DATASTREME OCEAN WEEK TWELVE: 26-30 April 2010

Ocean in the News:

• Eye on the tropics --
Late last week an area of low pressure initially identified as System 91S formed over the waters of the South Indian Ocean to the north-northwest of Port Hedland, Australia. This system organized and was then named Tropical Cyclone 24S and then finally Tropical Storm Sean as it traveled to the south-southwest. By late in the weekend, this tropical storm was showing signs of weakening to a tropical depression as it moved toward the southwest. For additional information and satellite imagery on Tropical Cyclone Sean, please consult the NASA Hurricane Page.
• Gulf Coast awareness tour commences --
NOAA hurricane experts will embark Monday on a five-day, five-city tour along the Gulf Coast in a "hurricane hunter" aircraft to raise public hurricane awareness. [NOAA News]
• The 2009 hurricane season reviewed --
The 2009 hurricane season in both the North Atlantic and North Pacific is reviewed and compared to the more than 150 years of record keeping in the North Atlantic and the 40 years in the eastern North Pacific. [AMS DataStreme Atmosphere]
• Responding to deepwater drilling disaster in Gulf --
Following last week's explosion, fire and oil spill on the deepwater drilling platform in the waters of the Gulf of Mexico approximately 50 miles off the Louisiana coast, several groups within NOAA responded to the incident. NOAA’s Office of Response and Restoration deployed a Scientific Support Team to help in the assessment of the situation. NOAA's National Weather Service was providing weather forecasting support, while NOAA's National Data Buoy Center was supplying information for oil trajectory forecasting. NOAA Fisheries was involved with issues involving fisheries and other marine life. [NOAA Office of Response and Restoration]
• Importance of recreational fishing is highlighted --
Two events sponsored in part by NOAA last week in the Washington, DC metropolitan area highlighted the importance of recreational fishing. A presidential memorandum was signed by President Obama at the America's Great Outdoors Conference that instructed federal agencies to promote outdoor recreation at the same time develop community-based models for conserving natural resources. This conference demonstrated the importance of recreational fishing as an integral part of the nation's outdoor legacy. The other conference was the 2010 Recreational Saltwater Fishing Summit, which was aimed at strengthening the relationship between NOAA and the recreational saltwater fishing community. [NOAA News]
• US makes statement on International Whaling Commission proposal --
Last week, the US Commerce Department Principal Deputy Under Secretary and US Commissioner to the International Whaling Commission (IWC) released a statement regarding the recent proposal made by the IWC Chair's proposal concerning the future of the IWC. [NOAA News]
• Contract for new fisheries survey vessel awarded --
NOAA officials recently announced that a $73.6 million contract was awarded to a marine construction company in northeastern Wisconsin to build a new high-tech fisheries survey vessel that will be used to conduct surveys of fish and other marine life in the waters of the eastern North Pacific. [NOAA News]
• Promotion of navigation safety sponsored --
NOAA’s Office of Coast Survey has become a co-sponsor with several organizations in the new Alliance for Safe Navigation that is designed to raise public awareness of safe boating procedures, including the use of up-to-date nautical charts. The Alliance also offers an instructional website. [NOAA News]
• Satellites show extent of Arctic Sea ice for last winter --
Two images made from data collected by the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) onboard NASA's Aqua satellite show the seasonal expansion of sea ice covering the Arctic Ocean during the recently concluded 2009-10 winter season in the Northern Hemisphere. One of the images was made in September 2009 when the seasonal ice cover was at a minimum, while the other image was in March 2010 near the winter maximum. Researchers at the National Snow and Ice Data Center claim that while the areal extent of the ice at winter maximum was greater than the March 2006 record low extent, the peak in this winter's sea ice was still smaller than the long-term (1979-2000) mean. [NASA Earth Observatory]
• Sea Ice for Walrus Outlook --
The Sea Ice for Walrus Outlook (SIWO) is a weekly feature updated every Friday through late June that provides information on sea ice conditions relevant to walrus along northern Alaska's Northern Bering Sea and southern Chukchi Sea coasts. These outlooks, prepared by the Study of Environmental Arctic Change (SEARCH) as part of the SEARCH Sea Ice Outlook, is designed to be a resource for Alaska Native subsistence hunters, coastal communities, and others interested in sea ice and walrus. [SEARCH]
• Level of Lake Huron could drop this summer --
A meteorologist with the US Army Corps of Engineers warns that the lack of snow during this past winter around the northern Great Lakes could signal a lower than normal level in the water level of Lake Huron during the upcoming summer. The lower water levels could also spell trouble for marinas along the lake. [Port Huron Times Herald]
• Ocean acidification due to carbon emissions progresses at rapid pace--
In a report requested by the US Congress, the National Research Council warns that changes in ocean chemistry due to increased emissions of atmospheric carbon dioxide had resulted in ocean acidification, which has become a growing global problem, ultimately affecting the ecosystem. The report also indicates that the National Ocean Acidification Program, which is being developed by the federal government, has been charged with coordinating efforts to understand and respond to the problem; six key elements were deemed necessary for this program to be a success. [National Academies]
• Marine microbes are a key to planet's food and carbon systems --
Four of 14 field projects of the decade-long Census of Marine Life are focused on the inventory and study of a variety of species of tiny life forms in the oceans, including microbes, zooplankton, larvae and burrowers in the sea bed. The researchers are finding that these tiny organisms, which are large in abundance and diversity, play an extremely important role in the Earth's food chain and the carbon cycle. [EurekAlert!]
• New book on climate change authored by a NASA climate scientist --
A new book designed to answer questions concerning climate change was published last week. The book, with the title " Coming Climate Crisis? Consider the Past, Beware the Big Fix," was written by Claire L. Parkinson, a well-known climate scientist at NASA's Goddard Space Flight Center. [NASA Earth Observatory]
• 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: Climate Feedback Processes

Earth's climate system includes many interacting variables. Some variables are external to the Earth-atmosphere system and some are internal. External variables include solar energy output and Earth-sun geometry (i.e., the Milankovitch cycles). Internal variables include properties of the Earth's surface (e.g., albedo, moisture), the concentration of key atmospheric components (e.g., greenhouse gases, sulfurous aerosols), and cloud cover and thickness.

