WEEKLY WATER NEWS

DataStreme WES Week Nine: 29 October-2 November 2007

Opportunity for Teachers: The National Ocean and Atmospheric Administration's (NOAA) Teacher at Sea program is now accepting applications until December 31, 2007. 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.

Water in the News:

(Thurs.) Increased risks foreseen with less Arctic ice cover -- At a meeting held at the European Space Agency's Earth Observation Centre in Frascati, Italy, polar ice experts from North America and Europe associated with the International Ice Charting Working Group warn that the diminished Arctic sea ice could pose of "significant hazards to navigation." These experts are relying on satellites to provide important up-to-date information for their forecast models. [ESA]
(Thurs.) Arctic lakes seen as major source of prehistoric methane -- A team of researchers from the University of Alaska, Fairbanks, the University of Southampton and the Russian Academy of Sciences report that methane that collected in some lakes in Alaska and Siberia called "thermokarst" lakes contained sufficient quantities of methane that bubbled out to contribute a large spike in the atmospheric methane concentration near the end of the last Ice Age (14,000 to 11,500 years ago). [University of Alaska, Fairbanks]
(Thurs.) Chinese rivers to get help -- A massive five-year cleanup effort has begun by China and the European Union to cut pollution and improve the water quality on China's Yellow and Yangtze Rivers. [US Water News Online]
(Thurs.) North Atlantic carbon uptake slowed -- Scientists from the United Kingdom's University of East Anglia report that uptake of atmospheric carbon dioxide by the North Atlantic, which represents a major carbon sink, slowed dramatically beginning in the mid 1990s and continued for the first several years of the new millennium. [EurekAlert!]
(Tues.) Hypoxia forecasting models are developed for two East Coast estuaries -- The University of Maryland Center for Environmental Science has been awarded $330,000 by NOAA to begin a five-year project designed to develop hypoxia forecasting models that will assist resource managers analyze and predict how hypoxia, water quality, and fishery production respond to nutrient loading and climatic factors in Chesapeake Bay and Delaware inland bays [NOAA News]
(Tues.) California wildfires are claimed to be consistent with climate change -- A bioclimatologist at Oregon State and the US Forest Service claims that the current catastrophic wildfires across southern California appear to be consistent with the projected changes in the vegetation and lengths of prolonged droughts suggested by climate models. [EurekAlert!]
(Tues.) World's poor could bear brunt of future changes in climate --An official from the Intergovernmental Panel on Climate Change recently warned that Latin America and other poor regions of the world will bear the brunt of future changes in climate, especially because water management issues will become an increasing problem. [USA Today]
(Tues.) Meteor may not have been prime suspect in "Great Dying" mass extinction -- Geologists at the University of Southern California claim that the "Great Dying", the Permian-Triassic mass extinction event approximately 250 million years ago may have been caused by slower environmental stress caused by volcanic eruptions and increased global temperatures, rather than the more rapid stress associated with a major meteor impact as commonly thought. This study also suggests that deep sea organisms began dying before those on reefs and ocean shelves, which may mean that hydrogen sulfide may have been released due to higher ocean temperatures. [EurekAlert!]
Eye on the tropics -- During the past week, the following tropical cyclone activity was detected:
- In the North Atlantic basin, Tropical Depression 16 formed over the central Caribbean Sea south of Hispaniola early Saturday morning. By Sunday afternoon this depression had intensified to Tropical Storm Noel, the fourteenth named tropical cyclone of the 2007 North Atlantic hurricane season. [USA Today]
- In the eastern North Pacific, Tropical Storm Kiko traveled northwestward parallel to the Mexican coast at the start of last week, but then turned west. This storm weakened to a tropical depression as it moved to west-southwest away from the Mexican coast by midweek.
- In the western North Pacific basin, Tropical Storm Faxai developed to the southeast of Okinawa late last week and initially traveled toward the northwest, before curving toward the north and then northeast.
- In the Indian Ocean, Tropical Cyclone 5 A formed over the weekend to the northwest of the Maldives and was moving to the west.
Heavy rain in the Big Easy -- An image generated by the NASA Goddard Space Flight Center's Multi-satellite Precipitation Analysis from data collected by sensors on the Tropical Rainfall Measuring Mission (TRMM) satellite show the distribution and extent of the heavy precipitation that fell over one week ago across coastal Louisiana, including the New Orleans metropolitan area. [NASA Earth Observatory]
Monsoon floods in Thailand -- Images made by the MODIS instrument on NASA's Terra satellite of Southeast Asia made in early September 2007 and one week ago show the rivers across northeast Thailand that have become swollen by the seasonal monsoon rain that falls across Southeast Asia during the high sun season (summer) due to an onshore circulation regime. [NASA Earth Observatory]
A paleo-thermometer developed -- A researcher working at the Royal Netherlands Institute for Sea Research developed an instrument that measures the changes in the cell wall composition of archeabacteria that are related to changes in seawater temperature. This paleo-thermometer can be used for climate reconstruction. [Netherlands Organisation for Scientific Research]
Unexpected increases in carbon dioxide detected -- Researchers affiliated with the Global Carbon Project, the University of East Anglia and the British Antarctic Survey report that the concentration of atmospheric carbon dioxide has increased at a greater rate than expected since 2000 from the inefficient use of fossil fuels and from the decline in the efficiency of land and ocean carbon sinks. [EurekAlert!] [CSIRO]
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]
Global Water News Watch -- Other water news sources can be obtained through the SAHRA Project at the University of Arizona [SAHRA Project]
Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

