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Decadal Signals In Precipitation
 

Decadal Signals In Precipitation

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Graphics supporting a February 20 lecture at the University of Arizona's Laboratory of Tree-Ring Research.

Graphics supporting a February 20 lecture at the University of Arizona's Laboratory of Tree-Ring Research.

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    Decadal Signals In Precipitation Decadal Signals In Precipitation Presentation Transcript

    • The prominence of decadal variability in North American precipitation S c ott St. G eorge Geological Survey of Canada Toby A ult University of Arizona
    • Greg McCabe, Michael Palecki, and Julio Betancourt, 2004: Pacific and Atlantic Ocean influences on multidecadal drought frequency in the United States PNAS 12, 4136 - 4141
    • Here be decadal variability Decadal variability in precipitation or drought as a signal detection problem Terrestrial climate records often processed to emphasize D2M timescales4
    • Does it matter at the regional scale? 5
    • 1920 1940 1960 1980 2000 Decadal variance 30% Decadal variance 5% 1920 1940 1960 1980 2000
    • Where is decadal variability in precipitation strong?
    • Dan Cayan, Michael Dettinger, Henry Diaz, and Nick Graham,1998: Decadal variability of precipitation over western North America. Journal of Climate 11, 3148-3166
    • Methods Photo: Christos_m2001
    • PDSI Temperature Precipitation Streamflow Storms Rain/snow
    • Gridded (0.5 deg) monthly precipitation, Climate Research Unit, University of East Anglia Period of record: 1901 - 2002
    • Decadal variability Decadal variabil Decadal varia Decadal v
    • Noise Interannual Trend Multidecadal Decadal
    • What did we find? Photo: futureshape
    • Slides missing* * Thank goodness
    • Winter decadal 0% 10% 20% 30% variance
    • Autumn decadal 0% 10% 20% 30% variance
    • Annual multidecadal 0% 10% 20% 30% variance
    • Northern California precipitation
    • Northern California precipitation Decadal variance = ~30 percent
    • D2M ‘hotspots’
    • “Decadal-scale fluctuations are crucial because they control water supplies, affect biota, and may modulate higher-frequency events such as floods and drought.” Dan Cayan and colleagues [1998]
    • Decadal hotspot - Oregon/California
    • Northern California
    • Sacramento River Photo: Patty Colmer
    • Northern California
    • Northern California
    • Photo: California Department of Water Resources Levee break, Sacramento basin
    • 1915 levee break Photo: California Department of Public Works Courtesy Joan Florsheim
    • Northern California
    • Northern California
    • Decadal hotspot - Minnesota
    • Minnesota
    • Mississippi River at Minneapolis Photo: Mulad
    • Minnesota
    • Minnesota
    • Minnesota
    • Mech et al. (1987): Does high snow over consecutive winters have a cumulative, negative, effect on the viability of moose offspring?
    • Minnesota
    • Minnesota
    • Minnesota
    • Associations with major climate modes
    • It’s complicated. 46
    • Winter precipitation and the PDO
    • Winter precipitation and the PDO
    • Three main points 49
    • location and seasonality make a big difference 50
    • D2M propagates into hydrology* and ecology** * clearly ** maybe 51
    • Is it a coincidence that D2M variability is strongest in the ENSO-PDO null? 52
    • Thank you Julio Betancourt Dave Meko Julia Cole Joellen Russell Susan Pullan Mike Wallace Mike Mann Connie Woodhouse Support Manitoba Hydro Natural Resources Canada National Science Foundation
    • S co t t St. G e o r g e Toby Au lt Geological Survey of Canada University of Arizona sstgeorg@nrcan.gc.ca tault@email.arizona.edu