For related articles on this topic, see List of Arctic research programs

The Surface Heat Budget of the Arctic Ocean (SHEBA) study was a National Science Foundation

National Science Foundation

The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...

-funded research project designed to quantify the heat transfer processes that occur between the ocean

Ocean

An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...

 and the atmosphere

Atmosphere

An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

 over the course of a year in the Arctic Ocean

Arctic Ocean

The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions...

, where the sun

Sun

The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

 is above the horizon

Horizon

The horizon is the apparent line that separates earth from sky, the line that divides all visible directions into two categories: those that intersect the Earth's surface, and those that do not. At many locations, the true horizon is obscured by trees, buildings, mountains, etc., and the resulting...

 from spring

Spring (season)

Spring is one of the four temperate seasons, the transition period between winter and summer. Spring and "springtime" refer to the season, and broadly to ideas of rebirth, renewal and regrowth. The specific definition of the exact timing of "spring" varies according to local climate, cultures and...

 through summer

Summer

Summer is the warmest of the four temperate seasons, between spring and autumn. At the summer solstice, the days are longest and the nights are shortest, with day-length decreasing as the season progresses after the solstice...

 and below the horizon the rest of the time. The study was designed to provide data for use in global climate model

Global climate model

A General Circulation Model is a mathematical model of the general circulation of a planetary atmosphere or ocean and based on the Navier–Stokes equations on a rotating sphere with thermodynamic terms for various energy sources . These equations are the basis for complex computer programs commonly...

s, which scientists use to study global climate change.

Background

Ice reflects sunlight more readily than open water. Snow-covered sea ice reflects about 80% of the incident sunlight. Seasonal changes in the Arctic result in clear skies and radiational cooling from snow-covered sea ice in the constantly dark arctic winter. In spring, with the return of sunlight, melt pools begin to form and increase the rate of heat absorption from the sun. In the summer, during constant daylight, clouds form which reflect light to the sky, but impede heat flow from the ocean. In order to quantify these effects over a large portion of earth's area—the Arctic Ocean—required a large-scale scientific data-gathering and analysis effort over the span of a year. Consequently, the National Science Foundation

National Science Foundation

The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...

, together with other sponsors, funded a study to better quantify these processes.

Ice Station SHEBA

The scientific party traveled aboard the Canadian Coast Guard Ship Des Groseilliers

CCGS Des Groseilliers

The CCGS Des Groseilliers is a T1200 Class Medium Arctic Icebreaker in the Canadian Coast Guard.The vessel is named after Médard Chouart Des Groseilliers a close associate of Pierre-Esprit Radisson in explorations west of the Great Lakes and the founding of the English Hudson's Bay Company.The...

 to the Arctic Ocean. It arrived at a location on 2 October 1997 where the plan was to allow the ship to become frozen in the pack ice and be the base for scientific observations. Those observations included measurements of the oceanic and atmospheric processes from the water beneath the ice, near the ship, to the top of the atmosphere. Measurements included:

• Radiative fluxes: longwave and shortwave
• Heat flux: turbulent fluxes of latent and sensible heat
• Cloud height, thickness and other properties
• Processes of energy exchange in the boundary layers of the atmosphere and ocean
• Snow depth and ice thickness
• Ocean salinity, temperature, and currents

The ship remained stationary with respect to the ice for one year, leaving on 11 October 1998. It became known as "Ice Station SHEBA."

Results

The scientists found clouds to be common at the ship's location throughout the year. In the midwinter, there was reportedly overcast 40% of the time and in the summer the sky was continually overcast. Air temperature was 0.6°C lower than the regional climatological average temperature. With no sun in the winter, the net flow of heat (flux) was from the surface of the ocean to the sky, marked with large differences in flux with changes in cloud cover. In April the flux changed toward solar warming of the surface of the sea, which reached a maximum in July when sunlight was strongest and the ice developed melt ponds which were much darker than snow and could absorb sunlight more efficiently.

The scientists also measured the net change in mass of the ice and snow pack at 100 sites. They noted a wide variability of change over the region surrounding the ship. They determined that, with the waning sunlight of fall, the temperature in the ice dropped such that, by November, it was generating new growth at the bottom of the ice pack. From these observations, they identified five phases of change in heat budget:

• Dry snow
• Melting snow
• Pond formation
• Pond evolution
• Fall freeze-up.

Modeling

The experimental results allowed meaningful modeling of the seasonal heat budget processes occurring through the Arctic Ocean sea ice and atmosphere. The scope of the model was the column from below the ice pack through the top of the atmosphere. The scientists realized that key to the model was correctly characterizing the changing reflectivity or albedo

Albedo

Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...

 of the ice surface, owing to changes in snow pack and ice melting. Cloud cover was key to describing how much energy reached or escaped the ocean surface.

Ocean processes

The model incorporated the observation that solar radiation is the dominant heat source to the surface. It accounted for the change in open ocean from a 5% maximum in June and the changes in albedo. Approximately 8% of incoming solar radiation was absorbed into the ocean through the ice.

Atmosphere processes

The scientists were able to define parameters for near-surface turbulence that characterize the degree to which air movement can cool or warm the surface of the ice, seasonally. In summer, the surface becomes rougher and slows down air flow. The lidar

LIDAR

LIDAR is an optical remote sensing technology that can measure the distance to, or other properties of a target by illuminating the target with light, often using pulses from a laser...

 cloud measurements and balloonsonde temperature and turbulence data allowed scientific characterization of the role of the atmosphere above the ice in promoting or inhibiting the warming or cooling of the ocean surface.