Concept of the Week: Seiche

You probably remember as a child agitating the bath water so that it sloshed back and forth in the tub. (If you never did this as a child, there's still time.) You produced a seiche, a phenomenon first studied in Lake Geneva, Switzerland in the 1700s. 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.

A seiche is a standing wave. Whereas wind-driven waves (pages 181-182 in your DataStreme WES textbook) are progressive in that they propagate through a body of water, standing waves are stationary. With progressive waves, crests and troughs travel along the water surface but with standing waves, crests alternate vertically with troughs at fixed locations. For both progressive and standing waves, the restoring force is gravity.

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.

A seiche can be induced by wind, regional differences in air pressure, earthquakes, or tidal forces. For example, wind blowing persistently in the same direction down the long axis of a bay causes water to pile up at the downwind end of the bay. When the wind slackens, the water oscillates (as a seiche) back-and-forth from one end of the bay to the other until eventually the water calms to a horizontal surface. A line of thunderstorms moving eastward from Wisconsin in late May 1998 produced a seiche in Lake Michigan that killed several people by drowning at the southern end of the lake. Previous seiches have produced 8 to 10 ft waves on Lake Michigan. A tsunami generated a seiche in the harbor of Hilo, HI following a major earthquake in the Aleutian Islands on 1 April 1946.

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 shorter than its period in a large coastal inlet. In addition, 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 values of basin length and depth. Conversely, one can estimate the average depth of a lake by determining the period of the seiche and the length of the lake.

Usually a seiche in a lake or harbor is of little concern because the changes in water level are minor--often only a few centimeters. Under certain circumstances, however, a seiche may grow to great heights with serious consequences including flooding and damage to moored vessels. A seiche grows as a consequence of resonance, that is, when the period of the disturbance (e.g., wind, earthquake) matches the natural oscillation period of a specific basin. Recall again your youthful bathtub experience. By timing your rhythmic disturbance of the water to match the natural period of the tub (about one second), you were able to cause the seiche to build until the water splashed out of the tub and onto the floor. Through resonance, vibrations from the 1994 Northridge, CA earthquake caused swimming pools to overflow throughout Southern California. In bays open to the ocean, if the period of tidal forcing matches the natural period of the bay, resonance can greatly increase the tidal range.

Concept of the Week: Questions

Seiches are [(standing) (progressive)] waves.
The natural period of a seiche [(depends on) (is independent of)] the size of an enclosed basin.

