WEEKLY OCEAN NEWS

DATASTREME OCEAN WEEK SEVEN: 17-21 October 2005

Ocean in the News:

(Thurs.) Wilma becomes the most intense hurricane -- Hurricane Wilma rapidly intensified from a category 2 hurricane (on the Saffir-Simpson Scale) to a major category 5 hurricane in only six hours early Wednesday, when a minimum central pressure of 884 mb was reported, which is the lowest minimum pressure ever measured in a hurricane in the North Atlantic basin. Maximum sustained surface winds reached 175 mph. Current forecasts indicate that Wilma could take a path across the Gulf of Mexico toward the southwest coast of Florida by late in the weekend, making landfall possibly as a major hurricane with maximum sustained winds in excess of 110 mph. [USA Today]
(Thurs.) Tons of marine debris collected -- More than 125 tons of debris were recovered from the ocean waters surrounding the Hawaiian Islands by teams led by the NOAA Fisheries Service in 2004, roughly 24 times the amount collected in 1996. [ENN]
(Thurs.) Source of California beach sand uncovered -- Scientists at the University of California, San Diego have recently found that the sand on the beaches south of Los Angeles comes primarily from the erosion of the area's sea cliffs. [EurekAlert!]
(Thurs.) Fate of British seabirds linked to two factors -- A team led by a professor at the University of Sheffield has shown that the mortality rate of British seabirds has increased due to major oil spills and a change in the climate over the North Atlantic. [EurekAlert!]
(Thurs.) Ice did them in -- British Antarctic survey researchers have determined that advancing ice sheets during the Ice Ages scoured the sea floor of the continental shelf to cause mass extinctions. [EurekAlert!]
(Tues.) Gulf Coast weary of Wilma -- A tropical depression in the Caribbean intensified to become Tropical Storm Wilma early Monday. By late Monday night, with additional intensification, Wilma was poised to become a hurricane. According to forecasts, this potential hurricane could move into the Gulf of Mexico later in the week and ultimately make landfall along the Gulf Coast of the US sometime over the weekend. [CNN]
(Tues.) A record tied -- National Hurricane Center officials report that with the formation of Tropical Storm Wilma, 2005 is now tied with 1933 as having the greatest number of named tropical storms and hurricanes in the North Atlantic basin in over 150 years of record. [NOAA News]
(Tues.) Useful navigation products are available -- The NOAA Office of Coast Survey, in cooperation with other NOAA agencies, is responsible for a variety of hydrographic surveys and nautical charts intended to ensure safe and efficient transportation, maritime engineering projects and recreational activities. [NOAA Magazine]
(Tues.) The island-modifying power of a hurricane studied -- A cooperative research project involving NASA, the US Geological Survey and the US Army Corps of Engineers has been investigating how Hurricane Charley sliced through North Captiva Island off the west coast of Florida in August 2005. A variety of techniques was employed to make a three-dimensional computer model, including data obtained by the MODIS instrument onboard the NASA Terra satellite. [NASA News]
(Tues.) Ancient ocean invasions studied -- Researchers at the Smithsonian Tropical Research Institute, Scripps Institution of Oceanography, Hofstra University and the University of Hawaii have been using DNA analysis to study the invasion of a species of fish from the Indian Ocean into the Atlantic as the ocean warmed during the last interglacial epoch. [EurekAlert!]
(Tues.) Structural damage by recent hurricanes to be studied -- The National Institute of Standards and Technology is deploying three teams of technical experts from several governmental agencies to assess the damage caused by Hurricanes Katrina and Rita to physical structures along the Gulf Coast. [National Institute of Standards and Technology]
(Tues.) Expedition to help save a treasure in Florida waters -- A group of scientists from several universities were participating in a six-day expedition of the deep coral reefs on the Oculina Bank off central Florida's Atlantic coast at the end of last week that was intended at ultimately starting a program intended at protecting this unique reef. [EurekAlert!]
Another tropical depression forms in the Caribbean -- A tropical depression that could become the twenty-first named tropical cyclone (tropical storm or hurricane) of the 2005 North Atlantic hurricane season formed in the Caribbean over the weekend. If this system strengthens, it would be named Tropical Storm Wilma, and it would tie the current hurricane season with 1933 as the most active season in over 150 years. [CNN]
Milestones noted in international float program -- NOAA officials recently noted two milestones involving the Argo submersible float observation program; one milestone was reached last week when a submersible float was deployed, joining 2056 other floats, or two-thirds of the intended international global array, while the other milestone was the collection of nearly 55,000 temperature and salinity profiles from these Argo floats. [NOAA News]
Some good news from the Gulf -- Scientists with the NOAA Fisheries Service reported that additional analyses of the fish, water and sediments from both coastal and offshore waters of the Gulf of Mexico two weeks after Hurricane Katrina made landfall in Louisiana do not indicate fecal contamination nor high levels of pesticides and other contaminants as originally feared. [NOAA News]
Toxic algae bloom continues to threaten Florida -- A toxic algae bloom, also known as "red tide", continues to plague the coastal waters of the Gulf of Mexico along Florida's Panhandle, causing swimmers to complain, fish kills and the closure of oyster harvesting areas. [ENN]
An ancient episode of global warming could have preserved fossils -- A geologist from the University of Oregon suggests that a global warming episode during the Cambrian (500 million years ago) associated with increased levels of atmospheric methane and carbon dioxide could have been responsible for massive kills of fish and other marine species that were then preserved as fossil assemblages. [EurekAlert!]
A surprise in Lake Pontchartrain -- The director of the Lake Pontchartrain Basin Foundation noted that the discovery of eight dolphins in the lake near New Orleans appears to indicate that the lake could be recovering from the disaster wrought by Hurricane Katrina faster than anticipated. [ENN]
Tropics played an active role in planetary climate control -- Researchers from the Universitat Autònoma de Barcelona and Durham University report that changes in the tropical circulation in the Pacific approximately one million years ago may have caused global changes in climate, resulting in large expansion of the polar ice caps. [EurekAlert!]
Cause of tropical ocean warming identified -- Scientists at the University of California, Santa Barbara claim that the paleoclimatic record obtained from a deep-sea core extracted from the equatorial Pacific indicates that warming of these ocean waters occurred during times of high levels of atmospheric greenhouse gases. They conclude that current increases in sea surface temperature in the tropics could be linked to increases in some greenhouse gases. [EurekAlert!]
"Popping" rocks recovered from Pacific waters -- A team of scientists from the US and Mexico, including those from Scripps Institution of Oceanography, recently returned to the waters near Guadalupe Island off the Mexican coast and retrieved deep-sea volcanic that explode with a popping sound when taken out of the water. High concentrations of volcanic gases trapped in the lava rocks are released when the rocks are exposed to the lower air pressure, resulting in the popping sounds. [Scripps Institution of Oceanography]
Condition of Indonesian coral reefs are assessed -- Three major marine conservation organizations should complete their assessment this week of the damage sustained by coral reefs in Indonesia from last December's earthquake and tsunami. [EurekAlert!]
Another CryoSat satellite considered -- The European Space Agency was considering the building of another CryoSat satellite to replace the one that was destroyed during launch two weeks ago. This satellite was intended to collect data on the thickness of polar sea ice during a three-year mission. [The New Scientist]
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 DataStreme Ocean textbook for more on seiches.)

