Total ozone determination by chappuis band absorption at an urban location

Abstract

Total columnar ozone was estimated at College Park, Maryland, from spectral measurements of the direct beam solar radiation in the visible wavelength spanning the Chappuis continuum (550 <A <700 nm). A comparison of total ozone derived by the Chappuis band measurements with Dobson spectrometer measurements of total ozone showed that the Chappuis band method differed from the Dobson method by approximately ±20% on the most stable days. These differences can be attributed to a combination of: large aerosol optical depths; diurnal variation of aerosol optical depth; the deviation from the assumed power law relationship used to estimate the change in aerosol optical depth with wavelength; and uncertainty in the values of ozone absorption coefficients.