Abstract.
Brown
carbon
(BrC)
is
a
fraction
of
Organic
Aerosols
(OA)
that
absorbs
radiation
in
the
ultraviolet
and
short
visible
wavelengths.
Its
contribution
to
radiative
forcing
uncertain
due
limited
knowledge
its
imaginary
refractive
index
(k
).
This
study
investigates
variability
k
for
OA
from
wildfires,
residential,
shipping,
traffic
emission
sources
over
Europe.
The
MONARCH
atmospheric
chemistry
model
simulated
concentrations
source
contributions,
feeding
an
offline
optical
tool
constrain
values
at
370
nm.
was
evaluated
against
mass
Aerosol
Chemical
Speciation
Monitors
(ACSM)
filter
sample
measurements,
aerosol
light
absorption
measurements
nm
derived
AethalometerTM
12
sites
across
Results
show
captures
temporal
environments
(regional,
suburban
urban
background).
Residential
emissions
are
major
colder
months,
while
secondary
organic
aerosols
(SOA)
dominate
warmer
periods.
Traffic
minor
primary
contributor.
Biomass
coal
combustion
significantly
influence
absorption,
with
shipping
also
notable
near
harbors.
Optimizing
revealed
significant
influenced
by
environmental
conditions.
Derived
biomass
burning
(0.03
0.13),
residential
(0.008
(0.005
0.08),
0.07)
improved
representation
compared
constant
k.
Introducing
such
source-specific
constraints
innovative
approach
enhance
models.
Journal of Geophysical Research Atmospheres,
Journal Year:
2022,
Volume and Issue:
128(2)
Published: Dec. 30, 2022
Abstract
The
NOAA/NASA
Fire
Influence
on
Regional
to
Global
Environments
and
Air
Quality
(FIREX‐AQ)
experiment
was
a
multi‐agency,
inter‐disciplinary
research
effort
to:
(a)
obtain
detailed
measurements
of
trace
gas
aerosol
emissions
from
wildfires
prescribed
fires
using
aircraft,
satellites
ground‐based
instruments,
(b)
make
extensive
suborbital
remote
sensing
fire
dynamics,
(c)
assess
local,
regional,
global
modeling
fires,
(d)
strengthen
connections
observables
the
ground
such
as
fuels
fuel
consumption
satellite
products
burned
area
radiative
power.
From
Boise,
ID
western
were
studied
with
NASA
DC‐8
two
NOAA
Twin
Otter
aircraft.
high‐altitude
ER‐2
deployed
Palmdale,
CA
observe
some
these
in
conjunction
overpasses
other
Further
conducted
three
mobile
laboratories
sites,
17
different
forecast
analyses
for
fire,
air
quality
climate
implications.
Salina,
KS
investigated
87
smaller
Southeast
in‐situ
data
collection.
Sampling
by
all
platforms
designed
measure
gases
aerosols
multiple
transects
capture
chemical
transformation
perform
observations
smoke
plumes
under
day
night
conditions.
linked
consumed
power
orbital
collected
during
overflights
sampling
fuels.
Atmospheric chemistry and physics,
Journal Year:
2022,
Volume and Issue:
22(12), P. 8009 - 8036
Published: June 21, 2022
Abstract.
Brown
carbon
(BrC)
associated
with
aerosol
particles
in
western
United
States
wildfires
was
measured
between
July
and
August
2019
aboard
the
NASA
DC-8
research
aircraft
during
Fire
Influence
on
Regional
to
Global
Environments
Air
Quality
(FIREX-AQ)
study.
Two
BrC
measurement
methods
are
investigated,
highly
spectrally
resolved
light
absorption
solvent
(water
methanol)
extracts
of
collected
filters
situ
bulk
particle
at
three
wavelengths
(405,
532
664
nm)
a
photoacoustic
spectrometer
(PAS).
A
light-absorption
closure
analysis
for
300
700
nm
performed.
