DATASTREME OCEAN WEEK SEVEN: 14-18 March 2011

Items of Interest:

• Time change --
Daylight Saving Time went into effect yesterday morning for essentially the entire nation -- the exceptions include Arizona, Hawaii, Puerto Rico and about 18 counties in Indiana. These changes have been mandated by the U.S. Congress in the Energy Policy Act of 2005, which extended Daylight Saving Time across the nation, with the start on the second Sunday in March (13 March 2011) and end on the first Sunday in November (6 November 2011). In other words, following the old adage of "spring ahead, fall behind", you will need to turn your clocks ahead by one hour to conform with the local time observance. Most of Canada also observes Daylight Saving Time changes at the same time [National Research Council Canada].
What does this time change mean to you (other than later sunsets)? Contrary to a popular belief that has surfaced at times, the change from Standard to Daylight Saving Time does not add an extra hour of daylight to the day nor does it affect weather patterns. While the weather will not change because of the time change, the times when you will be able to obtain weather charts will now be one hour later. The reason is that the National Weather Service operates on "Z time" (variously called Greenwich Mean Time or Universal Coordinated Time) which does not observe Daylight Saving Time, and the charts are still produced and transmitted at the same Z time.
While many people want additional daylight after work, some health experts say that the change to Daylight Saving Time is hard on human health, as it affects the natural sleep cycle and circadian rhythms. Increases in traffic accidents and heart attacks have been seen during the first several days after the time change. [Hartford Courant]
• Notice the Equinox --
The vernal equinox, which marks the commencement of astronomical spring, will occur late next Sunday afternoon (officially at 2321Z on 20 March 2011 or 5:21 PM EDT, 4:21 PM CDT, and so forth). If you checked the sunrise and sunset times in your local newspaper or from the climate page at your local National Weather Service Office, you would probably find that by midweek, the sun should have been above the horizon for at least 12 hours at most locations. As discussed previously, the effects of atmospheric refraction (bending of light rays by the varying density of the atmosphere) along with a relatively large diameter of the sun contribute to several additional minutes that the sun appears above the horizon at sunrise and sunset.
• "Earth-Sun Day"--
Since next Sunday is the vernal equinox, this coming Saturday (19 March 2011) has been declared Earth-Sun Day, which is includes a series of programs and events that occur throughout the year culminating with a celebration on the Spring Equinox. This year's theme is "Ancient Mysteries-Future Discoveries", designed to provide a deeper understanding of the Sun and its impact on societies across the ages. A live Sun-Earth Day Webcast, developed in conjunction with NASA EDGE (Exploration Systems Mission Directorate), will originate from several sites including: Chaco Canyon (New Mexico), Hovenweep (Utah), Chichen Itza (Mexico), Cahokia Mounds (Illinois), and Sunspot (New Mexico).
• Report from the Field --
Terri Kirby Hathaway, AMS DataStreme Oceans LIT Leader and Marine Education Specialist with North Carolina Sea Grant, reported on a sure sign of spring in her area, as she saw ospreys on North Carolina's Outer Banks. These birds return in early March and leave around mid-September. Terri noted seeing numerous nests.

Ocean in the News:

