Masahide Kimoto - DAMTP Atmosphere

Studies of natural and
anthropogenic climate variability
using GCMs
Masahide Kimoto
Center for Climate System Research
(CCSR)
University of Tokyo
Topics
• Natural climate variability
– Neutral mode theories of NAO/AO, TAM, and
Pacific-Indo Dipole
– Ocean-atmosphere interaction in the North
Atlantic
• Anthropogenic climate variability
– The K-1 Japan coupled GCM
– Climate change over the East Asia
– 20th century climate reproduction (prep.)
Zonal-eddy coupling and a neutral mode theory
for the Arctic Oscillation
Masahide Kimoto, Fei-fei Jin, Masahiro Watanabe, and Natsuko
Yasutomi
1 (Geophys. Res. Lett., 28, 737-740, 2001)
Neutral Modes
dx
= Ax + f ≈ 0
dt
A = U ? VT
Observation
AO 500hPa Height
u Tf
x = ∑ vi
σi
i
2L Linear Balance Model
1st Singular Mode
400hPa ?
Ubar & EP-flux
300hPa
Height & E-vector
Obs.
Neutral
mode
(T10L20)
Kimoto et al. (2001; GRL)
A ‘ tilted-trough’ mechanism for the zonal-eddy interaction
ua
ψ∗ c,ψ∗ a
_
_
+
ψ∗c+ψ∗ a
_
−(u∗v∗)a −∂y(u∗v∗)a
Tropical Axisymmetric Mode (TAM) of
Variability
Masahiro Watanabe, Fei-Fei Jin, and Masahide Kimoto (JC, 2002)
CCSR/NIES AGCM
NCEP
Leading Singular Mode
Global warming projection
Precipitation (mm/month)
Seasonal rainfall climatology
B ombay
Kagoshim
a
Londo
n
Tokyo
Mont
h
T21 June Climate Change
An old coupled model result
T106 June Climate Change
A time slice experiment
Surface Temperature simulated by a low-resolution
CGCM
CCSR CGCMs
1995-2001 :
• CCSR/NIES 1
for CMIP 1 & 2
…… T21L20 + 2.8 ox2.8oL17
Flux Corrected
• CCSR/NIES 2
for IPCC TAR
…… T21L20 + 2.8 ox2.8oL17 Flux Corrected
• Kookai
TOGA CGCM
…… T21 L20 + 0.5-2.0 ox2.5 oL20 No Flux Correction*
* except high latitudes
• MIROC 2.1 prototype of the ES model
…… T42 L20 + 0.5-0.9 ox1.4 oL43 No Flux Correction
2002- : ‘ K-1 project’ for high-resolution climate
change projection
• MIROC3.1-Hi … T106L56 + 1/6x1/4 L48
Correction
No Flux
Mid-CGCM*
Annual mean SST (Year 71-75)
CGCM
minus
Levitus
CGCM
Levitus
TEST: New
mid-CGCM
(w/o FA)
Old
(with FA)
SRES-A2
(with FA)
20 Century climate
th
reproduction with the Mid-CGCM
IPCC (2001)
External Forcings
Natural forcings
Solar variability (Lean et al., 1995)
Volcanic aerosols in the stratosphere (Sato et al., 1993)
Terpene and continuous volcanic eruptions
Anthropogenic forcings
Well-mixed greenhouse gases
Stratospheric ozone change
Sulfate aerosols due to fossil fuel use
Carbonaceous aerosols due to fossil fuel combustion,
agricultural waste burning, fuelwood consumption, and
forest fires
Sea salt and soil dust aerosols are calculated
interactively and are not considered as forcing
Radiative forcing (W m ­2) due to tropospheric ozone increase calculated by CHASER ( preindustrial present­day )
Tropospheric ozone increase
LW + SW ? total ozone forcing
197 TgO3 (preindustrial)
? +10.4 DU (+58%)
311 TgO3 (present-day)
Tropospheric ozone radiative forcing W m­2 (at tropopause, in annual mean)
Global
NH
SH
LW
0.402
0.485
0.319
SW
0.085
0.107
0.063
LW +
SW
0.487
0.592
0.382
DJF
Normalized radiative forcing = 0.047 W m­2 DU­1
JJA
Historical Emission of
Anthropogenic SO2
Country-base historical inventory
(Lefohn et al., 1999)
Gridded with population distribution map
obtained from SEDAC and HYDE database
Historical Emission of
Anthropogenic Black Carbon
Country-base historical inventory of
UN Energy Statistics, IEA Energy Balances,
International Historical Statistics for fossil fuel
combustion
FAOSTAT, FAO Production Yearbook,
International Historical Statistics for agricultural
waste burning
FAOSTAT / a few population data for fuelwood
consumption
GEIA scaled by historical population numbers for
forest fire
Gridded by population distribution
Global & Annual Mean SAT Change
OBSERVATION
No INDIRECT
With INDIRECT
Cloud Top Effective Cloud Radius
(Experiments With INDIRECT)
JMA K-4 20km AGCM
Conceptual figures of circulations. Left: assumed in the CCM. Right: developed in
the DCM/KCM. Blue arrows show net circulations of mass and water vapor, while
orange arrows show convectively forced circulation.
Iwaasa et al. (2002)