Embed Size (px)
Citation preview
WACCM6 CMIP6 SimulationsMike Mills
Experiment short name label Ensemble
members
Year range Ocean/sea ice coupling
CMIP6 DECK experiments
AMIP amip 3 1950-2014 Observed SSTs, prescribed SICs
Pre-industrial control piControl 1 1-500 Coupled atmosphere-ocean
Abrupt quadrupling of CO2
concentration
abrupt-
4xCO2
1 1-150 Coupled atmosphere-ocean
1% yr-1 CO2 concentration
increase
1pctCO2 1 1-150 Coupled atmosphere-ocean
Historical
Past ~1.5 centuries historical 3 1850-2014 Coupled atmosphere-ocean
Nudged to specified dynamics SD-MERRA2 1 1979-2017 Observed SSTs, prescribed SICs
ScenarioMIP
Sustainability ssp1-2.6 1 2015-2100 Coupled atmosphere-ocean
Middle of the road ssp2-4.5 1 2015-2100 Coupled atmosphere-ocean
Regional rivalry ssp3-7.0 1 (2 running) 2015-2100 Coupled atmosphere-ocean
Fossil-fueled development ssp5-8.5 1 2015-2100 Coupled atmosphere-ocean
Overshoot ssp5-3.4OS 1 2040-2100 Coupled atmosphere-ocean
Experiment short name label Ensemble
members
Year range Ocean/sea ice coupling
AerChemMIP
AMIP amip 1 1850-2014 Observed SSTs, prescribed SICs
AMIP histSST-piNTCF amip 1 1850-2014 PI Near term climate forcers
AMIP histSST-piCH4 amip 1 1850-2014 PI Methane
AMIP histSST-1950HC amip 1 1950-2014 1950 CFCs and hydro-carbons
Historical piNTCF historical 1 1850-2014 PI Near term climate forcers
Historical 1950HC historical 1 1950-2014 1950 CFCs and hydro-carbons
GeoMIP
G1 (4xCO2 + solar dimming) G1 1 (running) 100yrs Coupled atmosphere-ocean
G8 (ssp5-85 + sulfur
injections to reach 1.5C)
G8 ssp5-85 1 2015-2100 Coupled atmosphere-ocean
G8 (ssp5-34-OS + sulfur
injections to reach 1.5C)
G8 ssp5-34-
OS
1 2040-2100 Coupled atmosphere-ocean
G8 (ssp5-34-OS + sulfur
injections to reach 2.0CC)
G8 ssp5-34-
OS 2C
1 2034-2100 Coupled atmosphere-ocean
Fig
ure
fro
m G
ett
elm
an
et
al., su
bm
itte
d t
o J
GR
, 2
01
9
Stratospheric aerosol optical depth compared to lidars
Stratospheric temperatures compared to observations:Microwave Sounding Unit and Stratospheric Sounding Unit
Figure from Gettelman et al., submitted to JGR, 2019
WACCM AMIP
Polar ozone evolution
• WACCM6 reproduces well the observed evolution of the Antarctic ozone hole,
and Arctic ozone loss.
• Nudged with specified dynamics, WACCM6 reproduces the observed
interannual variability at both poles.
Figure from Gettelman et al., submitted to JGR, 2019
Ozone layer evolution
Biases in free-running
WACCM6 at mid-
latitudes and in the
tropics are not seen in
SD-WACCM6.
Tropical upwelling
vertical velocity is high
in WACCM6 compared
to SD, enhancing
advection of ozone-poor
air from the
troposphere.
Figure from Gettelman et al., submitted to JGR, 2019
Sea ice extent
WACCM6 has higher September NH SIE than CAM6, in better agreement
with observations.
Analysis: Less downward surface SW and LW in WACCM6 due to higher
LWP, which results from higher aerosol number. The higher aerosol number
increases CCN and cloud drop number, resulting in smaller drops that do
not precipitate as readily. Thus the tropospheric aerosol chemistry impacts
Arctic sea ice.
Figure from Gettelman et al., submitted to JGR, 2019
WACCM6 HIST1
WACCM6 HIST2
WACCM6 HIST3
SSP2-4.5
SSP1-2.6
SSP5-3.4OS
WACCM historical and future scenarios
6K warming!
Glo
bal
aver
age
surf
ace
tem
per
ature
Year
Coupled 4xCO2
piControl
CAM
WACCM
Climate Sensitivity: WACCM vs CAMA
nn
ua
l A
vera
ge
TS
~1 K
CAM SOM
4xCO2
Coupled 4xCO2
piControl
CAM: ~13K
WACCM:
~11.3K
Climate Sensitivity: WACCM vs CAM
WACCM
SOM 4xCO2
An
nu
al A
vera
ge
TS
~1 K
CAM SOM piControl
CAM SOM
4xCO2
Coupled 4xCO2
piControl
CAM: ~13K
WACCM:
~11.3K
Climate Sensitivity: WACCM vs CAM
WACCM
SOM 4xCO2
An
nu
al A
vera
ge
TS
~1 K
CAM SOM
4xCO2 with
transient O3
CAM SOM piControl
Summary
• WACCM6 represents the state of the art in simulation of the middle atmosphere up through the mesosphere
• WACCM6 is available in several different configurations:
• fully coupled in CESM2
• with fixed SSTs
• with specified dynamics
• with specified chemistry
• New features: CAM6 physics, self-generating QBO, interactive stratospheric aerosol, full tropospheric chemistry
• WACCM6 has completed CMIP6 DECK and Tier1 MIP simulations
• WACCM6 reproduces well observed stratospheric ozone, aerosol, water vapor, and sea ice extent evolution
• Future scenario projections indicate higher climate sensitivity than WACCM4
• Idealized 4xCO2 experiments indicate lower climate sensitivity than CAM6
Extra slides
WACCM version evolution
Gettelman et al., submitted to JGR, 2019
Water vapor “tape recorder”
Figure from Gettelman et al., submitted to JGR, 2019
• Vertical
propogation
speed is shifted
upward slightly
• Amplitude is
well-represented
• Improves on
WACCM4 speed
in upper
stratosphere
• ~0.5 ppmv
positive bias in
summer
Dashed:
WACCM4
Quasi-biennial oscillation
Figure from Gettelman et al.,
submitted to JGR, 2019
• Internally generated QBO is new in
WACCM6 at default horizontal
resolution (0.95°lat x 1.25° lon)
and 70-level vertical resolution.
• Observed period: ~28 months
• AMIP WACCM: 29 months
• Coupled WACCM: 27 months
• Amplitude in lower stratosphere is
too weak, disappears below 20 km
due to coarse vertical resolution.
This is greatly improved when
vertical resolution is increased to
110 levels.
Observations
AMIP
Top curves represent
volcanic forcing:
1.15 – 2 x global average SAOD
Warming in coupled historical simulations
Figure from Gettelman et al., submitted to JGR, 2019
WACCM6 HIST1
WACCM6 HIST2
WACCM6 HIST3
SSP2-4.5
SSP1-2.6
SSP5-3.4OS
WACCM historical and future scenarios
6K warming!
