Transcript Whole Atmosphere Community Climate Model (WACCM3

The Whole Atmosphere Community Climate
Model: Overview, Current Research and
Future Plans
Rolando Garcia
Outline
1. WACCM overview
2. Research with WACCM
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Solar cycle impacts
1950-2003 trend simulations
21st century prognostic simulations
Upper atmosphere dynamics (2-day wave)
3. Future work
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Acknowledgments…
the following colleagues contributed to the work
presented in this talk . . .
• Doug Kinnison (ACD)
• Dan Marsh (ACD)
• Katja Matthes (Free University Berlin)
• Astrid Maute (HAO)
• Jadwiga Richter (CGD)
• Fabrizio Sassi (CGD)
• Stan Solomon (HAO)
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and, of course, Byron Boville …
… to whose memory this talk is dedicated
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1. Overview of WACCM
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NCAR Whole Atmosphere Community Climate Model
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TIME-GCM
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MLT Processes
MOZART-3
WACCM-3
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Chemistry
CAM3
Dynamics +
Physical processes
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+ extensions
Based on The Community
Atmosphere Model (CAM3)
0-140 km (66 levels; Dz =1.3 km in
lower stratosphere to 3 km in
thermosphere)
Finite-volume dynamics
30 minute time step
MOZART-3 chemistry package
(55 species)
Upper atmosphere extensions:
– Lindzen GW parameterization
– Molecular diffusion
– NO cooling
– non-LTE long-wave heating in the
15 µm band of CO2 and the
9.6 µm band of O3
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WACCM3 additions
• The following processes are now dealt with in a selfconsistent manner in WACCM:
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Solar variability
Chemical heating
Airglow
Ion chemistry (5 ion species & electrons)
EUV and X-ray ionization
Auroral processes
• Particle precipitation
• Ion drag
• Joule heating
• Chemistry is completely interactive with dynamics
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Current interdivisional collaborators
Current external collaborations
• Mark Baldwin (NWRA)
– annular modes
• Natalia Calvo (U. of Madrid) and Marco Giorgetta
(MPI, Hamburg)
– effects of ENSO on the middle atmosphere;
comparison of models and reanalysis data
• Charlie Jackman (NASA/Goddard)
– impacts of solar proton events on ozone
• Judith Perlwitz and Martin Hoerling (NOAA/Boulder)
– climate impacts of changing chemistry and SST
• Cora Randall et al. (CU/LASP) [plus John Gille
(ACD/HIRDLS) and Laura Pan (ACD/UTLS initiative)]
– process-oriented evaluation of chemistry-climate
models vs. observations
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Zonal-Mean T: JULY
WACCM
140 K
270 K
200 K
• SABER: broadband IR radiometer onboard
TIMED satellite; measures T, O3, H2O, CO2
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Zonal-Mean U: JULY
WACCM
• URAP/UKMO: UARS/UK Met Office reference
atmosphere, based upon UARS satellite observations
assimilated with the UK Met Office GCM
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Zonal-Mean O3 : JULY
WACCM
SABER
11 ppm
• SABER: broadband IR radiometer onboard
TIMED satellite; measures T, O3, H2O, CO2
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2. Research with WACCM
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Solar min/max simulations
• Fixed solar minimum and solar maximum conditions
(constant F10.7 and Kp typical of minimum/maximum)
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definition of solar variability
• 15 years ea. solar maximum
and minimum conditions
• Smax: F10.7 = 210, Kp = 4
• Smin: F10.7 = 77, Kp = 2.7
• Photolysis and heating rates are
parameterized in terms of f10.7 and Kp
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Stratospheric temperature
response
WACCM (annual mean)
SSU/MSU4 (1979-2003)
Courtesy of Bill Randel (2005)
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WACCM (annual mean)
SAGE I/II ozone change
2.4%
3.6%
% ozone change over solar cycle
% ozone change for 1% change in Mg II
(~6% Mg II change over solar cycle)
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Ozone column vs. f10.7 regressions:
WACCM and observations
WACCM 1950-2003
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WACCM 1979-2003
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1950-2003 trends simulation
• An ensemble of “retrospective” runs, 1950-2003,
including solar variability, observed SST, observed
