Six-year observations of aerosol optical properties at a southern African grassland savannah site
Autor: | Aki Virkkula, Miroslav Josipovic, Lauri Laakso, Markku Kulmala, Johan P. Beukes, Marcell Venter, Ville Vakkari, Pieter G. van Zyl |
---|---|
Přispěvatelé: | Institute for Atmospheric and Earth System Research (INAR), Department of Physics, 10092390 - Beukes, Johan Paul, 22648143 - Josipovic, Miroslav, 10710361 - Van Zyl, Pieter Gideon, 33371210 - Vakkari, Ville T., 21240442 - Laakso, Lauri, 22120017 - Venter, Marcell |
Jazyk: | angličtina |
Rok vydání: | 2020 |
Předmět: |
Atmospheric Science
Angstrom exponent Absorption coefficient (σAP) Absorption coefficient (sigma(AP)) 010504 meteorology & atmospheric sciences SURFACE Single scattering albedo (ω0) 010501 environmental sciences VOLATILE ORGANIC-COMPOUNDS Atmospheric sciences REGIONAL BACKGROUND SITE CHEMICAL-COMPOSITION 01 natural sciences Population density 114 Physical sciences Grassland Aerosol scattering coefficient (σSP) Radiative transfer ABSORPTION Absorption (electromagnetic radiation) Ångström exponent of scattering (αSP) 0105 earth and related environmental sciences General Environmental Science Angstrom exponent of scattering (alpha(SP)) CONTINENTAL BOUNDARY-LAYER geography geography.geographical_feature_category Single-scattering albedo Scattering 15. Life on land Welgegund measurement station LIGHT-SCATTERING Aerosol Single scattering albedo (omega(0)) VARIABILITY ATMOSPHERIC AEROSOLS 13. Climate action BLACK CARBON Environmental science Aerosol scattering coefficient (sigma(SP)) |
Popis: | Atmospheric aerosols have a significant effect on earth's radiative budget, particularly on regional scales. This paper presents a similar to 6 year, in situ, ground level aerosol scattering and absorption dataset, measured at a background site strategically positioned to enable differentiation of the effect of anthropogenic, population density and open biomass burning activities on a regional scale. Relatively well-defined seasonal and diurnal patterns were observed for all the aerosol optical properties, i.e. scattering coefficient (sigma(SP)), absorption coefficient (sigma(AP)), single scattering albedo (omega(0)) and Angstrom exponent of scattering (sigma(SP)). These patterns were explained by considering southern African specific sources and metrological conditions. Using a receptor modelling method (auto-generated source maps) it was found that air masses that had higher sigma(SP), sigma(AP) and omega(0), and lower alpha(SP), if compared with the relatively clean background, passed over source regions with significant industrial or other anthropogenic activities, higher population density, re-circulation of polluted air masses and higher open biomass burning frequency. To quantify differences, four source regions were defined, i.e. Karoo, Kalahari, anti-cyclonic recirculation pattern and the industrial hub of South Africa. Air masses that had passed over the Karoo source region represented the cleanest regional background conditions, while air masses that had passed either over the industrial hub and/or the anti-cyclonic recirculation pattern represented the most significant anthropogenically impacted, as indicated by the aerosol optical properties. The omega(0) medians of air masses that had passed over the Karoo (0.80-0.86) were 9, 12 and 7% lower than in air masses that had passed over source regions with the highest omega(0) median, in the warmest/wettest, coldest, and driest, peak open biomass burning periods, respectively. |
Databáze: | OpenAIRE |
Externí odkaz: |