Weekly Ocean News

DATASTREME OCEAN WEEK SEVEN: 10-14 March 2008

Ocean in the News:

(Thurs.) Genetic "fingerprints" are obtained from Northern right whales -- Scientists from NOAA's National Marine Fisheries Service and state agencies in Georgia and Florida are ready to take DNA samples from the rare and endangered Northern right whales who have migrated south to their calving ground in the waters off South Carolina, Georgia and Florida. Collection of this genetic material will be used to identity individual whales and their parents, as well as help in the understanding of the population dynamics of this species of whales. [Northeast Fisheries Science Center]
(Thurs.) An Oregon county is ready for hazards -- The National Weather Service recently announced the Douglas County in southwestern Oregon has completed the Service's StormReady® and TsunamiReady™ programs designed to help the county handle severe weather and tsunami events. [NOAA News]
(Thurs.) Sea lion recovery plan is released -- NOAA’s National Marine Fisheries Service has recently published a new Steller Sea Lion Recovery Plan that identifies an array of actions designed to help restore the populations of the Steller sea lions that have been classified as endangered in western Alaska and threatened in eastern sections of the state. [NOAA News]
(Thurs.) Potential cause for low West Coast salmon returns determined -- Scientists at NOAA’s Northwest and Southwest Fisheries Science Centers have identified unusual environmental conditions in the eastern North Pacific commencing in 2005 that affected the California Current as the cause of a dramatically low return of Chinook and coho salmon to West Coast rivers and streams during 2007. [NOAA News]
(Tues.) Marine sanctuaries get help from Army divers -- During a three-week pilot project, divers from the U.S. Army Dive Company are repairing buoy moorings, removing trash from dive sites, and installing listening devices to track fish at NOAA's national marine sanctuaries off the Florida and Georgia coasts. [NOAA News]
(Tues.) Celebrate "International Polar Day" -- Wednesday, 12 March 2008, has been designated as the third "International Polar Day" with the focus upon the Changing Earth, Past & Present ice ages, paleoclimate, earth history. This series of quarterly International Polar Days coincides with the International Polar Year. [EurekAlert!]
(Tues.) Ocean "deserts' seen to be expanding -- Researchers with NOAA’s National Marine Fisheries Service and the University of Hawaii using data from SeaWiFS (Sea-viewing Wide Field-of-view Sensor) on NASA’s SeaStar spacecraft have found that those areas of the world's oceans that are least biologically productive have been expanding possibly as a result of a warming of sea surface waters, resulting a desert-like environment. [NOAA News]
(Tues.) Decline in eel fishery foreseen -- A team of scientists of the US, Japan and the United Kingdom warn that the stocks of American eels are declining rapidly across the North Atlantic because of changing conditions in the Sargasso Sea caused by the North Atlantic Oscillation, a decadal-long shift in oceanic and atmospheric conditions. [Northeast Fisheries Science Center]
(Tues.) Oceanic bacteria studied -- Researchers at the Massachusetts Institute of Technology and Penn State University have been studying how marine bacteria work to help control the natural cycles of carbon, water and energy in the planetary environment. [EurekAlert!]
(Tues.) Coral health could be affected by dissolved organic material -- Researchers at the University of Texas at Austin Marine Science Institute and Mote Marine Laboratory in Sarasota, FL report that the amount and type of natural and anthropogenic organic material dissolved in seawater could change the bacterial communities, resulting in an alteration in the health of coral. [EurekAlert!] In a corresponding study, recovery of coral reefs from increased seawater temperatures depends on how much the tiny coral polyps eat and how healthy then can maintain the microscopic algae that survive inside their bodies. [Ohio State University]
Eye on the tropics -- The South Indian Ocean basin remained active in terms of tropical cyclone activity last week. In the western sections of the basin, Tropical Cyclone Jokwe formed during the early part of the week and intensified, becoming a category 3 cyclone on the Saffir-Simpson Intensity Scale. It moved westward, brushing the northern end of Madagascar and the coast of Mozambique before turning to the south. As of late Sunday, this typhoon was traveling south across the Mozambique Channel. Images from the MODIS sensor on NASA's Aqua satellite show Jokwe as it moved between Madagascar and Mozambique. [NASA Earth Observatory] [NASA Hurricane Page]
Tropical Cyclone Kamba formed over the Southern Indian Ocean on Saturday southeast of Diego Garcia. As of late Sunday, this cyclone was traveling to the southwest.
In the eastern sections of the basin, Tropical Cyclone Ophelia, which had been a category 1 tropical cyclone, weakened and dissipated off the coast of northwestern Australia by midweek. An image obtained from the Atmospheric Infrared Sounder instrument on NASA's Aqua satellite shows the pattern of temperatures of the tops of the clouds surrounding Ophelia. [NASA Hurricane Page]
A rare white killer whale was spotted -- During the third week of February 2008, scientists onboard the NOAA research vessel Oscar Dyson cruising offshore of Alaska's Aleutian Islands sighted a rare white killer whale. [NOAA News]
Applicants sought for advisory positions to a marine sanctuary -- The Florida Keys National Marine Sanctuary, managed by NOAA and the state of Florida, is accepting applications for four seats on its sanctuary advisory council, which ensures public participation in sanctuary management. [NOAA News]
New method is developed to estimate sea ice thickness -- Scientists with the U.S. Geological Survey and the Russian Academy of Sciences, Moscow have developed a new technique using sea ice motion data for estimating the thickness of Arctic sea ice over the 1982 to 2003 seasons. [USGS]
Algae bloom detected in sea ice -- Images obtained from the MODIS sensor on NASA's Aqua satellite show a bloom of algae along the edge of the sea ice floating on Antarctica's Ross Sea. [NASA Earth Observatory]
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.

