COMPARISONS OF THE MG-II INDEX PRODUCTS FROM THE NOAA-9 AND NOAA-11 SBUV 2 INSTRUMENTS/

The Mg II Index is a proxy indicator of solar UV activity which is pro duced from measurements of the chromospheric Mg II absorption line at 280 nm. Mg II index data sets have been derived from the NOAA-9 and NO AA-11 SBUV/2 irradiance data sets using both discrete scan measurement s about the Mg II line and continuous scan (sweep) measurements over t he UV spectrum from 160-400 nm. This paper will discuss the rationale behind the creation of the different Mg II index products, and make a quantitative assessment of the differences between these products. Rec ommendations for future use of the Mg II index will also be presented.