Antarctic Geoscience Terms

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Aerosols

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- A suspension of a fine solid particle or liquid in a gas, typically air
-Are rapidly flushed from the environment by rain or snow, or settle; therefore they must be continuously input into the environment to cause an effect.
-Aerosols have the ability to influence climate directly by absorbing or reflecting incoming solar radiation, but they can also produce indirect effects on climate by modifying cloud formation or cloud properties.

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Albedo

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-A fraction of light that is reflected by a body or surface.
-Positive feed back, ice reflects more solar radiation because of it's high albedo.
-As the decrease of ice cover continues, more solar radiation will be absorbed.

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Antarctic Bottom Water

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-Densest and coldest water located on the Antarctic continental shelf.
-The densest water near the coast sinks to become the Antarctic Bottom Water.
-The density of the water manages the thickness of the seasonal sea ice.

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Antarctic Divergence

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-Point where North Atlantic Deep Water swells up toward the coast of Antarctica
- The NADW is cold and saline, therefore it sinks into the AABW.

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Basalt

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-igneous (volcanic) rock that is low in silica content, dark in color, and rich in iron and magnesium.

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Circum-Antarctic Current

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-surface oceanic current encircling Antarctica and flowing from west to east.
-Affected by adjacent landmasses, submarine topography, and prevailing winds, the Antarctic Circumpolar Current is irregular in width and course.
-Its motion is further complicated by continuous exchange with other water masses at all depths.

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Carbon Cycle

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-cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.
-Too much input of carbon in the atmosphere causes a greenhouse effect, which causes the planet to warm and begin the melting of glaciers.

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Convergent Plate Boundary

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-an actively deforming region where two (or more) tectonic plates or fragments of lithosphere move toward one another and collide.
-When two plates collide they form either a subduction zone (a point in which a plate moves beneath the other into the mantle) or a continental collision (a point where neither plate is subducted and a large mountain range is formed).

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Cryosphere

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-describes the portions of the Earth’s surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps and ice sheets, and frozen ground (which includes permafrost).
-Since the Cryosphere plays a large part in global climate, it is important to life on earth, and since Antarctica has the largest volume of solid water on the planet, it's preservation is key to managing the climate that sustains life.

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Diatom

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-A major group of algae and the most common type of phytoplankton. This unicellular organism is a large part of the food chain, especially within Antarctica.
-Diatoms are found within ice cores and help scientists to understand more about past climates within Antarctic research.
-Dr. Harwood loves Diatoms! :)

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Divergent Plate Boundary

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-a linear feature that exists between two tectonic plates that are moving away from each other.
-When plates move away from one another they produce rifts that produce new igneous rock at the point of divergence and push older rock towards the continents
-The West Antarctic Rift is an example of a rift valley created by divergent plates.

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Dufek Massif

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- a range of peaks in the Pensacola Mountains of Antarctica in West Antarctica.
-Dufek Massif is under consideration as a future drill site for the ANDRILL project
-Second largest igneous province in the world and geologists can learn a lot about igneous processes and evolution of magmas and initial mantle composition by studying these rocks.

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Gamburtsev Mountain

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-A subglacial mountain range located in Eastern Antarctica and is considered to be as large as the European Alps.
-Drilling in the Gamburtsev mountains has not happened because scientists fear that drilling might contaminate Lake Vostok (a subglacial lake which little is known about.).

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Glacial Movement

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Glaciers move, or flow, downhill due to the internal deformation of ice and gravity.
-Sometimes the presence of liquid water due to pressure lubricates the glacier and allows it to flow.

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Glacial Till

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-A term for unsorted glacial sediment that is deposited directly by the glacier.
-Glacial Till helps scientists to discover areas that were once covered with glaciers to understand the distance glaciers once covered.

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Gneiss

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-a type of metamorphic rock made from formations that were originally igneous or sedimentary rocks.
-The Napier Mountain complex is an example of a gneiss.

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Gondwana

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-An ancient super continent that consisted of South America, Africa, India, Australia, and Antarctica.
-The supercontinent explains the once warm climate in Antarctica and evidence comes from the existence of several fossils found in Antarctica that are found also in South Africa and Australia, thus proving that at one point the continents did form one supercontinent.

