Abstract
A six-channel Volz sunphotometer was used in the St. Louis urban area during Project METROMEX 1976 to monitor aerosol loading and atmospheric precipitable water. A weighted least-square fit of photometric observations to spatially and temporarily proximate radiosonde measured precipitable water vapor has enabled determination of the exponent (1/1.993) in the precipitable water equation indicating compliance with the square-root absorption law of band models.
Wavelength exponents calculated from least-square fits of water vapor transmission band optical depths to wavelengths have been found to be represented by α = 1.71 ± 0.54 for a set of 70 observations. Modal values of the wavelength exponent are centered at 1.60 and 1.90. Good agreement has been found between photometrically estimated aerosol distributions and in situ aircraft measured aerosol distribution daily trends.
