Transcript The CCAM multi-scale variable-resolution modelling system

The CCAM multi-scale variableresolution modelling system at CSIR
Francois Engelbrecht, Willem Landman and Mary-Jane Bopape
CSIR Natural Resources and the Environment
Climate Studies, Modelling and Environmental Health
Climate Modelling at the CSIR NRE
• NWP and RCM capacity build around the conformal-cubic
atmospheric model (CCAM) of the CSIRO
• A cube-based global model; semi-Lagrangian semi-implicit
solution of the primitive equations
• Includes a wide range of physical parameterizations
• Developed by the CSIRO Marine and Atmospheric Research
(McGregor, 2005)
• Runs in quasi-uniform or in stretched grid mode
• Multi-scale climate modelling.
© CSIR 2007
www.csir.co.za
Quasiuniform C48
grid with
resolution
about 210 km
Regional climate modelling and NWP over Africa
using CCAM
CCAM applied in
stretched-grid mode
Modest stretching
provides a resolution of
about 50 km over
southern Africa;
decreases to about 4
degrees in the far-field
Options for spectral
nudging, gridpoint
nudging or no nudging
from the host model
(atmospheric fields)
C64 stretched-grid with resolution about 50
km over southern Africa
© CSIR 2007
www.csir.co.za
CSIR CCAM 7-day forecast
CSIR seamless
forecasting system
Testing the CCAM code used for
projections of future climate change
through short-range and seasonal
forecasts leads to model development
and increased confidence climate
change projections
Routine CCAM short-range weather
forecasts over Africa (7-days ahead,
50 km resolution)
Higher-resolution forecasts are
produced over smaller domains
(downscaling) - False Bay example:
Engelbrecht et al. (2011) Water SA; Landman et al.
(2012) Water SA.
Forecast error as a
function of
integration time
Average Absolute
Error 500 hPa
geopotential height:
January 2005
Potgieter (2006), UP
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Forecast error as a
function of
integration time
Average Absolute
Error 500 hPa
geopotential height:
January 2005
Potgieter (2006), UP
© CSIR 2007
www.csir.co.za
Forecast error as a
function of
integration time
Average Absolute
Error 500 hPa
geopotential height:
January 2005
Potgieter (2006), UP
© CSIR 2007
www.csir.co.za
Landman et al.
(2012) Water SA
UM
Rainfall Bias ONDJFM 2007/8
CCAM
Rainfall Bias ONDJFM 2007/8
Landman et al.
(2012) Water SA
UM
Brier Skill Score ONDJFM 2007/8
CCAM
Brier Skill Score ONDJFM 2007/8
Landman et al.
(2012) Water SA
UM
Brier Skill Score ONDJFM 2007/8
CCAM
Brier Skill Score ONDJFM 2007/8
Seasonal forecast operational approach (SARVA, GFCSA)
Atmospheric ICs
NCEP/GFS
Boundary Conditions
Model Output Statistics
Verification of seasonal forecasts: CCAM and CGCMs
Spearman’s rank correlation between observed and
downscaled
DJF
seasonal
rainfall
totals.
The
correlations were calculated over the period from
1979/80 to 2004/05
CCAM
simulation
skill (ROC)
over northeastern
interior
Latest
system
based on
CCAMCABLE with
27 levels in
the vertical
Engelbrecht et al. (2011) Water SA;
Landman and Beraki (2012) IJC
Winsemius et al. (2014) HESS in press
Emission Scenarios and Representative
Concentration Pathways
CSIRO: Martin Dix
CRUTEMP3v
linear
temperature
trend 19612010 (°C per
century)
Strong warming
has occurred
over the
western+central
parts of
southern Africa
Warming more
moderate along
the coastal
areas
A strict test of the
seamless forecasting
system: simulation of
temperature trends
over southern Africa
Simulated trends for
1961-2010 are shown
(°C per century)
© CSIR 2007
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Taylor diagram: Verification of simulated linear trends in
annual average temperatures over southern Africa
The six ensemble
members produced very
different simulations of
the trends in annual
average temperatures
over southern Africa
The simulation of trends
in regional climate
provides a stringent test
to regional climate
models
© CSIR 2007
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CCAM-CABLE projections of future climate change (CORDEX)
CSIR-CSIRO collaboration
RCP4.5
Page 17
RCP8.5
Time-slabs annual
rainfall anomalies (mm)
– based on six CCAM A2
SRES scenarios
Most ensemble members
project southern Africa to
become generally drier under
climate change
Most ensemble members
project East Africa to become
generally wetter under climate
change
A robust signal of drying is
projected for the southwestern
Cape of SA.
