Climate Projections over Mainland
China under SRES A1B and
RCP4.5 Using PRECIS 2.0
Changgui Wang, Richard Jones
© Crown copyright Met Office
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
• Background and Objectives
• PRECIS 2.0 model description
• Model configuration for providing regional
climate projection over China
• Model evaluation - present and future climate
over China from downscaled QUMP and
Hadgem2-ES
• Conclusion
• Further development of the system - PRECIS
2.1
© Crown copyright Met Office
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
Background and Objectives:
•
GCMs provide information which is often too coarse for applications
•
To provide the best possible regional information available for downstream
applications:
• The full range of simulated climate changes from GCMs
• Information relevant to applications which accounts for this range of possible
future climate changes, such as “Adaptation Climate Change in China”
project
•
Address major uncertainties in simulated broad-scale climate changes come
from global climate models as well as emission scenarios
•
Enable PRECIS system to downscale the Hadley Centre CMIP5 GCM
(HadGEM2-ES) –PRECIS 2.0
© Crown copyright Met Office
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
PRECIS 2.0 model description
• PRECIS 2.0 is an updated version of PRECIS RCM system, at heart of
which is HadRM3P (Jones et al., 2004)
• It implements a hydrostatic version of the full primitive equations to
representing atmospheric dynamics (Gordon et al., 2000)
• Land-surcace processes – MOSESII (Essery, 2003)
• Sulphur cycle (Collins et al., 1997)
• Parameterisation of some physical processes: cloud, precip. Radiation, BL
and gravity wave drag etc
• Finer resolution (50-25km)
• Driven at its boundaries by a GCM, the newly introduced GCM is
HadGEM2-ES
• Sea surface status can be updated using SST/ICE from couple GCMs
© Crown copyright Met Office
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
Model configuration for providing regional climate over China
• Boundary conditions: Selected HadCM3 PPE members (SRES A1B) and
HadGEM-ES RCP4.5 (CMIP5)
•
HadCM3 PPE (3.75x2.5): hydrostatic, developed from HadCM3 and used for
quantifying uncertainty in model prediction (QUMP). The downscaling subset is Q0,
Q1, Q8, Q10 and Q13 for East Asia region
•
HadGEM2-ES (1.875x1.25) is a non-hydrostatic atmospheric dynamic model and was
designed to provide simulations for CMIP5
• Model domain
• Knowledge sharing – one of the ACCC project objectives
• Contribution to CORDEX
• CORDEX E. Asia domain is chosen for PRECIS 2.0 evaluation
© Crown copyright Met Office
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
Model configuration for providing regional climate over China
• The RCM was setup to run 141 years initialised from 1959 towards 2099
• Initial conditions from interpolated from GCM fields
• LBC: 6 hourly driving fields: winds (U.V), T, Q and surface pressure
• Surface conditions: sst/ice from Hadgem2-ES
• MOSEII land surface exchange scheme
RCM info:
50km (grid length=0.44) resolution model domain
Non-rotated polar RCM
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Rotated polar RCM
Corner position
longitude latitude
longitude latitude
Top left corner
57.38
58.0
Top left corner
315.56
49.28
Top right corner
177.98
56.5
Pole
295.22
77.61
Bottom right corner
74.83
-21.19
nx=219
ny=183
Bottom left corner
162.86
-22.37
Number of grid
points
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
Model evaluation:
•
China region characteristics: temperature difference in winter and summer and
also change from region to region due to it size and landscape variability.
•
To evaluate climate trend over China, the CORDEX region is divided into 6 subregions: NW, Tibet, CENTRAL-n, Central-S, NE and SW
© Crown copyright Met Office
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
Model evaluation: present temperature climate
•
Spatial distribution of temperature compared
with CRU data set. PRECIS 2.0 simulations
agree with observed climate in capturing large
scale patterns and provides more realistic
detailed variations
•
Distinct features exhibited: cold bias over Tibet,
warm bias in SW and Central-S
•
Downscaled HadGEM2-ES simulations agree
with downscaled HadCM3 PPE and corrected
cold bias appeared in the GCM, such as
Central-S, Central-N, NW
•
The formulation of HadRM3P in PRECIS 2.0
RCM plays a dominant role in determining
surface climatology
© Crown copyright Met Office
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
Model evaluation: present precipitation climate
•
Spatial distribution of precipitation compared with CRU
data set. PRECIS 2.0 simulations agree with observed
climate in capturing large scale patterns and provides
more realistic detailed variations but featuring gridscale “noise”
•
Distinct features: wet bias presented in HadCM3 is
reduced except Central-S where seems to be
enhanced; dry area seemed to simulated more
realistically in PRECIS 2.0, but SW tend to show dry
bias
•
Downscaled HadGEM2-ES seems to correct the
HadGEM2-ES’s wet biases over Southern, southeastern China, northern region towards Central part for
all seasons but it introduced much drier climate over
Eastern and NE China during JJA
•
The formulation of HadRM3P in PRECIS 2.0 RCM
plays a dominant role in determining surface
climatology
© Crown copyright Met Office
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
Model evaluation: annual cycle
of T and Precip (baseline)
Downscaled HadCM3 PPE:
•
T: Consistent with GCMs and CRU
with improvement but cold bias over
Tibet and enhanced warm bias over
North and N-W
•
Precip: downscaled results generally
follow the GCMs with improvement,
showing wet bias corrections in most
regiona. Exceptions include Tibetm,
E, SW during djf and C-S in mam
© Crown copyright Met Office
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
Model evaluation: annual cycle of T
and Precip (baseline)
Downscaled HadGEM2-ES:
•
T: Consistent with GCMs and
CRU with improvement but cold
bias over Tibet and enhanced
warm bias over C-S
•
Precip: downscaled results
generally follow the GCMs with
improvement, showing wet bias
corrections in most region.
