|
|
|
This perspective of northern Canada and northern Greenland was capturedby NASA's Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project.  hen Jonathan D. W. Kahl walked the four blocks to a Siberian disco one frigid night in 1993, he had more on his mind than “Staying Alive.”
Sure, the Arctic wind was biting, even in April. And yes, his ordinarily vegetarian system was digesting a supper of roasted caribou. But Kahl knew these hardships came with the territory he was visiting for the first time after six years of research from afar. Besides, the caribou tasted better than the seal blubber he had sampled. “That was terrible,” says Kahl, a professor of atmospheric sciences at UWM since 1990 and a faculty member in the Department of Mathematical Sciences since 1998. “I choked down a couple of bites.” Kahl and 14 U.S. colleagues had flown to Cherskiy, Siberia, to assess a former Soviet air base that was inaccessible by road or railroad and open to ship traffic just two months per year. The air base had served as a supply depot and emergency rescue station for a network of temporary Soviet Drifting Ice Stations that had collected Arctic weather data from 1937 to ‘91.
Bordering half the Arctic, the USSR was keenly interested in the region’s weather. The Soviets stationed scientists and technicians and their equipment on Arctic ice floes, at first in fur-lined tents, in later years in insulated buildings. They measured temperature, precipitation, winds, and air pressure as their stations drifted around the Arctic, Kahl explains. When the ice began to break up beneath them, usually after a year or two, the Cherskiy support team came to the rescue. The leader of the base when the USSR disintegrated, a former Soviet military commander named Babushkin, was trying to sell its access and services to Western scientists. The visiting U.S. scientists got the red-carpet treatment. Kahl and his colleagues were flown over the area; Kahl says he chose the spot where his pilot landed the plane on the ice. And his appreciation grew for the delicate work the Soviet scientists had undertaken during indelicate conditions. Kahl pointed out that releasing a weather balloon when the temperature is minus 40 Celsius and the winds are howling is no day at the beach. The visiting scientists were convinced that the Cherskiy station could aid their research, but leaders of the isolated town weren’t ready for the capitalism proposed by Babushkin, Kahl says. They nixed the potential deal. The collapse of the former Soviet Union meant a halt to science funding and thus the cessation of the drifting stations. The United States and Canada filled the vacuum somewhat by establishing their own small network of drifting stations. However, Kahl says, most Arctic weather data now comes from a buoy network that measures and transmits data, supplemented by data from weather satellites and instruments mounted on commercial planes that fly over the area. The data are “not quite as good as the ice stations, but are getting better all the time,” he says. Kahl would know. He is the first Western researcher to utilize the complete data collected by the Soviet drifting stations—work begun with a series of accidental discoveries. In 1987, Kahl was doing postdoctoral work at the National Oceanic and Atmospheric Administration (NOAA) in Boulder, Colo. He was collaborating with atmospheric researchers who were studying why the ostensibly pristine Arctic atmosphere was choked each March and April with pollutants like those over Pittsburgh. “Air from the northern cities with very poor emission controls, like Siberia,” was blowing into the Arctic and fouling the atmosphere, according to Kahl.
His assignment at NOAA was to develop models to simulate the upper-air movement of pollution over the permanent northern ice cover, an area the size of the continental United States. But he could find no meteorological measurements for the region. “I was very disheartened,” he says. In his reading he encountered notes about the Soviet Drifting Ice Station data. “They were very obscure references and I couldn’t find much,” he says. Then the proverbial apple of discovery bonked his head. On a night out in Denver, he and his wife wandered into a book store. He noticed a used coffee-table book featuring photos of the Canadian Air Force—hardly his usual reading material. “I happened to open the book and I found a picture of a Canadian fighter plane flying over Soviet Drifting Station NP-22,” he says. “Beneath the plane were 20 or 30 aircraft, buildings, and tents. I thought, ‘Yes, the data exist!’” But the information was closely held inside the Soviet Union. In 1990, he received a National Science Foundation grant to travel to the data repository, the Arctic and Antarctic Research Institute (AARI) in Leningrad, now called St. Petersburg. He went under the aegis of Working Group VIII of the United States-Russian Federation Agreement for Protection of the Environment and Natural Resources, an official dataexchange accord. He found two AARI bookshelves filled with bound volumes of handwritten data that had been collected by the drifting stations beginning in 1945. The Russians wouldn’t allow him to copy anything. “The best I could negotiate was a deal for them to input the data in the computer,” he says. He expected the data to be entered within two years, but two factors intruded. With the collapse of the Soviet Union, science funding disappeared there. “To their credit, the institute staff still did the work, but it was greatly delayed,” he says. Moreover, Arctic scientists were shifting their attention to the emerging warnings— alarmist, according to Kahl—that the polar ice caps were melting due to rampant global warming.
