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Some of the Many Applications of Archaeoclimatology Katherine McEnaney and Reid Bryson (The powerpoint will run itself automatically on the ‘slideshow’ setting)
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Intro Local Large Scale Storms Dunes Composite Archaeoclimatology l Sometimes called Macrophysical modeling l Tested hundreds of times against field data l Based on –orbital forcing of incoming radiation –modulation by aerosols and variable snow-ice albedo –standard dynamics –synoptic climatology
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Intro Local Large Scale Storms Dunes Composite Archaeoclimatology l Site specific l Yields monthly 200 year mean values l This makes the method unique l It [is now] possible to produce 100 year resolution for the past 20,000+ years
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Intro Local Large Scale Storms Dunes Composite Example: La Crosse, WI La Crosse appears to have had twice as much precipitation in Late Pleistocene and Early Holocene times Summer rains were less important in Mid Holocene Heaviest rains have shifted to summer
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Intro Local Large Scale Storms Dunes Composite Example: La Crosse, WI The difference between precipitation and evaporation is known as water stress Boreal Forests have an abundance of precipitation More recent times have a great deal of variability Grasslands have a deficit of precipitation
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Intro Local Large Scale Storms Dunes Composite Large Scale Features l Large scale features may be modeled –Sea Ice –Large River Discharge
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Intro Local Large Scale Storms Dunes Composite Large Scale Features l In the far north, human usage of an area seems to be related to sea ice
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Intro Local Large Scale Storms Dunes Composite Discharge of the Mississippi Intro Local Large Scale Storms Dunes Composite
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The Effect of the onset of the Holocene is obvious Northern Example: Dinwoody Creek, Wyoming Intro Local Large Scale Storms Dunes Composite
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Stream Discharge In Late Pleistocene time the river appears to have been frozen to the bottom with no winter discharge, even in May. The snowmelt of June produced an enormous freshet. In the warmer, less snowy, Holocene the freshet was greatly reduced and there was winter discharge. In the Holocene, there were times of greater discharge. These are associated with an increase in westerly storms, not local events.
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Storms and Snow These storms also brought more snow Intro Local Large Scale Storms Dunes Composite
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l Hurricane or Typhoon frequency l Thunderstorm frequency l High Tropical Humidities l Changing Prevailing Winds, Dunes Farther south, there are different problems Intro Local Large Scale Storms Dunes Composite
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Hurricanes l Hurricanes are important –Winds and storm surges –Heavy rains from their residuals l Heavy Rains, “Gully-washers” are often associated with deep masses of moist air originating in Tropical Storms and intruding into the Westerlies
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Intro Local Large Scale Storms Dunes Composite Hurricanes Farther North Cape Cod
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Intro Local Large Scale Storms Dunes Composite Hurricanes Farther North l Tropical storm number can be modeled
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Intro Local Large Scale Storms Dunes Composite Modeled Fire Hazard l Thunderstorm frequency is important in areas prone to fires Intro Local Large Scale Storms Dunes Composite
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Modeled Fire Hazard Stormy with Dry Air Intro Local Large Scale Storms Dunes Composite
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Dune Movement Departure of ice from the Cochrane Moraine may have increased dune movement in Southern Manitoba
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Intro Local Large Scale Storms Dunes Composite Dune Movement Note the dramatic increase in drift potential after 8000
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Intro Local Large Scale Storms Dunes Composite Composite Studies l Models may be combined for a given state/region l The results may be used to map precipitation values or anomalies through the past
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Intro Local Large Scale Storms Dunes Composite In Summary l Almost any important climatic variable may be modeled l Models are site-specific and high resolution l Models are economical l There seem to be no competitive models
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Intro Local Large Scale Storms Dunes Composite Please cite as McEnaney, K. A. and R. A. Bryson 2005Some of the Many Applications of Archaeoclimatology. Paper presented at the Wisconsin Archaeological Survey Research Reports Meeting, April 23, 2005, Madison, WI. For more information, please contact rabryson@wisc.edu or kamcenaney@wisc.edu. rabryson@wisc.edu kamcenaney@wisc.edu rabryson@wisc.edu kamcenaney@wisc.edu
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