Engelbrecht et al. (2009), IJC
Engelbrecht et al. (2011), Water SA
Engelbrecht et al. (2012), IJC
© CSIR 2007
www.csir.co.za
Climate Change,
climate dynamics and
extreme weather events
over southern Africa
MSG IR image
© CSIR 2007
www.csir.co.za
Climate Change
and Tropical
Cyclones+Lows
Model simulated (top)
and observed (bottom)
tropical cyclone track
climatology over
southern Africa – for
the period 1961-1990
Malherbe et al. (2013),
Climate Dynamics
© CSIR 2007
www.csir.co.za
Climate Change and
Tropical
Cyclones+Lows
Model projected change
in tropical cyclone and
tropical low frequencies
over the southwestern IO
and southern Africa, for
2071-2100 relative to
1961-1990.
Malherbe et al. (2013)
Climate Dynamics
© CSIR 2007
www.csir.co.za
Projecting latitudinal shifts in the
westerlies in response to
enhanced anthropogenic forcing:
the enhanced greenhouse effect
and (recovering) depleted
stratospheric ozone
Projected changes in mean winds and
storm tracks are relevant to Southern
Ocean dynamics, bio-chemistry and
carbon cycle
Simulated 1000 hPa u-winds (19611990) for January and projected
changes (2071-2100 vs 1961-1990).
A2 scenario with full radiative forcing
Page 22
© CSIR 2007
Latest research explores the effects of
stratospheric ozone depletion and
cooling on southern African rainfall at
inter-annual time-scales – implications
for predictability at the seasonal timescale
CSIR-NRE has capacity in
numerical model development
Simulations of nonhydrostatic
mountain waves
Scorer parameter =S ~ N/U = 0.001
1/S ~ a = 2000 m
Propagation of waves on the lee
side of the mountain
Janjic et
al. (2001)
Engelbrecht et al. (2007) SAJS
Non-hydrostatic atmospheric dynamics
and cloud microphysics scheme
development – consistent with
atmospheric component of the new
coupled model (MW equations)
Thunderstorms forced with observed large scale
forcing – T, qv, SST, surface p, zonal wind
NH tests inform the development of
larger-scale convection
parameterizations within the coupled
model
2K radiative cooling in troposphere
●Model is able to capture suppressed and deep
convection periods.
●
Simulations – convection triggered by 2K
perturbation with different micro-physics
Engelbrecht et al. (2006) SAJS
Bopape et al. (2013) APJAS
Bopape et al. (2014) SAJS in press
Tozuka et al. (2013) Climate Dynamics
Development of a new cube-based Earth System Model in Africa
(CSIR-CSIRO-JAMSTEC collaboration)
Based on cube-based global
atmospheric and land-surface
models of CSIRO and a cubebased global ocean model of
JAMSTEC (equi-angular
gnomonic-cubic grid)
Coupling of ocean and
atmosphere components
performed at CSIR
Seasonal forecasting
Projections of future climate
change (CMIP6)
Simulations of Southern
Hemisphere climate dynamics;
Simulations of the carbon cycle of
the Southern Ocean and southern
African landmass
Paleo-climate simulations