• Major earthquake off Japan generates large tsunami waves --
A major earthquake near the east coast of Honshu, Japan last Friday (0546 Z on 11 March 2011 or 2:46 PM Japan time) caused widespread destruction near Tokyo and created a sizable tsunami that traveled across the North and South Pacific Ocean. According to early estimates from the US Geological Survey, this earthquake that occurred was a magnitude 8.9 earthquake with an epicenter located off Miyagi Prefecture, approximately 230 miles northeast of Tokyo. Arguably, this earthquake was the most powerful earthquake to hit Japan in recorded history. This near-surface earthquake (epicenter depth of 24.9 km below the surface) occurred due to thrust faulting on or near the subduction zone interface plate boundary between the Pacific and North America plates. This thrust faulting produced a large displacement of ocean water that resulted in a large tsunami that propagated out across the North and South Pacific Oceans as shown by NOAA's Center for Tsunami Research; note that this site has a YouTube animation of the propagation of the Honshu tsunami, computed with the NOAA forecast method using MOST (Method of Splitting Tsunami) model with the tsunami source inferred from DART® (Deep-ocean Assessment and Reporting of Tsunamis) system data. A 10-meter high tsunami wave inundated coastal sections of Miyagi Prefecture on Japan's east coast. Traveling rapidly, the tsunami reached Adak, AK in the Aleutian Islands in less than five hours after the initial earthquake, Hawaii in slightly more than seven hours, and locations along the California coast at times that ranged between ten and twelve hours. In anticipation of the tsunami, NOAA's West Coast & Alaska Tsunami Warning Center in Palmer, AK and the Pacific Tsunami Warning Center in Ewa Beach, HI issued tsunami warnings, watches and advisories to 20 countries around the rim of the Pacific basin. Waves of nearly seven feet were reported in the harbor at Maui, HI and to 8.1 feet at Crescent City, CA. Some damage associated with the tsunami was reported to coastal communities in Hawaii and North America. Several photographers were swept out to sea by a wave at McKinleyville, CA (near Eureka); one of these people died.
• Eye on the tropics --
No organized tropical cyclone activity was detected across any of the world's major ocean basins during the last week.
• Nation making progress to end overfishing --
Early last week, the Assistant NOAA Administrator for Fisheries Eric Schwaab reported at a hearing of the US Senate Commerce Committee on the Magnuson-Stevens Act that the nation is making good progress toward meeting the mandate to end domestic overfishing. [NOAA News]
• New website tracks coastal investments and successes by state --
Last week, NOAA's Office of Ocean and Coastal Resource Management (OCRM) launched a new interactive web page called "OCRM in Your State" that displays the scope of coastal program investments and successes in NOAA's 34 partner states and territories. [NOAA News]
• Results from Gulf Oil Spill air pollution study have applications elsewhere --
A multi-agency effort designed to assess the atmospheric consequences that last year's BP Deepwater Horizon oil spill had on the air quality was conducted by researchers from NOAA's Earth System Research Laboratory and colleagues from the University of Colorado-Boulder, the University of Miami, the University of California, Irvine and Carnegie Mellon University using one of NOAA's "hurricane hunter" aircraft. One of the findings from the special NOAA-led airborne mission that sampled the air quality in June was the discovery of an important new mechanism by which air pollution particles form from the heavier organic compounds. This newly discovered pollution mechanism could change the way urban air quality is understood and predicted. [NOAA News] [University of Miami's Rosenstiel School of Marine & Atmospheric Science]
• Pollution forms invisible barrier for marine life --
Researchers at the University of Hawaii at Manoa who have been examining the genetic structure of a common, non-harvested sea star (starfish) have found that large pollution sources are increasing the genetic differentiation between populations as well as decreasing the genetic diversity of populations closest to them. [University of Hawaii at Manoa]
• Melting polar ice sheets losing mass at a faster pace --
Scientists at NASA's Jet Propulsion Laboratory and the University of California, Irvine report that their analysis of nearly 20 years of satellite data shows that the ice sheets on Greenland and Antarctica are losing mass at an accelerated pace, which is approximately three times faster than the loss from mountain glaciers and ice caps. Two sets of independent measurement techniques were used in their analysis. They also determined that in 2006, the mass loss by the polar ice sheets would raise global sea level by an average of 0.05 inches during the year. [NASA JPL]
• Superstorm hitting California could be costliest US disaster --
An economist at the University of Southern California has calculated that a superstorm with hurricane-force winds that is expected to hit California once every 200 years would cause devastation to the state's businesses, with monetary losses that would be greater than those sustained by the Gulf Coast by Hurricane Katrina in 2005. Such a superstorm, based upon a plausible simulation made by US Geological Survey scientists and termed "ARkStorm - or "atmospheric river storm", was patterned after the US West Coast storms that devastated California in 1861-62. Some climate scientists said increasing global temperatures due to climate change could increase the chances of another superstorm of this magnitude. In addition, ocean levels would be higher, which would create higher storm surges and more disastrous flooding in coastal areas of California. [University of Southern California News]
• 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:

• 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 History)
• 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)
• 17 March 1891...The British steamer SS Utopia sank off the coast of Gibraltar, killing 574 people. (Wikipedia)
• 17 March 1898...The USS Holland, the first practical submarine, was demonstrated by John Holland as it made its first dive in the waters off Staten Island, New York for one hour and 40 minutes. (Naval Historical Center)
• 17 March 1941...USCGC Cayuga left Boston with the South Greenland Survey Expedition onboard to locate airfields, seaplane bases, radio and meteorological stations, and aids to navigation in Greenland. (USCG Historian's Office)
• 17 March 1959...The submarine USS Skate (SSN-578) surfaced at the North Pole. (Naval Historical Center)
• 20 March 1866...The immigrant ship Monarch of the Seas left Liverpool, England, but was never seen again. The ship with 738 people was officially declared "lost" after 130 days. A message in a bottle was found at Plymouth, supposedly sent by a passenger. In July, wreckage was found around the Dingle coast in Southern Ireland.
• 20 March 2000...A large iceberg measuring approximately 170 mi by 25 mi calved off Antarctica's Ross Ice Shelf near Roosevelt Island. The iceberg was approximately 2.5 times the size of New York's Long Island. (Accord's Weather Guide Calendar)

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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.