WACCM: The High-Top Model - CESM - UCAR

WACCM: The
High-Top Model
WACCM top
Michael Mills
WACCM Liaison
mmills@ucar.edu
(303) 497-1425
http://bb.cgd.ucar.edu/
CAM top 40 km
Ozone Layer
Jarvis, “Bridging the
Atmospheric Divide”,
Science, 293, 2218, 2001

WACCM Additions to CAM
• Extends from surface to 5.1x10 -6 hPa (~150 km), with 66 vertical levels
• Detailed neutral chemistry model for the middle atmosphere,
• catalytic cycles affecting ozone
• heterogeneous chemistry on PSCs and sulfate aerosol
• heating due to chemical reactions
• Model of ion chemistry in the mesosphere/lower thermosphere (MLT), ion drag,
auroral processes, and solar proton events
• EUV and non-LTE longwave radiation parameterizations
• Imposed QBO, based on cyclic, fixed-phase, or observed winds
• Volcanic aerosol heating calculated explicitly
• Gravity wave drag deposition from vertically propagating GWs generated by
orography, fronts, and convection
• Molecular diffusion and constituent separation
• Thermosphere extension (WACCM-X) to ~500 km

WACCM Motivation
Roble, Geophysical Monograph, v. 123, p. 53, 2000
• Coupling between atmospheric layers:
• Waves transport energy and momentum from the lower
atmosphere to drive the QBO, SAO, sudden warmings,
mean meridional circulation
• Solar inputs, e.g. auroral production of NO in the mesosphere and
downward transport to the stratosphere
• Stratosphere-troposphere exchange
• Climate Variability and Climate Change:
• What is the impact of the stratosphere on tropospheric variability?
• How important is coupling among radiation, chemistry, and circulation?
(e.g., in the response to O3 depletion or CO2 increase)
• Response to solar variability: impacts mediated by chemistry?
• Interpretation of Satellite Observations

CESM-WACCM component configurations
CAM
specified chemistry
free-running
specified dynamics
free-running
atmosphere ocean
WACCM
static
(pre-industrial or
present-day)
transient
free-running
data
observations
climatology
land sea ice
data
observations
climatology
freerunning
data
observations
climatology

50N
EQ
50S
Stratospheric Sulfate Surface Area Density Climatology
50N
EQ
50S
El Chichón
17°N, 93°W
Agung
8°S, 115°E
Sulfate Surface Area Density, 43 hPa
Mt Pinatubo:
15°N, 120°E
1960 1970 1980 1990 2000 2010
Krakatau:
6°S, 105°E,
27-28 Aug 1883
1880 1885 1890 1895 1900 1905 1910
Santa
Maria:
14°N,
91°W,
24 Oct.
1902
• Observations
used: SAGE I,
SAGE II, SAM II,
and SME
instruments.
• Non-volcanic
periods filled
with monthly
mean of
1998-2002
values.
• Used Pinatubo
aerosol for
Krakatau and
Santa Maria.

Krakatoa 1883
Krakatoa 1883
Santa Maria 1902
Santa Maria 1902
Agung 1963
Agung 1963
Pinatubo 1991
Chichón 1982
Chichón 1982
Pinatubo 1991
Surface Temperature Anomalies
normalized to 1961-90
—CCSM-CAM4 1deg
—WACCM4 Pre-Indusrtrial
—WACCM4 20th Century
—WACCM4 1955-2005
—Observations (HadCRUT3)
Krakatoa 1883
Santa Maria 1902
Agung 1963
Chichón 1982
Pinatubo 1991

Volcanic heating in WACCM
2°N
Surface Area (cm 2 cm -3 )
Sulfate Mass (µg m -3 )
Multiple aerosol independent
parameters derived from
observations used as inputs.
2°N 2°N
Effective Radius (cm)