The
combined
pure
black
material,
including
enhancements
due
internally
mixed
materials,
plus
soluble
Mie-predicted
factor
conversion
BrC,
compared
spectra
from
power
law
fit
PAS
wavelengths.
For
various
parameters
used,
wavelength
roughly
400
they
agreed,
lower
individual
component-predicted
significantly
exceeded
higher
consistently
but
more
variable.
Limitations
extrapolation
data
below
405
missing
species
low
solubility
that
strongly
absorb
may
account
differences.
Based
measurements
closest
fires,
emission
ratio
PAS-measured
relative
monoxide
(CO)
average
0.13
Mm−1
ppbv−1;
ratios
also
provided.
As
smoke
moved
away
burning
regions,
evolution
over
time
observed
be
complex;
enhancement,
depletion
or
constant
levels
age
were
all
first
8
h
after
different
plumes.
Within
following
emissions,
4-nitrocatechol,
well-characterized
chromophore
commonly
found
particles,
largely
depleted
BrC.
In
descending
plume
where
temperature
increased
by
15
K,
4-nitrocatechol
dropped,
possibly
temperature-driven
evaporation,
remained
unchanged.
Evidence
reactions
ozone,
related
species,
as
pathway
secondary
formation
under
both
high
oxides
nitrogen
(NOx)
conditions,
while
bleached
regions
ozone
NOx,
consistent
complex
behaviors
laboratory
studies.
Although
hours
is
variable,
limited
number
aged
(15
30
h)
indicate
net
loss
It
yet
determined
how
near-field
affects
characteristics
longer
timescales
spatial
scales,
its
environmental
impacts
likely
greater.
Atmospheric chemistry and physics,
Journal Year:
2025,
Volume and Issue:
25(4), P. 2667 - 2694
Published: Feb. 28, 2025
Abstract.
Brown
carbon
(BrC)
is
a
fraction
of
organic
aerosol
(OA)
that
absorbs
radiation
in
the
ultraviolet
and
short
visible
wavelengths.
Its
contribution
to
radiative
forcing
uncertain
due
limited
knowledge
its
imaginary
refractive
index
(k).
This
study
investigates
variability
k
for
OA
from
wildfires,
residential,
shipping,
traffic
emission
sources
over
Europe.
The
Multiscale
Online
Nonhydrostatic
Atmosphere
Chemistry
(MONARCH)
model
simulated
concentrations
source
contributions,
feeding
an
offline
optical
tool
constrain
values
at
370
nm.
was
evaluated
against
mass
chemical
speciation
monitors
(ACSMs)
filter
sample
measurements,
as
well
light
absorption
measurements
nm
derived
Aethalometer™
12
sites
across
Results
show
MONARCH
captures
temporal
environments
(regional,
suburban,
urban
background).
Residential
emissions
are
major
colder
months,
while
secondary
(SOA)
dominates
warmer
periods.
Traffic
minor
primary
contributor.
Biomass
coal
combustion
significantly
influence
absorption,
with
shipping
also
notable
near
harbors.
Optimizing
revealed
significant
influenced
by
environmental
conditions.
Derived
biomass
burning
(0.03
0.13),
residential
(0.008
(0.005
0.08),
0.07)
improved
representation
compared
constant
k.
Introducing
such
source-specific
constraints
innovative
approach
enhance
atmospheric
models.
Aerosol Science and Technology,
Journal Year:
2023,
Volume and Issue:
57(8), P. 727 - 741
Published: June 13, 2023
The
Aerodyne
aerosol
mass
spectrometer
(AMS)
is
used
extensively
to
measure
the
chemical
composition
of
non-refractory
submicron
particles
for
laboratory
and
atmospheric
field
studies.
Typical
AMS
calibration
methods
are
mass-based,
involving
generating
pure
or
mixtures
with
a
known
size
number
concentration.
