Recent Developments in Deriving Accurate Total Column Ozone from Satellites: Application to NPP/OMPS

Total column ozone was among the first geophysical variables to be measured from space. By the early 80s, total ozone data produced using the SBUV and TOMS instruments had achieved accuracies comparable to the best-run ground-based stations. At present, the quality of data produced using the Backscatter Ultraviolet (BUV) technique is arguably better than most ground-based data at solar zenith angles larger than 75 degrees and can be produced over a wider range of atmospheric conditions, from clear to heavily overcast, than is possible from ground. We will discuss how this long-term quest to improve satellite ozone data quality has led to better understanding of how solar UV radiation interacts with the Earth's atmosphere. This, in turn, has led to the development of several innovative UV remote sensing techniques, including measurement of aerosol absorption, determination of cloud height, and the use of "cloud slicing" to study tropospheric ozone and other trace gases. We will discuss how recent advances in this field can be applied to new generation of operational ozone sensors on EUMETSAT, NPP, and NPOESS satellites. Finally, we will discuss the validation challenges we face in an era when the ground-based technology has started to lag behind the satellite technology making the traditional concept of "ground-truth" obsolete.