The importance of biomass burning as a
source of BC in the European Arctic
– Based on measurements at the Zeppelin Observatory, Svalbard
C. Lund Myhre, K.E. Yttri, S. Eckhardt, A. Stohl, M. Fiebig, C. Dye (NILU)
J. Ström (ITM)
Z. Klimont (IIASA)
ACCENT Plus Symposium
Urbino 17-20 September 2013
Outline
Introduction
- On aerosols and “black carbon” in the Arctic
- Aim of the study
- Levoglucosan as a tracer for biomass burning
- The Zeppelin Observatory
Results
- The level and seasonal variation of
- levoglucosan, equivalent black carbon (EBC) and ECbb at
Svalbard
- The relative contribution of ECbb to EBC
- Discussions of source regions and sources
- Outlook
Aerosols in the Arctic
3 km North of Svalbard, 79oN
Few Arctic local sources (but
this is increasing)
Lifetime of days-weeks ->
Transport to Arctic is main
source
Arctic haze
Seasonal phenomenon
(winter – early spring) when
aerosol concentrations in the
Arctic are very high
Sharma et al. (2006)
Joranger and Ottar,
Geophys.
Res.Report
Lett., 1984
AMAP
Technical
No.4 (2011)
Reported trends of BC in the Arctic
Hirdmann et al, 2010 (ACP)
EBC
− Alert: -3.8 % yr-1 (1989-2008)
− Barrow: not sig.(1998-2008)
− Zeppelin: -9 % yr-1 (2002-2009)
Collaud Coen et al., 2013 (ACP)
Absorption coefficient
– Barrow; -6.5 % yr-1 (2001–2010)
Sharma et al. 2013 (JGR)
“Surface BC (EBC)
measurements at the three
Arctic sites: overall decline of
40% in BC measurements in
the Arctic from 1990 to 2009”
Models prediction of ”BC” in the Arctic
Models struggle to capture Arctic Haze
Problems particularly severe for Black Carbon (BC)
Shindell et al. ACP (2008
Main objective of this study
To provide a quantitative estimate of biomass burning BC (here: ECbb) in
the European Arctic atmosphere by means of the biomass burning
tracer levoglucosan
ECresidential wood burning
ECwild and agricultural fires
ECbb at Zeppelin Observatory
The tracer levoglucosan for ECbb
•
•
•
•
Levoglucosan is a thermal degradation product of cellulose
High emission factor and a low vapour pressure
Stable over realistic transport time and conditions (?)
No emissions from fossil sources -> unique tracer of particulate matter
emissions from biomass burning
• Improve knowledge of fossil and non-fossil BC contribution in the Arctic
The Zeppelin Observatory
• A one year time series of levoglucosan with a 24 hr
time resolution
• 12th of March 2008 to 7th of March 2009, as
part of POLARCAT (IPY)
Complemented with measurements from the ongoing
measurement program
• Aerosol absorption coefficient (σap)
• Elemental carbon (EC)
ECbb = EC from wild and agricultural fires + EC from
residential wood burning
Zeppelin Mountain,
478 m asl, close to the
Ny-Ålesund settlement
at Svalbard
78°54’N, 11°53’E
Calculation of ECbb from the tracer levoglucosan
•ECbb was calculated using the
following equations
... and the followoing
emissions ratios
1)
TCbb = [Levo]×(TC/Levo)bb (1)
Residential wood burning
Mean (SD)
(TC/Levo)bb
14.7 (3.7)
0.78 (0.04)
OCbb = TCbb×(OC/TC)bb
(2)
(OC/TC)bb
ECbb = TCbb−OCbb
(3)
Wild/Agricultural fires
Equivalent Black Carbon (EBC)
2)
(TC/Levo)bb
48 (10)
(OC/TC)bb
0.85 (0.05)
used a site specific α-value of 5.7 ±
2.3 m2 g-1 derived from concurrent
measurements of EC and ap at the
Zeppelin observatory
1) Yttri et al. (2009/2011a); 2) Saarikoski et al. (2007)
30
20
ng m
-3
ng m
-3
8
6
4
2
300
200
100
50
EBC mean
c)
ECbb
-3
b)
40
Levoglucosan
0
400
a)
ng m
Results
10
Winter
March 2008- March 2009
Summer
Winter
12
10
0
08
20
08
20
08
20
08
20
08
20
ch
ar
M
ril
Ap
ay
M
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08
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st
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be
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09
20
ch
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09
01
20
ry
ua
br
Fe
01
09
20
y
ar
nu
Ja
8
01
00
r2
be
em
ec
D
8
00
01
r2
be
em
ov
N
01
08
20
er
ob
ct
O
08
20
01
01
01
01
01
01
01
01
2
A closer look at ECbb
0
400
EBC mean
b)
Pronounced seasonal variability of ECbb
= EC from wild and agricultural fires + EC from residential wood burning
ng m
-3
300
200
100
50
ECbb
c)
ng m
-3
40
30
20
10
0
r
be
em
pt
Se
08
20
08
20
08
20
08
20
08
20
08
20
st
gu
Au
ly
Ju
ne
Ju
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M
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Ap
ch
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M
09
20
ch
ar
M
09
01
20
ry
ua
br
Fe
01
09
20
y
ar
nu
Ja
8
01
00
r2
be
em
ec
D
8
00
01
r2
be
em
ov
N
01
08
20
er
ob
ct
O
08
20
01
01
01
01
01
01
01
01
• Winter time mean (3.7±1.2 ng m-3) 5x higher than summer time mean (0.8±0.3 ng
m-3)
• Episodes much more frequent in winter compared to summer
• Maximum 24 hour concentration observed in winter (34 ng m-3) was 5x higher
than the maximum 24 hour concentration observed in summer
• Due to possible degradation of levoglucosan by OH during transport, levels of ECbb
are minimum estimates. We are working on estimating a range taking into
account suggested degradation rates by Hoffmann et al. (2010, Environ. Sci.