Historical Events:

29 October 1999...Tropical Cyclone 5B, with sustained winds of 155 mph, made landfall at Paradwip (Orissa, India). A storm surge of at least 20-ft height swept at least 12 mi inland. More than 10,000 people were killed. With 2 million homes either damaged or destroyed, 35 million people were left homeless. Damage from this tropical cyclone was $1.5 billion. (Accord Weather Guide Calendar)
30 October-1 November 1991...After absorbing Hurricane Grace on the 29^th, an intense ocean storm took an unusual course and moved westward along 40 degrees north latitude and battered eastern New England with high winds and tides. Winds had already been gusting over 50 mph along the coast 2 days before, so seas and tides were very high. Major coastal flooding and beach erosion occurred all along the New England, New York, and New Jersey coastlines. Over 1000 homes were damaged or destroyed with tides 4 to 7 ft above normal. Wind gusts reached 78 mph at Chatham, MA and 74 mph at Gloucester, MA. One ship east of New England reported a 63-ft wave. Total damage from the storm was $200 million. On 1 November this ocean storm underwent a remarkable transformation. Convection developed and rapidly wound around the storm center and an eye became visible on satellite imagery. Air Force reconnaissance aircraft found a small but intense circulation with maximum winds of 75 mph. Th is evolution from a large extratropical low to a small hurricane is rare but not unprecedented. (Intellicast)
31 October 1876...A 10 to 50 ft storm surge ahead of the Backergunge cyclone flooded the eastern Ganges Delta in India (now Bangladesh). Over 100,000 people drowned. (The Weather Doctor)
31 October 1846...Eighty-seven pioneers were trapped by early snows in the Sierra Nevada Mountains that piled five feet deep, with 30 to 40 ft drifts. Just 47 persons survived the "Donner Pass Tragedy." (The Weather Channel)
31 October 1874...A waterspout (a tornado-like vortex that travels over water) formed over Lake Erie and reached the lakeshore approximately 0.5 mi west of Buffalo, MY. Upon reaching the shore, it dissipated, scattering sand in all directions. (Accord Weather Calendar)
31 October 1965...Fort Lauderdale, FL was deluged with 13.81 inches of rain over a two-day period (30^th-31^st), the second heavy rainfall in two weeks. This brought their rainfall total for the month of October to an all-time record of 42.43 inches. More road and street damage occurred and some homes were flooded for the second time. (David Ludlum) (The Weather Channel) (Intellicast)
31 October 1984...An exceptional thunderstorm at Al Wajh on the Red Sea coast of northern Saudi Arabia produced 4.81 inches of rain, which was more than the total rainfall there in the previous ten years. At Tabuk 150 miles to the north, 0.49 inches of rain fell to set a daily October rainfall record at that location. (Accord Weather Calendar)
1-6 November 1570...The All Saints Day Floods killed an estimated 400,000 people in Western Europe. (The Weather Doctor)
1 November 1861...A hurricane near Cape Hatteras, NC battered a Union fleet of ships attacking Carolina ports, and produced high tides and high winds in New York State and New England. (David Ludlum)
2 November 1946...A heavy wet snow began to cover the Southern Rockies. Up to three feet of snow blanketed the mountains of New Mexico, and a three-day snowstorm began at Denver, CO. By the time it ended, this storm had dropped 31 inches, making it the second greatest snowfall ever in city history and causing roofs to collapse. (David Ludlum)
2-4 November 1927...The "Great Vermont Flood" occurred as a two-day rain event totaling up to 15 inches at the higher elevations. The deluge put rivers in western New England over their banks and caused the worst flooding in the history of Vermont. Somerset, VT received 8.77 inches of rain to establish a 24-hour record for the state. (3^rd-4^th) The Winooski Valley was devastated. Eighty-four died in the Vermont town of Vernon. Flooding left up to eight to ten feet of water in downtown Montpelier. Across New England the flooding claimed 200 lives, caused $40 million in damage and halted traffic for days. (The Weather Channel) (Intellicast) (David Ludlum)
4-5 November 1966...The River Arno surged above flood stage and caused irreparable damage to much of the architectural and art treasure of Florence, Italy. Millions of historical library volumes were either damaged or destroyed. More than 15,000 vehicles were also destroyed. Roughly two-thirds of Florence was flooded, 113 people died and 30,000 were made homeless by the flooding on both the Arno and Po rivers. (Accord Weather Calendar) (Wikipedia)