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2626910 
Journal Article 
CHRISTINE: Code for high resolution satellite mapping of optical thickness and Angstrom exponent 
Sifakis, NI; Iossifidis, C; Kontoes, C 
2010 
Unk 
Proceedings of SPIE
ISSN: 0277-786X
EISSN: 1996-756X 
Proceedings of SPIE 
7827 
WOS:000287757200013 
According to the "contrast reduction" principle the aerosol optical thickness (AOT) can be retrieved and mapped over heterogeneous (such as urban) areas using a set of two satellite images of high spatial resolution: (i) one "reference image" with minimum aerosol content involving negligible AOT, and (ii) one "polluted image" with AOT to be assessed. AOT values retrieved in this way are thus relative to the reference image, and could be miscalculated when other than atmospheric changes have taken place in the time between the acquisitions of the two images. Previously developed DTA and SMA image processing codes are subject to this potential source of AOT miscalculation because the contrast reduction is applied to single spectral bands. The new CHRISTINE code takes into consideration contrast reduction in more than one spectral band and uses the Angstrom's power law to isolate atmospheric effects attributable to aerosols. Preliminary testing of the new code over the Athens urban area against results obtained using the previous codes showed a considerable improvement in terms of the area over which AOT can be retrieved with high confidence. CHRISTINE has also a complementary feature of providing information on the aerosol size distribution emerging from Angstrom coefficient approximation. 
Satellite; remote sensing; air pollution; urban; aerosols; optical thickness; Angstrom exponent