Oceanus Online Archive
The Women of FAMOUS
My FAMOUS story begins during my first year in graduate school at Dalhousie University in Nova Scotia.
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A Current Affair
oal of probing the earth’s inaccessible deep interior. But the technique remains something of a mystery even to many marine scientists. It has been used widely on land, particularly for regional-scale surveys, but only a few full-scale MT surveys have been carried out on the seafloor.
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The Oceanic Flux Program
The predawn hours at sea have a unique feel—an eerie stillness, regardless of weather. This morning is no exception as the Bermuda Biological Station’s R/V Weatherbird II approaches the OFP (Oceanic Flux Program) sediment trap mooring some 75 kilometers southeast of Bermuda.
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Marine Snow and Fecal Pellets
Until about 130 years ago, scholars believed that no life could exist in the deep ocean. The abyss was simply too dark and cold to sustain life. The discovery of many animals living in the abyssal environment by Sir Charles Wyville Thompson during HMS Challenger’s 1872-1876 circumnavigation stunned the late 19th century scientific community far more than we can now imagine.
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Extreme Trapping
One of oceanography’s major challenges is collection of data from extraordinarily difficult environments. For those who use sediments traps, two examples of difficult environments are the deepest oceans and the permanently ice-covered Arctic Basin.
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The Rain of Ocean Particles and Earth’s Carbon Cycle
WHOI Phytoplankton photosynthesis has provided Earth’s inhabitants with oxygen since early life began. Without this process the atmosphere would consist of carbon dioxide (CO2) plus a small amount of nitrogen, the atmospheric pressure would be 60 times higher than the air we breathe, and the planet’s air temperatures would hover around 300°C. (Conditions similar to these are found on Earth’s close sibling Venus.
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Deploying the Rain Catchers
Deployment of a deep-ocean sediment trap mooring begins with the ship heading slowly into the wind.
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Monsoon Winds and Carbon Cycles in the Arabian Sea
The monsoon, a giant sea breeze between the Asian massif and the Indian Ocean, is one of the most significant natural phenomena that influences the everyday life of more than 60 percent of the world’s population.
Read MoreA New Way to Catch the Rain
The carbon budget of the upper ocean includes an important loss to the deep ocean due to a very slowly falling rain of organic particles, usually called sediment. As this sediment falls through the upper water column it is consumed, mainly by bacteria, and the carbon is recycled into nonsinking forms (dissolved or colloidal organic carbon or inorganic forms). Thus the sediment rain decreases with increasing depth in the water column, and only a tiny fraction reaches the deep sea floor, less than about one percent.
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Continental Margin Particle Flux
The boundaries between the oceans and the continents are dynamic regions for the production, recycling, and deposition of sedimentary particles. In general, rates of biological productivity along continental margins are significantly higher than in the open ocean. This is due to a variety of factors including coastal upwelling of nutrient-rich waters and nutrient input from continental runoff. While continental margins account for only about 10 percent of the global ocean area, 50 percent of the total marine organic carbon production is estimated to occur in this limited region, with much of it exported to the deep sea.
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Geochemical Archives Encoded in Deep-Sea Sediments Offer Clues for Reconstructing the Ocean’s Role in Past Climatic Changes
Geochemical Archives Encoded in Deep-Sea Sediments Offer Clues for Reconstructing the Ocean’s Role in Past Climatic Changes
Paleoceanographers are trying to understand the causes and consequences of global climate changes that have occurred in the geological past. One impetus for gaining a better understanding of the factors that have affected global climate in the past is the need to improve our predictive capabilities for future climate changes, possibly induced by the rise of anthropogenic carbon dioxide (CO2) in the atmosphere.
Ground-Truthing the Paleoclimate Record
Sediment Trap Observations Aid Paleoceanographers
The geological record contains a wealth of information about Earth’s past environmental conditions. During its long geological history the planet has experienced changes in climate that are much larger than those recorded during human history; these environmental conditions range from periods when large ice sheets covered much of the northern hemisphere, as recently as 20,000 years ago, to past atmospheric concentrations of greenhouse gases that warmed Earth’s polar regions enough to melt all of the ice caps 50 million years ago. Since human civilization has developed during a fairly short period of unusually mild and stable climate, humans have yet to experience the full range of variability that the planet’s natural systems impose. Thus, the geological record has become an extremely important archive for understanding the range of natural variability in climate, the processes that cause climate change on decadal and longer time scales, and the background variability from which greenhouse warming must be detected
Catching the Rain: Sediment Trap Technology
WHOI Senior Engineer Ken Doherty developed the first sediment trap in the late 1970s for what has come to be known as the WHOI PARFLUX (for “particle flux”) group. Working closely with the scientific community, Doherty has continued to improve sediment traps for two decades, and these WHOI-developed instruments are widely used both nationally and internationally in the particle flux research community.
