skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Do biomass burning aerosols intensify drought in equatorial Asia during El Niño?

Abstract

During El Niño years, fires in tropical forests and peatlands in equatorial Asia create large regional smoke clouds. We characterized the sensitivity of these clouds to regional drought, and we investigated their effects on climate by using an atmospheric general circulation model. Satellite observations during 2000–2006 indicated that El Niño-induced regional drought led to increases in fire emissions and, consequently, increases in aerosol optical depths over Sumatra, Borneo and the surrounding ocean. Next, we used the Community Atmosphere Model (CAM) to investigate how climate responded to this forcing. We conducted two 30 year simulations in which monthly fire emissions were prescribed for either a high (El Niño, 1997) or low (La Niña, 2000) fire year using a satellite-derived time series of fire emissions. Our simulations included the direct and semi-direct effects of aerosols on the radiation budget within the model. We assessed the radiative and climate effects of anthropogenic fire by analyzing the differences between the high and low fire simulations. Fire aerosols reduced net shortwave radiation at the surface during August–October by 19.1±12.9 W m -2 (10%) in a region that encompassed most of Sumatra and Borneo (90° E–120° E, 5° S–5° N). The reductions in net shortwave radiationmore » cooled sea surface temperatures (SSTs) and land surface temperatures by 0.5±0.3 and 0.4±0.2 °C during these months. Tropospheric heating from black carbon (BC) absorption averaged 20.5±9.3 W m -2 and was balanced by a reduction in latent heating. The combination of decreased SSTs and increased atmospheric heating reduced regional precipitation by 0.9±0.6 mm d -1 (10%). The vulnerability of ecosystems to fire was enhanced because the decreases in precipitation exceeded those for evapotranspiration. Together, the satellite and modeling results imply a possible positive feedback loop in which anthropogenic burning in the region intensifies drought stress during El Niño.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
985002
Report Number(s):
PNNL-SA-72941
Journal ID: ISSN 1680-7316; TRN: US201016%%1703
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Atmospheric Chemistry and Physics
Additional Journal Information:
Journal Volume: 10; Journal Issue: 8; Journal ID: ISSN 1680-7316
Publisher:
European Geosciences Union
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; ABSORPTION; AEROSOLS; ASIA; BIOMASS; CARBON; CLIMATES; DROUGHTS; ECOSYSTEMS; FEEDBACK; FORESTS; GENERAL CIRCULATION MODELS; HEATING; PRECIPITATION; RADIATIONS; SATELLITES; SENSITIVITY; SOUTHERN OSCILLATION; WETLANDS

Citation Formats

Tosca, M G, Randerson, J, Zender, C S, Flanner, M G, and Rasch, Philip J. Do biomass burning aerosols intensify drought in equatorial Asia during El Niño?. United States: N. p., 2010. Web. doi:10.5194/acp-10-3515-2010.
Tosca, M G, Randerson, J, Zender, C S, Flanner, M G, & Rasch, Philip J. Do biomass burning aerosols intensify drought in equatorial Asia during El Niño?. United States. https://doi.org/10.5194/acp-10-3515-2010
Tosca, M G, Randerson, J, Zender, C S, Flanner, M G, and Rasch, Philip J. Fri . "Do biomass burning aerosols intensify drought in equatorial Asia during El Niño?". United States. https://doi.org/10.5194/acp-10-3515-2010.
@article{osti_985002,
title = {Do biomass burning aerosols intensify drought in equatorial Asia during El Niño?},
author = {Tosca, M G and Randerson, J and Zender, C S and Flanner, M G and Rasch, Philip J},
abstractNote = {During El Niño years, fires in tropical forests and peatlands in equatorial Asia create large regional smoke clouds. We characterized the sensitivity of these clouds to regional drought, and we investigated their effects on climate by using an atmospheric general circulation model. Satellite observations during 2000–2006 indicated that El Niño-induced regional drought led to increases in fire emissions and, consequently, increases in aerosol optical depths over Sumatra, Borneo and the surrounding ocean. Next, we used the Community Atmosphere Model (CAM) to investigate how climate responded to this forcing. We conducted two 30 year simulations in which monthly fire emissions were prescribed for either a high (El Niño, 1997) or low (La Niña, 2000) fire year using a satellite-derived time series of fire emissions. Our simulations included the direct and semi-direct effects of aerosols on the radiation budget within the model. We assessed the radiative and climate effects of anthropogenic fire by analyzing the differences between the high and low fire simulations. Fire aerosols reduced net shortwave radiation at the surface during August–October by 19.1±12.9 W m-2 (10%) in a region that encompassed most of Sumatra and Borneo (90° E–120° E, 5° S–5° N). The reductions in net shortwave radiation cooled sea surface temperatures (SSTs) and land surface temperatures by 0.5±0.3 and 0.4±0.2 °C during these months. Tropospheric heating from black carbon (BC) absorption averaged 20.5±9.3 W m-2 and was balanced by a reduction in latent heating. The combination of decreased SSTs and increased atmospheric heating reduced regional precipitation by 0.9±0.6 mm d-1 (10%). The vulnerability of ecosystems to fire was enhanced because the decreases in precipitation exceeded those for evapotranspiration. Together, the satellite and modeling results imply a possible positive feedback loop in which anthropogenic burning in the region intensifies drought stress during El Niño.},
doi = {10.5194/acp-10-3515-2010},
url = {https://www.osti.gov/biblio/985002}, journal = {Atmospheric Chemistry and Physics},
issn = {1680-7316},
number = 8,
volume = 10,
place = {United States},
year = {2010},
month = {4}
}