DATASTREME OCEAN WEEK EIGHT: 19-23 March 2012

Items of Interest:

• Notice the Equinox -- The vernal equinox, which marks the commencement of astronomical spring, will occur early Tuesday morning (officially at 0514Z on 20 March 2012 or 1:14 AM EDT, 12:14 PM CDT, etc.). 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.
• International observances -- Several days during this upcoming week have been designated as special days that are intended to focus public attention on the environment and earth science:
• "Earth-Sun Day"-- Since this coming Tuesday (20 March 2012) is the vernal equinox, Monday has been declared Earth-Sun Day, which includes a series of programs and events that occur throughout the year culminating with a celebration on the Spring Equinox. This year's theme is "Shadows of the Sun!" , designed to explore the nature of eclipses and transits throughout our solar system during 2012, a special year for several noteworthy astronomical events. NOTE: A special "Transit of Venus Celebration" will be observed on 5 June 2012.
• "World Water Day" -- Thursday, 22 March 2012, has been designated by the United Nations (UN) as the annual World Water Day, with this year's theme identified as "Water and Food Security: The World is Thirsty Because We are Hungry," which aims to raise awareness on the amount of water needed to produce food. [UN-Water]
  
• "World Meteorology Day" -- Thursday, 23 March 2012 is World Meteorology Day. This day is designated to celebrate the anniversary of the establishment of the World Meteorological Organization (WMO) on 23 March 1950. The WMO is an agency within the United Nations. The theme of this year's World Meteorological Day for 2012 is "Powering our future with weather, climate and water,"
  which focuses on the critical roles that weather, climate and water services would have in powering a sustainable future for current and future generations.

Ocean in the News:

• Eye on the Tropics -- In the last week, two weather systems were found over tropical waters of the South Indian Ocean. At the beginning of the week, Cyclone Koji, which had intensified to a category 1 cyclone on the Saffir-Simpson Scale over the previous weekend, traveled southward across the Indian Ocean before dissipating approximately 1500 miles to the south-southeast of Diego Garcia. The NASA Hurricane Page has satellite images and additional information on Cyclone Koji.
  Another tropical cyclone, identified as Cyclone Lua, formed early last week slightly more than 100 miles off the coast of Australia's Northern Territory. Initially this cyclone traveled to the northwest before curving to the east ant then to the southeast, becoming a category 2 tropical cyclone late in the week before it made landfall along the northwestern coast of Australia. Wind gusted to over 100 mph and sea waves reached over 30 feet as Lua approached the coast near Port Hedland. This system, which weakened to a tropical storm after making landfall on Saturday, produced locally heavy rainfall. Consult the NASA Hurricane Page for additional information and satellite images on Cyclone Lua.
• States are authorized to remove threatening sea lions -- During the last week officials with NOAA's Fisheries Service gave authorization to Idaho, Oregon and Washington to permanently remove up to 92 California sea lions who have been found to eat imperiled salmon and steelhead that congregate in the Columbia River below the Bonneville Dam during the time when the fish head upstream to spawn. [NOAA News]
• Ship tracks across Pacific seen from space -- A recent natural color image obtained from data collected by the MODIS sensor onboard NASA's Aqua satellite shows "ship tracks" across the eastern North Pacific off the California coast. These ship tracks, some of which may extend from hundreds of miles, are narrow clouds that form in the low atmosphere behind the moving ships from the water-soluble pollution particles in the exhaust generated by the ship engines. These particles could linger and affect the local radiation budget over the ocean surface, especially in sections of the eastern Pacific where ship traffic is heavy. Health risks due to the exhaust particles can also pose a problem. [NASA Earth Observatory]
• Another IceBridge scientific mission commences in the Arctic -- Early last week, researchers along with a flight crew began NASA's IceBridge 2012 Arctic Campaign, an airborne mission designed to collect data and study changes in polar ice across the Arctic basin. This field campaign, which will include a modified aircraft from NASA's Wallops Island Flight Facility, will conduct daily airborne missions from Greenland in order to measure sea and land ice. The annual IceBridge campaigns began as a means for continuing the multi-year records of ice elevation measurements after NASA's Ice, Cloud and Land Elevation Satellite's (ICESat) stopped collecting data in 2009. [NASA IceBridge 2012 Mission]
• GRACE turns 10 and shows "gravity is climate"-- NASA's twin Gravity Recovery and Climate Experiment (GRACE) spacecraft have been orbiting the Earth for 10 years, making detailed measurements of Earth's gravitational field. These measurements capture minute changes in gravity that are associated with local changes in the mass of the Earth, which are usually caused by redistribution of ice, air, water and solid Earth due to weather patterns, seasonal change, climatic change and tectonic events. For example, oceanographers and climate scientists have been using the data to study the ice melting rate on Greenland. [NASA JPL]
• Long-term record of carbon dioxide accumulations in world oceans assembled -- An international team of more than 100 scientists from the United States, the United Kingdom, Norway and France have recently assembled the Surface Ocean CO2 Atlas (SOCAT), a comprehensive data set that contains in excess of six million surface water carbon dioxide measurements that have made in the global oceans and coastal seas. These measurements have been made since 1968 from research vessels, commercial ships and moorings. [University of East Anglia]
• Diverse catches appear to be better for fishery ecosystems -- In a study conducted by conservation and fisheries scientists from Australia, Norway, Canada and France, a moderate level of fishing for a "balanced harvest" involving a diverse range of species, stocks and sizes appears to be capable of achieving productive fisheries with high catch levels along with environmental conservation and maintenance of biodiversity. [CSIRO Media Releases]
• Protected coral reefs are harmed by rising ocean temperatures -- A study conducted by scientists from Conservation International, the University of North Carolina at Chapel Hill and NOAA indicates that despite special conservation efforts offered by marine protected areas, coral reefs in these regions still are being harmed by warming ocean waters due to global climate change. The researchers warn that in order to protect these coral reefs from climate change, the marine protected areas need to be complemented with policies that would reduce greenhouse gas emissions in a meaningful way. [University of North Carolina News]
• Ancient sea-level rise estimate has been lowered by new evidence -- Climate scientists at Columbia University's Lamont-Doherty Earth Observatory and their colleagues at other research institutions report that their analysis of ancient shorelines on cliffs and reefs on Bermuda and the Bahamas during an extremely warm interval approximately 400,000 years ago the sea rose between 20 to 43 feet higher than current sea levels, which is nearly one third of previous estimates. The research indicates that while ice sheets on Greenland and Antarctica collapsed at that time, the larger East Antarctic Ice Sheet did not collapse. The researchers feel that their results will have important implications as to the height of future global sea-level rises. [The Earth Institute, Columbia University]
• 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: Loss of Louisiana's Coast

