WEEK SEVEN: 14-18 March 2016

Items of Interest:

• An "EPIC" view of lunar shadow passing across Earth -- Data collected by NASA's NASA's Earth Polychromatic Imaging Camera (EPIC) onboard the agency's Deep Space Climate Observatory (DSCOVR) spacecraft was used to produce an animated sequence of 13 full disc images of Earth, including the Moon's shadow passing across the western Pacific Ocean during last week's solar eclipse. Since the DSCOVR spacecraft is located 1 million miles from Earth, it provides a constant view of the sunlit portion of the planet, resulting in Australia appearing to moving toward the east. A sequence of images showing the traveling shadow was also obtained from the Japanese Meteorological Agency's Himawari-8 satellite, which is in orbit at 22,240 mi altitude, provides a geosynchronous view of Earth as its continents appear stationary. [NASA Earth Observatory]
  A more detailed image of the Sun's shadow on clouds over the South Pacific was also produced by the MODIS sensor onboard NASA's polar orbiting Aqua satellite. [NASA]
• Tsunami Awareness in the Caribbean -- Puerto Rico and the US Virgin Islands will be observing Tsunami Preparedness Week this week (13-19 March) as part of the annual Caribbean and Adjacent Regions Tsunami Exercise called CARIBE WAVE on Thursday (17 March) that will involve 48 Member States and Territories of the UNESCO IOC Intergovernmental Coordination Group for the Tsunami and Other Coastal Hazards Warning System for the Caribbean and Adjacent Regions (CARIBE EWS).
• Notice the Equinox -- The vernal equinox, which marks the commencement of astronomical spring, will occur during the late night hours of next Saturday night or early Sunday morning depending upon location (officially at 0430Z on 20 March 2016, or 12:30 AM EDT on Sunday the 20th, or 11:30 PM CDT, etc. on the 19th). 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.
• Dive with NOAA's Okeanos Explorer crew in the Pacific -- The public is invited to join the scientists onboard the NOAA Ship Okeanos Explorer during this week as they explore the deep-water environments of the Papahānaumokuākea Marine National Monument in the Hawaiian Archipelago with unmanned remotely operated vehicles (ROV). These televised dives from the ROV can descend to depths of 3.7 miles below the ocean surface and can provide the public with views of the real-time exploration of deep sea corals, sponges. [NOAA News]
• Oceanographic expeditions that made an impact -- This week's Supplemental Information ... In Greater Depth provides a historical perspective of some of the oceanographic expeditions that made an impact upon science, especially in terms of oceanography.

Ocean in the News:

