Transcript Downscaling Tools - University of Victoria

Downscaling Tools
Introduction to LARS-WG and SDSM
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
LARS-WG stochastic weather generator
( http:\\www.iacr.bbsrc.ac.uk\mas-models\larswg.html )
• Generation of long weather
time-series suitable for risk
assessment
• Ability to extend the
simulation of weather to
unobserved locations
• A computationally
inexpensive tool to produce
climate change scenarios
incorporating changes in
means and in variability
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
LARS-WG stochastic weather generator
( http:\\www.lars.bbsrc.ac.uk\model\larswg.html )
Parametric- e.g., WGEN
Semi-parametric - e.g., LARS-WG
0.1
0.12
0.09
0.1
0.08
(mean, sd)
0.07
0.08
0.06
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0
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Generates precipitation, min and max temperature and solar radiation
Modelling of precipitation events is based on wet/dry series
Semi-empirical distributions are used for precipitation amounts, dry/wet
series and solar radiation
Temperature and solar radiation are conditioned on the wet/dry status
of a day
Temperature and solar radiation are cross-correlated
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
LARS-WG
• Model calibration - SITE ANALYSIS
• Model validation - QTEST
• Generation of synthetic weather data GENERATOR
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
SITE ANALYSIS
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
QTEST
Compare observed and synthetic data to evaluate LARS-WG performance
Precipitation
Maximum
Minimum
Solar
Precipitation
radiation
temperature
temperature
variability
variability
variability
variability
Maximum
Minimum
Solar
temperature
radiation
temperature
1.8
160
1.8
30
70
123.5
25
Standard
deviation
Standard
deviation
(°C)
Standard
deviation
(m(°C)
m
)
Radiation
(MJm -2) (°C)
Maxim
Minim
um tem perature
Precipitation
total
(m m-2))
Standard deviation
(MJm
1.6
140
1.6
60
3
25
101.4
20
1.4
120
1.2
50
1.2
20100
82.5
15 1
40
21
80
1560.8
0.8
101.5
60
30
0.6
1040.6
40
0.4
20
1
0.4
5
5220
0.2
0.2
0.5
10
0
00 00
0
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WG
WG
WG WG
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The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
GENERATOR
Generate synthetic weather data: to extend time series, or for
climate change studies
Scenario file
Base scenario file
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
GENERATOR
Days with
withMinimum
minimum
temperature
30°C
> 0°C
temperature <
maximum
Days
temperature
Precipitation
Maximum
temperature
16
1.2
180
14
25
Num ber of days
Num
ber perature
of days (°C)
Minim
um tem
tem
Precipitation
total (m (°C)
m)
Maxim
um
perature
14160
1
12
140
12 20
10
0.8
120
10
15
100
8
0.6
8
80
6
10
6
0.460
4
4 40
0.225
20
2
0
000
0
Base
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Base
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2050s
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The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
Limitations of LARS-WG (and
weather generators in general) ...
• Temporal downscaling only
• Designed for use at individual sites only
(no spatial correlation)
• Can only represent events in calibration
data set
• Generally underestimate variability
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
SDSM
1. A decision support tool
for assessing local
climate change impacts
2. Facilitates the rapid
development of multiple,
low-cost, single-site
scenarios of daily
surface weather
variables under current
and future climate
forcing
3. Based on a multiple
regression-based
method
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
SDSM Structure
7 steps:
• Quality Control and Data Transformation
• Screening of Predictor Variables
• Model Calibration
• Weather Generation (using observed
predictors)
• Statistical Analyses
• Graphing Model Output
• Scenario Generation (using climate model
predictors)
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
Model Verification
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
Victoria: Maximum temperature
30
25
20
15
CGCM1 GA1
Downscaled
10
5
Dec
Nov
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Feb
0
Jan
(°C)
1961-1990
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
Tmax > 25°C
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
Cautionary Remarks
• SDSM provides a parsimonious technique of scenario
construction that complements other methods
• SDSM should not be used uncritically as a “black box”
(evaluate all relationships using independent data)
• Local knowledge is an invaluable source of information when
determining sensible combinations of predictors
• Daily precipitation amount at individual stations is the most
problematic variable to downscale
• The plausibility of all SDSM scenarios depends on the
realism of the climate model forcing
• Try to apply multiple forcing scenarios (via different GCMs,
ensemble members, time–slices, emission pathways, etc.)
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
Projet FACC (en cours 2003-2004)
Etude sur force/faiblesse de SDSM et LARS-WG
pour extrêmes et variabilité climatique
Coordonnateur
Philippe Gachon
Collaborateurs :
- Ouranos : Alain Bourque, René Roy, Claude Desjarlais,
Georges Desrochers, Vicky Slonosky, Diane Chaumont
- EC-SMC (Qc) : Jeanna Goldstein, Jennifer Milton, Nicolas
Major
- McGill : VTV Nguyen, Charles Lin
- INRS-ETE : André St Hilaire, Bernard Bobée, Taha Ouarda
- UQAM : Peter Zwack
- CCIS : Elaine Barrow
- Post-Doc et étudiants : Tan Nguyen (PostDoc); Massoud
Hessami (PostDoc); Mohamed Abul Kashem (PhD)
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
1st Objective : intercompare SDSM &
LARS-WG for downscaling extremes
(regional case-studies)
5 Régions à
étudier
(Stat. Downscaling)
2
1
1961-1990
Tmin
Tmax
Tmoy
Precipitation tot.
3
5
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
1
2
6
4
3
5
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
2nd Objective
Develop observed climate
indices used for
verification & analysis
(using STARDEX software)
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada
THANK YOU FOR
YOUR ATTENTION !!
The Canadian Climate Impacts Scenarios (CCIS) Project is funded by the
Climate Change Action Fund and provides climate change scenarios and related
information to the VIA community in Canada