Edwin L. Aguirre
We all rely on local weather forecasts to plan our travels and outdoor activities, or even to decide whether to water the lawn.
But researchers like Prof. Paul Song in the Department of Physics & Applied Physics are also interested in “space weather,” the constantly changing environmental conditions in interplanetary space, especially between the sun’s atmosphere and earth’s outer atmosphere. While meteorologists deal with clouds, air pressure, wind, precipitation and the jet stream, space-weather scientists concentrate on changes in the ambient plasma (ionized gas), solar wind, magnetic fields, radiation and other matter in space.
“Predicting space weather is the next frontier in weather forecasting,” says Song, who directs UMass Lowell’s Center for Atmospheric Research (CAR).
A Challenging Problem
“Inclement space weather has increasingly become a threat to modern space technologies and services, such as GPS, shortwave radio and satellite communications,” says Song.
While large space-weather events, known as space storms or solar storms, can trigger spectacular displays of auroras, the high-energy particles produced by these storms can harm the health of spacewalking astronauts as well as airline passengers and crews flying at high altitudes along polar routes. Geomagnetic storms can also create a surge in electrical current, overloading electric power grids and damaging transmission lines and oil pipelines, notes Song.
Solar storms start out with coronal mass ejections, or CMEs, which are enormous bubbles of plasma flowing out from the sun.
“CMEs travel through interplanetary space and eventually hit Earth, potentially affecting our lives and those of orbiting satellites,” says Song. “The effects we feel on the Earth depend on how the interactions take place between a CME and Earth’s magnetosphere, a region well above the atmosphere where most satellites fly, and the ionosphere, which is roughly the top of the atmosphere.”
Song, together with Distinguished Research Prof. Vytenis Vasyliunas and Asst. Research Prof. Jiannan Tu of the CAR, recently received a three-year grant from NASA worth more than $356,000 to study these interactions.
Song says the processes taking place between the magnetosphere and the ionosphere are particularly complicated since they involve different types of matter.
“For example, Earth’s atmosphere, known as the thermosphere in this region, consists of many different species of neutral atoms and molecules, while the interplanetary and magnetospheric particles are electrically charged. Auroras are a result of neutral atoms colliding with charged particles,” explains Song.
Because the interactions involved in the magnetosphere-ionosphere coupling are very complicated, current prediction models have to substantially simplify the mathematical and physical descriptions, based on a so-called steady-state description, he says.
“A good analogy is using a series of photos to describe a martial arts show and each photo has to be taken when the performer is posing on the floor and not moving,” says Song. “We are developing the most advanced theoretical models and numerical algorithms to describe the coupling. In the analogy, we are developing a video camera.”