Ground based measurements of aerosol properties using Microtops instruments.

The contribution of aerosols to the signals at top of the atmosphere must be accounted for remote sensing of the ocean and land surface, which is known as atmospheric correction. Validation of atmospheric correction procedures require ground based measurements of aerosol properties. Ground based measurements of aerosol properties give also a basis for validation of the aerosol models used by atmospheric correction algorithms. Ground based measurements of aerosol properties have been performed in the coastal area of the southern Baltic Sea and near Berlin with a Microtops II Sunphotometer and a Microtops II ozone monitor, both onboard a ship and on the land surface. The present paper gives examples of atmospheric parameters which can be obtained from Microtops measurements and reports some experience how to perform and analyze these measurements. Then application of these results is demonstrated with 2 examples. Validation of atmospheric correction algorithms is demonstrated with a comparison of aerosol optical thickness resulting from satellite data with total column aerosol optical thickness from ground based measurements at time of satellite overpass. The agreement is better than 0.03 at 750 nm. Another example uses the aerosol properties found from ground based measurements as input to radiative transfer modeling of the signals received at satellite. The agreement between modeled and measured signals is fine within the expectable uncertainty. [ABSTRACT FROM AUTHOR]