• Eye on the tropics --- As meteorological autumn continued across the Southern Hemisphere, no organized tropical cyclones were found across any of the globe's ocean basins last week.
• Updated El Niño/Southern Oscillation (ENSO) Diagnostic Discussion & El Niño advisory outlook released -- Late last week forecasters at NOAA's Climate Prediction Center (CPC) and the International Research Institute for Climate and Society (IRI) released their monthly El Niño/Southern Oscillation (ENSO) Diagnostic Discussion in which they still maintained their El Niño advisory as above-average sea surface temperatures (SST) persisted across most of the equatorial Pacific Ocean in February 2016, a sign of the continuation of the strong El Niño event (an anomalous large-scale atmospheric and oceanic circulation pattern characterized by warm waters in the eastern equatorial Pacific). However, SST anomalies have decreased in the eastern equatorial Pacific from values that ranged between two and three Celsius degrees above normal in December to values between one and two Celsius degrees by the start of March. The CPC forecasters envision this current strong El Niño event to gradually weaken and make a transition into ENSO-neutral conditions by late in the upcoming Northern Hemisphere spring (March through May) and early summer (June through August). The forecasters indicate that a nearly 50 percent chance for the development of La Niña conditions by Northern Hemisphere fall 2016. [NOAA Climate Prediction Center]
  A blog written by one of the scientists at NOAA's Climate Prediction Center discusses the current El Niño event, as well as describing the temperature and precipitation anomalies (differences from average) during the last three months (December 2015 through February 2016) that correspond to meteorological winter in the Northern Hemisphere, which is generally considered as the season most impacted by El Niño. The chance of the development of La Niña conditions by this upcoming boreal autumn is addressed. [NOAA Climate.gov News]
• El Niño Rapid Response Field Campaign comes to a close to study the Pacific's atmospheric river and to improve weather forecasts -- Researchers took airborne measurements of the atmospheric river using dropsondes deployed from NOAA's G-IV aircraft last Thursday as the plane traveled more than 3500 miles from the Hawaiian Islands to southern California. NASA's Global Hawk unmanned aircraft also captured additional atmospheric data just as the plume of humid subtropical air in the atmospheric river was making landfall along the California coast. These flights were on the last day of NOAA's six-week El Niño Rapid Response Field Campaign that was designed to study the current El Niño and gather data in an effort to improve weather forecasts thousands of miles away. [NOAA Office of Oceanic & Atmospheric Research News]
• Discovery of ghostly octopod highlights limited knowledge of deep-sea life -- A NOAA Fisheries zoologist was interviewed about last week's discovery of a ghostlike octopod at a depth of nearly 4300 meters below the sea surface by the unmanned submersible Deep Discoverer, operating from NOAA Ship Okeanos Explorer offshore of the Hawaiian Islands. He believes that this octopod may be a member of an unknown species. [NOAA Fisheries Feature Stories]
• Future of Alaskan crab fishery uncertain due to increasing ocean acidity -- In recently released studies, NOAA researchers and their colleagues warn that the Alaska crab fishery has an uncertain future unless the crabs can adapt to more acidic ocean waters that are the result of higher atmospheric carbon dioxide levels. More acidic ocean waters cause crabs to grow more slowly and to generate softer shells. However, the researchers noted some limited capacity for the crabs to adapt to some levels of acidification during their youth. [NOAA News]
• Influence of tides on Antarctic ice shelved being tracked -- Researchers from NASA's Goddard Space Flight Center and the Korea Polar Research Institute have installed five GPS units and two tilt meters at stations on the Nansen Ice Shelf that extends from the coast of Antarctica's Victoria land in order to study the influence that movements created by ocean tides would have upon the vertical and horizontal movements of the ice shelf. Using this knowledge, ice sheet modelers are attempting to create computer simulations of the Antarctic and Greenland ice sheets to project how the ice will flow in the future and how it will contribute to sea level rise. [NASA Goddard Space Flight Center]
• NASA drone to be used for studying Greenland glaciers -- An unmanned aircraft system (UAS) or drone named Viking-400 was recently delivered to the University of Kansas from NASA for student training and development of a radar system designed to analyze glaciers in Greenland associated with sea-level rise around the globe. The students also will generate 3-D models of the aircraft that NASA will use for engineering and analysis. [NASA Global Climate Change News]
• Streak of record low Arctic sea ice continues in February -- According to the National Snow and Ice Data Center, the Arctic sea ice extent in February 2016 as determined from satellite observations was only 5.5 million square miles, which marks the lowest February extent since satellite surveillance began in 1979. Typically the Arctic sea ice reaches its maximum extent for the year in mid to late March. [NASA Global Climate Change News]
• Jump in annual growth rate of atmospheric carbon dioxide during 2015 is detected -- According to the lead scientist at NOAA's Global Greenhouse Gas Reference Network, the annual growth rate of atmospheric carbon dioxide (CO₂) measured at NOAA's Mauna Loa Observatory in Hawaii jumped by 3.05 parts per million during 2015. This jump represents the largest year-to-year increase in this greenhouse gas in 56 years of that gas measurements have been made at Mauna Loa. Furthermore, 2015 was the fourth consecutive year that the concentration of CO₂ grew by more than 2 ppm. [NOAA News]
• GOES-West satellite turns six (years old) -- Last week marked the sixth anniversary of the launch of GOES-15, NOAA's Geostationary Operational Environmental Satellite that was placed in an orbit of 22,240 miles above the Equator. Since sensors onboard this satellite provide high resolution images across western North America, the eastern and central Pacific Oceans and the Hawaiian Islands, it is called GOES-West. The information obtained from this spacecraft is incorporated into weather monitoring and prediction models and climate studies. [NOAA NESDIS News]
• Annual report of the NOAA Climate Program Office for 2015 released -- Late last week NOAA's Climate Program Office (CPO) released its 44-page 2015 annual report that provides an overview of its activities and accomplishments made by this office in climate observation, research, modeling, and decision support activities for society. [NOAA Climate Program Office News]
• An All-Hazards Monitor -- This Web portal provides the user information from NOAA's National Weather Service, FAA and FEMA on current environmental events that may pose as hazards such as tropical weather, fire weather, marine weather, severe weather, drought and floods. [NOAA/NWS Daily Briefing]
• Earthweek -- Diary of the Planet [earthweek.com]

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 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)

Return to DataStreme Ocean's RealTime Ocean Portal

Prepared by DS Ocean Central Staff and Edward J. Hopkins, Ph.D.,
email hopkins@aos.wisc.edu
© Copyright, 2016, The American Meteorological Society.