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The Whole Atmosphere Community Climate Model: Overview, Current Research and
Future Plans
Rolando Garcia
CCSM June 2006 2
Outline
1. WACCM overview
2. Research with WACCM– Solar cycle impacts – 1950-2003 trend simulations– 21st century prognostic simulations – Upper atmosphere dynamics (2-day wave)
3. Future work
CCSM June 2006 3
Acknowledgments…
• Doug Kinnison (ACD)
• Dan Marsh (ACD)
• Katja Matthes (Free University Berlin)
• Astrid Maute (HAO)
• Jadwiga Richter (CGD)
• Fabrizio Sassi (CGD)
• Stan Solomon (HAO)
the following colleagues contributed to the work presented in this talk . . .
CCSM June 2006 4
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
MOZART-3
CAM3
WACCM-3
TIME-GCM
Chemistry
Dynamics +
Physical processes
MLT Processes
+ extensions
• Based on The Community Atmosphere Model (CAM3)
• 0-140 km (66 levels; z =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
CCSM June 2006 7
WACCM3 additions
• The following processes are now dealt with in a self-consistent manner in WACCM:
– 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
CCSM June 2006 9
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
CCSM June 2006 11
Zonal-Mean O3 : JULY
11 ppm
WACCMSABER
• 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
CCSM June 2006 15
SSU/MSU4 (1979-2003)
Courtesy of Bill Randel (2005)
WACCM (annual mean)Stratospheric temperature response
CCSM June 2006 16
SAGE I/II ozone change
2.4% 3.6%
% ozone change for 1% change in Mg II(~6% Mg II change over solar cycle)
WACCM (annual mean)
% ozone change over solar cycle
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Ozone column vs. f10.7 regressions: WACCM and observations
WACCM 1950-2003 WACCM 1979-2003
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• 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)
1950-2003 trends simulation
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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
CCSM June 2006 20
Total Column Ozone Trends (Global)
CCSM June 2006 21
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
CCSM June 2006 22
Temperature Trends (Global), K / Decade
Courtesy of Bill Randel (NCAR)
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Whole-atmosphere zonal-mean T trend 1950-2003
Note lack of trend at 80-90 km
Ozone decrease and CO2 increase
CO2 increase(greenhouse effect)
Antarctic O3 hole
CO2 decrease
CCSM June 2006 24
• 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.
21st century prognostic simulations
CCSM June 2006 25
Global-mean ozone column
1950-2003 sim
1980-2050 sim(A1B scenario)
column minimum ~2000-2010
recovery to 1980 values ~2040
smoothed with 12-month running mean
• 21st century prognostic simulation (red) shown together with the results of the 1950–2003 simulation (black) discussed earlier
CCSM June 2006 26
Global-mean ozone column
all smoothed with 12-month running mean
A1B scenario
“no-climate change” scenario
• 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.
CCSM June 2006 27
Stratospheric “age of air” is also affected by changing GHG
1950-2003
1980-2050 A1B
1980-2050 fix
GHG
CCSM June 2006 28
• 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
Upper atmosphere dynamics: The 2-day wave
CCSM June 2006 29
SABER T Spectrum
Similar spectral behavior in WACCM calculations as in SABER data
Wavenumber/frequency T spectra at 36°N and 80 km (July)
Note concentration of variance along line of constant c in both
data and model
WACCM T Spectrum
CCSM June 2006 30
Components of 2-day wave in SABER data and WACCM simulation
k=3, ~2-day
SABER
k=4, ~1.8 day
SABER
SABER observations and WACCM results for July
WACMM WACMM
CCSM June 2006 31
… more components of 2-day wave in SABER data and WACCM
k=2, ~3 day
SABER
k=2, ~ 2 day
SABERWACCM WACCM
CCSM June 2006 32
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
CCSM June 2006 33
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