Here
we
present
new
method
using
heated
platinum/molybdenum
catalyst-based
conversion
technique
that
provides
an
independent
measurement
reactive
nitrogen
(Nr)
total
organic
carbon
(Cy)
traceable
gas-phase
standards
nitric
oxide
(NO)
dioxide
(CO2),
respectively.
was
tested
dried
composed
ammonium
nitrate
(AN),
other
salts,
nitrogen-containing
species.
ionization
efficiencies
determined
single
particle
Nr
matched
within
experimental
uncertainties
(±15%).
By
measuring
lens
transmission
efficiency
incorporating
light-scattering
measurements
collection
efficiency,
catalyst
independently
showed
relative
(RIE)
essentially
same
among
different
containing
compounds
(±9%),
regardless
corresponding
anion
stoichiometry,
quantifying
support
major
assumption
inherent
in
calibrations.
Cy
were
calibrate
RIE
4-nitrocatechol
(1.1
±
0.4),
isosorbide
mononitrate
(1.2
0.1)
triammonium
citrate
(2.1
0.2),
which
range
RIEs
quantitation.
combined
system
provided
more
accurate
elemental
carbon-to-nitrogen
ratios
than
high-resolution
analysis
Improved-Ambient
plus
inorganic
nitrogen.
Atmospheric chemistry and physics,
Journal Year:
2024,
Volume and Issue:
24(10), P. 6275 - 6304
Published: May 29, 2024
Abstract.
Brown
carbon
(BrC)
is
an
absorbing
organic
aerosol
(OA),
primarily
emitted
through
biomass
burning
(BB),
which
exhibits
light
absorption
unique
to
both
black
(BC)
and
other
aerosols.
Despite
many
field
laboratory
studies
seeking
constrain
BrC
properties,
the
radiative
forcing
(RF)
of
still
highly
uncertain.
To
better
understand
its
climate
impact,
we
introduced
One-Moment
Aerosol
(OMA)
module
GISS
ModelE
Earth
system
model
(ESM).
We
assessed
sensitivity
primary
processed
a
novel
chemical
aging
scheme
secondary
formed
from
biogenic
volatile
compounds
(BVOCs).
Initial
results
show
that
typically
contributes
top-of-the-atmosphere
(TOA)
effect
0.04
W
m−2.
Sensitivity
tests
indicate
explicitly
simulating
(separating
it
OAs),
including
BrC,
bleaching
contribute
distinguishable
effects
should
be
accounted
for
in
schemes.
This
addition
prognostic
allows
greater
physical
complexity
OA
representation
with
no
apparent
trade-off
performance,
as
evaluation
optical
depth
against
Robotic
Network
(AERONET)
Moderate
Resolution
Imaging
Spectroradiometer
(MODIS)
retrieval
data,
without
scheme,
reveals
similar
skill
cases.
Thus,
simulated
allow
more
physically
based
composition,
crucial
detailed
like
comparisons
situ
measurement
campaigns.
include
summary
best
practices
within
at
end
this
paper.
Atmospheric chemistry and physics,
Journal Year:
2022,
Volume and Issue:
22(20), P. 13389 - 13406
Published: Oct. 18, 2022
Abstract.
Light
absorbing
organic
carbon,
or
brown
carbon
(BrC),
can
be
a
significant
contributor
to
the
visible
light
absorption
budget.
However,
sources
of
BrC
and
contributions
are
not
well
understood.
Biomass
burning
is
thought
major
source
BrC.
Therefore,
as
part
WE-CAN
(Western
Wildfire
Experiment
for
Cloud
Chemistry,
Aerosol
Absorption
Nitrogen)
study,
data
were
collected
on
board
National
Science
Foundation/National
Center
Atmospheric
Research
(NSF/NCAR)
C-130
aircraft
it
intercepted
smoke
from
wildfires
in
western
US
July–August
2018.
measurements
obtained
near
real-time
using
two
techniques.
