In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 18, No. 12 ( 2018-06-22), p. 8829-8848
Abstract:
Abstract. The aim of the presented study was to investigate the impact on the radiation
budget of a biomass-burning plume, transported from Alaska to the High Arctic
region of Ny-Ålesund, Svalbard, in early July 2015. Since the mean
aerosol optical depth increased by the factor of 10 above the average summer
background values, this large aerosol load event is considered particularly
exceptional in the last 25 years. In situ data with hygroscopic growth
equations, as well as remote sensing measurements as inputs to radiative
transfer models, were used, in order to estimate biases associated with
(i) hygroscopicity, (ii) variability of single-scattering albedo profiles,
and (iii) plane-parallel closure of the modelled atmosphere. A chemical
weather model with satellite-derived biomass-burning emissions was applied to
interpret the transport and transformation pathways. The provided MODTRAN radiative transfer model (RTM) simulations for the smoke event
(14:00 9 July–11:30 11 July) resulted in a mean aerosol
direct radiative forcing at the levels of −78.9 and −47.0 W m−2 at
the surface and at the top of the atmosphere, respectively,
for the mean value of aerosol optical depth equal to 0.64 at 550 nm. This
corresponded to the average clear-sky direct radiative forcing of −43.3 W m−2, estimated by radiometer and model simulations at the surface.
Ultimately, uncertainty associated with the plane-parallel atmosphere
approximation altered results by about 2 W m−2. Furthermore,
model-derived aerosol direct radiative forcing efficiency reached on average
−126 W m-2/τ550 and −71 W m-2/τ550 at the
surface and at the top of the atmosphere, respectively. The heating rate, estimated at up
to 1.8 K day−1 inside the biomass-burning plume, implied vertical
mixing with turbulent kinetic energy of 0.3 m2 s−2.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-18-8829-2018
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
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