trends in GHG and halogen species, and observed
aerosol surface area densities (for heterogeneous
chemistry)
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Calculated and Observed Ozone Trends
SAGE-I 1979-1981 and
SAGE-II 1984-2000
• Red inset on left covers approximately
same region as observations on right
• Agreement is quite good, including region of
apparent “self-healing” in lower tropical
stratosphere
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Total Column Ozone Trends (Global)
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Calculated and Observed Temperature Trends
SSU + MSU 1979-1998
• Red inset on left covers approximately same region
as observations on right
• Note comparable modeled vs. observed trend in
upper stratosphere, although model trend is somewhat
smaller
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Temperature Trends (Global), K / Decade
Courtesy of Bill Randel (NCAR)
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Whole-atmosphere zonal-mean T trend
1950-2003
CO2 decrease
Note lack of trend at
80-90 km
Ozone decrease and
CO2 increase
Antarctic O3 hole
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CO2 increase
(greenhouse effect)
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21st century prognostic simulations
• An ensemble of prognostic runs, 1975-2050, to
look at climate change and ozone recovery in the
21st century. Follows WMO A1B scenario.
• An additional ensemble assumed constant CO2,
CH4, N2O to assess the role of stratospheric
cooling by these gases.
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Global-mean ozone column
recovery to 1980 values ~2040
1950-2003 sim
1980-2050 sim
(A1B scenario)
smoothed with 12-month running mean
column minimum ~2000-2010
• 21st century prognostic simulation (red) shown together with the results of the 1950–2003
simulation (black) discussed earlier
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Global-mean ozone column
A1B scenario
“no-climate change” scenario
all smoothed with 12-month running mean
• A1B scenario produces “super-recovery” compared to “no climate change”
simulation wherein CO2, N2O, CH4 are held at 1995 values.
• This is due to colder stratospheric T in A1B scenario.
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Stratospheric “age of air” is also affected by changing GHG
1950-2003
1980-2050 A1B
1980-2050 fix GHG
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Upper atmosphere dynamics:
The 2-day wave
• Apart from the tides, the 2-day wave dominates high-frequency
variability in the MLT
• Has large amplitude at solstice, especially in the summer
hemisphere
• Has been interpreted as a normal mode (e.g., Salby, 1981), a
result of baroclinic instability (e.g., Plumb, 1983), and a
combination of both (e.g., Randel, 1994)
• Comparison of WACCM simulations and observations by the
SABER instrument on the TIMED satellite
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Similar spectral behavior in WACCM
calculations as in SABER data
Wavenumber/frequency T spectra at 36°N and 80 km (July)
SABER T Spectrum
WACCM T Spectrum
Note concentration of variance
along line of constant c in both
data and model
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Components of 2-day wave in SABER
data and WACCM simulation
SABER observations and WACCM results for July
k=3, ~2-day
SABER
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k=4, ~1.8 day
WACMM
SABER
WACMM
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… more components of 2-day wave
in SABER data and WACCM
k=2, ~3 day
SABER
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k=2, ~ 2 day
WACCM
SABER
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3. Future Work
• Climate sensitivity to doubling CO2: CAM vs. WACCM
• Impact of ozone hole and changing tropical SST on
Arctic/Antarctic surface climate
• Climatology of stratospheric sudden warmings: impacts
of resolution, gravity wave parameterization, SST
variability; relationship to annular modes
• Process-oriented evaluation of model chemistry
(comparisons with EOS/Aura observations)
• Impact of solar proton events on mesospheric and
stratospheric composition
• Energy budget and dynamics of the MLT – comparison
with SABER observations
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To keep in touch ….
WACCM website and new model release
• WACCM website is being hosted under ACD
(http://waccm.acd.ucar.edu/index.shtml)
• Website has been updated and reformatted
• 2006 CSL proposal posted on site
• WACCM3 description to be completed
• Release WACCM3 in summer 2006
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