MFRSR-based climatologies of atmospheric aerosols, trace gases and water vapor

摘要

Measurements from ground-based sunphotometer networks can be used both to provide a ground-truth validation of satellite aerosol retrievals and to produce a land-based aerosol climatology which is complementary to satellite retrievals that currently are being performed mostly over ocean. The Multi-Filter Rotating Shadow-band Radiometer (MFRSR) has become a popular network instrument in recent years, several existing networks operate about a hundred instruments providing good geographical coverage of the US. We describe and validate a retrieval algorithm for processing MFRSR data from clear and partially cloudy days. This method uses consistency between direct normal and diffuse horizontal measurements together with a special repgression technique for retrieval of daily time series of column mean aerosol particle size, aerosol optical depth, NO_2, ozone and water vapor column amounts together with the instrument's calibration constants. This method has been successfully used to analyze MFRSR measurements from a number of instruments both from large networks and those operated by individual users. The analysis of long-term MFRSR measurements provides a description of seasonal and inter-annual changes in aerosol parameters and in column amounts of ozone, NO_2 and water vapor as a function of geographical location. Application of this analysis method to the measurements from growing numbers of MFRSRs opens the possibility to build large-scale climatologies basing on MFRSR network data.