge flooding -- Scientists from NOAA National Geophysical Data Center and the Cooperative Institute for Research in Environmental Sciences have been developing a high-resolution digital elevation model for Tidewater Virginia near Virginia Beach that would serve to help local emergency managers prepare their communities against potentially deadly coastal flooding from tsunamis and wind-driven storm surges. Similar models have been developed for coastal communities in the Carolinas, Georgia, Florida, Puerto Rico, California and Alaska, with more than 100 additional models to be prepared during the next several years. [NOAA News]
Climate change could fuel stronger Atlantic hurricanes -- Scientists at the University of Wisconsin-Madison, the University of Miami and the National Climatic Data Center claim that higher ocean temperatures due to recent increases in air temperature have resulted in stronger hurricanes in the North Atlantic Ocean, while similar trends are not as apparent in the other ocean basins. Their investigation included a careful reanalysis of the long-term hurricane data. [EurekAlert!]
Hurricanes can intensify along with an eyewall replacement -- A scientist at the University of Washington and colleagues have developed a conceptual model of a hurricane that can undergo an eyewall replacement along with rapid intensification based upon observations of data collected from Hurricanes Katrina and Rita in 2005 as part of the Hurricane Rainband and Intensity Change Experiment. [EurekAlert!]
Tropical rainfall trends detected -- NASA scientists at the Goddard Space Flight Center recently reported that they have used a new technique to analyze rainfall data from surface rain gauges and from NASA's Tropical Rainfall Measuring Mission (TRMM) satellite that indicates an increase in rainfall in the tropics. [NASA Earth Observatory]
Marine life could be in trouble -- The European Science Foundation-Marine Board recently released a report entitled, "Impact of climate change on European marine and coastal environment - Ecosystem approach" that claims that even moderate future climate scenarios that have been proposed would have a marked impact upon the European marine ecosystem environment. [European Science Foundation]
A sediment wedge could affect glacial movement and sea level changes -- A geoscientist from Penn State University and colleagues reported that their analysis of data collected from a snowmobile-towed radar unit across Antarctica's Whillans Ice Stream indicates that sediments wedged beneath ice shelves could help stabilize the glacial ice sheets and serve as a buffer against moderate sea level rise. [EurekAlert!]
Studying the call of blue whales -- Scientists at Scripps Institution of Oceanography have been using electronic tags on blue whales along with acoustic recordings to monitor the movement and worldwide distribution of these whales, as well as to learn about the specific behavior and gender classifications associated with whale calls. [Scripps Institution of Oceanography]
Marine life gets iron supplements from rivers -- Oceanographers at Oregon State University report that iron-rich winter runoff flowing from rivers in the Pacific Northwest out into the Pacific Ocean help fertilize the coastal waters, leading to robust phytoplankton production and fisheries. [EurekAlert!]
Some coral could fight warming -- A Cornell University professor claims that some coral species appear to be temperature resilient, allowing them to possibly survive increased water temperatures that are projected over the next century. Most coral do not cope well with increased temperatures, with a resulting decline in coral reefs. [Cornell University]
River plumes could put Great Barrier Reef at risk -- Scientists at Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) have used satellite images to study the plume of sediment from Australian rivers that travel out across the Great Barrier Reef Lagoon to the Great Barrier Reef, putting this reef at risk. [CSIRO]
"Finger rafting" described -- Scientists at Yale University and Cambridge University have described how ice sheets mesh when they meet through the interlacing of a series of thin fingerlike ice sheets that raft together. [EurekAlert!]
Unraveling the Atlantic's mysteries -- Scientists from Cardiff University will set sail this week on the new research ship RRS James Cook to study a large area on the floor of the North Atlantic between the Caribbean and the Cape Verde Islands where the mantle is exposed, while the Earth's crust appears missing. [EurekAlert!]
Space agency robotic sub to investigate ocean depth -- Researchers at Carnegie Mellon University are ready to field test an underwater robot that they developed through a NASA-funded Deep Phreatic Thermal Explorer (DEPTHX) mission, which will ultimately be used to study the world's deepest sinkhole. [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, 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 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 file, 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 extend to the bottom of the ocean where the velocity of a bottom current increases ten-fold to about 1.5 km per hr (1 mph). While that is unimpressive for 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)