Abstract. A large body of information on emissions from the various types of biomass burning has been accumulated over the past decade, to a large extent as a result of International Geosphere-Biosphere Programme/International Global Atmospheric Chemistry research activities. Yet this information has not been readily accessible to the atmospheric chemistry community because it was scattered over a large number of publications and reported in numerous different units and reference systems. We have critically evaluated the presently available data and integrated these into a consistent format. On the basis of this analysis we present a set of emission factors for a large variety of species emitted from biomass fires. Where data were not available, we have proposed estimates based on appropriate extrapolation techniques. We have derived global estimates of pyrogenic emissions for important species emitted by the various types of biomass burning and compared our estimates with results from inverse modeling studies. IntroductionHuman evolution and the use of fire have gone hand in hand ever since the origin of our species in the savannas and woodlands of Africa [Schh'le, 1990]. As a result, air pollution from the smoke of biomass fires has been humanity's constant companion for some 2 million years, and its ancient impact on human health is reflected in soot deposits in the lungs of mummies. Emissions from fossil fuel burning gained notoriety as air pollutants in medieval England, but only in the last 2 centuries have they begun to play an important role worldwide. Yet the scientific exploration of air pollution has focused initially only on this much more recent threat, and the first pioneering papers on the impact of biomass burning on the chemistry of the atmosphere were only published in the 1970s To assess the atmospheric impact of biomass burning, and especially to represent it quantitatively in models of atmospheric transport and chemistry, accurate data on the emission of trace gases and aerosols from biomass fires are required. Emissions must typically be represented in the form of spatiotemporally resolved fields, where the emission per unit area and time is provided at a specified spatial and temporal resolution. These fields are obtained by multiplying an exposure term, for example, the amount of biomass burned within a grid cell during a time interval, with an emission factor, that is, the amount of the chemical species released per mass of biomass burned.In The objective of this paper is to synthesize the currently available data on fire emission characteristics for a large number of chemical species into a consistent set of units. In contrast to some previous summaries that gave only generic estimates independent of the type of fire [e.g., Andreae, 1993], here we provide separate emission factors for the different types of biomass burning, such as deforestation fires in the tropics, savanna fires, etc. We then combine the emission factor data with exposure estimates for the various fire categories to ...

Abstract.Measurements of aerosol optical properties (aerosol optical depth, scattering and backscattering coefficients) have been conducted at two groundbased sites in Northern Greece, Ouranoupolis (40 • 23 N, 23 • 57 E, 170 m a.s.l.) and Thessaloniki (40 • 38 N, 22 • 57 E, 80 m a.s.l.), between 1999 and 2002. The frequency distributions of the observed parameters have revealed the presence of individual modes of high and low values, indicating the influence from different sources. At both sites, the mean aerosol optical depth at 500 nm was 0.23. Values increase considerably during summer when they remain persistently between 0.3 and 0.5, going up to 0.7-0.8 during specific cases. The mean value of 65±40 Mm −1 of the particle scattering coefficient at 550 nm reflects the impact of continental pollution in the regional boundary layer. Trajectory analysis has shown that higher values of aerosol optical depth and the scattering coefficient are found in the east sector (former Soviet Union countries, eastern Balkan countries), whereas cleaner conditions are found for the NW direction. The influence of Sahara dust events is clearly reflected in the Angström exponents. About 45-60% of the observed diurnal variation of the optical properties was attributed to the growth of aerosols with humidity, while the rest of the variability is in phase with the evolution of the sea-breeze cell. The contribution of local pollution is estimated to contribute 35±10% to the average aerosol optical depth at the Thessaloniki site during summer. Finally, the aerosol scale height (aerosol optical depth divided by scattering coefficient) was found to be related to the height of the boundary layer with values between 0.5-1 km during winter and up to 2.5-3 km during summer.