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Photo: NASA
Linking Regional Aerosol Emission Changeswith Multiple Impact Measures through
Direct and Cloud-Related Forcing Estimates
Tami C. Bond, Yanju Chen, and Kevin Hade University of Illinois at Urbana-Champaign
Xin-Zhong Liang & Hao He University of Maryland
David G. Streets, Ekbordin Winijkul, and Fang Yan Argonne National Laboratory
Praveen Amar, Danielle Meitiv Clean Air Task Force
Project Design
2
The initial project concept remains:Find a dose-response curve for the atmosphere.
Forcing
Emission
As shown in May 2012, Nov 2014 Project Design Bond et al.: Aerosol Emission Changes & Metrics 3
The project period kicked off by finishing “Bounding-BC”
Bond et al. JGR 2013 Figure by D. Fahey
Project Design Bond et al.: Aerosol Emission Changes & Metrics 4
Bounding-BC fingered the big uncertaintyin BC-rich sources
� BC � direct forcing ~ bounded � BC � cloud forcing
~ large uncertainties – especially in ice/mixed � OC + SO4 � direct forcing
~ small for BC-rich sources � OC + SO4 � cloud forcing
~ large and probably negative
It’s the indirect effects of co-emitted species that cause big questions about immediate forcing
Review from May 2012, Nov 2014 Project Design Bond et al.: Aerosol Emission Changes & Metrics 5
Despite all the scientific complexity,
6
So you got [some scientific thing]
right. Who cares? Tell me if I should
turn this off!
Can you wait 6 months? I have
to run my model…
Bond et al.: Aerosol Emission Changes & Metrics
policy discussions need simplicity
Project Design
This simplicity is distilled into climate “metrics”
Normal people think: A metric is something you can measure, and report
The climate policy community says: A metric is a well-defined calculation that can be used to equate impact of a mass emission of some species to a mass emission of the big bear, CO2
Project Design Bond et al.: Aerosol Emission Changes & Metrics 7
Climate metrics for short-lived species can be calculatedfrom a single measure
Absolute global warming potential Global warming potential
Global temperature potential Specific forcing pulse
For short-lived species (τ<4 mo),ENF Emission-Normalized Forcing is the
only model output required to calculate any of these metrics.forcingENF = Other considerations affect the values of emission metrics, emission but they all come from models of the carbon cycle or Earth’s heat capacity, NOT from models of aerosols
Project Design Bond et al.: Aerosol Emission Changes & Metrics 8
Thought process for project design
For use in climate metrics, we need emission-normalized forcing for: -black & organic carbon - direct & cloud-related forcing
And the aerosol-cloud interactions aren’t any good if the aerosol size and number isn’t right.
Also, we should check with policy-makers if we are making this too complicated to understand.The cloud-related forcing
isn’t any good if the clouds aren’t right.
Project Design Bond et al.: Aerosol Emission Changes & Metrics 9
Project objectives reflected those considerations
For use in climate metrics, we need emission-normalized forcing for: -black & organic carbon - direct & cloud-related forcing
And the aerosol-cloud interactions aren’t any good if the aerosol size and number isn’t right.
Objective 2: Employ an ensemble of parameterizations in regional-scale models to identify best estimates and uncertainties for direct and cloud-related forcing
Also, we should check with policy-makers if we are making this too complicated to understand.
Project Design Bond et al.: Aerosol Emission Changes & Metrics 10
Project objectives reflected those considerations
For use in climate metrics, we need emission-normalized forcing for: -black & organic carbon - direct & cloud-related forcing
Objective 1: Develop size-resolved, speciated emission inventories of aerosols and aerosol precursors
Objective 2: Employ an ensemble of parameterizations in regional-scale models to identify best estimates and uncertainties for direct and cloud-related forcing
Also, we should check with policy-makers if we are making this too complicated to understand.
Project Design Bond et al.: Aerosol Emission Changes & Metrics 11
Project objectives reflected those considerations
Objective 3: Determine functional relationships that express changes in direct and cloud radiative forcing as a function of emission changes in particular locations
Objective 1: Develop size-resolved, speciated emission inventories of aerosols and aerosol precursors
Objective 2: Employ an ensemble of parameterizations in regional-scale models to identify best estimates and uncertainties for direct and cloud-related forcing
Also, we should check with policy-makers if we are making this too complicated to understand.