The
first
coupled
particle-into-liquid
sampler
(PILS)
with
liquid
waveguide
capillary
cell
total
analyzer
water-soluble
WSOC
(water-soluble
carbon).
second
employed
custom-built
photoacoustic
aerosol
spectrometer
(PAS)
measure
at
405
660
nm.
PAS
nm
(PAS
Abs
BrC)
was
calculated
by
assuming
determined
equivalent
black
(BC)
BC
Ångström
exponent
1.
Data
PILS
combined
investigate
vs.
various
wildfire
plumes
sampled
during
WE-CAN.
WSOC,
405,
tracked
each
other
out
plumes.
correlated
(R2
value
=0.42
=0.60)
CO
(carbon
monoxide)
=0.76
=0.55)
all
sampled.
corrected
non-water-soluble
fraction
UHSAS
(ultra-high-sensitivity
spectrometer)
mass.
showed
good
closure
factor
∼1.5
2
difference.
This
difference
explained
particle
bulk
solution
measured
PILS,
respectively,
confirmed
Mie
theory
calculations.
During
WE-CAN,
∼
45
%
(ranging
31
65
%)
observed
due
species.
ratio
ΔCO
no
clear
dependence
fire
dynamics
time
since
emission
over
9
h.
ACS Earth and Space Chemistry,
Journal Year:
2023,
Volume and Issue:
7(3), P. 632 - 641
Published: Feb. 24, 2023
Nitrophenols
are
a
major
component
of
light-absorbing
atmospheric
organic
aerosols,
commonly
referred
to
as
brown
carbon
(BrC).
Most
nitrophenol
formation
pathways
involve
reactions
phenolic
compounds
with
OH,
NO3,
and
NO2
in
the
gas
phase.
In
this
study,
an
aqueous
production
pathway
is
investigated
that
can
proceed
dark
without
apparent
OH
radical
formation.
Using
high-performance
liquid
chromatography–mass
spectrometry,
we
demonstrate
catechol
reacts
acidic
solutions
dissolved
nitrite
form
nitrocatechol.
The
rate
nitration
increases
significantly
from
pH
4.4
3.4
such
nitrocatechol
susceptible
second-generation
under
most
conditions
producing
chromophores
absorb
visible
region
(peak
at
425
nm).
Increases
N:C
ratio
reaction
solution,
detected
by
aerosol
mass
enhanced
absorption
300
500
nm
wood
peat
smoke
extracts
exposed
suggest
general
pathway.
which
BrC
process
may
occur
discussed.
Journal of Geophysical Research Atmospheres,
Journal Year:
2025,
Volume and Issue:
130(5)
Published: Feb. 26, 2025
Abstract
The
evolution
of
organic
aerosol
(OA)
composition
and
size
distributions
within
smoke
plumes
are
uncertain
due
to
variability
in
the
rates
OA
evaporation/condensation
coagulation
a
plume.
It
remains
unclear
how
varies
across
different
parts
individual
plumes.
We
use
large
eddy
simulation
model
coupled
with
aerosol‐microphysics
radiation
models
simulate
Williams
Flats
fire
sampled
during
Fire
Influence
on
Regional
Global
Environments
Air
Quality
field
campaign.
At
aircraft
altitude,
captures
observed
changes
through
4
hr
aging.
primary
(POA),
oxidized
POA
(OPOA),
secondary
(SOA)
shows
that
>90%
SOA
formation
occurs
before
first
transect
(∼40
min
aging).
Lidar
observations
show
significant
amount
planetary
boundary
layer
(PBL)
free
troposphere
(FT)
having
equal
amounts
PBL
FT.
Due
faster
initial
dilution,
concentrations
more
than
factor
two
lower
FT
concentrations,
resulting
slower
coagulational
growth
PBL.
A
20
K
temperature
decrease
height
influences
evaporation
near
surface,
while
net
is
driven
by
continued
dilution
after
transect.
Net
condensation
result
areas
higher
OH
concentration
leading
OPOA
formation.
Our
results
motivate
need
for
systematic
vertical
gradients
