Error analysis of the BUV total ozone algorithm

The backscatter ultraviolet (BUV) experiment was launched on the Nimbus-4 satellite in April, 1970. Recently, NASA's Ozone Processing Team (OPT) has archived the processed seven years (1970-77) of total ozone and vertical profile data. An overview is presented of the errors involved in retrieving total ozone from the measured radiances using the operational algorithm. The total ozone is derived by comparing the measured albedo with computed albedos. The computed albedos are obtained by a precise calculation of the radiative transfer in model atmospheres containing different amounts of total ozone. There are three classes of algorithmic errors involved in the procedure. These errors are related to computational errors, errors in external information, and modelling errors. The modelling errors are discussed in greater detail, taking into account the separation model, errors caused by tropospheric absorbers, and errors due to stratospheric scattering.