D12305 TILMES ET AL.: IMPACT OF THE GEOENGINEERED AEROSOLS D12305
Volcanic heating in WACCM
D12305 TILMES ET AL.: IMPACT OF THE 30 GEOENGINEERED hPa occurred after AEROSOLS 1991 for both the differencesD12305 in the
simulations (black line) and radiosonde anomalies (grey
30 line) hPa (Figure occurred 1). For afterall 1991 three forpressure both thelevels, differences temperature in the
simulations anomalies
Temperature
agree (blackwell line) between and radiosonde model
anomalies
and anomalies observations. (grey
line) Therefore, (Figurewe 1). expect For alla three reliable pressure response levels, of temperature the aerosol
anomalies heating in the agree model well runbetween when using model geoengineered and observations. volcanic-
Therefore, sized aerosols. we expect a reliable response of the aerosol
heating in the model run when using geoengineered volcanicsized
2.2. aerosols. Setup of the Future Control and Geoengineering
Model Runs
pressures in the lower
2.2. [14] Setup We performed of the Future two simulations Control and to analyze Geoengineering the impact
Model of geoengineered Runs aerosols on the tropospheric and stratospheric
[14] We dynamics, performed andtwo stratospheric simulations chemistry. to analyzeThe thecontrol, impact
of or ‘‘baseline’’ geoengineered model aerosols run, is on initialized the tropospheric as a REF2 and model strato- run,
spheric following dynamics, the CCMVal and stratospheric definition [Eyring chemistry. et al., The 2006],and control,
or covers ‘‘baseline’’ the period modelbetween run, is initialized 2010 and as a2050. REF2 model Increasing run,
following greenhousethe gases, CCMVal baseddefinition on the IPCC [Eyring A1Betscenario al., 2006],and [IPCC,
covers 2007], are theincluded period in between this simulation, 2010 and as well 2050. as Increasing changes in
greenhouse anthropogenic gases, halogen basedemissions. on the IPCC Initialized A1B scenario SAD and [IPCC, the
2007], resulting areHincluded 2SO4 mass in this in the simulation, model are as prescribed well as changes usingina anthropogenic climatology for halogen a nonvolcanic emissions. Initialized period from SADSAGE and the II
resulting [Thomason H et al.,
2SO4 mass 1997]. in the model are prescribed using a
climatology [15] The geoengineering for a nonvolcanic model run period is set from up identically SAGE to II
[Thomason the baselineet run al., between 1997]. 2010 and 2020. However, starting
in[15] the year The geoengineering 2020, the SAD model is increased run isfrom set upbackground identically to to
the an enhanced, baseline run fixed between SAD2010 distribution. and 2020. This However, SAD isstarting calcu-
in lated the from year 2020, the SO the4 SAD distribution is increased derived frominbackground the study of to
an Rasch enhanced, et al. [2008b]. fixed SAD Rasch distribution. et al. [2008b] Thisused SADtheisNCAR calculated
CAM from model thetoSO derive
4 distribution aerosol distributions derived in the for study different of
Rasch scenarios, et al. with [2008b]. varying Rasch amounts et al. of [2008b] sulfur used injection the NCAR in the
CAM tropics,
Figure model two
1.
different-sized toTemperature derive aerosol aerosol
difference distributions types,
between
and two forthe different
REF1.3v
Pinatubo 1991
Pinatubo 1991
calculated with WACCM (black
lines) and observed (grey lines) at
stratosphere (Tilmes et al., 2009)
Pinatubo 1991
Model Run
[14] We p
of geoengin
spheric dyn
or ‘‘baseline
following th
covers the
greenhouse
2007], are i
anthropogen
resulting H 2
climatology
[Thomason
[15] The g
the baseline
in the year 2
an enhance
lated from
Rasch et al.
CAM mode
scenarios, w
tropics, two
CO 2 conditi
al. [2008b],
into a prese
sols are assu
astandardd
effective rad
[16] The
is an appro
size spectru
ulation time
scheme (in
aerosols alr
by Rasch et
distribution
considered
Tilmes et a

Grading of Chemistry in CCMs: Chapter 6 of the
SPaRC CCMVal
• CCMs were evaluated on
their ability to represent longlived
constituents
(precursors) and short-lived
substances (radicals).
• WACCM graded out high in
all categories (i.e., grade of 1
is the highest possible).
• This is a reflection of the:
1) completeness of the
chemical processes
included
2) accuracy of photolysis
rates (J’s)
3) and accuracy of the
numerical solution
approach.
SPARC CCMVal, Report on the Evaluation of Chemistry-Climate Models, V.Eyring, T. G. Shepherd, D. W. Waugh
(EDs.), SPARC Reprot No.4, WCRP-X, WMO/TD-No. X, http://www.atmosp.physics.utoronto.ca/SPARC, 2010.

Temperature
WACCM Heterogeneous Chemistry Module
>200 K
188 K
(T sat)
185 K
(T nuc)
Sulfate Aerosols (H 2O, H 2SO 4) - LBS
k=1/4*V*SAD*γ (SAD from SAGEII)
Sulfate Aerosols (H 2O, HNO 3, H 2SO 4) - STS
Thermo. Model (Tabazadeh)
Nitric Acid Hydrate (H 2O, HNO 3) – NAT
R NAT = ƒ {Log Normal Size; # particles cc;
width distribution; condensed phase HNO 3}
ICE (H 2O, with NAT Coating)
R ice= 10-30 μm
?
R lbs = 0.1 μm
R sts = 0.5 μm

WACCM Ozone Trend: CCMVal and WMO
Antarctic Spring WACCM
Redrawn from: Austin, J., et al., J. Geophys. Res., in press., 2010.
does better
than most
models at
calculating
the evolution
of the ozone
hole.

