Weekly Ocean News

WEEKLY OCEAN NEWS

Break Week One: 13-17 October 2008

This is the first Break Week for the Fall 2008 offering of the DataStreme Ocean course. This Weekly Ocean News will contain new information items and historical data, but the Concept of the Week is repeated from Week 6.

Ocean in the News

Eye on the tropics -- Several tropical cyclones formed last week over the North Atlantic and Pacific basins:

In the Gulf of Campeche, Tropical Storm Marco formed off the eastern Mexican coast early last week, but was shorted lived as it made landfall and dissipated within two days. See the NASA Hurricane Page for additional details, including satellite imagery.
At the start of this current week, Tropical Storm Nana, the fourteenth named tropical cyclone of the 2008 North Atlantic hurricane season, formed over the central tropical waters west of the Cape Verde Islands.
In the east North Pacific, Tropical Storm Marie, previously a category 1 hurricane (on the Saffir-Simpson Scale), weakened and dissipated well to the west of the Mexican coast at the start of last week. The NASA Hurricane Page has additional information on Tropical Storm Marie, along with satellite images.
Another tropical cyclone, Norbert, formed off the Mexican coast early last week and intensified to become the seventh hurricane of the 2008 hurricane season in the eastern North Pacific. It intensified to become a major category 4 hurricane by midweek as it traveled to the northwest. After curving toward the northeast and weakening, Hurricane Norbert made an initial landfall along Mexico's Baja California Peninsula at the start of the weekend, followed by a second landfall along the coast of mainland Mexico. Attention is directed to the NASA Hurricane Page for additional discussion of former Hurricane Norbert.
Tropical Storm Odie formed late last week off the Central American coast and traveled to the northwest along the Mexican coast before weakening and dissipating at the end of this past weekend. See the NASA Hurricane Page for images and additional information concerning Odie.

Regulation issued to protect North Atlantic right whales -- Last week, NOAA officials issued a regulation requiring large ships to reduce speed in areas frequented by endangered North Atlantic right whales to reduce the risk of ship collisions with the whales, thereby helping protect these whales. [NOAA News]

Coral monitoring network goes global -- NOAA recently expanded its Coral Reef Watch bleaching monitoring network of 24 stations to 190 "virtual stations" located worldwide, aided in part by the GEF-World Bank Coral Reef Targeted Research Program. These stations are designed to warn coral reef managers when an elevated risk of coral bleaching is imminent, based on sea surface temperature data obtained from NOAA’s environmental satellites. [NOAA News]

Public comment invited on Columbia River fisheries -- NOAA’s Fisheries Service is seeking public comment on a proposed recovery plan for the threatened steelhead salmon in the middle Columbia River between Washington State and Oregon. [NOAA News]

Education grants announced -- Last week, the US Department of Commerce Secretary announced that NOAA Bay Watershed Education and Training (B-WET) grants had been awarded to five recipients in the Pacific Northwest [NOAA News], five groups in New England [NOAA News] and five along the Gulf of Mexico coast [NOAA News]. These grants are designed to enhance local hands-on K-12 level environmental education.

Assessing role of climate change on future hurricane risks -- Researchers at the National Center for Atmospheric Research (NCAR) have been collaborating with colleagues in federal agencies as well as the insurance and energy industries in investigating how increases in global temperatures could influence hurricanes in the next several decades. Armed with global climate and regional weather models, the project's goal is to provide information to coastal communities along with others who have interests in the Gulf of Mexico and Caribbean Sea. [NSF News]

High tech imaging equipment to aid in response to natural disasters -- A low-cost, high resolution imaging system has been developed at the Georgia Tech Research Institute for use in assessing the need for health and humanitarian services following natural disasters, such as hurricanes. This system can be attached to low-flying helicopters. [EurekAlert!]

Arctic storm activity affects sea ice and climate -- Researchers at NASA's Goddard Space Flight Center, Woods Hole Oceanographic Institution and the Arctic and Antarctic Research Institute in St. Petersburg, Russia have shown that the increased frequency and intensity of arctic storms during the last half century appears to contributed to warmer sea water that has accelerated the rate of arctic sea ice drift, an indicator of climate change. [NASA GSFC]

A southeastern Pacific climate study commences -- An international team of scientists from eight nations, including those from the US Department of Energy's Brookhaven National Laboratory are about to commence upon an international field experiment called the "Variability of the American Monsoon Systems’ (VAMOS) Ocean-Cloud-Atmosphere-Land Study Regional Experiment." This experiment is over the southeastern Pacific along the Chilean coast designed to make observations of the components of the region's climate system. [Brookhaven National Laboratory]

Celebrate Earth Science Week -- The National Oceanic and Atmospheric Administration, to include the National Weather Service, along with NASA, the US Geological Survey and several professional scientific organizations such as the American Geological Institute have recognized this week (12-18 October 2008) as Earth Science Week to help the public gain a better understanding and appreciation for the earth sciences and to encourage stewardship of the Earth. This year's theme for the 11th annual Earth Science Week is "No Child Left Inside", designed to encourage young people to learn about the geosciences, by going outdoors, leaving behind the indoor activities involving the television or computer. [American Geological Institute]

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, 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, including drought, floods, and storms during the current month. [NCDC]

Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

This Concept of the Week is repeated from Week 6.

