[1] Biomass burning during wildland fires is an important source of atmospheric trace gasses and particulate matter. A meeting sponsored by Global Observation of Forest Cover/Global Observation of Land Dynamics and International Geosphere-Biosphere Program/International Global Atmospheric Chemistry/Biomass Burning Experiment to review the status of efforts using satellite-based burned-area products to estimate global emissions from biomass burning was held in July 2002. Here we summarize the results of papers submitted from this meeting and contained in this special section. In addition, the findings and recommendations from the workshop are summarized. While new burned-area products make it possible to estimate wildland fire emissions at continental and global scales, differences in approaches to quantify fuel loads and combustion factors lead to significant variations in emissions estimates. These differences highlight the need for in-depth comparisons between emission estimation approaches and further research directed toward integration of research conducted at regional scales into the global-scale approaches to estimate emissions. INDEX TERMS: 0315 Atmospheric

[1] In many regions of the world, fires are an important and highly variable source of air pollutant emissions, and they thus constitute a significant if not dominant factor controlling the interannual variability of the atmospheric composition. This paper describes the 41-year inventory of vegetation fire emissions constructed for the Reanalysis of the Tropospheric chemical composition over the past 40 years project (RETRO), a global modeling study to investigate the trends and variability of tropospheric ozone and other air pollutants over the past decades. It is the first attempt to construct a global emissions data set with monthly time resolution over such a long period. The inventory is based on a literature review, on estimates from different satellite products, and on a numerical model with a semiphysical approach to simulate fire occurrence and fire spread. Burned areas, carbon consumption, and total carbon release are estimated for 13 continental-scale regions, including explicit treatment of some major burning events such as Indonesia in 1997 and 1998. Global carbon emissions from this inventory range from 1410 to 3140 Tg C/a with the minimum and maximum occurring in 1974 and 1992, respectively (mean of 2078 Tg C/a). Emissions of other species are also reported (mean CO of

[1] In this paper, we address the issues of the representation of boreal fires in a global chemistry and transport model (GEOS-Chem) as well as their contribution to the Arctic aerosol optical thickness and black carbon (BC) deposition, with a focus on the 2003 Russian fires. We use satellite observations from the MOPITT, POLDER and MODIS sensors to evaluate the model performances in simulating the fire pollution export over the North Pacific. Our results show that aerosol and carbon monoxide (CO) outflow is best reproduced in our model when fire emissions are (1) increased to 72 Tg for CO, 0.5 Tg C for BC, and 5.3 Tg C for organic carbon over the entire fire season; (2) prescribed on a daily basis; and (3) injected up to 4.5 km in July and August. The use of daily, rather than monthly, biomass burning emission inventories improves significantly the representation of the aerosol outflow, but has little impact on CO. The injection of fire emissions above the boundary layer influences both the CO and aerosol columns but only during the late fire season. The model improvements with respect to the standard configuration induce an increase of a factor up to 2 on the aerosol optical thickness and the mass of BC deposited in the Northern Hemisphere. According to our improved simulation, the 2003 Russian fires contributed to 16–33 % of the aerosol optical thickness and to 40–56 % of the mass of BC deposited, north of 75N in spring and summer. They contribute to the aerosol optical thickness by more than 30 % during the days of Arctic haze events in spring and summer.

[1] This paper compares the results of emission estimates of trace gases from open vegetation fires in southern hemisphere Africa for the year 2000 using different data sets. The study employs several approaches, deriving carbon monoxide (CO) emissions from a variety of satellite information, measurement data sets, and empirically-based techniques to estimate burned areas (BA), fuel consumption (FC), and emission factors (EF). Three BA data sets are used: the Moderate Resolution Imaging Spectroradiomter (MODIS) burned area data set, the Global Burned Area data set for the year 2000 (GBA2000), and the Global Burn Scar Atlas (GLOBSCAR) in July and September, 2000. The estimated total BA in southern Africa varies significantly among data sets from 210,000 to 830,000 km2 for the sum of July and September. Temporal and spatial variations associated with CO emissions are analyzed using three different techniques for calculating the FC and EF. The first set of FC and EF extrapolates monthly variations in Zambia to southern Africa, the second extrapolates spatially resolved data for September to July, and the last includes monthly and spatial variations in both FC and EF. This analysis suggests the importance of accounting for the temporal and spatial

Abstract not found

Air pollution generated by vegetation fire smoke (VFS) is a phenomenon that has influenced the global environment in prehistoric and historic time scales. Although historic evidence of the impacts of VFS on societies is scarce, there are indications that VFS has been a factor that influenced society significantly since the Middle Ages. In recent decades, increasing application of fire as a tool for land-use change has resulted in more frequent occurrence of extended fire and smoke episodes with consequences on human health and security. Some of these events have been associated with droughts that are attributed to inter-annual climate variability or possible consequences of regional climate change. In metropolitan or industrial areas, the impacts of VFS may be coupled with the emission burden from fossil fuel burning and other technogenic sources, resulting in increasing adverse affects on the human population. We review the character, magnitude, and role of pyrogenic gaseous and particle emissions on the composition and functioning of the global atmosphere, human health, and security. Special emphasis is given on radioactive emissions generated by fires burning in peatlands and on terrain contaminated by radionuclides. The transboundary effects of VFS pollution are a driving argument for developing international policies to address the underlying causes for avoiding excessive fire application, and to establish sound fire and smoke management practices and protocols of cooperation in wildland fire management at an international level.

Multiyear satellite observations are used to document a relationship between the large-scale variability in precipitation over the tropical Atlantic and aerosol traced toAfrican sources. During boreal winter and spring there is a significant reduction in precipitation south of the Atlantic marine intertropical convergence zone (ITCZ) during months when aerosol concentrations are anomalously high over a large domain of the tropical Atlantic Ocean. This reduction cannot be linearly attributed to known climate factors such as El Niño– SouthernOscillation, the North Atlantic Oscillation, and zonal andmeridional modes of tropical Atlantic sea surface temperature or to meteorological factors such as water vapor. The fractional variance in precipitation related to aerosol is about 12 % of the total interannual variance, which is of the same order of magnitude as that related to each of the known climate and weather factors. A backward trajectory analysis confirms the African origin of aerosols that directly affect the changes in precipitation. The reduction inmean precipitation mainly comes from decreases in moderate rain rates (10–20 mm day21), while light rain (,10 mm day21) can fluctuate in the opposite direction. The results cannot be readily explained in terms of wet deposition or uncertainties in satellite retrievals, and suggest that the observations demonstrate clearly identifiable effects of African aerosol on large-scale variability in precipitation in the tropical Atlantic region. 1.

Global burned area and biomass burning emissions from small fires

Global burned area and biomass burning emissions from small fires

Global burned area and biomass burning emissions from small fires