Weekly Ocean News

WEEKLY OCEAN NEWS

WEEK SIX: 10-14 October 2011

ITEM OF INTEREST --

Celebrate Earth Science Week -- The National Oceanic and Atmospheric Administration, including the National Weather Service, along with NASA, the US Geological Survey and several professional scientific organizations such as the American Geological Institute have recognized this week (9-15 October 2011) as Earth Science Week to help the public gain a better understanding and appreciation for the earth sciences and to encourage stewardship of the Earth. This year's theme for the 12th annual Earth Science Week is "Exploring Energy", designed to "engage young people and the public in learning about Earth's energy resources." [American Geological Institute]

Ocean in the News

Eye on the tropics -- Several tropical cyclones traveled across the tropical waters of the Northern Hemisphere's ocean basins during the last week:

In North Atlantic basin, Hurricane Ophelia crossed Newfoundland's Avalon Peninsula as a tropical storm at the start of last week. Earlier during the previous weekend, Ophelia briefly reached major category 4 hurricane status on the Saffir-Simpson Scale as it traveled northward across the western North Atlantic to the east of Bermuda. After passing Newfoundland, Ophelia continued to weaken, loosing its tropical characteristics as it traveled across the North Atlantic. For additional information and satellite images on Hurricane Ophelia, consult the NASA Hurricane Page.
At the beginning of last week Tropical Storm Philippe traveled generally toward the northwest and the west-northwest across the central tropical North Atlantic. During the week, Philippe turned briefly toward the southwest before returning to a track that took it to the northwest, to the north and then to the northeast. By late in the week, this system strengthened to become the fifth hurricane of the 2011 Atlantic hurricane season. Over this past weekend, Philippe weakened to a tropical storm and then lost its tropical characteristics, becoming a post-tropical cyclone as it passed well to the west of the Azores. The NASA Hurricane Page has additional information and satellite images on Hurricane Philippe.
In the eastern North Pacific basin, two tropical depressions off the coasts of Mexico and Central America evolved into hurricanes late last week. One of the tropical depressions that formed well off the southwestern coast of Mexico intensified to become Hurricane Irwin early last Friday as it traveled to the west-northwest. By late Saturday, this category 1 hurricane (on the Saffir-Simpson Scale) had weakened to a tropical storm as it turned toward the north and then to the northeast. See the NASA Hurricane Page for additional information on Irwin.
The second tropical depression, which formed off the central American coast traveled northward to become Hurricane Jova, the ninth hurricane of the 2011 eastern Pacific hurricane season this past Saturday. By Sunday, Hurricane Jova continued to strengthen as it turned toward the east and headed for the southwestern Mexican coast. See the NASA Hurricane Page for satellite images and additional information on Hurricane Jova.
In western North Pacific basin, Typhoon Nalgae weakened into a tropical storm as it moved westward across the South China Sea early last week after crossing Luzon in the Philippines. Before reaching Luzon one week ago last Saturday, Nalgae had become a super typhoon as it intensified to become a category 4 typhoon on the Saffir-Simpson Scale. By the midpoint of last week, Nalgae had weakened to a tropical depression as it crossed China's Hainan Island. Remnants of this former super typhoon continued across the Gulf of Tonkin toward northern Vietnam. The NASA Hurricane Page has additional information on Super Typhoon Nalgae, together with satellite imagery.

NOAA Administrator provides testimony in New England groundfish management -- Dr. Jane Lubchenco, the NOAA Administrator and the Undersecretary of Commerce for Oceans and Atmosphere recently provided testimony before the US Senate's Committee on Commerce, Science and Transportation on management of New England groundfish in an effort to maintain sustainable coastal economies. [NOAA News]

Special agent named for Northeast fisheries compliance -- NOAA's Office of Law Enforcement recently announced that a new special agent had been named to be in charge of the agency's Northeast Division in Gloucester, MA in order to improve relationships between fisheries, industry leaders and enforcement agencies and to identify compliance priorities. [NOAA News]

Multibeam sonar units used to map undersea gas seeps --Researchers at the University of New Hampshire and NOAA have used a multibeam sonar unit onboard the NOAA ship Okeanos Explorer in the Gulf of Mexico to detect gas seeps in a water column extending from the surface to the seafloor over depths ranging from 3000 to 7000 feet. [University of New Hampshire]

German research vessel reports differences in Arctic sea ice -- Scientists from Germany's Alfred Wegener Institute for Polar and Marine Research returning to port from the 26th Arctic expedition onboard the Institute's research vessel Polarstern reported more young and thin sea ice across the central Arctic Ocean than the normal old and bulky ice cover. The vessel reached the North Pole during this year's voyage. [Alfred Wegener Institute for Polar and Marine Research]

Arctic sea ice shrinks to 2011 summer minimum -- Researchers at NASA's Goddard Space Flight Center and the National Snow and Ice Data Center have found that the sea ice covering the Arctic Ocean decreased to the second-smallest extent on record on 9 September 2011, the date of minimal extent for this year. The record extends back to 1979 when satellite surveillance of the sea ice began. They base their analysis on Arctic sea ice data obtained by the AMSR-E instrument onboard NASA's Aqua satellite. [NASA Earth Observatory]

