Operation IceBridge
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Operation IceBridge (OIB) was a
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
mission to monitor changes in
polar ice A polar ice cap or polar cap is a high-latitude region of a planet, dwarf planet, or natural satellite that is covered in ice. There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap, nor a ...
by utilizing airborne platforms to bridge the observational gap between the
ICESat ICESat (Ice, Cloud, and land Elevation Satellite) was a NASA satellite mission for measuring ice sheet mass balance, cloud and aerosol heights, as well as land topography and vegetation characteristics. It operated as part of NASA's Earth Obser ...
and
ICESat-2 ICESat-2 (Ice, Cloud, and land Elevation Satellite 2), part of NASA's Earth Observing System, is a satellite mission for measuring ice sheet elevation and sea ice thickness, as well as land topography, vegetation characteristics, and clouds. ICES ...
satellite missions. The program, which ran from 2009 to 2019, employed various aircraft equipped with advanced instruments to measure ice elevation, thickness, and underlying bedrock topography. The data collected helped scientists understand ice dynamics, contributing to predictive models of ice and sea-level rise. IceBridge played a crucial role in discovering the longest canyon on Earth beneath the Greenland ice sheet.


Program history

From 2003 to 2009,
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
used a space-based laser altimeter, ICESat, for observing polar ice. ICESat was retired in 2009 due to a technical malfunction, leaving NASA without a satellite dedicated to ice observance. A next-generation satellite, ICESat-2, launched in September 2018. In order to maintain annual observations of ice sheets and sea ice, NASA introduced the IceBridge program to "bridge the gap" between satellite missions. The program utilizes aircraft platforms to make airborne measurements of the polar regions. IceBridge flights began in March 2009, on an Arctic Spring campaign based out of
Thule Air Base Pituffik Space Base ( ; ; ), formerly Thule Air Base (), is a United States Space Force base located on the northwest coast of Greenland in the Kingdom of Denmark under a defense agreement between Denmark and the United States. 150 United Stat ...
, Greenland. Southern Hemisphere flights began during the first Austral Spring campaign in October 2009, based out of
Punta Arenas Punta Arenas (, historically known as Sandy Point in English) is the capital List of cities in Chile, city of Chile's southernmost Regions of Chile, region, Magallanes Region, Magallanes and Antarctica Chilena. Although officially renamed as ...
, Chile. Flights during field campaigns can contain either dedicated land ice and
sea ice Sea ice arises as seawater freezes. Because ice is less density, dense than water, it floats on the ocean's surface (as does fresh water ice). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world' ...
flights, or a combination thereof, based upon platform, weather and location constraints. To date there have been Spring campaigns in the Arctic and Antarctic, as well as flights monitoring summer melt on Alaskan glaciers every year since 2009. Additional campaigns have occurred in the Arctic summer and East Antarctica.


Platforms

IceBridge flights began in March 2009 using a
Lockheed P-3 Orion The Lockheed P-3 Orion is a four-engined, turboprop Anti-submarine warfare, anti-submarine and maritime patrol aircraft, maritime surveillance aircraft developed for the United States Navy and introduced in the 1960s. It is based on the Lockheed ...
in the Arctic, and were followed later that year by a
Douglas DC-8 The Douglas DC-8 (sometimes McDonnell Douglas DC-8) is an early long-range Narrow-body aircraft, narrow-body jetliner designed and produced by the American Douglas Aircraft Company. Work began in 1952 towards the United States Air Force's (USA ...
in the Antarctic. Other aircraft have been used throughout the program, such as a King Air B-200,
Gulfstream V The Gulfstream V (Model GV, pronounced "G-five") is a large, long-range business jet aircraft produced by Gulfstream Aerospace, derived from the previous Gulfstream IV. It flies up to , up to and has a range. It typically accommodates four c ...
and Guardian Falcon. There are tradeoffs to using an aircraft instead of a satellite. One drawback is that a satellite can observe a far wider area. Also, satellites take measurements full-time, while IceBridge aircraft measurements are limited to annual campaigns that are several weeks long. Aircraft, however, have the advantage of being able to carry more instruments, change or upgrade instruments from campaign to campaign and target scientifically interesting areas instead of following a fixed path. Also, certain instruments such as ice-penetrating radar only work from the lower altitudes afforded by aircraft like the P-3 Orion and DC-8.


Instruments

IceBridge aircraft carry a suite of specialized science instruments. Among these is the Airborne Topographic Mapper, a laser that measures the surface elevation of the ice. Also on board is a
gravimeter Gravimetry is the measurement of the strength of a gravitational field. Gravimetry may be used when either the magnitude of a gravitational field or the properties of matter responsible for its creation are of interest. The study of gravity c ...
, an instrument capable of measuring the shape of cavities in the ice. There are numerous other pieces of equipment on board, including the Land, Vegetation and Ice Sensor, the Multichannel Coherent Radar Depth Sounder, a Snow Radar, a Ku-Band Radar Altimeter, a magnetometer and the Digital Mapping System.