Project Design Bond et al.: Aerosol Emission Changes & Metrics 12
Project objectives reflected those considerations
Objective 3: Determine functional relationships that express changes in direct and cloud radiative forcing as a function of emission changes in particular locations
Objective 1: Develop size-resolved, speciated emission inventories of aerosols and aerosol precursors
Objective 4: Iterate emission-to-forcing measures as communication tools between decision makers and climate scientists
Objective 2: Employ an ensemble of parameterizations in regional-scale models to identify best estimates and uncertainties for direct and cloud-related forcing
Project Design Bond et al.: Aerosol Emission Changes & Metrics 13
Size-resolved inventories
Objective 1: Get the size right
(David Streets, Ekbordin Winijkul – Argonne)
Size-resolved inventories Bond et al.: Aerosol Emission Changes & Metrics 14
Global size-resolved emission inventory has been produced.
Size-resolved global emission inventory of primary particulate matter (PM) from energy-related combustion sources E. Winijkul, F. Yan, Z. Lu, D. G. Streets, T. C. Bond, Y. Zhao Atmos Env, 28 August 2015
Size-resolved inventories Bond et al.: Aerosol Emission Changes & Metrics 15
This work includes uncertainty and illustrative reductionscenarios
Residential: Industrial: Switching from Baghouses on cement kilnssolid fuel to LPG
Winijkul et al., Atmos Env., 2015
Size-resolved inventories Bond et al.: Aerosol Emission Changes & Metrics 16
The connections still need work.
Objective 3: Determine functional relationships that
changes in particular locations
Objective 1: Develop size-resolved, speciated emission inventories of aerosols and aerosol precursors
express changes in direct and cloud radiative forcing as a function of emission
Disconnect: Most models are not ready to accept spatially-dependent,
size-resolved emissions.
Size-resolved inventories Bond et al.: Aerosol Emission Changes & Metrics 17
Teaser: We are now using aerosol-resolved models toestimate plume-exit composition and CCN.
10-2 10-1 100 0
1
2
3
4
5 x 1015
Supersaturation [%]
EI C
CN
[kg -1
]
OC BC Inorganic BC & OC BC & Inorg OC & Inorg
There’s a limit on CCN emission.
Mena, Fierce, Bond & Riemer, in prep for ACP
Size-resolved inventories Bond et al.: Aerosol Emission Changes & Metrics 18
Regional Cloud Modeling
Objective 2: Get the Clouds Right
(Hao He, Xin-Zhong Liang – Univ of Maryland) Regional cloud modeling Bond et al.: Aerosol Emission Changes & Metrics 19
eeee ooooo oooo666666
Aerosol(106)
Cloud(1010)
n
We used CWRF with an ensemble model to choose one combination of cloud-aerosol-radiation.
cst ( 3)
ccs ( 4)
ccb ( 5)
cci ( 2)
bin ( 3)
rel ( 6)
rei ( 7)
rer ( 1)
liquid ( 7)
ice (16)
rain ( 3)
graup ( 1) snow ( 1)
liquid ( 4)
ice (17)
rain ( 2)
graup (1)
snow ( 1)
emis ( 3)
binding ( 3)
overlap ( 3)
types (13)
bgd (1)
sul (2)
ssa (2)
dst (2)
cab (2)
tot (3)
bgd (1)
sul (2)
ssa (2)
optics (1152)
vertical profiles
(8)
(72)
(16) dst (2)indirect effects (18) ccn (6)
cab (2)
cloud radius (3)
cover (360)
optics (137088)
water (3)
radius (42)
(336)
(408)
geometry (9)
mosaic (9)
(4000 8)
(333333333 6)
Cloud
Radiation
AAAAAAAAA AAAA AAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAA AAAAAA AAAAAAAA AAAAAAAeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr rrrrrrrrrrroooooooooooooooooooooooooooooooooooooooooooooooo ssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssoooooooooooooooo oooooooooooooo ooooooooooooooooooooooooooooooooooooooooooooooooooooooooo lllllllllllllllllllllllllllll (((((((((((((((((((( 1111100000000000000000000 6666666666666666 66666666666666666666666666666666666666666666666 )))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))) Aerosol
(1010) (106)
(102)
1018
configurations
earth orbit
surface characteristics radiative gases
n C
However, when clouds were right, aerosol wasn’t, so we used offline aerosol fields (not ideal).
Regional cloud modeling Bond et al.: Aerosol Emission Changes & Metrics 20
Comparison between modeled and observed fluxes(average over Continental US)Error bars are std dev of all grid boxes
(MISR)
Regional cloud modeling Bond et al.: Aerosol Emission Changes & Metrics 21
Biases appear lower (but not perfect) withGOCART fields
22
TOA
Flu
x C
loud
rad.
forc
ing
Bond et al.: Aerosol Emission Changes & Metrics Regional cloud modeling
ISCCP and MISR ISCCP and GOCART
The connections still need work.
