Saturday, August 27, 2016
Last updated: 11 months ago

UBC’s mysterious green laser

The green laser sometimes seen emanating from Totem Field is more than just a pretty light show or an omen of alien invasion—it’s helping scientists measure the amount of small particles in the atmosphere which affect air quality and climate change. And it’s the first of its kind in Canada.

The laser is a part of a project called the Canadian Operational Research Aerosol Lidar Network (CORALNet), and was first launched at UBC in April 2008.

According to CORALNet’s website, the laser is a form of Light Detection and Ranging, or lidar, which uses light rays much the same way that radio waves are used in radar. The lidar beam is emitted every ten seconds 24/7, only stopping in the event of rain or if the instrument’s radar picks up a bird or airplane passing nearby.

Every ten seconds, it is projected into the sky to an altitude of twenty kilometres. At the same time, an instrument on the ground measures the amount of light refracted off tiny suspended particles in the air, called aerosols. The laser isn’t visible during the day, but if the beam passes through low cloud at night, it can give off a ghostly green glow.

Aerosols are usually invisible to the naked eye and come from both man-made and natural sources such as volcanic activity, vehicle and industrial pollution, smoke from forest fires, burning fossil fuels and ocean spray. The results are plotted hourly on CORALNet’s website.

Dr. Ian McKendry, manager of the CORALNet project at UBC and a specialist on issues surrounding air quality, said they affect the climate by absorbing and reflecting radiation from the sun, affecting the amount of rays the earth receives.

“[Our goal is] to be able to use the data collected to forecast particular events that may affect human health,” he said.

McKendry plays an active role in the project maintaining the instruments, including cleaning the window through which the laser shines.

Although lidar has been used to measure aerosols since the 1960s, the CORALNEt project is “novel in the sense that the lidar installations are completely autonomous and are controlled remotely” from another station in Ontario, said McKendry.