An analysis of TOVS data during the FROST special observing periods

Much of the Antarctic continent and surrounding oceans are devoid of observing platforms, making the southern hemisphere, south of 50°S, the most data-sparse area on the planet. To adequately define initial conditions for global atmospheric modelling, scientists are having to rely primarily on remotely sensed data from satellite-based systems. In this study, data from the TIROS Operational Vertical Sounders (TOVS) on the NOAA11 and NOAA12 polar-orbiting satellites are compared with balloon-based soundings from Antarctic stations using data from the three special observing periods of the FROST project. Results from the study suggest that, in general, TOVS-derived thickness values over continental Antarctica are highly suspect and likely to deviate significantly from the 'truth'. However, retrievals taken over oceanic regions, between 50°S and the Antarctic coast, are highly correlated with radiosonde measurements and should prove useful in deriving upper-air analyses for the FROST analysis project. In the second part of the study, where TOVS retrievals were compared with analyses from the Australian Bureau of Meteorology's Global Assimilation and Prediction (GASP) system, large discrepancies were found between GASP and TOVS analyses over continental Antarctica. Whether the major source of the discrepancies was in the TOVS retrievals or the model analyses is not clear.