The research objectives of this proposal are twofold; (i) to analyze the coherence and complementarity of scanning Lidar data and passive sunphotometry over a three year period at the Egbert Ont. site and (ii) to develop a methodology for the algorithmic testing and validation of the MODIS/CALIPSO1 vertical profile algorithms.
The relationship between aerosol vertical profile information and the variability of passively derived optical parameters (aerosol optical depth in particular) is an open research question and a key motivation for the recent large scale aerosol characterization projects such as the Indoex campaign in the Indian Ocean. Regular active/passive ground-based optical measurements can serve as a means of investigating this relationship over temporal periods which extend beyond the event-scale duration of such experiments. Such measurements are interesting in their own right as a means of understanding the influence of local atmospheric inhomogenieties on the retrieval of passively measured optical parameters and in terms of inferring certain optical parameters from the combination of both types of data. These comparisons along with regularily acquired sky scanner data would also facilitate the development of a sunphotometer cloud screening algorithm which goes beyond the purely temporal criteria of the current (AERONET) algorithm.
The analysis of active/passive data at such stations will permit development of a methodology for the validation the MODIS/CALIPSO1 inversion algorithms in preparation for the altitude profile products of this sensor tandem. Although a ground based inversion algorithm which resembles the system to be validated would be something less than a true validation it would, for example, yield AODs which were significantly more accurate than the estimated MODIS AODs and it would yield particle size information (from the sky scanning capability of the network sunphotometers). To better evaluate the validity of such methods, we propose to also employ the Pacific2001 experiment results as a benchmark test.
1 formerly PICASSO-CENA