Weekly Ocean News

DATASTREME OCEAN WEEK FOUR: 12-16 February 2007

Ocean in the News

(Thurs.) Sea lions and satellites help improve ocean models -- Marine scientists at the University of California, Santa Cruz and NASA's Jet Propulsion Laboratory have been using data collected by two unlikely sources -- the movement of sea lions and other marine animals along with data collected by sensors onboard satellites -- to improve their 3-dimensional ocean models. [NASA Earth Observatory]
(Thurs.) Tracking near surface winds in a tropical cyclone -- An image of near surface winds generated over one week ago by the SeaWinds Scatterometer on NASA’s QuikSCAT satellite shows the circulation around Tropical Cyclone Dora in the Southern Indian Ocean east of Madagascar. This tropical cyclone, a low-pressure system that formed over tropical waters ( the Indian Ocean's counterpart of a hurricane), reached a category 4 on the Saffir-Simpson Intensity Scale. [NASA Earth Observatory] [Editor's note: Observe that the winds circulate in a clockwise fashion in toward the center of this Southern Hemisphere cyclone, the reverse of the counterclockwise low-level inflow into a Northern Hemisphere low-pressure system. EJH]
(Thurs.) Examining global change effects in Antarctica -- Researchers from the University of Texas at San Antonio recently completed a two-week trip to Antarctica onboard the Swedish icebreaker Oden as part of an international expedition to investigate the effects that the upward global temperature trend have had upon the size of the ice sheets that cover the ocean surrounding that continent. During their trip they made observations of sea ice, along with routine meteorological and oceanic observations. [EurekAlert!]
(Thurs.) Lights, now camera, ACTION -- Researchers have filmed the large deep-sea squid as it feeds at up to 900 m depth for the first time. The squid emits bright flashes of light to disorient prey during the attack. [BBC News]
(Tues.) Slight decline in seafood consumption noted -- The NOAA Fisheries Service released the statistics in the 2005 edition of its annual publication, "Fisheries of the United States," which indicate that a slight decrease in the national annual consumption of seafood was noted during 2005, countering an increasing trend in overall seafood consumption during the prior five years. [NOAA News]
(Tues.) Giant sea turtles die along Indian Ocean beaches -- The bodies of nearly 1000 giant sea turtles recently washed ashore along the coasts of India and Bangladesh. Experts blame fishing nets that were poorly laid for trapping and drowning the turtles. [National Geographic News]
(Tues.) East Coast communities ready for Atlantic tsunami -- As many as nine communities along the East Coast from Florida north to Virginia have become certified by the National Weather Service as ready to respond to a possible tsunami that could travel across the western North Atlantic. A tsunami-detection monitor currently is deployed approximately 320 miles offshore of Charleston, SC. Seven tsunamis have been recorded along the Atlantic and Gulf Coasts in the last 121 years. [USA Today]
(Tues.) Warning is made of accelerated extinction risk to marine species -- In a recent study, scientists from the US and Canada warned that the combined effects of habitat fragmentation, overexploitation, and increases in global temperature could accelerate the decline in numerous marine as well as terrestrial species, resulting in an increased risk of their ultimate extinction. [EurekAlert!]
Two hundred years of federal science and service are on display -- The NOAA Administrator and Undersecretary of Commerce for Oceans and Atmosphere recently unveiled an exhibit entitled "Treasures of NOAA’s Ark: Journey Through Time" that display the science, stewardship and service that NOAA and its predecessor agencies have engaged in for the last 200 years. [NOAA News]
Next year's NOAA budget request announced -- The NOAA Administrator and Undersecretary of Commerce for Oceans and Atmosphere announced the NOAA request of $3.8 billion for its 2008 budget, with emphasis placed on several items, including support for the U.S. Ocean Action Plan, advancement of ocean science and research, improvement of weather warnings and forecasts and climate monitoring and research. [NOAA News]
Last year was warm -- Climatologists at NASA's Goddard Institute for Space Studies (GISS) recently reported that their analysis of the annual average temperatures from around the world, including surface and satellite observations, leads them to conclude that 2006 was the fifth warmest year during the instrumental period extending back to 1880. [NASA Earth Observatory] Graphs of the temperature trends over the last century and maps of the surface temperature anomalies (arithmetic differences in observed and average temperatures) have been generated by GISS. [NASA GSFC] [Editor's note: Earlier, NOAA scientists at the National Climatic Data Center (NCDC) reported that 2006 was also the fifth warmest since 1880. Additional graphics of temperature, snow cover and ice extent also appear in this preliminary NCDC report. EJH ]
Effects of arctic air on the Sea of Okhotsk seen from space -- An image made one week ago by the MODIS sensor on NASA's Terra satellite shows the effect of the flow of arctic air from interior Siberia out over Russia's Sea of Okhotsk, with long streamer-like cloud streets over the open water, as well as the large ice floats that cover much of this sea, frozen because of the extended presence of cold air during the winter. [NASA Earth Observatory]
Methane from seafloor sediments help form undersea hills -- Geologists from the Monterrey Bay Aquarium Research Institute and colleagues at other laboratories have found that methane gas seeping through seafloor from deep hydrate sediment deposits have created several hundred low hills with heights of up to 130 feet on the Arctic Ocean floor. [Monterrey Bay Aquarium Research Institute]
Rumblings from deep-sea "black smokers" are studied -- Scientists have been attempting to listen to the low rumbling sounds made by deep-sea vents known as "black smokers" in order to see how these vent flows respond to tides, earthquakes and volcanic eruptions. [National Geographic News]
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]
Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