Objective : Determine functional relationships that express changes in direct and cloud radiative forcing as a function of emission changes in particular locations
Disconnect: Model components are
getting more rigid– difficult to switch in
components that work best
Objective 2: Employ an ensemble of parameterizations in regional-scale models to identify best estimates and uncertainties for direct and cloud-related forcing Size-resolved inventories Bond et al.: Aerosol Emission Changes & Metrics 23
Emission-to-forcing measures
Objective 3: Model Interpretation for Policy Relevance
(Yanju Chen– Univ of Illinois) Emission-to-forcing Bond et al.: Aerosol Emission Changes & Metrics 24
25
Basic approach: Global model, regional reductions
Reported previously: � Used Community Atmosphere Model (CAM), version
modified for polar transport � Determined that 30°x30° is optimum aggregation region
���
������������������ �� ����� �������� Emission
region
Extensive assistance from H. Wang, P. Rasch at PNNL
Emission-to-forcing Bond et al.: Aerosol Emission Changes & Metrics 25
We developed a “linearity diagnostic” R
50% present-day
100% present-day
emission R =
F100 − F50
F100 − F0
emission
0 emission
R� 0.5: Forcing is linear in emission. R< 0.5: Small emission change from present-day
produces less forcing change than one would expect
Emission-to-forcing Bond et al.: Aerosol Emission Changes & Metrics 26
Direct forcing is linear, as expected
Not much to see here. Just checking.
Greater response than expected
Lower response
than expected
Emission-to-forcing Bond et al.: Aerosol Emission Changes & Metrics 27
Indirect forcing is nonlinear and lower than expected
Greater response than expected
Lower response
than expected
Cause: Saturation; CCN not activating
Not a new finding, but we didn’t know magnitude. Asian OC CRF is about 40% less negative than simple proportion would predict.
Emission-to-forcing Bond et al.: Aerosol Emission Changes & Metrics 28
Policy-relevant metrics
Objective 4: Tell the Story
Praveen Amar, Danielle Meitiv– Clean Air Task Force Kevin Hade, Tami Bond – University of Illinois
Policy-relevant metrics Bond et al.: Aerosol Emission Changes & Metrics 29
Common metrics have common failings
� Global Warming Potential• Integrated forcing per emission• Doesn’t take Earth system inertia into account• Doesn’t communicate immediacy• Requires choice of time horizon
� Global Temperature Potential• Temperature change at single year in future • Doesn’t communicate trajectory experience
• Doesn’t communicate immediacy• Requires choice of time
Two sets of surveys conducted
� Original goal: Survey state decisionmakers
� Survey 1: 35 policy-oriented people and scientists
� Survey 2: Eight city managers (where the climate action is now)
2 reports have been communicated to EPA
Policy-relevant metrics Bond et al.: Aerosol Emission Changes & Metrics 31
Main messages had nothing to do with metrics
� Non-specialists need simple ways to communicate black carbon’s effects to non-specialists• Even terms like “radiative forcing” and “feedback” are
not as straightforward as you think. � People want to hear about certainty, not uncertainty.
Policy-relevant metrics Bond et al.: Aerosol Emission Changes & Metrics 32
Scientists understand the importance of GWP timehorizon…
images: smh.com.au, dalje.com
…but policymakers don’t care
Policy-relevant metrics Bond et al.: Aerosol Emission Changes & Metrics 33
The challenge
�Communicate immediacy …without minimizing importance of CO2
�Communicate timing �Make it relevant
Also, scenarios & emissions should have parallel
treatment?!
Our solution… which WILL be redacted from this presentation…
involved a simple energy-balance model that was calibrated against MAGICC
Policy-relevant metrics Bond et al.: Aerosol Emission Changes & Metrics 34
TP = (Tscen,i −Tref ,i )i∑
generational Integrated Temperature Perturbation
gI fsceenn ,,ii rree ffee ,,ii i
scen i refe i
Super simple. Sum of temp changes across 1 generation.
Following Peters et al. 2011 Can be used for both emission metrics & scenario
Policy-relevant metrics Bond et al.: Aerosol Emission Changes & Metrics 35
Avoided gITP for SLCF at different rates and CO2
In G1, SLCF avoids as much temperature as RCP 8.5�RCP 2.5 Don’t forget you need INVESTMENTS to achieve both
Avoi
ded
Policy-relevant metrics Bond et al.: Aerosol Emission Changes & Metrics 36