An important consideration in understanding how Earth's climate system responds to some perturbation is feedback. Feedback is defined as a sequence of interactions among variables in a system that determines how the system responds to some initial perturbation in one or more of the variables. Variables in Earth's climate system may interact in such a way as to either amplify (positive feedback) or lessen (negative feedback) a change in climate. An example of positive feedback is the ice-albedo effect described in Chapter 12 of the DataStreme Ocean textbook. Less ice cover in the Arctic greatly reduces the albedo of the Arctic Ocean causing higher sea surface temperatures and accelerated melting of the multiyear pack ice.

Consider an example of negative feedback. Increasing concentrations of atmospheric carbon dioxide enhances the greenhouse effect causing global warming. Global warming in turn raises sea surface temperatures and increases the rate of evaporation. A more humid atmosphere means more persistent and thicker cloud cover but clouds have both a cooling and warming effect on the lower atmosphere. The relatively high albedo of cloud tops causes cooling whereas absorption and emission of infrared radiation by clouds causes warming by contributing to the greenhouse effect. Satellite measurements and numerical models indicate that cooling would dominate.

In general, negative feedback tends to dominate over positive feedback in Earth's climate system, limiting the magnitude of climate change. The great thermal inertia of the ocean is the principal reason for dampening the planetary temperature response.

Concept of the Week: Questions

1. Feedback in Earth's climate system that amplifies climate change is described as [(positive)(negative)] feedback.
2. In general, [(negative)(positive)] feedback tends to prevail in Earth's climate system.

Historical Events:

• 27 April 1521...The Portuguese navigator Ferdinand Magellan was killed by natives during a tribal skirmish on Mactan Island in the Philippines after completing nearly three-quarters of a trip around the world. One of his ships, the Victoria, under the command of the Basque navigator Juan Sebastiżn de Elcano, continued west to arrive at Seville, Spain on 9 September 1522, the first ship to circumnavigate the globe. (The History Channel)
• 28 April 1947...Norwegian anthropologist Thor Heyerdahl and five others set out in a balsa wood craft known as Kon Tiki to prove that Peruvian Indians could have settled in Polynesia. The trip took 101 days.
• 29 April 1770...The British explorer, Captain James Cook, arrived at and named Botany Bay, Australia. (Wikipedia)
• 30 April 1492...Spain gave Christopher Columbus his commission of exploration. (Wikipedia)
• 30 April 1894...An Antarctic iceberg fragment was sighted at a latitude comparable to Rio de Janeiro. Reported by the ship Dochra, this sighting remains the nearest to the equator that an iceberg has been seen. (Today in Science History)
• 30 April 1991...Southeast Bangladesh was devastated by a tropical cyclone with sustained winds of approximately 150 mph during the early morning. A 20-foot storm surge inundated offshore islands south of Chittagong, taking water from the Bay of Bengal inland for miles. This cyclone resulted in up to 200,000 deaths and $1.4 billion damage. (Accord Weather Guide Calendar)
• 1 May 1683...A patent was awarded in England for the extraction of salt from seawater. (Today in Science History)
• 1 May 1883...At Cape Lookout, NC, a storm tide swept over the island drowning sheep and cattle. (Intellicast)
• 1 May 1921...The first radio fog signals in the United States were placed in commission on Ambrose Lightship, Fire Island Lightship, and Sea Girt Light Station, NJ. These signals installed by the US Lighthouse Service were meant to guide ships approaching New York Harbor. (USCG Historian's Office)
• 1 May 1936...The Whaling Treaty Act outlawed the taking of right whales or calves of any whale. This law was enforced by the Coast Guard. (USCG Historian's Office)
• 2 May 1775...Benjamin Franklin completed the first scientific study of the Gulf Stream. His observations began in 1769 when as deputy postmaster of the British Colonies he found ships took two weeks longer to bring mail from England than was required in the opposite direction. Thus, Franklin became the first to chart the Gulf Stream. (Today in Science History)
• 2 May 1880...The first U.S. steamboat to successfully employ electric lights was the Columbia, a 309-ft long vessel which operated between San Francisco, CA and Portland, OR. An "A" type dynamo was placed in operation to illuminate the passenger rooms and main salons. (Today in Science History)
• 2 May 1932...After a Convention with Canada, the Northern Pacific Halibut Act re-enacted the Act of 7 June 1924 and made it unlawful to catch halibut between 1 November and 15 February of each year in territorial waters of United States and Canada, as well as on the high seas, extending westerly from there, including the Bering Sea. The Coast Guard enforced this act. (USCG Historian's Office)
• 2-3 May 1998...Ocean swells from storms in the South Pacific caused surf heights of 7 to 9 feet, with sets to 12 feet along the southern California coast. A man fishing on rocks at Rancho Palos Verdes, CA was swept away. (Accord 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, 2010, The American Meteorological Society.