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Replacing the Fleet
When R/V Atlantis arrived in Woods Hole for the first time on a bright, beautiful April 1997 day, it represented not only a welcome addition to the WHOI fleet but also the culmination of a 15-year UNOLS fleet modernization.
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WHOI and Access to the Sea
In the mid-term future, two WHOI ships (Knorr in about 2006 and Oceanus in about 2009) will reach the end of their planned service lives. There is general agreement that WHOI should work to replace them with two vessels.
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A Northern Winter
As the 1996-1997 ship schedule began to take shape in 1995, we learned that Voyage 147 would take R/V Knorr into the North Atlantic from October ’96 through March of ’97. The various science missions would require station keeping during CTD casts, deployment of current drifters, and expendable bathythermograph (XBT) launches, as well as weather system analysis designed to put Knorr in the path of the harshest weather conditions possible during the winter season. Long before the cruise, we began to tap all available assets that would help us with this challenge.
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Adventure in the Labrador Sea
The sound of the general alarm bell reverberated through the ship. At 2:30 AM, this couldn’t be a drill. Even more puzzling, we were still dockside in Halifax, four hours from our scheduled departure for the Labrador Sea.
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“What a Year!”
Four technologies that have been developing separately for some time were brought together this year by WHOI’s Deep Submergence Laboratory (DSL) to serve three very different user communities. With images from the towed vehicle Argo II and the remotely operated vehicle Jason, DSL scientists and engineers created mosaic images of a sunken British cargo ship and 20-meter-tall hydrothermal vent chimneys, both in the Pacific Ocean, and ancient shipwreck sites in the Mediterranean. The three expeditions thus served the marine safety, scientific, and archaeological communities.
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Access to the Sea
Oceanographic fieldwork has traditionally meant going to sea on a ship. In recent years, it has expanded to include activities that may require a ship for a short period but then continue independently. Floats that drift with ocean currents, periodically reporting their positions via satellite, for example, are generally launched from ships but do most of their work independently. Long-term seafloor observatories may need ships to set them up and service them occasionally, but, again, they are designed to collect data for long periods without needing a ship. We have come to think of the body of ways oceanographers glean information from the ocean as “access to the sea,” and so that is the topic for this issue of Oceanus.
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The Magnetic Thickness of a Recent Submarine Lava Flow
Submarine lava flows and their associated narrow feeder conduits known as dikes constitute the basic building blocks of the upper part of the ocean crust. We are only beginning to understand how lava erupts and forms on the seafloor by flooding topographic lows, flowing through channels or tubes, centralizing into volcanoes, or some combination of all of these.
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North Atlantic’s Transformation Pipeline Chills and Redistributes Subtropical Water
Warm and salty waters from the upper part of the South Atlantic flow northward across the equator and then progress through the tropical and subtropical North Atlantic to reach high latitudes. Beginning with the intense northward flow of the Gulf Stream off the East Coast of the United States, these waters are exposed to vigorous cooling, liberating considerable oceanic heat to the atmosphere. This is the first stage of “warm water transformation within the North Atlantic, a process that culminates in the high latitude production of cold and fresh waters that return to the South Atlantic in deep reaching currents beneath the warm waters of the subtropics and tropics.
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Computer Modelers Stimulate Real and Potential Climate, Work Toward Prediction
Although weather forecasting is accepted by the public as part of daily life, oceanic forecasting is not yet so advanced. There are, however, successful examples of oceanic forecasting—one is the newly developed skill to predict El Nino/Southern Oscillation (ENSO) events, largely due to improvements in ocean modeling.
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A Century of North Atlantic Data Indicates Interdecadal Change
For hundreds of years mariners have recorded the weather over the world ocean. Some 100 million marine weather reports have accumulated worldwide since 1854, when an international system for the collection of meteorogical data over the oceans was established. These reports include measurements of sea surface temperature, air temperature, wind, cloudiness, and barometric pressure. In the 1980s, the National Oceanic and Atmospheric Administration (NOAA) compiled these weather observations into a single, easily accessible digital archive called the Comprehensive Ocean-Atmosphere Data Set. This important data set forms the basis for our empirical knowledge of the surface climate and its variability over the world’s oceans: One example of a variable system is the phenomenon known as El Nino in the tropical Pacific. A major challenge in climate research is to use these data to document and understand the role of the oceans in long-term—decadal and centennial—climate change.
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The El Niño/Southern Oscillation Phenomenon
The El Niño/Southern Oscillation (ENSO) phenomenon, an eastward shift of warm water in the tropical Pacific and associated effects on the atmosphere, is at the heart of global interannual climate variability.
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