He and colleagues collected and analyzed data from more than 8 million weather balloon ascents in other parts of the Arctic. They observed warming, but found it was insignificant and part of a highly variable temperature range at surface level. “Temperatures can vary from minus 40 to 0 Celsius in one day,” Kahl notes. They published their conclusions in the prestigious scientific journal Nature in 1993. The article earned Kahl his “15 minutes of fame,” including interviews in Time, U.S. News & World Report, the London Times, and other major media outlets. More recently, he has learned about the variability of the Arctic climate at different altitudes. “For example, the climate is highly variable at surface level from year to year and it gets a little bit less variable as you go up. Also, the climate trends in the Arctic are highly variable from place to place,” he says. “We’re also detecting some significant cooling happening up in the stratosphere, the layer of the atmosphere that begins about 10 kilometers above the earth’s surface. That’s a sort of fresh result. We see it widespread throughout the Arctic and in all the seasons.” The classic model of global warming caused by increasing concentrations of greenhouse gases would lead to warming at the surface and cooling in the stratosphere, Kahl adds. “Of course, we don’t see the warming of the surface. [The findings present a] more complex picture than the theory would suggest.” So he continues his research. Kahl’s other main topic also involves the Arctic winds, but his colleagues in this effort have a subterranean focus. They are analyzing a 3,000-meter-deep ice core dug in Greenland, encompassing 250,000 years of geological and atmospheric history, to learn how weather movement affects the climate. In northern Greenland’s case, climate essentially means snow. The technical terms for the scientists’ focus is the air-snow transfer function. “We’re trying to determine the relationship between atmospheric transport patterns and the chemistry of snow and use that to extrapolate backwards,” he says. For example, the Roman Empire is thought to have succumbed to rampant lead poisoning. The Greenland ice core samples show “a spike in atmospheric lead levels at that time,” Kahl says. Educating children The atmospheric scientist also is breaking new ground in meteorological education for high school students via computer and the most traditional medium, books. He is author of the six-book How’s the Weather? series for Lerner Publications Co. in Minneapolis.
The series, which he wrote from 1991 to ‘98, grew out of a phone call from a college friend who was a Lerner editor. That series led to his invitation to write the National Audubon Society First Field Guide: Weather, published in 1998 by Scholastic, Inc. The 160-page book has sold 200,000 copies, he says. His books have received six awards, including an international award from the Society of School Librarians International. Kahl has since collaborated on four regional National Audubon Society Field Guide books for Alfred A. Knopf. “Writing for kids is really a challenge,” concedes Kahl, a profilic author of articles for scientific journals. “You have to balance simplification with truth. It’s very difficult to explain complex phenomena to kids.” But it’s worth the effort for Kahl. “Educating young kids is every bit as important as the big kids we educate here” at UWM. His other major effort for the pre-college set is an online meteorology curriculum he developed for high school students. The effort allows students to forecast weather using data available on the Internet. The curriculum is part of CoVis, short for Collaborative Visualization, a program developed at Northwestern University to maximize technology’s role in high school education. Approximately 2,000 students in 110 high school classrooms throughout North America make forecasts using Kahl’s “Internet Weather Forecasting Activity.” Students’ work is evaluated based on their reasoning. Kahl also teaches advanced air pollution modeling, air pollution meteorology, and introductory courses in meteorology at UWM. Kahl’s plate is so full, there isn’t room for a slice of roasted caribou. “I guess I don’t sleep much,” he says. Just another minor hardship he endures for his science. 
|
National Oceanic & Atmospheric Administration
