Optical characteristics of aerosol determined by Cimel, Prede, and Microtops II sun photometers over Belsk, Poland

Abstract

An experimental campaign was carried out at Central Geophysical Laboratory at Belsk (Poland) in October 2007. Three sun photometers: Cimel CE-318, Prede POM-01L and Microtops II were used to obtain the atmospheric aerosol optical characteristics. Cimel CE-318 and Prede POM-01L are automatic sun-tracking devices common in the world networks for aerosol investigations AERONET and SKYNET. Microtops II is a hand-held manual device often used in field experiments because of its mobility. The results obtained show similar behavior of the aerosol optical depth variations and close values obtained by the three devices at the common wavelengths over rural area. The Microtops II readings are between the readings of the other two sun photometers. The experiment carried out is helpful and shows that the Microtops II sun photometer provides comparable results to these obtained by the Cimel CE-318 and Prede POM-01L sun photometers and potential of using Microtops II for measurement over an urban and rural area. Aerosols are an enigmatic yet indispensable component in global climate studies and modeling. The physical characteristics, composition, abundance, and spatial distribution and dynamics of aerosols are still very poorly known 1 . Aerosol spectral optical depth (AOD), Angstrom coefficients and precipitable water vapor amount are very important physical parameters for characterizing aerosols. Routine observation of total atmospheric column AOD and water vapour globally is a fundamental way of determining aerosol optical characteristics and its influence in the global radiation budget and climate change. The most practical means of making these observations is by remote sensing, which can be either from the ground (looking in the skyward direction with sun photometers) or from space (looking toward the ground through the atmosphere with imaging radiometers onboard satellites or high altitude aircraft) 1 . The ground-based measurements can be used for comparison with satellite data and their calibration but they also have independent regional and local significance. In remote sensing different devices are used to carry out the measurements. Generally, they are divided in two groups: passive (sun photometers) and active (lidars) devices. Different methods and algorithms are used and different accuracy is obtained. Due to this, joint experiments, comparisons and calibrations