Technol).
Results – ECbb relative to EBC
26
120
ECbb/EBC (%)
24
Winter (Oct - May):
-3
EBC (ng m )
-3
ECbb (ng m )
22
100
ECbb to EBC (%)
80
16
14
60
12
10
40
8
-3
18
ECbb and ECB (ng m )
20
Mean ECbb to EBC: 8.8 ± 4.5%
Summer (May - Oct):
Mean ECbb to EBC: 6.1 ± 3.4%
6
20
4
2
0
0
b
Fe
n
Ja
ec
D
ct
ov
N
O
p
Se
g
Au
l
Ju
n
Ju
ay
M
r
Ap
ar
M
b
Fe
2008
2009
• ECbb to EBC exceeded 10% for Aug-Oct, Dec and Jan as a low estimate.
• Taking degradation of levoglucosan by OH into account
•Preliminary results : 22% during winter as high estimate, and ca 10%
during summer.
Source region and sources
Modeled concentration of ECbb using FLEXPART and a ECbb tracer subject
to dry and wet deposition (Stohl et al, 2013) and the ECLIPSE emission
data (Klimont et al. (2013) and available through the ECLIPSE website
http://eclipse.nilu.no)
50
a)
40
-3
ng m
ECbb
*
30
20
10
0
50
b)
Residential biomass burning
GAINS biofuel
inventory
ng m
-3
40
30
20
10
ng m
-3
0
50
c)
GFED for
wild and
agricultural fires
GFED daily emission (wild + agricultural fires)
40
30
20
10
0
r
be
em
pt
Se
08
20
08
20
08
20
08
20
08
20
08
20
st
gu
Au
ly
Ju
ne
Ju
ay
M
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Ap
ch
ar
M
09
20
ch
ar
M
09
01
20
ry
ua
br
Fe
01
09
20
y
ar
nu
Ja
8
01
00
r2
be
em
ec
D
8
00
01
r2
be
em
ov
N
01
08
20
er
ob
ct
O
08
20
01
01
01
01
01
01
01
01
Source region and episodes
50
a)
40
*
-3
ng m
ECbb
30
20
10
0
50
b)
Residential biomass burning
ng m
-3
40
30
Indicates
thatofthe
Distribution
the
residential
wood burning
biomass burning
source
in Russia
emissions
in the is
model:
underestimated
in the
residential heating
and
emission
inventory fires
wild and agricultural
20
10
ng m
-3
0
50
c)
GFED daily emission (wild + agricultural fires)
40
30
20
10
0
r
be
em
pt
Se
08
20
08
20
08
20
08
20
08
20
08
20
st
gu
Au
ly
Ju
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Ju
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M
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Ap
ch
ar
M
01
09
20
y
ar
nu
Ja
8
01
00
r2
be
em
ec
D
8
00
01
r2
be
em
ov
N
01
08
20
er
ob
ct
O
08
20
01
01
01
01
01
01
01
01
Other sources of BC in the Arctic
Flaring: Gas burnoff at Melkøya, 70 oN
Flaring seems to be a very important source of
Arctic near-surface BC:
“we find that flaring contributes 42% to the annual
mean BC surface concentrations in the Arctic. In
March, flaring even accounts for 52% of all Arctic
BC near the surface.”
