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4253114 
Journal Article 
Correction of ozone influence on TOA radiance 
Richter, R; Heege, T; Kiselev, V; Schlaepfer, D 
2014 
Yes 
International Journal of Remote Sensing
ISSN: 0143-1161
EISSN: 1366-5901 
35 
23 
8044-8056 
WOS:000345583500014 
An accurate atmospheric correction (AC) of Earth remote-sensing data in the spectral region 450-800nm has to account for the ozone gas absorption influence. Usual operational AC codes employ a fixed ozone concentration corresponding to a climatologic average for a certain region and season, e.g. the mid-latitude summer atmosphere of the Moderate Resolution Atmospheric Transmission (MODTRAN) code. The reasons for a fixed ozone column are that ozone does not vary rapidly on a spatial and temporal scale, and additionally, the look-up table (LUT) size for AC is already big. This means that another degree of freedom for the ozone parameter would dramatically increase the size of the LUT database and the time required for LUT interpolation. In order to account for this effect, we use already existing LUTs that were calculated for a certain ozone reference level, e.g. an ozone column of g=330 Dobson Units (DU) for MODTRAN's mid-latitude summer atmosphere. Then the deviation of the top-of-atmosphere (TOA) radiance L(g) from the reference level L(g=330) is calculated as a function of solar and view geometries. The calculation is performed for a set of 36 wavelengths in the ozone-sensitive spectrum (450-800nm) and five ozone columns. The last step computes the linear regression coefficients for each wavelength and geometry. The results are stored in a small table (11kB). It is shown that the ozone influence is accurately accounted for by multiplying the modelled radiance L(g=330) with a factor depending on g and wavelength yielding TOA radiance relative errors smaller than 0.5% for a wide range of ozone concentrations between 180 and 500DU. Selected examples of a sensitivity study of the ozone effect on the retrieval of water constituents demonstrate the need to account for ozone in the AC step.