According to the Louisiana Coastal Wetlands Conservation and Restoration Task Force, Louisiana has been losing its coastal wetlands (bayous, marshes, and swamps) to the waters of the Gulf of Mexico at an alarming rate of about 65 to 100 square km (25 to 38 square mi) per year for the past several decades. This loss adversely affects fisheries in the Gulf of Mexico and makes the coastal zone more vulnerable to storm surges such as that produced by Hurricane Katrina in August 2005. Since the early 1930s, the state's coastal wetlands have shrunk by an area equivalent to the state of Delaware. According to USGS estimates, an additional 1800 square km (700 square mi) could be lost by mid-century. The price tag for reversing this trend, restoring some marshes, and protecting the remaining 15,000 square km (5800 square mi) of wetlands could top $14 billion and take decades to complete. Many people argue that the value of Louisiana's coastal wetlands is well worth the expense.

As much as 75% of the fish and other marine life in the northern Gulf of Mexico depend on Louisiana's coastal wetlands. The wetlands are a nursery for commercially important catches of shrimp, crawfish, blue crab, and oysters. It is a food source for larger fish including yellow fin tuna, red snapper, and swordfish. In 2003, about three-quarters of the nation's fish and shellfish catch by weight came from Louisiana's waters. In addition, the wetlands are a stopover for millions of birds migrating between North and Central/South America. Furthermore, wetlands and associated barrier islands protect the ports, buildings, and other coastal zone structures from storm surges. Wetlands are particularly important in buffering the levees surrounding New Orleans, much of which is below sea level.

Many factors contribute to the loss of Louisiana's coastal wetlands. Thousands of kilometers of pipelines transporting oil and natural gas through the marshes plus the extensive network of navigation channels allow saltwater to intrude the wetlands. Increased salinity of the originally fresh or brackish waters kill wetland grasses, shrubs, and other vegetation that anchor soil in place. The canals also allow tidal currents to flow farther inland, accelerating erosion of wetland soils. The most important factor, however, is the consequence of flood control structures (levees) constructed along the banks of the Mississippi River. Levees constrict the flow of the river so that waters and suspended sediment discharge rapidly into the Gulf. Deprived of a continuous input of sediments and vegetation-supporting nutrients, existing sediments compact, wetlands subside and Gulf waters invade the wetlands. With the anticipated continued rise in sea level due to global climate change (discussed in Chapter 12 of your textbook), erosion of Louisiana's coastal wetland may accelerate in the future.

Plans to reverse the loss of Louisiana's coastal wetlands (the Coast 2005 plan and the Louisiana Coastal Area plan) seek to restore the structure and function of coastal wetlands. One proposal is to breach some levees along the lower Mississippi. This partial diversion of the Mississippi would increase the supply of sediments to the wetlands. Closing or installing locks on some navigation canals would reduce saltwater intrusion. In addition, dredged sediment would be used to re-build wetlands and restore barrier islands.

Concept of the Week: Questions

1. The most important factor contributing to erosion of Louisiana's coastal wetlands is [(saltwater intrusion)(levees along the banks of the Mississippi River)].
2. Global climate change that is accompanied by a rise in sea level is likely to [(accelerate)(have no effect on)] the rate of erosion of Louisiana's coastal wetlands.

Historical Events:

• 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)
• 22 March 1778...Captain James Cook of the British Royal Navy sighted Cape Flattery, in present day Washington State.
• 22 March 1999...Tropical Cyclone Vance produced Australia's highest measured wind speed of 166 mph at Learmonth, West Australia. Gusts reaching 185 mph were estimated in the eyewall in the Exmouth Gulf. All homes in the village of Exmouth were either damaged or destroyed. (Accord's Weather Guide Calendar)
• 24 March 1955...The first seagoing oil drill rig (for drilling in over 100 feet of water) was placed in service by the U.S. company C.G. Glasscock Drilling Co. The rig was able to drive piles with a force of 827 tons and pull a pile with the force of 942 tons. (Today in Science History)
• 24 March 1989...The tanker Exxon Valdez grounded on a reef in Prince William Sound, AK, spilling 10.1 million gallons of crude oil, resulting in the worst oil spill in U.S. history. Coast Guard units responded and prevented the entire cargo from spilling, cleaned up the oil which did spill, and conducted an investigation into the causes of the accident. The spill provided the impetus for the passage of the Oil Protection Act in 1990. (US Coast Guard Historians Office)
• 25 March 2000...A rouge wave near Shelter Cove, CA swept a lady from a Canadian school group into the ocean. Four members of the group tried to rescue her, but were overcome by the waves and currents. A fishing vessel and the US Coast Guard rescued two of the rescuers. (Accord's 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, 2012, The American Meteorological Society.