With a typical seiche in an enclosed basin, the water level near the center does not change at all although 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:

18 October 1910...Northeasterly winds as high as 70 mph (from a hurricane moving northward up the Florida peninsula) carried water out of Tampa Bay and the Hillsboro River. The water level lowered to nine feet below mean low water. Forty ships were grounded. (The Weather Channel)
19 October 1843...Captain Robert Stockton of the Princeton, the first screw propelled naval steamer, challenged the British merchant ship Great Western to a race off New York, which Princeton won easily. (Naval Historical Center)
20 October 1892...After ten years of difficult and costly construction, the St. George Reef Lighthouse, built on a rock lying six miles off the northern coast of California, midway between Capes Mendocino and Bianco, was first lighted. (USCG Historian's Office)
20 October 1956...A German physician, Dr. Hannes Lindemann, began a voyage on which he would become the first person to cross the Atlantic in the smallest craft. Using a double-seat folding kayak that was 17 feet in length and outfitted with an outrigger and sail, he made the trip from Las Palmas in the Canary Islands to St. Thomas in the US Virgin Islands in 72 days. He had made a prior crossing in a 23-foot African dugout canoe. He later wrote a book, Alone at Sea, describing his experiences. (Today in Science)
20 October 1984...The Monterey Bay Aquarium opened on Cannery Row in Monterey, CA as the largest artificial environment for marine life, housing 500 marine animals from at least 525 species. The aquarium also supports active research and conservation programs. (Today in Science)
21 October 1797...The USS Constitution was launched at the Charlestown Navy Yard in Boston, MA. The ship, nicknamed "Old Ironsides," is now the oldest commissioned ship in the U.S. Navy. (Naval Historical Center)
21 October 1580...Portuguese navigator Ferdinand Magellan on his famous circumnavigation voyage of the globe reached Cape Virgenes and the strait at the tip of South America that now bears his name. Only three ships entered the 373-mile long passage separating Tierra del Fuego (land of fire) and the continental mainland. Navigating the treacherous strait in 38 days, the expedition entered the South Pacific Ocean, which Magellan named "Mar Pacifico" for the relatively tranquil seas that he found. However, one ship had been wrecked and another deserted. (The History Channel)
21-26 October 1998...Hurricane Mitch, a category 5 hurricane (on the Saffir-Simpson Scale), developed as a tropical depression over the southwestern Caribbean Sea about 360 mi south of Kingston, Jamaica on the 21^st. It would intensify over the next few days to become the second deadliest Atlantic hurricane on record, on the 24^th. By the 26^th, Mitch finally dissipated after remaining a category 5 hurricane for 33 hours. Estimated rainfall totals of up to 75 in. caused devastating flooding and mudslides in Honduras and Nicaragua for days. Estimated death toll from this hurricane was more than 11,000, the worst since 1780. (The Weather Doctor) (Accord Weather Calendar)
22 October 1988...A "nor'easter" swept across the coast of New England. Winds gusted to 75 mph, and large waves and high tides caused extensive shoreline flooding. (The National Weather Summary) (Storm Data)
23-24 October 1918...The Canadian steamship Princess Sophia carrying miners from the Yukon and Alaska became stranded on Vanderbilt Reef along coastal British Columbia. A strong northerly gale hampered rescue attempts, and the next day, the ship sank with the loss of the 268 passengers and 75 crewmen on board. (The Weather Doctor)