Participants

The following individuals and organizations participated in SHEBA:

Name	Affiliation	Location
Uttal and Intrieri	NOAA/Environmental Technology Laboratory Environmental Technology Laboratory The Environmental Technology Laboratory was a laboratory in the National Oceanic and Atmospheric Administration /Office of Oceanic and Atmospheric Research...	Boulder, Colorado Boulder, Colorado Boulder is the county seat and most populous city of Boulder County and the 11th most populous city in the U.S. state of Colorado. Boulder is located at the base of the foothills of the Rocky Mountains at an elevation of...
Curry and Maslanik	University of Colorado University of Colorado The University of Colorado system is a system of public universities in Colorado consisting of three universities in four campuses: University of Colorado Boulder, University of Colorado Colorado Springs, and University of Colorado Denver in downtown Denver and at the Anschutz Medical Campus in...	Boulder, Colorado Boulder, Colorado Boulder is the county seat and most populous city of Boulder County and the 11th most populous city in the U.S. state of Colorado. Boulder is located at the base of the foothills of the Rocky Mountains at an elevation of...
Mcphee	McPhee Research Company	Naches, Washington Naches, Washington Naches is a town in Yakima County, Washington, United States. The population was 795 individuals at the 2010 census.-Infrastructure:Naches' infrastructure is based mainly on timber and agriculture, known for its large masses of apple, cherries, pears and various other fruits.-Geography:Naches is...
Perovich and Grenfeld	Cold Regions Research and Engineering Laboratory Cold Regions Research and Engineering Laboratory The Cold Regions Research and Engineering Laboratory is a United States Army Corps of Engineers, Engineer Research and Development Center research facility headquartered in Hanover, New Hampshire that provides scientific and engineering support to the U.S. government and its military with a core... , U.S. Army	Hanover, New Hampshire Hanover, New Hampshire Hanover is a town along the Connecticut River in Grafton County, New Hampshire, United States. The population was 11,260 at the 2010 census. CNN and Money magazine rated Hanover the sixth best place to live in America in 2011, and the second best in 2007....
Moritz, Stern, Heiberg, Morison, and Lindsey	University of Washington University of Washington University of Washington is a public research university, founded in 1861 in Seattle, Washington, United States. The UW is the largest university in the Northwest and the oldest public university on the West Coast. The university has three campuses, with its largest campus in the University...	Seattle, Washington Seattle, Washington Seattle is the county seat of King County, Washington. With 608,660 residents as of the 2010 Census, Seattle is the largest city in the Northwestern United States. The Seattle metropolitan area of about 3.4 million inhabitants is the 15th largest metropolitan area in the country...
Guest and Stanton	Naval Postgraduate School Naval Postgraduate School The Naval Postgraduate School is an accredited research university operated by the United States Navy. Located in Monterey, California, it grants master's degrees, Engineer's degrees and doctoral degrees...	Monterey, California Monterey, California The City of Monterey in Monterey County is located on Monterey Bay along the Pacific coast in Central California. Monterey lies at an elevation of 26 feet above sea level. As of the 2010 census, the city population was 27,810. Monterey is of historical importance because it was the capital of...
Moore	University Corporation for Atmospheric Research University Corporation for Atmospheric Research The University Corporation for Atmospheric Research is a nonprofit consortium of more than 75 universities offering Ph.D.s in the atmospheric and related sciences. UCAR manages the National Center for Atmospheric Research and provides additional services to strengthen and support research and...	Boulder, Colorado
Turenne	Canadian Coast Guard Canadian Coast Guard The Canadian Coast Guard is the coast guard of Canada. It is a federal agency responsible for providing maritime search and rescue , aids to navigation, marine pollution response, marine radio, and icebreaking...	Quebec City, Quebec, Canada Canada Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
Serreze and Persson	Cooperative Institute for Research in the Environmental Sciences	Boulder, Colorado
Wylie	University of Wisconsin, Madison	Madison, Wisconsin Madison, Wisconsin Madison is the capital of the U.S. state of Wisconsin and the county seat of Dane County. It is also home to the University of Wisconsin–Madison....
Paulson, Wheeler, and Pegau	Oregon State University Oregon State University Oregon State University is a coeducational, public research university located in Corvallis, Oregon, United States. The university offers undergraduate, graduate and doctoral degrees and a multitude of research opportunities. There are more than 200 academic degree programs offered through the...	Corvallis, Oregon Corvallis, Oregon Corvallis is a city located in central western Oregon, United States. It is the county seat of Benton County and the principal city of the Corvallis, Oregon Metropolitan Statistical Area, which encompasses all of Benton County. As of the 2010 United States Census, the population was 54,462....
Halle and Pinkel	Scripps Institute of Oceanography	La Jolla, California
Makshtas	University of Alaska	Fairbanks, Alaska Fairbanks, Alaska Fairbanks is a home rule city in and the borough seat of the Fairbanks North Star Borough in the U.S. state of Alaska.Fairbanks is the largest city in the Interior region of Alaska, and second largest in the state behind Anchorage...
Welch		Winnipeg, Manitoba, Canada
Shupe	Science and Technology Corporation	Boulder, Colorado
Stamnes	Stevens Institute of Technology Stevens Institute of Technology Stevens Institute of Technology is a technological university located on a campus in Hoboken, New Jersey, USA – founded in 1870 with an 1868 bequest from Edwin A. Stevens. It is known for its engineering, science, and technological management curricula.The institute has produced leading...	Maplewood, New Jersey Maplewood, New Jersey Maplewood is a township in Essex County, New Jersey, United States. As of the 2010 United States Census, the township population was 23,867.-History:...