Antarctica -1 Brrrrrrrr
I’m McKensie Daugherty, your host for On the Ocean. Feel that chill in the air? It’s getting cold outside. But beware, even now in the midst of summer at bottom of the Earth, it is much colder there. That’s right, this month we are talking about the white continent, and how the Antarctic region uniquely influences the rest of the planet. The Antarctic continent itself covers about 14.1 million square miles, nearly one and a half times larger than the U.S., but its terrain is almost entirely covered by ice. A trans-Antarctic mountain range separates West and East Antarctic Ice Sheets over a mile thick in some areas that weigh down the bedrock to below sea level. Frozen, but not stationary, the Antarctic ice is always on the move. It is discharged into the Southern Ocean by a network of continental ice streams, glaciers, and floating ice shelves. The world’s strongest winds fuel the continuous eastward flow of the Antarctic Circumpolar Current around Antarctica, the largest ocean current on Earth. This swirling current extends throughout the entire water column, and essentially isolates Antarctic glaciers and ice shelves from direct oceanic influences. In some segments of the Antarctic continental shelf, the coldest and densest waters on the planet are produced during wintertime. In summer these areas are home to whales, seals, penguins, exotic cold-water species of algae, and unique invertebrates that thrive in nutrient-rich waters. Antarctica has no permanent human establishments by any nation or ethnic group, but a couple of thousand people live year-round on the continent at research stations established by several countries. In 1961 The Antarctic Treaty System, now involving 52 parties (including the U.S.), was established to ensure that Antarctica is used only for scientific investigation. Researchers study the ocean-ice-atmosphere interactions at key Antarctic locations with global relevance. This has been On the Ocean, a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station. For more information and links, please go to ocean.tamu.edu and click On the Ocean.
Antarctica -2 Ice making and ice melting
I’m McKensie Daugherty, your host for On the Ocean. Ice is ubiquitous in Antarctica, and many different types of ice are found both over the continent and the Southern Ocean. Snowfall over the Antarctic Ice Sheets adds to the continental ice volume year round, which in turn feeds ice streams terminating in coastal glaciers and floating ice shelves. Sea ice forms as surface seawater freezes from extreme cold temperatures and strong winds. Although seasonal sea ice is only about one meter thick, its insulating layer covers an area much larger than the Antarctic continent by the end of the winter. Ice floes are generally the results of surviving patches of multiyear sea ice, about 3-4 meters thick and topped with lots of snow, that float adrift and change direction as dictated by ocean surface currents. When ice floes collide and rift the pack ice field they produce prominent ridges a few meters tall. Coastal polynyas are known as the true sea ice factories in the Southern Ocean, where extremely cold air from nearby ice shelves is brought down to polynyas by energetic kabatic winds, more effectively freezing seawater and blowing new sea ice to areas farther offshore. Eventually the additional salt left behind during sea ice formation makes the remaining near-freezing surface seawater denser than the waters below and it sinks to the bottom. During the past few decades the atmospheric warming and expanding of mid-latitude regimes has resulted in higher temperatures of the underlying upper ocean. Warmer subtropical waters incorporated to the Antarctic Circumpolar Current could potentially magnify oceanic heat transport toward Antarctic continental and sea ice. Warmer subsurface water upwelled to near the shelf break of certain continental shelves of Antarctica would increase the melt rate of floating ice shelves and glaciers, and therefore current rates of global sea level rise. This has been On the Ocean, a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station. For more information and links, please go to ocean.tamu.edu and click On the Ocean.
Contributing Professor: Dr. Alejandro Orsi
More information and links:
Antarctica -3 Dangerous
I’m McKensie Daugherty, your host for On the Ocean. The Antarctic is a beautiful place, with many scientific discoveries just waiting to be made. However, there are many challenges that come with working in the coldest place on earth, far away from any human civilization. The distance from populations poses a problem in resources. To the many thousands of researchers on the continent, things like food and basic supplies are in high demand. However, the continent is too far for a round trip by air, and the winds are incredibly dangerous to fly in. Therefore, the interactions between Antarctic researchers and their home countries are by ice breakers, the ships equipped to handle the thick ice needed to pass through to get to research stations, such as McMurdo station, of the United States. These ships are required to carry at least 2 years worth of food onboard for every mission, in the event they get stuck or need to resupply another station. Another challenge is the time it takes to get to the continent. It takes an average of 7 to 10 days to sail across the circumpolar current flowing around Antarctica in the coldest, windiest place on earth. Ice breakers have reinforced hulls, but they are still vulnerable to icey dangers like ridges that can penetrate a hull and endanger the ship. Ice breakers can also get stuck, causing a massive delay and potentially requiring outside help. The strong winds can keep ships away from the continent, and cause severe frostbite to the crew if they are above deck. The waves too, are incredibly strong, causing problems for the ships and those aboard them. One of the greater dangers are icebergs, a large piece of frozen freshwater that has broken off from shelf ice or a glacier. These are incredibly dangerous, as the strong winds can cause huge chunks of ice to break off at any moment. Ships try to avoid icebergs, to prevent this ice from falling on them, or to get hit by the massive underwater part of the floating iceberg, which could have sharp peaks or ridges. This has been On the Ocean, a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station. For more information and links, please go to ocean.tamu.edu and click On the Ocean.
Contributing Professor: Dr. Chrissy Wiederwohl
R.V.I. Nathanial Palmer with ice scratches in the Antarctic
Scientists Deplaning in Antarctica
Antarctica -4 R.V.I. Nathanial Palmer
I’m McKensie Daugherty, your host for On the Ocean. Antarctica claims many unique attributes as the southernmost continent on Earth. For this reason, many scientists from many nations are highly interested in studying the frozen continent up close. In order to carry out this research, Research Vessel Ice breakers are used, with many instruments and scientists on board. The American Ice Breaker used by Texas A&M University to study Antarctica is the R.V.I. Nathanial Palmer, often travelling to the U.S. McMurdo Station on the mainland. Scientists on the R.V.I. Nathanial Palmer use many instruments to gather information about the Southern Ocean and the mainland of Antarctica. For example, one cruise involved 7 Principle Investigators and 14 students from 7 different institutions. All these researchers have varying interests, from sediment cores, seismic data, ocean dredges, to currents and water and wind speeds and directions. Other instruments include sensors taking data such as oxygen levels and nutrient levels (including nitrates, phosphates, and silicates). Texas A&M University researchers work with the Southern ocean, gathering data to provide accurate atlases of the mainland and Southern ocean variables. Using a probe on a wench structure, scientists drag the probe behind the ship to get a working picture of the ocean variables over distances in the Antarctic. Another method is to use buoys that can gather data on water and current movements and directions, as well as salinity, temperature, and density of the Antarctic water. This has been On the Ocean, a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station. For more information and links, please go to ocean.tamu.edu and click On the Ocean.
Contributing Professor: Dr. Chrissy Wiederwohl
Sampling of the Southern Ocean
R.V.I. Nathanial Palmer in the Southern Ocean