Development and Validation of a Technique for Merging Satellite Derived Aerosol Optical Depth from SeaWIS and MODIS.

Merging time series of satellite derived aerosol products from independent missions can support aerosol science by combining in a consistent way temporally overlapping data sets and by increasing data coverage. A merging technique applied to satellite aerosol optical depth ta is presented and tested with SeaWiFS and MODIS-Aqua data. The technique relies on least squares fitting of the available ta spectra onto a linear or second-order polynomial relation between log-transformed ta and wavelengths. First, the sensor specific products are compared with field observations collected by a sun-photometer installed on the Acqua Alta Oceanographic Tower in the northern Adriatic Sea. Mean absolute percentage differences are approximately 21% at 412 and 443 nm, and increase with wavelength, with large overestimates at the red and near-infrared bands. The mean absolute differences are typically 0.04. When inter-compared, the 2 satellite products agree well, with mean absolute percentage differences lower than 20% at all wavelengths and little bias. The results of the comparison of the merger outputs with the field data are well in line with the validation results of the sensor-specific products, and are comparable for the various merging procedures. The benefits of merging in terms of data coverage are briefly illustrated for the Mediterranean basin.

MELIN Frederic;  ZIBORDI Giuseppe;  DJAVIDNIA Samuel; 

2007-05-14

ELSEVIER SCIENCE INC

JRC35462