Space Weather

NCAR scientist Stanley Solomon captured this aurora unfolding above NCAR's Mesa Laboratory on the evening of 20 November 2003. Solar storms can have dramatic effects on Earth’s atmosphere. When many tons of magnetized gas strike the Earth's magnetic field (the magnetosphere), the result can be geomagnetic storms that spark million-ampere electric currents and distort the magnetosphere. This can scramble radio waves, disrupt navigational systems, and pump extra electricity into power lines.

In March 1989, a magnetic storm burned up a transformer in New Jersey, collapsing the entire power grid in Quebec and leaving six million people without power. Such storms also heat the upper atmosphere, exerting a drag on low-orbiting satellites. Astronauts in space can be subjected to potentially lethal doses of radiation.

How best to prepare society for these inevitable storms? As part of their work for the Center for Integrated Space Weather Modeling, NCAR scientists are creating new computer models of the Sun and the upper regions of Earth’s atmosphere. This work may lead to numerical forecasts of solar activity, much the way weather forecasters use computer models to generate forecasts of rain, snow, hail, and wind storms. In time, forecasts of coronal mass ejections and other major solar disturbances may become as commonplace as forecasts of thunderstorms.

The same research will lead to forecasts of the beautiful atmospheric lights known as the aurora borealis (in the Northern Hemisphere) and aurora australis (Southern Hemisphere). The aurora is produced when the solar wind interacts with Earth’s magnetic field to produce high-energy particles. These particles are guided by the magnetic field toward the upper atmosphere above Earth's high latitudes, where they collide with oxygen, nitrogen, and other molecules. Each molecule is electrically excited and emits light in a characteristic hue. For example, oxygen emits red and yellow-green, and nitrogen emits blue.

Although the aurora are often called northern or southern lights because they are most visible in polar regions, viewers in the Northern Hemisphere can sometimes see them as far south as Los Angeles, Rome, and Tokyo. Another benefit of accurate forecasts will be alerting the public to the best times and places to view these spectacular sky shows.