Post Ice Age increases in carbon dioxide not linked to Pacific Ocean -- Scientists from Oregon State University, the University of Michigan and the University of California, Irvine recently reported that their studies of benthic foraminifera found in a sediment core extracted from the Gorda Ridge off Oregon coast appears to indicate that the increases of atmospheric carbon dioxide at the end of the last Ice Age was not from the deep waters of the northeastern Pacific Ocean as previously hypothesized. The researchers reconstructed the ventilation history of the deep North Pacific. [Oregon State University]

Herbivore populations could decrease with increased temperatures -- A team of scientists at the University of Toronto report that increased air temperatures associated with a change in global climate would cause a decrease in the number of herbivores, which would affect the human food supply. They claim that with increased temperatures, herbivores would grow more quickly than plants, resulting in the herbivores running out of food. [University of Toronto]

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.

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

10-16 October 1780...The most deadly Western Hemisphere hurricane on record raged across the Caribbean Sea. This "Great Hurricane of 1780" killed 22,000 people on the islands of Martinique, St. Eustatius, and Barbados. Thousands more died at sea. (The Weather Doctor)
10 October 1845...Naval School, renamed the U.S. Naval Academy, opened in Annapolis, MD with 50 midshipmen students and seven faculty. (Navy Historical Center)
10 October 1861...Fridtjof Nansen, the Norwegian explorer, oceanographer, statesman, and humanitarian was born. Nansen led a number of expeditions to the Arctic (1888, 1893, 1895-96) and oceanographic expeditions in the North Atlantic (1900, 1910-14). He wrote The Oceanography of the North Polar Basin (1902). For his relief work after World War I, he was awarded the Nobel Prize for Peace in 1922. (Today in Science History)
10 October 1913...President Woodrow Wilson with the aid of a telegraph signal sent from Washington, DC triggered the demolition of the Gamboa Dike, allowing water to fill the Culebra Cut and create Lake Gatun, at 85 ft above sea level, the largest man-made lake at that time. This act signaled the completion of construction of the Panama Canal, which would eventually open to ship traffic between the Atlantic and Pacific Oceans on 14 August 1914. (Wikipedia, Today in Science History)
11 October 1737...A deadly cyclone and storm surge of 42 ft raced up the Hooghly River in India and through the city of Calcutta destroying an estimated 40,000 boats and drowning as many as 300,000 people. (The Weather Doctor)
11 October 1846...A very intense hurricane caused great destruction in the Florida Keys. Key West was virtually destroyed with 5 feet of water reported in the city. Fort Taylor was reduced to ruins. (Intellicast)
11 October 1897...Property saved at Cape Hatteras, NC. During a severe storm, the surf threatened to wash away a fish house, with valuable nets and other gear. Surfmen saved the property and took it to a place of safety. They also assisted a lighthouse keeper by removing lenses from the beacon to a secure place. The lighthouse was in danger of being washed away by the sea. (US Coast Guard Historian's Office)
12 October 1492...Italian explorer Christopher Columbus sighted and landed on an island (possibly Watling Island) in the Bahamas during his travels westward across the Atlantic Ocean in search of an ocean route to eastern Asia. Apparently he underestimated the size of the world and assumed that he had reached East Asia after setting sail with three ships from Palos, Spain on 3 August 1492. During this expedition, which was the first known European expedition to the Americas since the 10^th century Viking colonies in Newfoundland, he sighted Cuba and landed on Hispaniola. (The History Channel)
12 October 1886...A hurricane made landfall between Sabine Pass, TX and Johnson's Bayou, LA. Waves were said to be as high as 2-story buildings. The surge extended 20 mi inland, with 150 people killed. Survivors clung to trees or floated on mattresses. Only two of 100 homes in Sabine Pass were reparable. (Accord Weather Calendar)
12 October 1954...Hurricane Hazel pounded Haiti and the island of Hispaniola with winds of 125 mph. Many villages were reported totally destroyed and more than 1000 Haitians died. (The Weather Doctor)
12 October 1965...End of Project Sealab II where teams of naval divers and scientists spent 15 days in Sealab moored 205 feet below surface near La Jolla, CA. (Navy Historical Center)
12 October 1979...The lowest observed sea-level barometric pressure (870 millibars or 25.69 inches of mercury) was recorded near Guam in the western Pacific Ocean at the center of Typhoon Tip. (The Weather Doctor)
13 October 1775...Birthday of U.S. Navy. The Continental Congress established the Continental Navy, later the U.S. Navy. (Naval Historical Center)
13 October 1884...The longitude that passes through the principal Transit Instrument at the Observatory in Greenwich, England was selected as the single universal meridian at the International Meridian Conference held in Washington, DC. A universal day was also selected. (Today in Science History)