chemistry-climate interactions€¦ · aerosol erf* = −1.17±0.4 net rf = −0.84 ± 0.50 w m...
TRANSCRIPT
![Page 1: Chemistry-Climate Interactions€¦ · Aerosol ERF* = −1.17±0.4 NET RF = −0.84 ± 0.50 W m −2 ... Naik et al. ACP [2013b] 8 Global mean OH is well-buffered against perturbations](https://reader034.vdocument.in/reader034/viewer/2022050402/5f806e9cd7c41d1be96dcea7/html5/thumbnails/1.jpg)
Geophysical Fluid Dynamics Laboratory Review
May 20 – May 22, 2014
Presented by
Chemistry-Climate Interactions
Vaishali Naik
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Geophysical Fluid Dynamics Laboratory Review
May 20-22, 2014
Atmospheric Chemistry plays a key role in the Climate System
1
IPCC-AR5
Lifetime ~days to months
Lifetime ~hours to days
? Radiative Forcing
(aerosols, O3)
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Geophysical Fluid Dynamics Laboratory Review
May 20-22, 2014
Seamless Atmospheric Chemistry in CM3
2
Donner et al. [2011] Austin et al. [2013] Naik et al. [2013a]
No Climate Feedback
Delworth et al. [2006] Ginoux et al. [2006] Horowitz [2006]
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Geophysical Fluid Dynamics Laboratory Review
May 20-22, 2014
AM3 (observed SST and Sea Ice) Captures Observations
3
Naik et al. JGR [2013a]
AM3 – TES Tropospheric O3 (ppbv)
(2005-2007)
Global Mean Oceanic Aerosol Optical Depth
(AOD) @ 550 nm
AM3 captures the observed zonal mean O3 to within ± 4 ppbv in much of the troposphere
AM3 reproduces the observed evolution of total AOD over the ocean from 1982-2006
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Geophysical Fluid Dynamics Laboratory Review
May 20-22, 2014
Net Negative Radiative Forcing (RF) due to Preindustrial to Present-day Increases in Tropospheric O3 and Aerosols
4
Naik et al. JGR [2013a]
Multi-model Mean [Shindell et al., 2013]
O3 RF = 0.33±0.18
Aerosol ERF* = −1.17±0.4
NET RF = −0.84 ± 0.50 W m−2
ΔAerosol Optical Depth (2000-1860)
*NET EffectiveRF: Change in TOA net radiative flux with fixed sea surface temperature
(2000-1860) NET ERF* -1.05 Wm-2
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Geophysical Fluid Dynamics Laboratory Review
May 20-22, 2014
Contribution to the Atmospheric Chemistry Climate Model Intercomparison Project (ACCMIP)
5
IPCC – AR5
WG I
ACCMIP CMIP5
Tropospheric
O3
Radiative
Forcing
of O3 and
Aerosols
Black
Carbon
Methane
Lifetime &
Hydroxyl (OH)
radical
Nitrogen &
Sulfur
Deposition
• Dominant atmospheric oxidizing agent abundance and lifetime of
radiatively active species (e.g. CH4, ozone depleting substances)
• Extremely short-lived (~1s) global measurements are hard to make,
rely on proxy methods (e.g. CH3CCl3 lifetime) or forward models to estimate
global mean OH
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Geophysical Fluid Dynamics Laboratory Review
May 20-22, 2014
Global Chemistry Climate Models (CCMs) overestimate mean OH relative to observational constraints
6
OH North/South Ratio
Naik et al. ACP [2013b]
Years
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Geophysical Fluid Dynamics Laboratory Review
May 20-22, 2014
OH
OH
OH
OH
H2O Clouds/Aerosols
CFCs/UV NET CHANGE??
OH ?
NM
VO
Cs
(T
g y
r-1)
NO
x (
Tg
N y
r-1)
CO
(T
g y
r-1)
How has global mean OH changed in response to historical (1850-2000) emission increases and climate change?
7
No consensus amongst prior modeling
studies (1991-2012)
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Geophysical Fluid Dynamics Laboratory Review
May 20-22, 2014
Large intermodel diversity in the sign of OH change over the historical period with no clear trend
Naik et al. ACP [2013b]
8
Global mean OH is well-buffered against perturbations [Lelieveld et al. 2004, Montzka et al. 2011]
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Geophysical Fluid Dynamics Laboratory Review
May 20-22, 2014
Future Directions: Realistic CH4 Simulation
• Realistic simulation of CH4 will
allow us to investigate:
– drivers of past and future
changes in atmospheric CH4
– impact on other chemical species,
e.g., tropospheric O3 and its RF
9
2000
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Geophysical Fluid Dynamics Laboratory Review
May 20-22, 2014
Future Directions: Atmospheric Chemistry in the Earth System
10
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Geophysical Fluid Dynamics Laboratory Review
May 20-22, 2014
Summary
• A comprehensive treatment of atmospheric chemistry
within GFDL’s global climate model (CM3) allows us to
advance the scientific understanding of the effect of short-
lived pollutants on climate
• GFDL helped lead a multi-model investigation of the global
mean OH historical trend
– Models do not give clear indication of global OH trend; multi-model
mean change is consistent with recent observational inference
• Integrating atmospheric chemistry within the Earth
System Model opens up the possibility of addressing whole
new sets of questions within the broader Earth System
Science
11