Concept of the Week: Variations in Marine Sediment Thickness

Sediments are particles of organic or inorganic origin that accumulate in loose form in depositional environments such as lake or ocean bottoms. Marine sediments, the central focus of this week's investigations, have a variety of sources and exhibit a wide range of composition, size, and shape. Marine sediments settle to the ocean floor as unconsolidated accumulations but ultimately may be converted to solid sedimentary rock via compaction and cementation. The pattern of variations in marine sediment thickness on the ocean floor confirms some basic understandings regarding marine geological processes.

Go to the DataStreme Ocean Website and under "Geological," click on "Sediment Thickness." This map of marine sediment thickness in the ocean basins was compiled by the National Geophysical Data Center (NGDC), Marine Geology and Geophysics Division primarily based on existing maps, ocean drilling, and seismic reflection profiles. Sediment thickness is color-coded in meters from violet (thinnest) to red (thickest). Many factors account for the variation in the thickness of marine sediment deposits including type and location of sediment sources, sediment transport mechanisms, and the age of the underlying crust.

According to the map, sediment thickness generally increases with distance from near the central portion of an ocean basin to the continental margin. This pattern may be explained by the principal sediment source and/or the age of the underlying crust. Rivers and streams that empty into the ocean slow and diverge, releasing the bulk of their suspended sediment load in coastal environments (e.g., bays, estuaries, deltas) and onto the continental shelf. Ocean currents transport sediment along the coast. In some areas of the continental shelf, massive amounts of sediment accumulate, become unstable, and flow down the continental slope to the base of the continental rise and beyond. However, only the finer fraction of river-borne sediment is swept into the deep ocean waters. Thickening of marine sediments in the direction of the continental margin may also reflect the aging of oceanic crust with distance away from diverging (spreading) plate boundaries where new oceanic crust forms. The older the crust the longer is the period that sediment rains down on the ocean bottom and the thicker is the blanket of accumulated sediment.

The map indicates that the thickness of marine sediment deposits is greater in the continental margin along the Atlantic coast of North America than along the Pacific coast. The Atlantic coast of North America is a passive margin; that is, the continental margin is not affected significantly by tectonic processes (no plate boundary) and the principal geological processes consist of sedimentation along with erosion by ocean waves and currents. In fact, passive margins and relatively thick marine sediment deposits occur on both sides of the Atlantic. (Passive margins also occur around the Arctic Ocean and surrounding Antarctica.) On the other hand, the Pacific coast of North America is an active margin; that is, the continental margin is associated with plate boundaries and is subject to deformation by tectonic stresses. Active continental margins are relatively narrow so that sediment delivered to the coast by rivers and streams flows directly into deeper water or trenches--preventing thick accumulations of marine sediments from building in the continental margin.

Concept of the Week: Questions

The thickness of marine sediment deposits is greater in the [(continental margins)(deep-ocean basins)].
The thickness of marine sediment deposits generally is greater in [(active)(passive)] continental margins.

