Remote Sensing of Atmospheric Aerosols and Trace Gases by Means of Multifilter Rotating Shadowband Radiometer. Part II: Climatological Applications

Abstract

Measurements from ground-based sun photometer networks can be used both to provide ground-truth validation of satellite aerosol retrievals and to produce a land-based aerosol climatology that is complementary to satellite retrievals that are currently performed mostly over ocean. The multifilter rotating shadowband radiometer (MFRSR) has become a popular network instrument in recent years. Several networks operate about a hundred instruments providing good geographical coverage of the United States. In addition, international use of the MFRSR has continued to increase, allowing MFRSR measurements to significantly contribute to aerosol climatologies. This study investigates the feasibility of creating a ground-based aerosol climatology using MFRSR measurements. Additionally, this analysis allows for testing of the performance of the retrieval algorithm under a variety of conditions. The retrieval algorithm is used for processing MFRSR data from clear and partially cloudy days to simultaneously retrieve daily time series of column mean aerosol particle size, aerosol optical depth, NO2, and ozone column amounts together with the instrument's calibration constants directly from the MFRSR measurements for a variety of sites covering a range of atmospheric and surface conditions. This analysis provides a description of seasonal changes in aerosol parameters and in column amounts of ozone and NO2 as a function of geographical location. In addition, the relationship between NO2 column amount and aerosol optical depth as a potential indicator of tropospheric pollution is investigated. Application of this analysis method to the measurements from growing numbers of MFRSRs will allow for expansion on this developing climatology.