UCAR Communications


staff notes monthly

July/August 2003

NCAR names two new senior scientists

Two NCAR researchers were appointed senior scientists at the June meeting of the UCAR Board of Trustees. Senior scientists, who provide the center with long-term scientific leadership, are selected on the basis of individual competence in research and other activities that enhance NCAR’s interaction with scientists elsewhere. The position is analogous to that of full professor at a tenure-granting university.

Maura Hagan of the High Altitude Observatory focuses her research on atmospheric tides and their effects on the different layers of Earth’s atmosphere. She traces the tides from their beginnings, studying how solar radiation is absorbed by molecules in the atmosphere’s lower layers and creates oscillations that extend into the higher layers, where the wave amplitudes enlarge because of decreasing air density.

Atmospheric tides are global-scale waves with periods that are harmonics, or multiples, of a 24-hour day. They have important implications for climate, atmospheric chemistry, and such phenomena as geomagnetic storms. The tides are driven in large part by the absorption of ultraviolet radiation by stratospheric ozone and of infrared radiation by tropospheric water vapor. Recently, Maura participated in a research project that found some tropical storms can also trigger tides that affect the thermosphere and ionosphere.

Maura arrived at HAO in 1992. She earned both her master’s degree and Ph.D. in physics from Boston College, and worked as a research staff member at the Massachusetts Institute of Technology before coming here. She is a member of the NASA Geospace Management Operations Working Group, and she also is a scientific discipline representative on the Scientific Committee on Solar-Terrestrial Physics for the International Council of Scientific Unions.

One of Maura’s principal achievements at NCAR was developing the Global Scale Wave Model, a two- dimensional linear representation of global atmospheric waves. Researchers use it to investigate tidal and planetary wave signatures in the upper atmosphere, comparing model results with radar, lidar, and satellite data and also investigating the sensitivity of planetary waves to winds in the middle atmosphere. The GSWM results are also used by general circulation modelers at NCAR and throughout the atmospheric research community. Because many of the general circulation models do not reach down to Earth’s surface, the modelers import GSWM tidal data to account for the missing atmospheric tidal physics below their models’ lowest boundaries.

Maura has also applied her knowledge of tides beyond Earth, participating in the development of a model of tides in the atmosphere of Mars.

Jim Hurrell of the Climate and Global Dynamics Division is also interested in large-scale atmospheric phenomena but with a different focus. His research centers on understanding the processes that govern hemispheric and global patterns of atmospheric circulation variability, and the impact of those patterns on regional climate and weather.

Jim earned both his master’s and Ph.D. in atmospheric science from Purdue University. After graduating in 1990, he came to NCAR as a visiting scientist. His research here has been recognized with the NCAR Outstanding Publication Award in 1997 and the 2001 Clarence Leroy Meisinger Award of the American Meteorological Society (AMS). His community service includes appointments to panels of the National Research Council, AMS committees, and several panels of the Climate Variability and Predictability (CLIVAR) research effort of the World Climate Research Programme, including a current stint as co-chair of the Scientific Steering Committee of U.S. CLIVAR.

Jim is best known for his research into the North Atlantic Oscillation (NAO), the large-scale seesaw in atmospheric pressure that spans the North Atlantic and influences weather and climate from North America through Europe. This year, he edited a monograph on the topic, The North Atlantic Oscillation: Climatic Significance and Environmental Impact, which brought together leading atmospheric scientists, oceanographers, paleoclimatologists, and biologists to present a state-of-the-art assessment of current understanding of the phenomenon.

Jim’s recent work also may point to the influence of human-caused emissions on the recent behavior of the NAO. The NAO has been stuck in an unusually pronounced positive index phase over the past two decades during the winter months, which means that low-pressure has been generally hovering over Iceland with abnormally high pressure over the middle latitudes of the Atlantic from the Azores to the Iberian Peninsula. This phase causes warm, moist westerly winds to blow over Europe and Asia, warming land surfaces there, while stronger-than-usual northerly winds bluster over Greenland and northeastern Canada, carrying cold air south and chilling both land and sea. Jim’s research attributes this holding pattern to a warming of tropical ocean waters, possibly due to the buildup of greenhouse gases in the atmosphere.

Jim’s next step? Studying the connection between projections of future tropical ocean water temperatures and climate change on a regional level. In particular, he wants to use climate models to determine how ocean temperatures may change in coming decades and how, in turn, the water temperatures are likely to affect not only the NAO but also regional climate around the world.

In addition, two NCAR researchers have been promoted to the scientist III level, which is one step below senior scientist. They are Jeff Anderson, who has a joint appointment to the Climate and Global Dynamics and Mesoscale and Microscale Meteorology divisions, and Frank Flocke of the Atmospheric Chemistry Division. •David Hosansky


Also in this issue...

Taking charge of GLOBE

Ann-Elizabeth's iggies

A SOARS summer

One hail of a storm

Fire Season

Tackling the MS150

Delphi Question: Priarie dog display

Short takes


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