Historical Events

12 February 1907...A collision of the steamer Larchmont and large schooner, the Harris Knowlton, during a blizzard resulted in the deaths of 332 people. Only nine survivors were rescued. The incident occurred off Rhode Island's Block Island and was the worst disaster in New England maritime history. (RMS Titanic History)
12 February 1997...A combination of heavy surf and high winds contributed to the overturning of a U.S. Coast Guard motor life boat (MLB 44363) on a search and rescue mission when responding to a distress call from the sailing vessel Gale Runner in the stormy North Pacific Ocean off Washington State's Quillayute River Bar. Three of four crewmembers lost their lives in the first fatal sinking of this type of ship in its 35-year history. (Accord's Weather Guide Calendar) (USCG Historian's Office)
13 February 1784...Ice floes blocked the Mississippi River at New Orleans, then passed into the Gulf of Mexico. The only other time this occurred was during the "Great Arctic Outbreak" of 1899. (David Ludlum)
13 February 1969...The National Transportation Safety Board issued its "Study of Recreational Boat Accidents, Boating Safety Programs, and Preventive Recommendations". (USCG Historian's Office)
13 February 1997...Ocean swells generated by a storm well to the northwest of the Hawaiian Islands generated surf with heights to 20 feet and some sets to 25 feet along the northern shores of the islands. A professional surfer was killed by 25-foot surf at Alligator Rock on Oahu's North Shore. Lifeguards aided more than thirty people. (Accord's Weather Guide Calendar)
14 February 1779...The famous British scientific navigator, Captain James Cook, Royal Navy, was killed by natives of the Sandwich Islands on the Kona coast of what is now the state of Hawaii's Big Island. His geographic discoveries and three scientific expeditions of the Pacific made him the most famous navigator since Magellan. (Wikipedia) (Today in Science History)
14 February 1840...Officers from the USS Vincennes made the first landing in Antarctica on floating ice. (Naval Historical Center)
14 February 1903...An Act of Congress (31 Stat. L., 826, 827) that created the Department of Commerce and Labor provided for the transfer of the Lighthouse Service from the Treasury Department. This allowed the Secretary of Commerce and Labor to succeed to the authority vested in the Secretary of the Treasury under the existing legislation. (USCG Historian's Office)
14 February 1912...The first diesel-powered submarine was commissioned in Groton, CT. (Wikipedia)
14 February 1954...A waterspout was observed two miles east of Baranof, AK, an unusual occurrence for Alaska, particularly in winter. Just prior to the formation of the waterspout, a "terrific wind from the south out of a bay inside Warm Springs Bay" lifted water 20 feet and looked "as if it were boiling". (Accord's Weather Guide Calendar)
15 February 1912...Fram reached latitude 78º 41' S, farthest south ever by ship. Therefore, the "Fram" became the first ship to have sailed the farthest north and the farthest south.
15 February 1954...An ocean exploration depth record of 13,287 feet (over 2,000 fathoms, or over 2-1/2 miles) was attained when Georges Houot and Pierre Willm reached the Atlantic Ocean floor off Dakar, Senegal. (Today in Science History)
15 February 1982...An intense cyclone (low pressure system) off the Atlantic coast of Newfoundland capsized the Ocean Ranger, a drilling rig, killing 84 persons, and sank a Soviet freighter resulting in 33 more deaths. The cyclone produced 80-mph winds that whipped the water into waves fifty feet high. (David Ludlum)
15 February 1998...A "rogue" wave from the Pacific Ocean swept into the harbor at Port Arena, CA. This wave continued through a harbor parking lot, depositing sand, debris and logs, as well as moving thirty parked vehicles. No injuries were sustained. (Accord's Weather Guide Calendar)
16 February 1832...The HMS Beagle with Charles Darwin onboard reached St-Pauls (1ºN, 29ºW).
16 February 1993...The Haitian passenger ferry Neptune sank, sending 1,215 Haitians to their deaths. Coast Guard units participated in the search and rescue operation but found no survivors. They then assisted in recovering the bodies of the victims. (USCG Historian's Office)
17 February 1836...The HMS Beagle and Charles Darwin left Tasmania.
17 February 1867...The first ship passed through the Suez Canal. (Wikipedia)
18 February 1828...More than 100 vessels were destroyed in a storm at Gibraltar.
18 February 1846...A General order was issued by the Secretary of the US Department of Navy "on Port and Starboard," in which the term "port" replaced "larboard." (Naval Historical Center)