Download Downscaling of Global Climate Model

Seminar on Impact of Climate Change in Bangladesh and Results from Recent Studies
Organized by Institute of Water Modeling (IWM)
Downscaling of Global Climate
Model (GCM)
A.K.M. Saiful Islam
Associate Professor, IWFM
Coordinator, Climate Change Study Cell
Bangladesh University of Engineer and Technology (BUET)
Presentation Outline
• Overview of the Climate System
• Modeling of Climate Change
• General Circulation Model (GCM)
• IPCC SRES Scenarios
• Regional Climate Model (RCM)
• Climatic Modeling at BUET
Climate Models
• Climate models are computer-based simulations that use
mathematical formulas to re-create the chemical and
physical processes that drive Earth’s climate. To “run” a
model, scientists divide the planet into a 3-dimensional grid,
apply the basic equations, and evaluate the results.
• Atmospheric models calculate winds, heat transfer,
radiation, relative humidity, and surface hydrology within
each grid and evaluate interactions with neighboring points.
Climate models use quantitative methods to simulate the
interactions of the atmosphere, oceans, land surface, and
ice.
General Circulation Model (GCM)
• General Circulation Models (GCMs) are a class of computerdriven models for weather forecasting, understanding climate
and projecting climate change, where they are commonly
called Global Climate Models.
• Three dimensional GCM's discretise the equations for fluid
motion and energy transfer and integrate these forward in
time. They also contain parameterizations for processes such as convection - that occur on scales too small to be
resolved directly.
• Atmospheric GCMs (AGCMs) model the atmosphere and
impose sea surface temperatures. Coupled atmosphereocean GCMs (AOGCMs, e.g. HadCM3, EdGCM, GFDL CM2.X,
ARPEGE-Climate) combine the two models.
GCM typical horizontal resolution of between 250 and 600 km, 10 to 20 vertical
layers in the atmosphere and sometimes as many as 30 layers in the oceans.
Heart of Climate Model
Complexity of GCM
Hardware Behind the Climate Model
• Geophysical Fluid Dynamics Laboratory
Special Report on Emissions
Scenarios (SRES)
• The Special Report on Emissions Scenarios (SRES)
was a report prepared by the Intergovernmental Panel on
Climate Change (IPCC) for the Third Assessment Report
(TAR) in 2001, on future emission scenarios to be used for
driving global circulation models to develop climate
change scenarios.
• It was used to replace the IS92 scenarios used for the
IPCC Second Assessment Report of 1995. The SRES
Scenarios were also used for the Fourth Assessment
Report (AR4) in 2007.
SERS Emission Scenarios
• A1 - a future world of very rapid economic growth, global
population that peaks in mid-century and declines
thereafter, and the rapid introduction of new and more
efficient technologies. Three sub groups: fossil intensive
(A1FI), non-fossil energy sources (A1T), or a balance
across all sources (A1B).
• A2 - A very heterogeneous world. The underlying theme
is that of strengthening regional cultural identities, with
an emphasis on family values and local traditions, high
population growth, and less concern for rapid economic
development.
• B1 - a convergent world with the same global population,
that peaks in mid-century and declines thereafter, as in
the A1 storyline.
• B2 - a world in which the emphasis is on local solutions
to economic, social and environmental sustainability.
GCM output described in the 2007 IPCC Fourth
Assessment Report (SRES scenarios), multilayer mean
Models
Scenarios
Variables
BCC:CM1
BCCR:BCM2
CCCMA:CGCM3_1-T47
CCCMA:CGCM3_1-T63
CNRM:CM3
CONS:ECHO-G
CSIRO:MK3
GFDL:CM2
GFDL:CM2_1
INM:CM3
IPSL:CM4
LASG:FGOALS-G1_0
MPIM:ECHAM5
MRI:CGCM2_3_2
NASA:GISS-AOM
NASA:GISS-EH
NASA:GISS-ER
NCAR:CCSM3
NCAR:PCM
NIES:MIROC3_2-HI
NIES:MIROC3_2-MED
UKMO:HADCM3
UKMO:HADGEM1
1PTO2X
1PTO4X
20C3M
COMMIT
PICTL
SRA1B
SRA2
SRB1
specific humidity
precipitation flux
air pressure at sea level
net upward shortwave flux in air
air temperature
air temperature daily max
air temperature daily min
eastward wind
northward wind
Arctic Sea Ice Prediction using
community climate system model
Arctic Sea Ice in
2000
Arctic Sea Ice in
2040
Prediction of Global Warming
• Figure shows the distribution of warming during the late 21st
century predicted by the HadCM3 climate model. The average
warming predicted by this model is 3.0 °C.
