ANALYSIS OF MONTHLY AVERAGE ATMOSPHERIC PRECIPITABLE WATER AND TURBIDITY IN CANADA AND NORTHERN UNITED-STATES

Atmospheric turbidity and precipitable water data are necessary as inputs to solar radiation or daylight availability models, and to daylighting simulation programs. A new model is presented to obtain precipitable water from long-term averages of temperature and humidity. Precipitable water data derived from this model are tabulated for some Canadian and northern U.S. sites. A discussion on the available turbidity data is presented. An analysis of the datasets from the WMO turbidity network is detailed. The effect of volcanic eruptions is discussed, as well as the possible comparisons with indirect determinations of turbidity from radiation data. A tabulation of the monthly average turbidity coefficients for ten Canadian stations and seven northern U.S. stations of the WMO network is presented.