In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 21, No. 18 ( 2021-09-24), p. 14177-14197
Abstract:
Abstract. The Amazon experiences fires every year, and the resulting biomass burning
aerosols, together with cloud particles, influence the penetration of
sunlight through the atmosphere, increasing the ratio of diffuse to direct
photosynthetically active radiation (PAR) reaching the vegetation canopy and
thereby potentially increasing ecosystem productivity. In this study, we use
the NASA Goddard Earth Observing System (GEOS) model with coupled aerosol,
cloud, radiation, and ecosystem modules to investigate the impact of Amazon
biomass burning aerosols on ecosystem productivity, as well as the role of
the Amazon's clouds in tempering this impact. The study focuses on a
7-year period (2010–2016) during which the Amazon experienced a variety
of dynamic environments (e.g., La Niña, normal years, and El Niño).
The direct radiative impact of biomass burning aerosols on ecosystem
productivity – called here the aerosol diffuse radiation fertilization
effect – is found to increase Amazonian gross primary production (GPP) by
2.6 % via a 3.8 % increase in diffuse PAR (DFPAR) despite a 5.4 %
decrease in direct PAR (DRPAR) on multiyear average during burning seasons.
On a monthly basis, this increase in GPP can be as large as 9.9 %
(occurring in August 2010). Consequently, the net primary production (NPP)
in the Amazon is increased by 1.5 %, or ∼92 Tg C yr−1 –
equivalent to ∼37 % of the average carbon lost due to
Amazon fires over the 7 years considered. Clouds, however, strongly
regulate the effectiveness of the aerosol diffuse radiation fertilization
effect. The efficiency of this fertilization effect is the highest in
cloud-free conditions and linearly decreases with increasing cloud amount
until the cloud fraction reaches ∼0.8, at which point the
aerosol-influenced light changes from being a stimulator to an inhibitor of
plant growth. Nevertheless, interannual changes in the overall strength of
the aerosol diffuse radiation fertilization effect are primarily controlled
by the large interannual changes in biomass burning aerosols rather than by
changes in cloudiness during the studied period.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-21-14177-2021
DOI:
10.5194/acp-21-14177-2021-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2021
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
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