Transcript THE CLIMATE SEVERITY INDEX FOR CANADA

Scenarios of the Canadian
Climate Severity Index
Trevor Murdock, M.Sc.
Canadian Institute for Climate Studies
5 Nov 2003
Ouranos derived data and climatic indices meeting, Montréal
Scenarios of the Canadian
Climate Severity Index
Trevor Murdock, M.Sc.
Canadian Institute for Climate Studies
5 Nov 2003
Ouranos derived data and climatic indices meeting, Montréal
Based on project Funded by CCAF. Collaborators: Rick Lee1,
Francis Zweirs2, Elaine Barrow 3, Ron Hopkinson4, David W. Phillips4,
Badal Pal1 and Fred Herfst1.
1Canadian
Institute for Climate Studies (CICS), 2Canadian Center for
Climate Modelling and Analysis (CCCma), 3Canadian Climate
Impacts and Scenarios Project (CCIS), 4Environment Canada
Outline
1.
2.
3.
4.
CICS and CCIS
Goals
What is the CSI?
Steps & Results
a) Original
b) Revised
c) Model
5. Overview
6. Recommendations and Summary
*
Scatterplots
1. Canadian Institute for Climate Studies
www.cics.uvic.ca
• Launched in 1993 to “further the understanding of the
climate system, its variability and potential for change and
to further the application of that understanding to decision
making in both the public and private sectors.”
• Climate Research Network, Climate Applications Projects
(consulting), Seasonal Climate Predictions, Climate
Network Newsletter, Canadian Climate Impacts and
Scenarios Project (CCIS)
1. Canadian Climate Impacts and Scenarios (CCIS)
www.cics.uvic.ca/scenarios
• Delivery (since 1999) of consistent scenarios over Canada,
background info, tools, user assistance, training, workshops
• Staff:
– Dr. Elaine Barrow Co-Principal Investigator (AIRG, Regina)
– Dr. Philippe Gachon Co-principal Investigator (AIRG-Ouranos,
Montreal)
– Trevor Murdock Senior Research Associate & Webmaster (CICS,
Victoria)
– AIRG provides project direction and support staff; CICS provides
support staff
2. Goals
• Compute projections of a climate change index
that Canadians can relate to
• Environment Canada’s Climate Severity Index
• To make it available online
www.cics.uvic.ca/severity
3. What is the CSI?
• Index 0 to 100 developed by Phillips and Crowe (EC)
• Measures spatial variation of severity of climate
• Weighted factors and sub-factors chosen based on
combination of survey results and climate expertise
(different weightings of factors considered)
• Constrained by the data available (daily data records
and hourly data summaries) at time of development
• Note: CSI is not the same as recent analysis which has
received media attention by David Phillips based on various
measures of severity at 100 cities across Canada (not an
aggregate index) http://www.on.ec.gc.ca/weather/winners/
What is The CSI?
Winter Discomfort 35%
10% Length of Winter
• Number of months with temperature less
than 0ºC
10% Severity of Winter
• Temperature of coldest month
15% Wind Chill
• Percent of time in January that (hourly) wind
chill exceeds 1400 W/m2
What is The CSI?
Summer Discomfort 15%
• Humidex, Length of Summer, Warmth of
Summer, Dampness
Psychological 20%
• Darkness, Sunshine, Wet Days, Fog
Hazard 20%
• Strong Winds, Thunderstorms, Blowing Snow,
Snowfall
Outdoor Mobility 10%
• Snowfall, Visibility, Freezing Precipitation
4. Steps
a. Original CSI
Recreated to validate methodology
and analyze changes over observed
record
b. Revised CSI
Adjustments to accommodate
differences between station and
GCM
c. Model CSI
Generate CSI scenarios from GCM
output
4a. Original CSI Map of Canada
Phillips, D.W. and R.B. Crowe (1984): Climate Severity Index for Canadians,
Atmospheric Environment Service, Environment Canada CLI-1-84. 43 pp.
4a. Original CSI Map of Canada
Phillips, D.W. and R.B. Crowe (1984): Climate Severity Index for Canadians,
Atmospheric Environment Service, Environment Canada CLI-1-84. 43 pp.
4a. Observed Change in CSI
• The original CSI based mainly on daily climate data
(1941-1970) and hourly data summaries (1957-1966)
for 146 stations
• CSI project had 1953-1995 data for 15 stations
• Recent climate generally warmed and gotten wetter.
