Weekly Ocean News

WEEKLY OCEAN NEWS

DATASTREME OCEAN WEEK SIX: 27 February-2 March 2012

Ocean in the News

Eye on the tropics --- The tropical waters of the South Indian Ocean remained active last week as the Southern Hemisphere's meteorological summer was drawing to a close. The following tropical cyclones were reported:
At the start of the week, Cyclone Giovanna finally weakened over the waters of the South Indian Ocean to the southeast of Madagascar after a 13-day travel across the ocean basin, including passage across Madagascar. During its travels, it had intensified into a major category 4 tropical cyclone on the Saffir-Simpson Scale. Additional information on Cyclone Giovanna can be found on the NASA Hurricane Page. NASA's TRMM satellite measurement systems estimated rainfall amounts of over 10 inches across Madagascar, causing serious flooding. At least 23 deaths were attributed to Giovanna. .
A minimal tropical storm, identified as Tropical Storm Hilwa (formerly Tropical Storm 13) , continued its slow track to the west-southwest across the central and western South Indian Ocean. By midweek, this system had weakened with remnants detected to the southeast of the island nation of Mauritus. The NASA Hurricane Page has additional information and satellite images on Tropical Storm Hilwa. [Editor's note: This NASA Hurricane Page incorrectly identifies the basin as the Southern Pacific Ocean. EJH]
Appointment to Mid-Atlantic Fishery Management Council announced -- The US Department of Commerce announced last week the appointment of Francis D. Hemilright Jr., a commercial fisherman from North Carolina to the Mid-Atlantic Fishery Management Council, one of eight regional councils established by the Magnuson-Stevens Fishery Conservation and Management Act that prepare fishery management plans for marine fish stocks in their respective geographical areas of responsibility. [NOAA News]
Arctic sea life persists in winter -- Researchers who participated in a recently completed National Science Foundation(NSF) funded research cruise onboard the US Coast Guard icebreaker Healy to the Bering, Chukchi and Beaufort Seas were surprised by the amount of non-dormant marine life including active zooplankton in these frigid and dark waters surrounding the Alaskan coast even in winter. These surprising results may have implications for climate modeling, especially in the Arctic basin where changes in the ecosystem have been occurring in conjunction with changing climate. [National Science Foundation News]
Tracking an ocean current off Australia --Oceanographers from Australia's by University of Technology Sydney and Commonwealth Scientific and Industrial Research Organisation (CSIRO) have been tracking an ocean current through the Bass Strait using instrumented deep-diving ocean "gliders" that are being deployed by Australia's Integrated Marine Observing System. This ocean current flows through the Bass Strait separating Tasmania and New South Whales in southern Australia. [ CSIRO News]
A "storm of the century" could become more frequent in the future -- Researchers from Princeton University and the Massachusetts Institute of Technology report that because of projected increases in global sea level along with potentially stronger storms, coastal regions such as the New York City metropolitan area that currently experience a disastrous flood once every century could be hit by such flooding every one or two decades. They obtained these findings on the anticipated severity of future flooding from a simulation tool they developed using various global climate models. [News at Princeton University]
Clouds are found to be lowering from a satellite perspective -- Using cloud-top height data collected over a ten-year span (2000 to 2010) from the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra satellite, scientists at New Zealand's University of Auckland in have found that the global-average cloud heights appear to have been lowering by approximately one percent. The investigators claim the these results could have an important impact on global climate. [NASA JPL]
Airborne research program to monitor Earth system processes in 2012 -- As part of NASA's Airborne Science Program and its Earth system science research initiatives, the agency's fleet of research aircraft will be used as part field campaigns in the United States, Canada, Greenland, Europe, Asia and South America during 2012. These highly modified aircraft that can fly to altitudes of 70,000 feet will carry specialized sensors that will be capable of making high-resolution measurements of local phenomena and processes, such as ice sheet thickness, precipitation and air quality. [NASA Earth Mission]
"Climate Data Guide" is launched -- A group of scientists at the National Center for Atmospheric Research (NCAR) recently launched the "Climate Data Guide," a new online portal to a variety of datasets available to climate scientists that include climate indices, observational reanalysis datasets and model diagnostics. [NCAR/UCAR AtmosNews]
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

27 February 1949...Aerial ice observation flights by long-range aircraft operated from Argentia, Newfoundland. An International Ice Patrol by vessels was neither required nor established during the 1949 season, and it was the first time that aircraft alone conducted the ice observation service. (USCG Historian's Office)
27 February 1988...A major rain event occurred across Saudi Arabia's Foroson Islands in the Red Sea and on the adjacent mainland around Jizon when 1.15 in. fell. The monthly average rainfall is only 0.02 in. On the following day, flash flooding south of Riyadh killed three children. (Accord's Weather Calendar)
28 February 1849...Regular steamboat service to California from the East Coast via Cape Horn arrived in San Francisco for the first time. The SS California had left New York Harbor on 6 October 1848 on a trip that took 4 months and 21 days. (Wikipedia)
28 February 1964...A world 12-hour rainfall record was set at Belouve, La Reunion Island in the western Indian Ocean when 52.76 inches of rain fell. World records for 9 hours and 18.5 hours were also set with 42.79 and 66.49 inches, respectively. (Accord's Weather Calendar) (The Weather Doctor)
29 February 1504...Christopher Columbus used his knowledge of a lunar eclipse that night to convince Native Americans to provide him with supplies. (Wikipedia)
1 March 1498...The Portuguese explorer, 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)