multidecadal trend analysis of in-situ aerosol radiative ...and the sargan group: trend analysis of...
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Federal Department of Home Affairs FDHA
Federal Office of Meteorology and Climatology MeteoSwiss
M. Collaud Coen
E. Andrews, C. Lund Myhre, J. Hand, M. Pandolfi, and P. Laj
and the SARGAN group: trend analysis of aerosol radiative properties
Multidecadal trend analysis of in-situ aerosol
radiative properties over the world (52 stations)
[email protected] Coen et al., ACPD, 2020
Analysed aerosol properties:
Scattering and backscattering coef.
Absorption coef.
Single scattering albedo
Scattering and absorption Ångström exponent
Backscattering fraction
Methodology:
Detection of rupture by visual
inspection + station history
Mann-Kendall with three
prewhitening methods
Sen’s slope
LMS and GLS/ARB
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EGU, Mai 2020Collaud Coen et al., ACPD, 2020
Present day (2016-2018) scattering coef. trend
49% ss negative trends (mostly in Europa, North America)
13% ss positive
38% not ss
Scattering coefficient trend [Mm-1/y]
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EGU, Mai 2020Collaud Coen et al., ACPD, 2020
60% ss negative (also in Asia)
36% not ss
3% ss positive (by only one method)
Absorption coef. [Mm-1/y]
Present day (2016-2018) absorption coef. trend
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EGU, Mai 2020Collaud Coen et al., ACPD, 2020
Present day single scattering albedo trends
18% ss negative trend
(mostly in North America and Western Europa)
52% ss positive trend
30% not ss trend
SSA= scattering/(scattering + absorption)
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EGU, Mai 2020Collaud Coen et al., ACPD, 2020
Mean trend [%/y]
Regions Scattering coef. Absorption coef. Single scattering albedo
nb tot/ss all ss nb tot/ss all Ss nb tot/ss all Ss
all 37/23 -2.11 -2.85 33/21 -2.94 -4.02 27/19 0.02 0.01
Africa 1/0 -4.6 1/1 -3.84 ) -3.84 1/0 -0.02
Asia 3/0 -1.3 3/2 -3.31 -4.83 3/3 0.12 0.12
Europe 12/8 -2.92 -4.03 15/11 -3.72 -4.45 11/8 -0.03 -0.09
N.-America 14/10 -2.66 -3.66 6/2 -1.85 -4.24 6/5 -0.01 -0.01
Pacific 2/1 0.96 3.57 2/1 -1.4 -3.74 2/1 0.13 0.27
Polar regions 5/4 0.15 -0.05 6/4 -2.25 -2.47 4/2 0.05 0.11
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EGU, Mai 2020Collaud Coen et al., ACPD, 2020
• Decrease of aerosol burden
• Larger decrease of the absorption coef. (mainly driven by black
carbon) than the scattering coef.
• 50% of ss positive SSA trend (increase of the aerosol negative
climate forcing)
• 20% of ss negative SSA trend (decrease of the aerosol
negative climate forcing).
• Environmental pollution regulations have positive effects
for health and the environment but may have an adverse
effect on efforts to reduce climate change.
Conclusion