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Granite

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A type of igneous rock that typically has a medium to coarse grained texture.
-The presence of granite helped scientists to prove that Antarctica was a continent instead of a group of islands.

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Greenhouse Effect and Greenhouse Gasses

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-a process by which thermal radiation from the earths surface is absorbed by atmospheric greenhouse gases and is re-radiated in all directions.
-This process causes the earths climate to warm.
-Greenhouse gas include carbon dioxide, methane, nitrous oxide and ozone. They are a natural part of the atmosphere, but burning of fossil fuels have contributed to a great increase of carbon dioxide in the atmosphere.

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Grounding line on the ice shelf, ice sheet.

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-It is the point at which the ice shelf that is grounded meets water and feeds the ice sheet. Pressure from gravity causes the ice shelf to move seaward which creates the ice sheet.
-Many portions of Antarctica's coast have ice sheets that extend from the ice shelves.

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Ice Divide

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-a boundary on an ice sheet, ice cap or glacier that separates opposing flow directions of ice.
-Ice divides are important in ice coring studying over time because scientists understand that in order to get a good sample they must drill vertically to avoid interferences caused by the horizontal ice movement.

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Ice Streams in West Antarctica

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-An ice stream is a region of an ice sheet that moves significantly faster than the surrounding ice.
-West Antarctica contains the most rapidly flowing ice streams which drain much of the West Antarctic Ice Sheet into the Ross Sea.

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Insolation

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-a measure of solar radiation that is received on a given surface area in a given time.
-Insolation is useful in the application of Milankovitch cycles (describes the collective effects of changes in the Earths movements upon it's climate.)

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Intergovernmental Panel on Climate Change

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-a scientific intergovernmental body[1][2] tasked with reviewing and assessing the most recent scientific, technical and socio-economic information produced worldwide relevant to the understanding of climate change.
-The IPCC does not do original scientific research, but aims to educate the public with a clear scientific view on the current state of climate change and its potential consequences.

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Iron fertilization ocean experiments

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-the intentional introduction of iron to the upper ocean to stimulate a phytoplankton bloom. This is intended to enhance biological productivity, which can benefit the marine food chain and remove carbon dioxide from the atmosphere.
-This was believed to be a mechanism that could slow or potentially reverse global warming by sequestering CO2 in the sea

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Katabatic Winds

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-a wind that carries high density air from a higher elevation down a slope under the force of gravity.
-The entire near-surface wind field over Antarctica is largely determined by the katabatic winds.

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Keeling curve

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-A graph that shows the variation in concentration of atmospheric carbon dioxide since 1958.
-It is based on constant measurements taken at the Mauna Loa Observatory in Hawaii.
-Was the first piece of significant evidence for rapidly increasing carbon dioxide levels in the atmosphere.

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Krill

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-a shrimp-like marine crustacean that is found in all oceans of the world.
-Krill are considered important within the food chain because they are the food source for many animals within the Southern Ocean

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Lake Vostok

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-the largest subglacial lake in Antarctica located under the Russian Vostok Station on the East Antarctic Ice Sheet.
-It is similar in size to Lake Ontario and consists of fresh water.
-No water sample has been collected because scientists do not want to contaminate the water.

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Limiting nutrient

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-essential in understanding biological processes. The nutrient in short supply relative to others will be exhausted first and will limit cellular growth.
-This applies to the growth of diatoms which are essential to food production in Antarctica with iron being the limiting nutrient.

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Little Ice Age

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-A period of cooling that occurred after the Medieval Warm Period. However, the Little Ice Age was not a true ice age
-Cores from Antarctica suggest that the Little Ice Age was a global event.

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Mantle

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-a highly viscous layer between the crust and the outer core.
-The upper mantle consists of two zones, the asthenosphere(consists of flowing rock in the in the state of plasticity) and the lithosphere(consists of rigid rock known as tectonic plates).
-Tectonic plates are responsible for the movement and formation of the continents.

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Metamorphic facies or grades

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-groups of mineral compositions in metamorphic rocks, that are typical for a certain field in pressure-temperature space.
-When the temperature or pressure in a rock body change, the rock can cross into a different facies and some minerals become stable while others become unstable or metastable.

