Basic set of common indices

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Basic set of common indices
www.ec.gc.ca
Xuebin Zhang With some slides stolen from Tom
Peterson
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Outline

• 27 ET indices and regional workshops
• Applications
• Contribution to AR4
• Near-real time extreme monitoring
• ET website
• Future plan

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A desirable index

• Easy to compute, and update
• Easy to understand
• Physically meaningful
• High S/N ratio for climate change detection
• Impact relevant

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27 ET indices

• Sub-set from early indices with some modification
• Suggested by many people
• Recommended by Lisa Alexander, Albert Klein Tank,
  and Xuebin Zhang
• New method for computing percentile indices
• New software both in R and FORTRAN

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Indices were using

• Most are throughout the year
• Warm nights just as likely in winter as in
  summer
• Harder for the public to understand
• Better for detection as shorter return period
• Impact relevant in someway
• Some are absolute thresholds that make physical
  sense
• T lt 0o, T gt 30o, P gt 20 mm
• Easy for the public to understand
• For drought a simple count of consecutive dry
  days is used

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Physically based indices

• Frost days
• Summer days
• Ice days
• Tropical nights
• Growing season length
• Diurnal temperature range

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Extreme temperature values for the year

• Max Tmax
• Max Tmin
• Min Tmax
• Min Tmin

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Percentile temperature indices

• Cool nights
• Cool days
• Warm nights
• Warm days
• Warm spell duration indicator
• Cold spell duration indicator

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Precipitation indices

• Max 1-day precipitation amount
• Max 5-day precipitation amount
• Simple daily intensity index
• Number of heavy precipitation days 10 mm
• Number of very heavy precipitation days 20 mm
• Number of days above nn mm
• Consecutive dry days
• Consecutive wet days
• Very wet days 95th percentile
• Extremely wet days 99th percentile
• Annual total wet-day precipitation

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2002 Frich et al. Climate Research global
indices paper
Note large blank areas in global indices map
From Tom Peterson
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Workshops in 2004 and 2005
Tom Peterson
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Workshop Results

• New data filled in large gap, 6 regional workshop
  papers
• South America had separate temperature and
  precipitation articles
• One global paper (Alexander et al. 2006) with
  authors including
• Canada Xuebin Zhang and Lucie Vincent
• US Tom Peterson and Byron Gleason
• Mexico Jorge Luis Vazquez-Aguirre
• Along with people from the UK, Australia, China,
  Spain, Argentina, India, New Zealand, Jamaica,
  and the Netherlands
• Release of indices from most countries
• Via ET web site (not public yet)
• From Lisa and Xuebin
• Release of data from very few countries

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Contribution to AR4

• Alexander et al. contributed heavily to AR4
• Other detection related papers
• Hegerl et al. 2004 (potential detection, Ch9)
• Tabaldi et al. 2005 (observed and projected
  changes in indices, Ch10, 11)
• Christidis et al. 2005 (detection paper with ET
  indices, and Alexander et al. data, Ch9)

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ET indices for extreme monitoringNorth American
Extremes Monitoring

• Just being developed at NCDC with contribution
  from Canada
• Uses a subset of the ETs indices
• Starting focus is on North America
• US data from those stations that the
  Menne-Williams homogeneity test could not find a
  discontinuity in
• 1,000 stations
• Different station list for Tmax and Tmin
• Canadian and Mexican stations

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Web page

• So any interested party could produce custom
  analysis
• Maps and time series
• The lead programmer is Nina Stroumentova (Pasha
  Groismans wife)
• Web page not on line yet

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CMA is considering to develop ET indices based
extreme monitor
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ET website

• Information
• Software
• Data
• No dedicated resources

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Update

• Easy to maintain
• New face (done)
• Easy assess to data
• http download (global indices being QCed and
  reformatted)
• Controlled upload
• Not possible to update indices
• Software updated regularly
• Workshop summaries, links to paper/report

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Data from ET web

• Workshop indices
• Peterson et al. North American indices
• Other regional indices
• Related daily/monthly data

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Summary

• ET indices useful for climate change detection,
  assessment, and monitoring
• Easy comparison across different regions
• Update of website on the plan, with new face and
  indices data available for download
• Indices need timely update !!!
• IPCC next assessment?
• Near real time monitoring
• World climate summary
• Welcome suggestions and contributions