Prediction of Temperature increase
Prediction of Sea level rise
Regional details of Climate Change
Regional Climate modeling
• An RCM is a tool to add small-scale detailed information of
future climate change to the large-scale projections of a
GCM. RCMs are full climate models and as such are
physically based and represent most or all of the processes,
interactions and feedbacks between the climate system
components that are represented in GCMs.
• They take coarse resolution information from a GCM and
then develop temporally and spatially fine-scale information
consistent with this using their higher resolution
representation of the climate system.
• The typical resolution of an RCM is about 50 km in the
horizontal and GCMs are typically 500~300 km
RCM can simulate cyclones and
hurricanes
Regional Climate change modeling in
Bangladesh
• PRECIS regional climate
modeling is now running
in Climate change study
cell at IWFM,BUET.
• Uses LBC data from
GCM (e.g. HadCM3).
• LBC data available for
baseline, A2, B2, A1B
scenarios up to 2100.
• Predictions for every
hour. Needs more than
100 GB free space.
Domain used in PRECIS experiment
Topography of Experiment Domain
Simulation Domain = 88 x 88
Resolution = 0.44 degree
Zoom over Bangladesh
Predicted Change of Mean
Temperature (0C) using A1B
Baseline = 2000
2050
2090
Predicting Maximum Temperature
using A2 Scenarios
[Output of PRECIS model using SRES A2 scenario]
Predicting Minimum Temperature
using A2 Scenarios
[Output of PRECIS model using SRES A2 scenario]
Change of Mean Rainfall (mm/d)
using A1B Scenarios
Baseline = 2000
2050
2090
Predicting Rainfall using A2
Scenarios
[Output of PRECIS model using SRES A2 scenario]
Change of mean climatic variables of
Bangladesh using A1B Scenarios
Temperate (0C)
Rainfall (mm/d)
Trends of Temperature of
Bangladesh (1947-2007)
Max. Temp. = 0.63 0C/100 year
Min. Temp. = 1.37 0C/100 year
2008
2005
2002
1999
1996
1993
1990
1987
1984
1981
1978
1975
2008
2005
2002
1999
1996
1993
1990
1987
1984
1981
1978
1975
1972
1969
1966
20
1963
29.4
1960
20.2
1957
20.4
29.6
1954
20.6
1951
30
29.8
1966
20.8
1963
21
30.2
1960
21.2
30.4
1957
30.6
1954
21.4
1951
30.8
1948
21.6
1948
y = 0.0137x - 6.0268
21.8
31
1972
y = 0.0063x + 17.855
31.2
Trends of Minimum Temperature
22
1969
Trends of Maximum Temperature
31.4
Spatial Distribution of Trends of
Temperature (1947-2007)
Maximum Temperature
Maximum increase: 0.0581 at Shitakunda
Minimum increase: -0.026 at Rangpur
Minimum Temperature
Maximum increase: 0.0404 at Bogra
Minimum increase: -0.023 at Tangail
Conclusions
 Analysis of the historic data (1948-2007) shows that
daily maximum and minimum temperature has been
increased with a rate of 0.63 0C and 1.37 0C per 100
years respectively.
 PRECIS simulation for Bangladesh using A1B climate
change scenarios showed that mean temperature will be
increased at a constant rate 40C per 100 year from the
base line year 2000.
 On the other hand, mean rainfall will be increased by
4mm/d in 2050 and then decreased by 2.5mm/d in
2100 from base line year 2000.
Recommendations
• In future, Climate change predictions will be
generated in more finer spatial scale(~25km).
• PRECIS model will be simulated with other
Boundary condition data such as ECHAM5 using
A1B scenarios.
• Results will be compared with other regional
climate models such as RegCM3 etc.
Thank you