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Moraine

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-any glacially formed accumulation of unconsolidated glacial debris (soil and rock) which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past ice age.
-Can range in size from small silt sized particles to large boulders.
-Help scientists to know where and how far glaciers extended to.

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Oceanic Conveyer Belt

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-large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes.
-a key component of modern climate system
-warm surface waters eventually mix with cold subsurface waters and continue through the process which is what balances the climate.

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Ozone Layer

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A layer in the Earth's atmosphere which contains relatively high concentrations of ozone (O3). This layer absorbs 97–99% of the Sun's high frequency ultraviolet light, which is damaging to life on Earth.
-Located in the Stratosphere.
-Ozone depletion is caused by harmful release of man-made compounds know as chlorfluorocarbons and bromofluorocarbons.
- a major ozone hole was produced in the Antarctic region which is slowly closing up but it is expected to continue for decades.

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Pancake Ice

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-a form of ice that consists of round pieces of ice with diameters ranging from a few inches to many feet, depending on the local conditions that affect ice formation.
-This is formed when slabs of ice that are forming are jostled by the wind and/or movement of the sea. The pancakes of ice bash against each other around the edges and start to curl upwards at the edges.

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Polar Frontal Zone

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-a curve continuously encircling Antarctica where cold, northward-flowing Antarctic waters meet the relatively warmer waters of the subantarctic.
- Antarctic convergence

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Phytoplankton

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-autotrophic (able to make their own food through photosynthesis) component of the plankton community.
- Have a limiting nutrient of iron in the Southern Sea which has led some scientists to advocate for iron fertilization as a way to accumulate human-produced carbon dioxide in the seas.

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Precession

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-A change in the orientation of the rotation axis of a rotating body.
-The Earth goes through a complete processional cycle in the period of about 26,000 years.

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Primary Productivity in the Southern Ocean

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-is influences by sea surface temperature, sea ice cover, nutrient availability, and upwelling/wind mixing of the photic zone

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Principle of uniformitarianism

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-assumes that the same natural laws and processes that operate in the universe now, have always operated in the universe in the past and apply everywhere in the universe.
-Allows scientists to make hypotheses and theories about Earth's past based on research of present processes.

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Ring of Fire

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-Ridges and Transforms that surround the Antarctic Plate that have active volcanism and active glacial loading and unloading.
-Evidence for the supercontinent Gondwana.

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Sea-ice diatoms, seasonal growth

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-Diatoms will live in sea-ice and cause the base of the ice to become green.
-Operate in a "bloom and bust" manner. For a time, they will bloom and some will stay in the ice while others sink and are brought back again to bloom.

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sea-ice formation

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Sea ice starts a thin layer called Nilas Ice which has a rather elastic crust. As this process continues, Pancake Ice forms from ice bashing together which causes the ice to curl upward. Once these pile together, they become sea ice.
-Antarctica's sea ice never extends past the polar frontal zone

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Snowball Earth

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-A hypothesis that states the Earth's surface was entirely frozen or nearly entirely frozen at least once, probably earlier that 650 million years ago.
-Many geologists accept they hypothesis because it helps to explain why glacial deposits are found in tropical regions.
-Opponents argue that it isn't feasible that the ocean was once ice or slush covered and that it would be difficult to escape an entirely frozen earth.

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Stratosphere

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-the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down.
-contains the Ozone Layer which is what separates the temperatures.

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Subduction

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-the process that takes place at convergent boundaries when one plate moves under another into the earth's mantle as the plates converge.
-produce volcanoes and earthquakes.

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Troposphere

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-The lowest portion of Earth's atmosphere made up of primarily water vapor and aerosols.
-Contains most of the weather we experience

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West Antarctic Rift System

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-a major, active rift valley lying between East and West Antarctica. It encompasses the Ross Sea, the area under the Ross Ice Shelf and a part of West Antarctica. Its evolution is due to lithospheric thinning of the non-cratonic area of West Antarctica.
-The source of recently active volcanoes within Antarctica and also has a major influence on ice flows in West Antarctica.