Above the Poles - Draft Summary
Polar weather, with extreme cold, fierce winds, and constant wintertime darkness, remains a deterrent and a threat to modern researchers. The polar regions provide crucial cooling processes for our global climate system, and polar weather in both hemispheres influences weather as far away as the tropics. The atmosphere over ice- and snow-covered surfaces has unique properties, and a remarkable sequence of reactions in the snow and ice influence the chemistry of polar air. Auroras in both hemispheres provide a glimpse of planetary-scale geomagnetic processes in the outer atmosphere.
Arctic Weather and Climate
Arctic weather can have dramatic impacts on northern hemisphere weather and climate. Conversely, many Arctic storms develop from initial conditions in tropical latitudes. These hemispheric interactions, coupled with the properties of the underlying ocean, ice and land surfaces, a complicated cloud environment, and extreme seasonal variations in heating and cooling, make the Arctic a challenge for predictions. Researchers use observations of clouds, precipitation, temperature, and winds together with numerical models to improve their skills at predicting extreme Arctic weather events such as abrupt spring thaws, rapid sea ice movements, and severe winter storms. The Arctic atmosphere also mediates emissions of greenhouse gases from degrading permafrost and influences the timing and type of precipitation. Already the Arctic climate shows strong warming, which will very likely impact the weather, chemical and hydrological processes in the Arctic atmosphere.
Antarctic Weather and Climate
Dry, stable conditions over the high Antarctic plateau, particularly in the winter, produce some of the coldest air on the planet making Antarctica the primary heat sink of the global climate system. As cold air masses flow off the plateau toward the ocean, they produce very strong winds and interact with vigorous coastal storm systems. Conditions on the plateau, and complex connections to the tropics, determine the frequency and intensity of Antarctic coastal storms and the strength of the winds over the Southern Ocean. These Antarctic atmospheric circulations influence ocean processes such as sea ice formation and deep ocean currents. Processes in the Antarctic snowpack and in the surrounding sea ice control the chemistry of the lower atmosphere. Improved climate predictions require proper representation of Antarctic atmospheric processes.
Global Connections and Transport
Large scale atmospheric circulations that move warm moist air from the tropics toward the poles transport a variety of particulate and gaseous materials. These materials, which include persistent organic pollutants and trace metals from local and distant sources, tend to deposit on polar terrestrial, aquatic and snow surfaces. Some of the gaseous pollutants condense in the cold polar air. Due to their environmental persistence and potential toxicity, the pollutants, which often bioaccumulate through polar food chains, can significantly affect the health of wildlife and humans. Winds, temperature and precipitation influence the amount of pollutants delivered to Arctic and Antarctic regions. The Antarctic environment has few local sources of pollutants, so it may serve as a global reference. Pollutant and toxicity data from the Arctic may allow prediction of current and future impacts in the Antarctic.
The Upper and Outer Atmospheres
Circumpolar vortices and associated polar ozone holes occur in the Arctic and Antarctic stratosphere. IPY occurs during the period of peak concentrations of man-made ozone depleting substances in the stratosphere. Depletion of stratospheric ozone in polar regions has greatly enhanced the amounts of harmful UV radiation reaching polar marine and terrestrial ecosystems. A variety of geoelectric and geomagnetic processes, strongly influenced by the sun, occur in the outermost atmospheric layers above the stratosphere. The auroras visible over both poles provide hints of the dynamic and turbulent processes occurring in these outer layers. Working in collaboration with the International Heliophysical Year, IPY researchers are focusing on inter-hemispheric linkages and on active and passive connections between processes in the outer atmospheres and weather at the Earth’s surface.
View into Space
With their extremely dry, cold, clear and stable atmospheric conditions, the polar plateaus provide the best sites on Earth for a wide range of astronomical observations. Polar astronomical observations include measurements of cosmic microwaves resulting from the Big Bang, the use of optical and infrared telescopes to examine the formation of galaxies, telescopes and interferometers at other frequencies to probe the dense molecular clouds where stars are born, and the measurement of the earthshine from the Moon to probe the variations in the Earth’s reflectance primarily resulting from changing cloud cover. A unique one-cubic-kilometer neutrino observatory installed in the ice below the South Pole Station allows researchers to open unexplored bands for astronomy.
View from Space
Satellite observations provide essential high-resolution, frequent and all-weather observations over large and often inaccessible polar regions, particularly of sea ice and ice sheets. The satellite-borne sensors include cameras, radars, thermal mappers, and ultra-sensitive gravity detectors. An international team of researchers works to optimize the operations and data from these satellites and sensors to provide a comprehensive and unprecedented picture of the polar regions during IPY. Human-guided observations of clouds and the aurora from the International Space Station will complement ground and satellite observations.