What had that done to the CSI?
• CSI recalculated for 15 stations using daily and
hourly data for:
• 1953-1970 (closest overlap with original)
• 1953-1980 (next 30 yr normal period)
• 1961-1995 (most recent period)
4b. Revised CSI
• Hourly / daily parameterizations (26% of index) CSI recalculated
using only daily data (because scenarios of future climate do
not provide hourly output)
• Humidex: synthetic hourly temperature and specific humidity
obtained by adjusting the daily average data by the difference
between the mean observation for each hour (by month) and the
daily mean
• Strong winds: synthetic reconstruction not applicable – no
consistent diurnal cycle; instead fit linear trend between daily
mean wind and # of hours above threshold
• Wind chill: neither approach worked well – instead used the
exact ratio of number of hours to number of days with wind chill
above threshold
4a-b. Results - CSI recalculated
Average results 15 stations across Canada
Hourly
1940-1971
1953-1970
1953-1980
1961-1995
Daily
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47
46
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47
46
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4c. Scenarios of CSI
• Canadian CGCM1 IS92A GHG+A1 (ga1) model grid
(coupled general circulation model version 1 using
greenhouse gas and sulphate aerosol forcing)
• Time slices: 2010-2039 (2020s), 2040-2069 (2050s),
and 2070-2099 (2080s)
• Steps to compute Model CSI:
– Derivations of CSI factors from available model output
– Interpolation from stations to grid of hourly/daily
parameterizations
– Removal of model bias
Sub-factor
Model output
Length of Winter (10%), Severity of
Winter (10%), Length of Summer
(2.5%), and Warmth of Summer (2.5%)
T
Wind Chill (15%) *
T, U, V *
Darkness (7%)
LAT
Snow (6%)
T, P (not snow depth)
Strong Winds (6%) *
U, V *
Humidex (5%) *
T, SHUM *
Dampness (5%)
T,SHUM
Sunshine (5%)
CLOUD FRACTION
Wet Days (5%)
P
Fog (3%), Thunderstorms (2%),
Visibility (4%), Blowing Snow (8%) and
Freezing Precipitation (4%)
1953-1995 station values
interpolated to grid
* (daily/hourly parameterization)
Interpolation
• Hourly/daily parameterizations required at each
location that model CSI would be computed at
• Ideally, model data would be interpolated to the 15
available stations
• Project specifications required gridded model CSI
• Parameterizations interpolated from sparse stations
to model grid
• Sensitivity to low number of stations tested … found
account for likely no more than 7% of value of CSI
Removal of model bias
• Model typically cloudier, less windy, wetter, warmer, and
more humid than observations over 1961-1995
• Ideally change fields of each parameter would be
computed at stations and applied to the CSI but not
straightforward for daily output and requires
computation at stations only then interpolation to grid
• Instead, CSI computed for future from direct GCM
output then change between model CSI future and
baseline applied to observed baseline for CSI scenarios
4c Results - Model CSI Change 2050s
4c Results - Model CSI Change 2050s
Model CSI 1961-1995
Model CSI 2050s
Note on interpretation
• CSI reflects personal comfort only - other aspects of
climate with indirect effects beyond scope of project:
– no penalty for dry winter causing water supply problems
following summer (dryness no matter how severe improves CSI)
– no attempt to address health risk, economic impacts, etc.
– no new sub-factors included such as UV index
• Modelled decrease in CSI cannot be interpreted as
overall improvement in climate
– indicates only an increase in how often individuals might
consider the weather "a nice day"
• In this narrow perspective only, the modelled CSI
implies an improvement over the next century.
6. Summary
• First step
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–
–
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Slight decrease over observed record
Reconstructed CSI close to original at most stations
Scenarios - pattern of national decrease over the next century
www.cics.uvic.ca/severity
• Interpret with caution!!
• Recommend development of new technique that:
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–
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–
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makes use of currently available station data and/or GCM outputs
can be computed from multiple GCM runs
varies temporally instead of (or as well as) spatially
can be extended to sectoral/economic indices
can be computed on different spatial scales
• Partially completed proposal to extend
Merci de votre
attention
CCIS - ScatterPlots
CCIS - ScatterPlots
CCIS - ScatterPlots
CCIS - ScatterPlots
Canadian Climate Impacts and
Scenarios Project (CCIS)
www.cics.uvic.ca/scenarios