Exceptions include Tibetm, E,
SW during djf and C-S in mam
© Crown copyright Met Office
Grey bar –CRU; dash lines – HadGEM2-ES GCM; dotted linesdownclaed HadCM3 PPE mean; solid lines – downscaled
HadGEM2-ES
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
Model evaluation: Temporal
trend and future projections
•
T: overall 0.26/decade for present
day, noticeable changing points in
1960,1970 and 1980. By the end of
21st Century, projected T is in order
of 3-4.5oC in South and 4-6 in
North
•
Precip: a clear interannual change,
generally shows either increase or
decrease before 2010. The
decreasing trend in 1960s is well
simulated. Future projections also
show large variations but with clear
long-term increasing trend
© Crown copyright Met Office
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
Model evaluation: Temporal
trend and future projections
• Precip: increasing
trend in North show
potential to improve
drought condition but
variability's continue
in the future implies
that the droughts are
likely to persist there
© Crown copyright Met Office
Region
Obs.
Mean
(mm/day)
Rainfall Change rate (%)
PPE ensembles (A1B)
Minimum
Maximum
2050 2080
2050 2080
2050
2080
2050
2080
0.29
16.34 25.15
40.13 65.10
27.90
41.88
20.36
22.03
Tibetan 1.11
14.35 23.13
30.22 47.59
20.45
32.32
22.58
25.65
CN
0.98
21.40 25.05
39.10 46.01
27.78
36.90
9.06
14.42
CS
3.71
2.82
14.84
22.41 31.04
10.82
21.01
-1.3
7.11
NE
1.48
8.36
11.20
25.85 35.95
16.02
24.78
14.50
11.74
SW
2.63
5.28
14.80
12.56 25.4
8.72
18.24
7.49
9.40
NW
Mean
Hadgem2-ES
RCP4.5
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
Conclusions & Further work
•
•
•
•
•
This talk demonstrates the capability of new version of PRECIS 2.0
for downscaling one of CMIP5 GCM (HdGEM2-ES)
It includes HdCM3 PPE thus provide uncertainty in these projections
and information relevant to assessing climate change impacts and
adaptations over China.
Both downscaled HdCM3 PPE and HadGEM2-ES are generally
captured broad spatial, annual variations observed
DownscaledHadCM3 PPE and HadGEM2-ES simulate a wide range
of plausible future climate changes for precipitation, where
significant seasonal and geographical variability is seen in the spatial
and temporal distribution
a wider range of possible future conditions related to rainfall is
simulated, e.g. allowing for both continued drought conditions and
enhanced flood risk
© Crown copyright Met Office
Climate projection over mainland China
under SRES A1B and RCP4.5 using
PRECIS 2.0
Conclusions & Further work
• The lower temperature trends in the downscaled HadGEM2-ES
projections than in the corresponding HadCM3 PPE driven
projections is consistent with the lower greenhouse gas
emissions/concentrations present in the RCP4.5 compared to the
SRES A1B scenario.
• The results provide some indication of the range of expected
temperatures given uncertainty in both the modelling and future
emissions
• The further work on PRECIS will enable more CMIP5 GCM
members to be downscaled in the system, such as CNRM, GFDL,
CSIRO and IPSL etc
• A new release PRECIS 2.1 should be expected in next year.
© Crown copyright Met Office
Questions?
A scientific paper entitled “Climate projection over mainland
China under SRES A1B and RCP4.5 using PRECIS 2.0
(Changgui Wang, Richard Jones et al.) ” has been submitted
to IJC and is currently under peer review
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