Antarctic sea-ice extent
CCSM4 (CAM4)
-- Pre-Industrial
— 1979-2005
WACCM4
-- Pre-Industrial
— 1979-2005
Observed 1979-2005 ave
-- ice-ocean hindcast
— Satellite
CCSM4 (CAM)
dashed lines:
(1960-1979 ave) - PI
solid lines:
(1979-2005 ave) - PI
WACCM4
The more realistic ozone loss in WACCM drives changes in winds that enhance
sea-ice loss, producing sea-ice extent closer to modern observations.

Acceleration of the Brewer–Dobson Circulation due to Increases in Greenhouse Gases
L OF THE ATMOSPHERIC SCIENCES VOLUME
Garcia and Randel, J. Atmos. Sci., vol. 65 (8), pp. 2731-2739, 2008.
65
and lower stratopper
stratosphere
sphere to enhanced and therere
were made at
5° longitude. The
idation activity of
Role subtropics in Climate
scribed in detail
(specifically for
• faster circulation in
greenhouse world due
propagation of wave
activity into the lower
stratosphere and its
dissipation in the
• changes in meridional
temperature gradient
affect zonal winds,
which change the
regions where waves
dissipate, increasing
momentum deposition
of three ensemble
rst, or reference
ive” simulation of
with sea surface
HG and halogen
The second simu-
20th
Century
Age of Air (y),
~10 hPa, tropics
Future,
increasing GHGs
Future,
fixed GHGs

Impact of geoengineered aerosols on the troposphere and stratosphere
Tilmes et al., J. Geophys. Res., vol. 114, pp. 12305, 2009.
• ~5 years for adjustment of temperatures
• Constant temperature offset
Annual mean, zonally averaged global temperature difference between present day (2010–
uture (2040–2050) for (a) the baseline run and (b) the geoengineering run. (c) Annual mean,
raged global temperature difference between geoengineering and baseline runs for future
) conditions. Hatched areas are not significant at 95% level based on Student’s t test.
of geoengineered aerosols is constant.
d in the case of geoengineering would
elmed by increasing greenhouse gases
ission scenario, unless the content of
tosphere were adjusted. In our case,
ys global warming by approximately
appreciated from Figure 4. Therefore,
of 2 Tg S per year of volcanic-sized
Temperature:
Geoengineering - Baseline
• The fixed amount of sulfur cools the Earth’s
surface by ~0.9 K (Tropics), ~1.2 K (Global)
aerosols is shown to counteract global warming through
about 2050 with respect to the situation in 2010.
• Delay of global warming by ~ 40 years
• Dependence on continuous injection of sulfur
4. Impact of Geoengineered Aerosols on Surface
Temperatures and Climate
[28] Increasing greenhouse gases result in increasing
tropospheric and decreasing stratospheric temperatures.
T anomaly (K) Baseline / Geoengineering
40 km
year 2020 2030 2040 2050
30 km
year 2020 2030 2040 2050
10 km
year 2020 2030 2040 2050
surface
year 2020 2030 2040 2050

Altitude (km)
Impact of geoengineered aerosols on the troposphere and stratosphere
Tilmes et al., J. Geophys. Res., vol. 114, pp. 12305, 2009.
Impacts of geoengineering on ozone
in the lower stratosphere compared to
arcia and Randel, 2008]. Further, the
D12305 TILMES ET AL.: IMPACT OF THE GEOENGINEERED AEROSO
Baseline –Geoengineering
Latitude
Difference of annual mean zonally averaged global ozone values between present day (2010–
future (2040–2050) for (a) the baseline run and (b) the geoengineering run. (c) Difference of
n zonally averaged global ozone values between geoengineering and baseline runs for future
0) conditions. Hatched areas are not significant at 95% level based on Student’s t test.
tion is discussed below for the tropics, midlatitudes and
polar regions.
Impact of geoengineering

Massive global ozone loss predicted following regional nuclear conflict
Mills et al., PNAS, vol. 105, pp. 5307, 2008
• WACCM input: new
estimates of smoke
produced by fires in
contemporary cities
following a regional
nuclear war between
India and Pakistan
• Solar radiation heats
the soot, lofting it to
the stratopause,
heating the the entire
stratosphere for 10
years, altering
reaction rates
affecting ozone.
• Calculated ozone losses exceed 20% globally, 25-45% at midlatitudes, and 50-70% at northern high
latitudes persisting for 5 years, with substantial losses continuing for 5 additional years. Column ozone
amounts remain below that which defines the Antarctic ozone hole everywhere outside of the tropics.

Nuclear winter in WACCM4
Black Carbon Input
150-300 hPa
GISS ModelE
(Robock et al., 1997)
Year
WACCM4
GISS ModelE
Year
WACCM4
GISS ModelE
WACCM4

WACCM and CAM-Chem Customer Support
CGD Forum: http://bb.cgd.ucar.edu/
Mike Mills
WACCM Liaison
mmills@ucar.edu
(303) 497-1425
Simone Tilmes
CAM-Chem Liaison
tilmes@ucar.edu
(303) 497-1425