Sunphotometer measurements at Yellowknife
Principal Investigator: O'Neill, Norm T (3)
Licence Number: 14936
Organization: Université de Sherbrooke
Licenced Year(s): 2011 2010 2009
Issued: Jul 15, 2011
Project Team: Bruce McArthur (co-I, Environment Canada), Ihab Aboud (co-I, Environment Canada), Jim Freemantle (co-I, Université de Sherbrooke)

Objective(s): To measure the aerosol optical depth and sky radiance at Yellowknife using an automated, sun-tracking, CIMEL sunphotometer

Project Description: The objective of this research project is to measure the aerosol optical depth and sky radiance at Yellowknife using an automated, sun-tracking, CIMEL sunphotometer.

In this project, measurements of instruments in the network (called AEROCAN which is the Canadian sub-network of the world-wide NASA-led network called AERONET) are performed using a CIMEL sunphotometer / sky radiometer. This instrument tracks the solar disk all day and makes measurements of atmospheric extinction of the solar beam while occasionally scanning out along the solar almuncantar to measure sky radiance (the solar almucantar is the fixed elevation-angle circle defined by scanning a radiometer from the centre of the sun out to an azimuth angle of 180 degrees away from the sun). Both types of measurements give information about the columnar concentration, size and nature of the aerosols at the time of measurement.

A small instrument has been installed on the roof of the Aurora College building in Yellowknife. The
sunphotometer is a passive instrument (it does not emit radiation) and does not present any risk to the public. For more information on the CIMEL sunphotometer / sky radiometer go to the AEROCAN web site at; and the AERONET’s website, at

Aside from the technical tasks which require a site operator the data from the Yellowknife sunphotometer can be viewed on-line in near real time. Local people can then, for example, monitor the relative impact of forest fire smoke over the region.

Dr. O'Neill and the rest of the co-investigators have done many media presentations and would be happy to do interviews for local media.

The fieldwork for this study will be conducted from July 15, 2011 to December 31, 2011.