WEEK SEVEN: 17-21 October 2011

• Opportunity for Teachers: The National Ocean and Atmospheric Administration's (NOAA) Teacher at Sea 2012 Field Season program is now accepting applications until 30 November 2011. 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.

• Eye on the tropics -- A few tropical cyclones were detected last week across tropical waters of the major ocean basins of the Northern Hemisphere:
• No organized tropical cyclone activity was found in the North Atlantic basin last week.
• In the eastern North Pacific Basin, Tropical Storm Irwin traveled slowly toward the east and then to the east-northeast during most of last week. As it traveled, this minimal tropical storm weakened to a tropical depression and then intensified to become a tropical storm. Over this past weekend, Tropical Storm Irwin turned to the south and weakened to become a tropical depression. The NASA Hurricane Page has additional information and satellite images on former Hurricane Irwin.
  Hurricane Jova intensified to a major category 3 hurricane on the Saffir-Simpson Scale as it traveled to the northeast toward the western coast of Mexico last week. By midweek, Hurricane Jova made landfall along the Mexican coast. This hurricane weakened to a tropical storm and then to a tropical depression before becoming a remnant low-pressure system over the mountainous terrain of Mexico. See the NASA Hurricane Page for additional information on Hurricane Jova.
  Tropical Depression 12-E formed near the Gulf of Tehuantepec at the mid-point of last week. This system was relatively short-lived, as it traveled to the north and made landfall along the southwestern Mexican coast less than 24 hours after formation. The NASA Hurricane Page has additional information on Tropical Depression 12-E.
  Torrential rains from these tropical cyclones (including Hurricane Jova) drenched Nicaragua, El Salvador, and Guatemala, causing mudslides, floods, blocked roads and power outages. As many as 23 storm related deaths were reported in Central America. Information on the heavy rainfall that fell across Mexico and Central America from last week's tropical systems, along with satellite images, is found on the NASA Hurricane Page.
• In the western North Pacific basin, Tropical Storm Banyon (or Ramon according to the Philippines) formed over the waters east of the Philippines at the beginning of last week. This tropical storm traveled westward across the southern Philippines and then curved to the north over the South China Sea. By late in the week, Tropical Storm Banyon weakened and dissipated before reaching the southeastern coast of China. Additional information and satellite imagery on Tropical Storm Banyon are available from the NASA Hurricane Page.
• Portion of marine sanctuary designated as research area -- Recently, the southern third of Gray's Reef National Marine Sanctuary in the North Atlantic waters off the Georgia coast was designated a research area, where scientists can study how human activities and natural processes affect the sanctuary's marine resources. [NOAA News]
• Project funded for investigation of Florida's deep coral reefs -- NOAA's National Centers for Coastal Ocean Science recently made an award of $998,703 to the University of Miami to investigate the role that Florida's deep coral reefs play in fisheries and ecosystems. Researchers at the University will study how the deep coral reefs of Florida's Pulley Ridge may replenish key fish species and other organisms in the downstream reefs of the Florida Keys National Marine Sanctuary and Tortugas Ecological Preserve. [NOAA News]
• Counting down to launch of new polar-orbiting environmental satellite -- NASA scientists and engineers are preparing for the launch within ten days of a new polar-orbiting environmental satellite called the National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) that is intended to measure both global climate changes and key weather variables, which should ultimately enable NOAA to improve weather forecasting accuracy. NPP instruments will include a "Visible Infrared Imaging Radiometer Suite" to monitor the surface characteristics of the land and ocean; an "Ozone Mapper Profiler Suite" to measure the concentration of ozone in the atmosphere; a "Clouds and Earth's Radiant Energy System" to monitor the amount of energy entering and exiting the top of the atmosphere; a "Cross-track Infrared Sounder" that measures atmospheric temperature profiles; and an "Advanced Technology Microwave Sounder" that generates detailed vertical profiles of atmospheric pressure, heat and humidity. [NOAA NESDIS] [NASA]
• Review of September 2011 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 2011 was 0.95 Fahrenheit degrees above the 20th century average (1901-2000) for the month. Therefore, last month's global temperature was the eighth highest September temperature since global temperature records began in 1880. When considered separately, the monthly temperatures of the land surface for this recently concluded month resulted in the fourth highest September land surface temperature on record, while September monthly average temperature over the global oceans was the 14th highest September ocean temperature in 132 years. La Niña conditions were strengthening during September, which may have reduced the September ocean temperatures. Furthermore, when considering the combined land-ocean global temperature for the year to date, this temperature was the eleventh highest nine-month global temperature since 1880.
  Arctic sea ice coverage after the end of the first week of September reached its annual minimum, which was the second smallest annual extent since satellite surveillance began in 1979. On the other hand, the areal extent of the Antarctic sea ice cover during September was slightly above the long-term average, ranking as the 14th largest since 1979. [NOAA News] Additional information is available on the monitoring of this past summer's minimum in Arctic sea ice by satellite. [NASA's Earth Science News Team]
• Critical survey of Antarctica's changing ice continues -- During the last week, scientists participating in NASA's Operation IceBridge began this mission's third year of surveys on the changing ice of Antarctica. This Operation IceBridge mission, represents the largest airborne research campaign flown over this polar cap, is designed to collect critical ice sheet measurements that can be used to determine how this major ice sheet could contribute to an anticipated global sea level rise. [NASA GSFC]
• Tsunami debris found near where predicted -- A Russian sail training ship, the STS Pallada, recently found an array of unmistakable tsunami debris on its homeward voyage from Honolulu to Vladivostok in a region of the North Pacific where scientists with the International Pacific Research Center at University of Hawaii at Manoa had predicted. [International Pacific Research Center at University of Hawaii at Manoa] [NOTE: This link requires the Adobe Acrobat Reader; see below]
• Baltic Sea adds to atmospheric carbon dioxide -- Scientists at Sweden's University of Gothenburg have found that the Baltic Sea emits more carbon dioxide to the overlying atmosphere than it sequesters in its waters. From their analysis of 15 years of seawater data, they found large differences in the flux of carbon dioxide between atmosphere and the seawater between seasons, between years and between regions. [EurekAlert!]
• New technology developed to detect deep-sea gas leaks -- Scientists at the United Kingdom's University of Southampton have developed a new ultra-sensitive technology using underwater microphones that would be capable of monitoring deep-sea gas leaks from underwater gas pipelines. [University of Southampton]
• Investigating how life may have survived "snowball Earth" -- Researchers at the University of Washington propose that simple photosynthetic algae life forms could have survived "snowball Earth", episodes of global glaciation between 800 million and 550 million years ago in a narrow body of water with characteristics similar to the present-day Red Sea. [University of Washington]
• 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.

• 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, 2011, The American Meteorological Society.