Summary and outlook
Large seasonal variations in ECbb; highest
concentrations during winter
Minimum estimates of ECbb:
Winter time mean 3.7±1.2 ng m-3
summer time mean 0.8±0.3 ng m-3
The relative contribution of ECbb to EBC
seem to be around 10 % in summer
and 25% In winter, but this is still
under analysis
Emissions from residential wood burning
in Russia is significant, and seem to
be underestimated in the emission
inventories
Flaring is a strong source of absorbing
aerosols in the Arctic, will likely
increase!
Annual increase of CO2: ca 2 ppm per year,
~0.03 Wm-2 Over 10 years: 0.3 Wm-2
Annually averaged growth rate of CO2
from WMO GHG Bulletin - 2012
Thank you for your attention!
Acknowledgements
Norwegian Research Council through the IPY project Polarcat
European Union FP 7th under grant agreement no 282688 – ECLIPSE:
ECMWF and met.no granted access to ECMWF analysis data
0
400
EBC mean
b)
-3
300
ng m
Results - Levoglucosan
100
12
50
10
40
8
ngmm-3
ng
-3
200
a)
c)
Levoglucosan
ECbb
b)
EBC mean
6
30
4
20
2
10
0
400
0
-3
ng m
r
be
em
pt
Se
08
20
08
20
st
gu
Au
ly
Ju
08
20
08
20
08
20
09
20
ch
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M
09
01
20
ry
ua
br
Fe
01
09
20
y
ar
nu
Ja
8
01
00
r2
be
em
ec
D
8
00
01
r2
be
em
ov
N
01
08
20
er
ob
ct
O
08
20
01
01
01
01
ne
Ju
ay
M
ril
Ap
08
20
100
01
01
01
ch
ar
M
200
01
300
50 time mean (1.0 ng m-3) 10 x higher than summer time mean (0.1 ng m-3)
•Winter
EC
c)
bb
ng m
-3
40
•Episodes
much more frequent in winter (multiple) compared to summer (two)
20
30
10
•Peak values
up to 10 x the seasonal mean for both summer and winter
0
r
be
em
pt
Se
08
20
st
gu
Au
ly
Ju
ne
Ju
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M
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Ap
ch
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M
09
20
ch
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09
01
20
ry
ua
br
Fe
01
09
20
y
ar
nu
Ja
8
01
00
r2
be
em
ec
D
8
00
01
r2
be
em
ov
N
01
08
20
er
ob
ct
O
08
20
01
01
01
01
01
01
01
01
08
20
08
20
08
20
08
20
08
20
•Maximum 24 hour concentration observed exceeded 10 ng m-3
•Winter time mean concentration was 1-2 orders of magnitude less compared to European
rural areas and 2-3 orders of magnitude less than for European urban areas in winter
•Levoglucosan levels observed at the Zeppelin Observatory should be considered
conservative, as levoglucosan is likely subjected to degradation by OH during LRT
Calculations cont.
•EBC was calclulated according to eq. 4, using a site specific α-value
(5.7 ± 2.3) derived from concurrent measurements of EC and ap at
the Zeppelin observatory (See eq. 5)
EBC = ap / α (eq. 4)
α = ap / EC
(eq. 5)
•calculation of the relative contribution of ECbb to EBC:
ECbb,rel = ECbb / EBC
= [LG] (TC/LG)bb (1 – (OC/TC)bb) / ap/α
Results – Atmospheric life time of levoglucosan
•Atmospheric sinks of levoglucosan discussed in the literature:
•Depletion by OH [Hennigan et al. (2010); Hoffmann et al. (2010)]
•Oligomerization (Holmes and Petrucci, 2007)
•Suggested atmospheric life time based on chamber studies (Hennigan et al., 2010):
0.7 – 2.2 days (exposed to typical summer time OH conc 1 × 106 molecules cm−3)
•Suggested τ1/2 in a combined experimental and model study by Hoffmann et al. (2010):
12.7 – 83.2 hrs (depending on OH-concentration, rx rates, and in-cloud/non-cloud)
PRELIMINARY results from sensitivity runs (FLEXPART) in the current study:
•Summer time degradation rates suggested by Hoffmann et al. (2010) appears much too high
•Winter time degradation rates suggested by Hoffmann et al. (2010) appears not too far off
•FLEXPART sensitivity runs suggest life time of approximately 10 days will reconstruct observed
seasonal means of levoglucosan
Source region and sources
Emission sensitivity: used the FLEXPART model to calculate the
emission sensitivity of BC tracer aerosols for the summer and
winter months.
For each measurement 50000 particles were released and followed 30 days
backward in time. Dry and wet scavenging is included.
BC on snow
Polluted snow at Tryvann, ca 531 m.a.s.l Oslo,1974
Hole digged into
clean snow below
Decreased snow reflectivity (”albedo”)
Bill Watterson, “The Complete Calvin and Hobbes”, 1994