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The decadal blind spot - understanding low-frequency behavior in the climate system
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The decadal blind spot - understanding low-frequency behavior in the climate system

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The decadal blind spot - understanding low-frequency behavior in the climate system The decadal blind spot - understanding low-frequency behavior in the climate system Presentation Transcript

  • White cedar 1452Source: Danny Margoles
  • Bur oak >450 yrSource: Joe Zeleznik NDSU
  • Climate history of North America Younger Demise of Laurentide Dryas Ice Sheet 20 16 12 8 4 0 THOUSANDS OF YEARS AGO Final Drainage of Lake AgassizLAST GLACIAL MODERN MAXIMUM OBSERVATIONS
  • DECADALCLIMATE VARIABILITY
  • “ ‘Drought’ people get. ‘Decadal-scale climate variability’ gets me that glazed eye look. John Fleck Albuquerque Journal ”
  • Behold, there comes seven years of great plenty throughoutall the land of Egypt: And there shall arise a er them sevenyears of famine; and all the plenty shall be forgo en in theland of Egypt; and the famine shall consume the land; Genesis 41, 29-30
  • “ We shall speak of “Joseph-wild” behavior when the we est decade within a century includes an extraordinary “term” of wet years. ”
  • Pacific Decadal Oscillation index3210-1-2-3 1900 1920 1940 1960 1980 2000
  • Atlantic Multidecadal Oscillation index
  • “ An improved understanding of [Decadal Climate Variability] is very important because stakeholders and policymakers want to know the likely climate trajectory for the coming decades for applications to water resources, agriculture, energy, and infrastructure development. ”
  • Observations Models Proxies
  • THE DECADAL BLIND SPOT
  • MINNESOTA THE DECADAL BLIND SPOT OBSERVATIONS
  • Source: Franklin Hunting
  • The Atlantic Multidecadal Oscillation and its relationto rainfall and river flows in the continental U.S.David B. Enfield, Alberto M. Mestas‐Nuñez and Paul J. TrimbleGeophysical Research Le ers, 2001
  • Does the state of the PDO and AMO influence the frequency of drought? AMOnegative AMOpositive PDOpositive PDOnegativeMcCabe et al, Proceedings of the National Academy of Sciences, 2004
  • “ The decadal time scale offers a critical bridge for informing adaptation strategies as ” climate varies and changes. Meehl et al., BAMS, 2009
  • OCEAN
  • LAND
  • Toby Ault National Corporation for Atmospheric Research
  • Is precipitation every red?
  • Using singular spectral analysis to decompose precipitation recordsAult and St. George, Journal of Climate, 2010
  • GEOGRAPHYMATTERS A LOT
  • Decadal ‘hotspots’ in winter precipitation 0% 10% 20% 30% varianceAult and St. George, Journal of Climate, 2010
  • Central Pacific Coast
  • Ault and St. George, Journal of Climate, 2010
  • Ault and St. George, Journal of Climate, 2010
  • NOT LOCALLY FIELDSIGNIFICANT SIGNIFICANT
  • Carlo Emilio Bonferroni 1892 - 1960
  • Decadal ‘hotspots’ in winter precipitation 0% 10% 20% 30% varianceAult and St. George, Journal of Climate, 2010
  • “ ... the use of high-resolution paleoclimate proxy data should be expanded because the short observational record and model uncertainty are unable to simulate [Decadal Climate Variability]... ” Mehta et al. Bulletin of the American Meteorological Society 2011
  • MINNESOTA THE DECADAL BLIND SPOT PROXIES
  • “ RINGS IN THE BRANCHES OF SAWED TREES SHOWTHE NUMBER OF YEARS AND, ACCORDING TO THEIR THICKNESS, THE YEARS WHICH WERE MORE OR LESS DRY.” Leonardo da Vinci
  • Tree-ring display at elementary school Photograph:Tom Swetnam
  • water stressnarrow ring reduced photosynthesis less cell expansion reduced cell division
  • Central Pacific Coast
  • Source: Dan Griffin
  • St. George and Ault, Journal of Geophysical Research - Atmospheres, 2011
  • really decadalSt. George and Ault, Journal of Geophysical Research - Atmospheres, 2011
  • really not that decadal decadalSt. George and Ault, Journal of Geophysical Research - Atmospheres, 2011
  • 7 track this signal23 don’t
  • “ THERMOMETERS ” TREES ARE NOT OR RAIN GAUGES. Keith Briffa and colleagues
  • White pine 1714Source: Kurt Kipfmueller
  • ∆S
  • Vit Klemeš 1932 - 2010
  • “ Discharge or lake records ‘‘have a tendency to exhibit more pronounced and smoother cycles’’ than precipitation because of storage. ” Vit Klemeš
  • Do proxiesPUMP UP low-frequency signals?
  • Source: Stella Cousins
  • Source: Jansen Cardy Sarah Truebe University of Arizona
  • Source: Sarah Truebe, University of Arizona
  • Truebe et al., IOP Conference Series : Earth and Environmental Science, 2010
  • “ ...variability in this range [less than 100 years] can represent a mixed signal of climate input and subsurface storage. ” Truebe et al. IOP Conference Series : Earth and Environmental Science, 2010
  • Observations Models Proxies
  • MINNESOTA THE DECADAL BLIND SPOT MODELS
  • “ Although global coupled models designed in the last 15 years are able to generate DCV pa erns that resemble observed DCV pa erns, the models tend to displace them spatially ” and temporally with respect to observed pa erns. Mehta et al. Bulletin of the American Meteorological Society 2011
  • Toby Ault National Corporation for Atmospheric Research
  • The power-law scaling parameter β relates variance to timescale.
  • The spectrum of SST observations is either ‘red’ or ‘white’ Beta value of SST
  • The spectrum of simulated SST is too ‘white’ or too ‘blue’ Beta value of SST
  • Because the interannual components are too energetic,is it possible they might be forcing decadal components in unrealistic ways?
  • THE DECADAL BLIND SPOT
  • Observations Models Proxies
  • 1We need to test the ability of models tosimulate terrestrial climates at decadal timescales.
  • 2We need to use (or develop) physically-basedforward models to test how proxies record(and possibly distort) low-frequency climate signals.
  • “ The decadal time scale offers a critical bridge for informing adaptation strategies as ” climate varies and changes. Meehl et al., BAMS, 2009