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The endless summer? The growing season continues to grow longer, with spring arriving a week early and autumn delayed by 10 days, according to a recent study completed by Liming Zhou (GRS'01), a recipient of the NASA Earth System Science Graduate Fellowship, Ranga Myneni, a CAS associate professor of geography, and their associates in the geography department and at the NASA Goddard Space Flight Center. The summary of their findings was released this week.

Extending a 1997 study that first reported what Myneni calls "the greening greenhouse," the research correlates temperature data and satellite observations of vegetation recorded from 1981 to 1999 in the latitudes between 45°N and 70°N (roughly the latitude of St. Paul, Minn., to the northern coast of Alaska) in North America and Eurasia. The current study confirms that plant life in the northern hemispheres has been growing more vigorously since 1981, the result of rising temperatures and the accumulation of greenhouse gases. It further revealed differing patterns on the two continents, with Eurasian greening over an enormous contiguous area encompassing the forests and woodlands that stretch from central Europe through Siberia to far-east Russia. North American greening was more fragmented, evident primarily in the forests of the East and the grasslands of the upper Midwest.

The researchers cite several studies that report behavioral changes in animals in response to the longer spring and summer. These include birds laying their eggs earlier in the season and birds and butterflies migrating farther north.

This research will appear in the September 16 issue of the Journal of Geophysical Research-Atmospheres. Further information, including figures, is available online at http://cybele.bu.edu.

Magnetic resonance. From navigation to high-speed trains, from MRIs that produce highly accurate images of the body to high-energy particle colliders that help probe the nature of matter, magnetic fields play a significant role in life on Earth. They may also, according to Dan Clemens, a CAS associate professor of astronomy and director of the Institute for Astrophysical Research, play a central role in the formation of stars, and in the very existence of the universe as we know it.

Armed with Mimir, a powerful new instrument that he and his colleagues are constructing in cooperation with the Lowell Observatory and with funding from NASA, the National Science Foundation, and the W. M. Keck Foundation, Clemens will chart the magnetic fields that lace through the Milky Way. Named after the Norse giant who guards the Well of the Highest Wisdom, Mimir is a wide-field imaging spectrometer and polarimeter that will be used in conjunction with the Lowell Observatory's 72" Perkins telescope. It utilizes near-infrared radiation (light with wavelengths between about 1,000 and 5,000 nanometers that is invisible to the human eye), enabling it to penetrate even into the dense clouds of gas where stars take form, which are opaque to light in the visible spectrum.

Clemens believes that data collected by Mimir will help clarify the role of magnetic fields in star formation, a question that has eluded scientists up until now because of the enormous difficulty involved in measuring these fields. It may, in fact, shed light on a theory that holds that magnetic fields regulate the speed at which stars form. In this scenario, without magnetic fields to slow down star formation, the Milky Way would no longer exist -- all of its stars would have formed and blazed out of existence eons before man evolved on Earth.

"Research Briefs" is written by Joan Schwartz in the Office of the Provost. To read more about BU research, visit http://www.bu.edu/research.

7 September 2001
Boston University
Office of University Relations