WEEK SEVEN: 18-22 October 2010

Items of Interest:

• Opportunity for Teachers:
The National Ocean and Atmospheric Administration's (NOAA) Teacher at Sea 2011 Field Season program is now accepting applications until 30 November 2010. Gain your "sea legs" and first-hand experience in one-week to one-month voyages. For more information, or to apply, see http://teacheratsea.noaa.gov.

Ocean in the News

• Eye on the tropics --
During the last week several tropical cyclones developed and traveled across tropical waters of the major ocean basins of the Northern Hemisphere:
• In the North Atlantic basin, Hurricane Paula formed as a tropical storm at the start of last week off the coast of Honduras and Nicaragua. Moving across the western Caribbean, this tropical storm became the ninth hurricane of 2010 in the Atlantic basin as it traveled to the north-northwest. By midweek Hurricane Paula intensified to a category 2 hurricane on the Saffir-Simpson Hurricane Scale as it passed just off the coast of Mexico's Yucatan Peninsula. Curving to the east, Paula crossed the Yucatan Channel and made a brief landfall near the western tip of Cuba, where this hurricane quickly weakened to a tropical storm and then a tropical depression by early Friday. Additional information on Paula, along with satellite images can be obtained from the NASA Hurricane Page.
• In the western North Pacific basin, a tropical depression formed at midweek over the waters near Guam. This depression intensified into Typhoon Megi, the seventh typhoon of 2010, by the end of the week as it traveled initially to the northwest and then the west. By Sunday (local time) Megi had become a supertyphoon, with a category 5 classification (on the Saffir-Simpson Scale) as maximum sustained surface winds reached 165 mph. This supertyphoon was forecast to approach the northern sections of Luzon in the Philippines. [USA Today] For more information and a satellite image on Typhoon Megi, consult the NASA Hurricane Page.
• More of Gulf waters reopened to fishing --
Following consultation with the US Food and Drug Administration and Gulf state representatives, NOAA reopened nearly 7000 square miles in the waters of the Gulf of Mexico off the Florida Panhandle to commercial and recreational fishing at the end of last week. As of that time, 93 percent of the federal waters in the Gulf were open to fishing, following last spring's Deepwater Horizon BP oil spill. [NOAA News]
• Catch shares applications sent to West Coast fishers --
During the past week, NOAA’s Fisheries Service mailed applications to almost 240 trawl fishers and processors on the West Coast. A new catch shares program marks one of the most significant changes in the West Coast trawl fisheries management in more than 20 years. The completed applications are due by the start of November. [NOAA News]
• Illegal fishing vessels can be denied port entry --
Before the end of the month, a new federal rule will allow NOAA’s assistant administrator for fisheries to deny a vessel that has been listed for engaging in illegal, unreported and unregulated fishing entry into any US port or access to port services. [NOAA News]
• Live webcasts of corals research from undersea lab are available to nation's classrooms --
In a collaboration between academic, federal, industry, and private partners, including NOAA, UNCW, California State University Monterey, Morgan State University, AT&T and the National Marine Sanctuary Foundation, live webcasts from NOAA's Undersea Lab are being made available to the nation's classrooms. This within the Florida Keys National Marine Sanctuary. The web programs will be broadcast daily, one in English and one in Spanish, to reach underrepresented students and communities as part of a NOAA partnership with the Multicultural Education for Resource Issues Threatening Oceans (MERITO) program and the National Association of Black Scuba Divers. [NOAA News]
• Construction of NOAA's supercomputing center started--
Last week, a ribbon-cutting ceremony marked the start of construction for the NOAA Environmental Security Computing Center in Fairmont, WV, a new state-of-the-art supercomputer center that is designed to develop and improve the accuracy of global and regional climate and weather model predictions. [NOAA News]
• Review of September 2010 global temperatures --
Preliminary data analyzed by scientists at NOAA’s National Climatic Data Center indicated that the global combined land and ocean average surface temperature for the September 2010 was 0.9 Fahrenheit degrees above the 20th century average for the month. Last month's temperature tied for the eighth highest September temperature since global temperature records began in 1880. When considered separately, the monthly temperatures of the land surface and the ocean surface for this recently concluded month were the ninth highest September temperature on record. A La Niña event had developed, which may have reduced the September ocean temperatures. Furthermore, when considering the combined land-ocean global temperature for the year to date, this temperature would tie 1998 for the highest nine-month global temperature since 1880. Arctic sea ice coverage during September was the third lowest for any September since satellite surveillance began in 1979. [NOAA News]
• Coral records document rise in Pacific Ocean thermocline --
Researchers at Ohio State University and the University of Toronto report that their analysis of coral records from the western tropical Pacific Ocean indicates that the thermocline, a boundary between warm surface water and the colder deep water, has become shallower over the last several decades in response to the increase in global temperatures. These researchers also indicate that this change in thermocline depth has an important relationship with the subsurface oceanic circulation patterns. [Ohio State University Research]
• Regional sea surface temperature rise and coral bleaching event detected in western Caribbean --
Researchers at the Smithsonian Tropical Research Institute's Bocas del Toro Research Station and Galeta Point Marine Laboratory have reported an anomalous sea temperature rise and a major coral bleaching event in the western Caribbean during the last several months. [EurekAlert!]
• Underwater robot to explore Antarctic ice shelf and ice-covered ocean --
Researchers at the University of British Columbia are about to deploy an autonomous underwater vehicle to survey the waters under the Antarctic ice shelf and the surrounding ice-covered ocean for a nearly four-week mission. [University of British Columbia]
• 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: 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

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

Historical Events:

• 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 Blanco, 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 History)
• 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 History)
• 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 onboard. (The Weather Doctor)

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Prepared by AMS DS Ocean Central Staff and Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2010, The American Meteorological Society.