SATELLITE AND GROUND BASED MONITORING OF AEROSOL PLUMES

摘要

Plumes of atmospheric aerosol have been studied using a range of satellite and ground-based techniques. The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) has been used to observe plumes of sulphate aerosol and Saharan dust around the coast of the United Kingdom. Aerosol Optical Thickness (AOT) was retrieved from SeaWiFS for two events; a plume of Saharan dust transported over the United Kingdom from Western Africa and a period of elevated sulphate experienced over the Eastern region of the UK. Patterns of AOT are discussed and related to the synoptic and mesoscale weather conditions. Further observation of the sulphate aerosol event was undertaken using the Advanced Very High Resolution Radiometer instrument (AVHRR). Atmospheric back trajectories and weather conditions were studied in order to identify the meteorological conditions which led to this event. Co-located ground-based measurements of PM_(10) and PM_(2.5) were obtained for 4 sites within the UK and PM_(2.5/10) ratios were calculated in order to identify any unusually high or low ratios (indicating the dominant size fraction within the plume) during either of these events. Calculated percentiles of PM_(2.5/10) ratios during the 2 events examined show that these events were notable within the record, but were in no way unique or unusual in the context of a 3 yr monitoring record. Visibility measurements for both episodes have been examined and show that visibility degradation occurred during both the sulphate aerosol and Saharan dust episodes.