Laser altimeters

Airborne Topographic Mapper (ATM) – The Airborne Topographic Mapper (ATM) is a laser altimeter that bounces laser light off the ice surface and measures how long it takes to return. By combining this timing data with information about the aircraft's position and attitude, researchers can calculate ice elevation. By flying over the same areas of ice year after year, they can build a
time series In mathematics, a time series is a series of data points indexed (or listed or graphed) in time order. Most commonly, a time series is a sequence taken at successive equally spaced points in time. Thus it is a sequence of discrete-time data. ...
of changes in elevation. This instrument works similarly to the
lidar Lidar (, also LIDAR, an acronym of "light detection and ranging" or "laser imaging, detection, and ranging") is a method for determining ranging, ranges by targeting an object or a surface with a laser and measuring the time for the reflected li ...
instrument used in ICESat and is helping maintain a record of elevation changes until ICESat-2 becomes operational. Land Vegetation and Ice Sensor (LVIS) - The Land, Vegetation and Ice Sensor (LVIS) is a laser altimeter optimized for operation at higher altitudes. LVIS was created by scientists at the Laser Remote Sensing Laboratory at NASA's Goddard Space Flight Center. LVIS has flown on a wide variety of aircraft such as NASA's P-3, DC-8, B-200 and HU-25C Guardian Falcon and NSF's Gulfstream G-V. By flying at a higher altitude, LVIS can survey larger areas and expands IceBridge's range.


Radars

Operation IceBridge uses up to four different radar instruments operated by the Center for the Remote Sensing of Ice Sheets (CReSIS) at the
University of Kansas The University of Kansas (KU) is a public research university with its main campus in Lawrence, Kansas, United States. Two branch campuses are in the Kansas City metropolitan area on the Kansas side: the university's medical school and hospital ...
.
Indiana University Indiana University (IU) is a state university system, system of Public university, public universities in the U.S. state of Indiana. The system has two core campuses, five regional campuses, and two regional centers under the administration o ...
provides
data management Data management comprises all disciplines related to handling data as a valuable resource, it is the practice of managing an organization's data so it can be analyzed for decision making. Concept The concept of data management emerged alongsi ...
services for CReSIS activities in Operation IceBridge. Multichannel Coherent Radar Depth Sounder (MCoRDS) - The Multichannel Coherent Radar Depth Sounder (MCoRDS) is used to measure ice thickness and map beneath the ice. This instrument uses multiple channels and a large range of radar frequencies to image internal ice layering and bedrock beneath ice sheets. Information on sub-ice terrain is useful for modeling ice sheets. Snow Radar - The CReSIS Snow Radar instrument is used to measure the thickness of snow layers on top of land and sea ice. Measuring snow thickness is crucial for estimating sea ice thickness. Ku-band Radar Altimeter - IceBridge also carries a
Ku band The Ku band () is the portion of the electromagnetic spectrum in the microwave range of frequencies from 12 to 18  gigahertz (GHz). The symbol is short for "K-under" (originally ), because it is the lower part of the original NATO K ban ...
radar altimeter, which can penetrate snow layers to measure sea and land ice surface elevation. Accumulation Radar - The accumulation radar instrument is used to gather high-resolution data on the top part of ice. Looking at the uppermost part of ice allows researchers to map past snow accumulation rates.


Mapping instruments

Digital Mapping System (DMS) - The Digital Mapping System (DMS), created by researchers at NASA's Ames Research Center, is an airborne digital imaging system that is used to detect openings in sea ice and build high-resolution maps of polar ice. The DMS instrument is a downward-facing digital camera that captures multiple individual frames that are combined into image mosaics using computer software. Gravimeter - Operation IceBridge also uses a gravity-measuring instrument known as a
gravimeter Gravimetry is the measurement of the strength of a gravitational field. Gravimetry may be used when either the magnitude of a gravitational field or the properties of matter responsible for its creation are of interest. The study of gravity c ...
. This instrument measures the strength of gravitational fields beneath the aircraft, which researchers can use to determine the shape of water cavities beneath floating ice shelves. Because water is less dense than rock, areas of floating ice show weaker gravitational fields than areas with rock underneath. Magnetometer - The NASA P-3 Orion carries a
magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, ...
that can be used to gather data on the properties of sub-ice rock. Density and magnetic properties can be used to infer bedrock type, which is helpful for determining sub-ice basal conditions.


Research

The project, headed by project scientist Joseph MacGregor, from NASA's Goddard Space Flight Center, uses a suite of airborne science instruments to get a three-dimensional view of Arctic and Antarctic ice. The mission's goals are to monitor changes in polar ice, gather data for predictive models of ice and sea-level rise and bridge the gap in measurements between NASA's ICESat and ICESat-2 satellites. IceBridge achieves this by collecting data over ice sheets,
glaciers A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
and sea ice. Pine Island Glacier is one such area of focus. There, Operation IceBridge has been observing the underside of the ice-sheet using an advanced radar, as well as closely monitoring an area of Pine Island Glacier known as the ice tongue that, were it to melt, would allow a large portion of the glacier to slide into the
Amundsen Sea The Amundsen Sea is an arm of the Southern Ocean off Marie Byrd Land in western Antarctica. It lies between Cape Flying Fish (the northwestern tip of Thurston Island) to the east and Cape Dart on Siple Island to the west. Cape Flying Fish ...
. In August 2013 the discovery of the longest canyon on Earth under the Greenland ice sheet was reported, based on an analysis of data from Operation IceBridge.


Outreach and collaborations


References


External links


Operation IceBridge
at NASA.gov
Antarctic Bedrock: Visualizations
at NASA.gov * {{cite news , url=https://www.nasa.gov/topics/earth/features/antarctic-map.html , title=NASA's IceBridge Mission Contributes to New Map of Antarctica , publisher=NASA , date=4 June 2013 NASA programs 21st century in the Arctic Arctic research Science and technology in Antarctica United States Antarctic Program Geology of Antarctica 2009 establishments in Antarctica 2009 establishments in the United States Articles containing video clips Earth observation projects 2019 disestablishments in the United States