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Exploring the Earth SystemTogether with a diverse set of colleagues, NCAR scientists are increasingly involved in research on the interconnected parts of our planet’s anatomy—land, ice, water, plants, and air—known as the Earth system. Some of this field work examines how the land and atmosphere exchange the energy sent to us by the Sun. Different parts of Earth absorb and emit that radiation in different ways based on land cover, moisture, and other factors. These variations help determine where and how clouds and precipitation develop. On a global scale, they influence Earth's radiative budget—the balance sheet that's being altered by increases in greenhouse gases.
Some projects probe the foundations of the radiative budget by examining the physics and chemistry at work within a single type of cloud. For instance, a series of studies called DYCOMS (Dynamics and Chemistry of Marine Stratocumulus) has gathered data on vast sheets of low, highly reflective clouds that predominate over cool subtropical oceans. Other studies have focused on cirrus and cumulus clouds. Ecologists at NCAR and elsewhere pay special attention to how various plant types interact with the atmosphere. Although scientists can learn much by isolating a plant in a closed environment, they head to the field to study the collective effects of large groups of trees, grasses, and other plants. In recent years, NCAR's biosphere-atmosphere specialists have joined colleagues to study ecosystems in Brazil, Botswana, South Africa, Finland, and China, as well as Colorado, Wisconsin, and Michigan. The global carbon cycle involves all aspects of the Earth system, and is particularly interesting because atmospheric carbon dioxide (CO2) is an important greenhouse gas. Recent studies have found that a large portion of the CO2 emitted during fossil-fuel burning is being taken up by Northern Hemisphere land plants, but scientists do not understand these processes well enough to predict their future behavior. To address this issue, NCAR researchers have deployed instruments on a 1,500-foot tall (455-meter) tower in northern Wisconsin, on a research jet flying across North America, and on towers and aircraft over Colorado forests. Plants also have a direct impact on a wide range of other environmentally important atmospheric gases. Recent work in China, Brazil, and Costa Rica shows that tropical deforestation may have a major impact on the amount of carbon emitted by plants in the form of volatile organic compounds—chemicals that play a role in air pollution and the life cycle of some greenhouse gases. Ice and snow bring a far different flavor to the climate of polar regions. NCAR researchers and colleagues have journeyed to Antarctica, the North Pole, Greenland, northern Canada, and other high-latitude locations to study how dramatic seasonal shifts affect air chemistry. In 2003, NCAR followed up previous sulfur studies at the South Pole with the Antarctic Tropospheric Chemistry Investigation (ANTCI), investigating how sulfur and nitrogen enter and exit the vast Antarctic snow pack. A previous study in 2000, Tropospheric Ozone Production about the Spring Equinox (TOPSE), sent an NSF/NCAR aircraft on multiple trips from Colorado to polar Canada to measure changes in air chemistry as the spring Sun slowly returned. Among other findings, TOPSE found pockets of low-level polar air virtually depleted of their expected ozone content. At the top of the troposphere—the "weather layer" of Earth's atmosphere—yet another set of processes rule. Even as Earth's surface air temperatures rise, readings in the upper troposphere and lower stratosphere have plummeted to record lows with the depletion of stratospheric ozone (a greenhouse gas). With the arrival in 2005 of a new high-altitude NSF/NCAR aircraft called HIAPER, scientists will have a valuable tool for studying ozone depletion, changes in water vapor, and other aspects of this region.< previous | index | next >
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Localized field studies of the interactions between land and the
atmosphere employ sensors and aircraft to see how radiation and
moisture are being exchanged over a cotton field or a paved urban
area—or open rangeland, as was the case in the 
