Analyses of haze and mist situations over Swiss lowlands duringsummer smog-periods with NOAA-AVHRR data

摘要

Within the Swiss interdisciplinary summer-smog research programmePOLLUMET (POLLUtion and METeorology), systematical analyses of haze andmist concentrations over the Swiss lowlands with digitalweather-satellite data (NOAA-AVHRR) were made. The aim of this study wasto learn about the temporal and spatial behaviour of haze and mist whichis very important for air pollution situations. A model was createdwhich is based on the calculation of the sky light reaching thesatellite sensor in the visible and near-infrared channels. The skylight is caused by the particles in the lower region of the troposphere(haze and mist causing particles) and, therefore, the sky light can beconsidered proportional to the loading of haze and mist. Taking the skylight as an indicator of haze and mist, the main advantages are that noadditional information concerning the atmosphere is needed and theparameter “sky light” is itself one part of the incomingradiation at the satellite sensor. With the model developed, this amountof the signal received at the satellite sensor can be calculated. Withthis new tool, time series of haze and mist concentrations during summersmog-periods over the Swiss lowlands could be calculated and analysed.The main interest focused on the behaviour of haze and mist quantitiesin different areal scales and over different objects on the earth'ssurface. The analyses showed interesting and even surprising results