Concept of the Week: Seiche Model

A seiche (pronounced "say-sh") is a rhythmic oscillation of water in an enclosed basin (e.g., bathtub, lake, or reservoir) or a partially enclosed coastal inlet (e.g., bay, harbor, or estuary). With this oscillation, the water level rises at one end of a basin while simultaneously dropping at the other end. A seiche episode may last from a few minutes to a few days. (Refer to pages 156-157 in your textbook for more on seiches.)

With a typical seiche in an enclosed basin, the water level near the center does not change at all but that is where the water exhibits its greatest horizontal movement; this is the location of a node. At either end of an enclosed basin, vertical motion of the water surface is greatest (with minimal horizontal movement of water); these are locations of antinodes. The motion of the water surface during a seiche is somewhat like that of a seesaw: The balance point of the seesaw does not move up or down (analogous to a node) while people seated at either end of the seesaw move up and down (analogous to an antinode).

Go to the University of Delaware's Seiche Calculator at http://www.coastal.udel.edu/faculty/rad/seiche.html. Set the "Modal Number" to 1 and then press "Calculate" for a graphical simulation of a seiche in an enclosed basin.

Partially enclosed basins usually have a node located at the mouth (rather than near the center) and an antinode at the landward end. Go to the Seiche Calculator, set the "Modal Number" to 0.5 and then press "Calculate" for a simulation of a seiche in a basin open to the right. Furthermore, some basins are complex and have multiple nodes and antinodes; these can be simulated on the Seiche Calculator by selecting different values of "Modal Number" greater than one.

The natural period of a seiche depends on the length and depth of the basin and generally ranges from minutes to hours. The period is directly proportional to basin length. For example, the natural period of a seiche in a small pond is considerably less than its period in a large coastal inlet. Also, for the same basin, the natural period is inversely proportional to water depth; that is, the period shortens as water deepens. Using the Seiche Calculator, you may wish to experiment with different basin lengths and depths. Conversely, one can determine the average depth of a lake by determining the period of the seiche and the length of the lake.

Concept of the Week: Questions

In an enclosed basin the node of a seiche is located [(at either end) (near the center)] of the basin.
The natural period of a seiche [(depends on) (is independent of)] the size of an enclosed basin.

Historical Events:

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)
13-15 March 1952...The world's 5-day rainfall record was set when a tropical cyclone produced 151.73 inches rain at Cilos, Reunion Island in the Indian Ocean. The 73.62 inches that fell in a 24-hour period (15^th-16^th) set the world's 24-hour rainfall record. (Accord's Weather Calendar)
14 March 1891...The submarine Monarch laid telephone cable along the bottom of the English Channel to prepare for the first telephone links across the Channel.
14 March 1903...President Theodore Roosevelt issued an executive order making Pelican Island near Sebastian Florida a "preserve and breeding ground for native birds," including pelicans and herons, marking the birth of the National Wildlife Refuge System. (Wikipedia)
14 March 1918...The first US concrete seagoing ship was launched at Redwood City, CA. (Today in Science)
15 March 1493...Christopher Columbus returned to Spain after his first voyage to the New World. (Wikipedia)
15 March 1778...Nootka Sound, Vancouver Island was discovered by Captain James Cook.
15 March 1946...For the first time, U.S. Coast Guard aircraft supplemented the work of the Coast Guard patrol vessels of the International Ice Patrol, scouting for ice and determining the limits of the ice fields from the air. (USCG Historian's Office)
15 March 1960...Key Largo Coral Reef Preserve in the Florida Keys was established as the nation's first underwater park. This preserve currently includes John Pennekamp Coral Reef State Park and the adjacent Florida Keys National Marine Sanctuary.
16 March 1521...Portuguese navigator Ferdinand Magellan reached the Philippines. He was killed the next month by natives.
16 March 1834...The HMS Beagle anchored at Berkeley Sound, Falkland Islands.
16 March 1889...A war between the U.S. and Germany was likely averted as a hurricane sank all three U.S. and three German warships in the harbor at Apia, Samoa. Joint U.S., German and Samoan rescue cooperation led to the Treaty of Berlin (1889) that later settled the dispute. (Accord's Weather Calendar)