Concept of the Week: Abyssal Storms

Until recently, ocean scientists thought of the deep ocean abyss as a dark and cold, but serene place where small particles rained gently onto the ocean floor. However, instruments lowered to the sea floor to measure ocean motion or currents and resulting mobilization of bottom sediments detected a much more active environment. Scientists found that bottom currents and abyssal storms occasionally scour the ocean bottom, generating moving clouds of suspended sediment. A surface current of 5 knots (250 cm/sec) is considered relatively strong. A bottom current of 1 knot ( 50 cm/sec) is ripping. Although this may be called an abyssal storm, the water motion pales by comparison to wind speeds in atmospheric storms.

Abyssal currents and storms apparently derive their energy from surface ocean currents. Wind-driven surface ocean currents flow about the margins of the ocean basins as gyres centered near 30 degrees latitude. (Refer to Figure 6.6, page 152, in your textbook.) Viewed from above, these subtropical gyres rotate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. For reasons given in Chapter 6 of your textbook and this week's Supplemental Information, surface currents flow faster, are narrower, and extend to greater depths on the western arm of the gyres. These are known as western boundary currents and include, for example, the Gulf Stream of the North Atlantic basin. Abyssal currents are also most vigorous on the western side of the ocean basins, moving along the base of the continental rise, which is on the order of several kilometers deep.

Abyssal storms may be linked to or may actually be eddies (rings) that occasionally break off from the main current of the Gulf Stream (and other western boundary currents). During an abyssal storm, the eddy or ring may actually reach to the bottom of the ocean where the velocity of a bottom current increases ten-fold to about 1.5 km (1 mi) per hr. While that is an unimpressive wind speed, water is much denser than air so that its erosive and sediment-transport capacity is significant even at 1.5 km per hr. At this higher speed, the suspended sediment load in the bottom current increases by a factor of ten. Abyssal storms scour the sea floor leaving behind long furrows in the sediment. After a few days to a few weeks, the current weakens or the eddy (ring) is reabsorbed into the main surface circulation and the suspended load settles to the ocean floor. In this way, abyssal storms can transport tons of sediment long distances, disrupting the orderly sequence of layers of deep-sea sediments. Scientists must take this disruption into account when interpreting the environmental significance of deep-sea sediment cores.

Concept of the Week: Questions

In the subtropical ocean gyres, boundary currents flow faster on the [(western)(eastern)] side of an ocean basin.
Currents in an abyssal storm erode, transport, and redeposit sediments that have accumulated on the [(continental shelf)(deep ocean bottom)].

Historical Events

13 October 1775...Birthday of U.S. Navy. The Continental Congress established the Continental Navy, later the U.S. Navy. (Naval Historical Center)
13 October 1884...The longitude that passes through the principal Transit Instrument at the Observatory in Greenwich, England was selected as the single universal meridian at the International Meridian Conference held in Washington, DC. A universal day was also selected. (Today in Science History)
15 October 1947...A hurricane made a hairpin turn off the Georgia coast after being seeded with dry ice. The storm passed over Savannah and tracked inland through Georgia. (Intellicast)
15 October 1954...Hurricane Hazel struck the Carolina coastline near Cape Fear, NC. The hurricane (category 4 on the Saffir-Simpson Scale) demolished every pier along a 170-mile stretch from Myrtle Beach, SC to Cedar Island, NC, and obliterated rows of beach homes. At Long Beach, 300 homes vanished; no debris remained. Hurricane Hazel also destroyed 1500 homes as it made landfall with 17-ft tides. Winds between Myrtle Beach, SC and Cape Fear, NC gusted to 150 mph. Later, the remnants of Hazel moved northward into Ontario and became the most remembered storm in Canadian history. Winds gusted to 75 mph and as much as 7.2 inches of rain fell. Eighty people died, mostly from flooding in the Toronto area (David Ludlum) (The Weather Channel) (The Weather Doctor)
15 October 1999...A waterspout (a tornado over water) moved onshore at Fort Lauderdale Beach, FL and blew out a plate glass window in a bar, injuring 8 patrons. The waterspout also overturned a vehicle and caused other significant damage on Los Olas Blvd. (Accord Weather Calendar)
16 October 1877...Bjørn Helland-Hansen, the Norwegian pioneer of modern oceanography, was born on this date. His studies of the physical structure and dynamics of the ocean were instrumental in transforming oceanography from a descriptive science to one based on the principles of physics and chemistry. (Today in Science History)
17-20 October 2004…Humid air from a former typhoon east of Japan helped deepen low pressure to 941 mb over the Gulf of Anadry west of Nome, AK (18th). Winds between 50 and 80 mph, with an unofficial gust to 114 mph at Red Dog Mine on the 19th, raked western Alaska. Storm surges reached approximately 11 feet. As much as $19.9 million in damage resulted from this storm. (Accord Weather Guide Calendar)
18 October 1910...Northeasterly winds as high as 70 mph (from a hurricane moving northward up the Florida peninsula) carried water out of Tampa Bay and the Hillsboro River. The water level lowered to nine feet below mean low water. Forty ships were grounded. (The Weather Channel)
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)