Aeroecology: Transcending boundaries among ecology, meteorology, and physics

The title comes from a session at the American Association for the Advancement of Science’s annual meeting, which was held in Washington, DC, and ended yesterday.

The annual AAAS meetings are somewhat odd. At the other meetings I attend, scientists give talks for other scientists. At AAAS meetings, scientists give talks for science journalists. As you might expect, AAAS talks are accessible and informative for nonexperts. However, if your job, like mine, entails keeping up with advances in a particular field, you’ll learn more from the sessions devoted to topics outside your field—which is why I spent Saturday afternoon learning about the ecology of Earth’s aerosphere.

Belying the sweeping scope of its title, the aeroecology session was about using radar, lidar, and other imaging modalities to track and count bats, birds, and airborne insects. The narrow focus did not lessen my interest. Rather, I learned that just gathering ecologically relevant radar data, let alone using them, is a fascinating problem that’s rewarding to solve.

The map, which you can enlarge by clicking on it, shows the locations of the 159 high-resolution Doppler radars operated by the National Oceanic and Atmospheric Administration. Together, the networked radars—known as NEXRAD—provide meteorologists with a detailed and near-complete view of precipitation over the continental US.

The network is in the midst of a major upgrade. Old radars that use only horizontally polarized waves are being replaced with more advanced radars that use both horizontally and vertically polarized waves. By rapidly switching between the two polarizations, the new radars can tell whether precipitation is rain, sleet, hail, or snow.

They can also tell the difference between precipitation and airborne fauna. Indeed, meteorologists routinely filter out from their radar maps the signals from swarms of bats and other animals. Ecologists, however, are using the data to better understand how colonies of insectivorous bats and birds wax and wane in response to climate and other factors.

In her talk, ecologist Winifred Frick of the University of California, Santa Cruz, described using radar data to determine what local weather conditions influence when colonies of Brazilian free-tailed bats debouch from their caves for their evening feed.

But what of the physics promised in the title? One of the session speakers, Phillip Chilson of the University of Oklahoma in Norman, is a physicist. Among the problems he tackles is how to get as much information as possible from NEXRAD. Dual polarization radar, he said, could be used to distinguish long skinny insects, such as dragonflies, from round squat insects, such as bumblebees.

At the end of the session, the speakers fielded questions from their audience. One questioner asked about the challenges of working in an interdisciplinary team. Language—or rather jargon—was cited as one barrier to effective teamwork, but its negative effect was more than offset by the benefits of interdisciplinary teamwork.

Frick recalled that before she worked with Chilson, she tended to regard the atmosphere as a static medium, a place for bats and other aerosphere-dwelling animals to fly and feed in. From Chilson and his colleagues, she learned to appreciate the atmosphere’s dynamic properties—which, as it turns out, are important to the bats, birds, and insects that she studies.