hemispheric enso cycling and lake michigan coastal dune · pdf filehemispheric enso cycling...
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Hemispheric ENSO Cycling and Lake Michigan Coastal Dune Evolution:
A Relationship?
Alan F. ArbogastDepartment of GeographyMichigan State University
G. William MonaghanIndiana Geological Survey
William A. LovisDepartment of AnthropologyMichigan State University
South Africa Australia
EnglandNew Zealand
1) westerly winds
2) long fetch (~ 110 km)across Lake Michigan
3) Lot’s of sand!
America’s North Coast
Lake Superior
Canada
U.S.
Mississippi River
Nipissing Dunes
Formed in a SingleContinuous Event
But No Dates!!
Photo: Ed Hanson Van Buren, 1999
A horizon
C horizon
Most dunes contain 4 or 5Entisols like this one. Thissoil represents a brief periodof landscape stability (i.e.,no growth) as the duneevolved.
A
E horizon
Bs horizon
Most dunes also contain onerelatively well developed soilwith Spodic-like characteristics.This soil is usually found inthe upper part of the dunesandrepresents a relativelylong period of landscapestability (i.e., no growth) asthe dune evolved.
Sleeping Bear Dunes
Sand dunes
Reconstructing Dune Chronology
• Radiocarbon (C-14):soil organics
• Optically StimulatedLuminescence (OSL):burial age of sand in dunes
6005 - 4960
3726 - 3362
464 - 129
2183 - 1868313 - 0
159 - 0
4424 - 4063
Lake Sediments
Dune Sand
* all ages are calibrated to the tree-ring curve
Van Buren State Park
B
Torch Bay Transect
PDD of OSL ages around Lake Michigan
Ho
llan
dIn
terv
al
A
E horizon
Bs horizon
Most dunes also contain onerelatively well developed soilwith Spodic-like characteristics.This soil is usually found inthe upper part of the dunesandrepresents a relativelylong period of landscapestability (i.e., no growth) asthe dune evolved.
PDD of OSL ages for dunes around Lake Michigan
• What are the drivers and forcing variables that promotebasin-wide cycles of dune growth?
• We can look at a cuple of different obvious drivers ofdune growth and stabilization?• For example, water lever changes in Lake Michigan or
broad temperature variation
175
m18
0m
Monaghan andLovis (2005)
historic mean water-level
Thompson,et al. (2004)
Lake Michigan hydrographs(corrected for uplift at Port Huron)
-du
nebu
ildin
g+
Great Lakes (162)
01 ka5 ka6 ka 2 ka3 ka4 ka
0.4-0.4
0
warmer
cooler
mid-latitude temp.anomaly (C)
1) Dunes appear to have grown mostly (5x) during transgressive events (but not always)
2) Dunes stabilized when lake levels subsequently fell.
Medieval Warm Period
What Does the Very Recent Past Tell Us?
Photo: Ed Hanson Van Buren, 1999
Van Buren, 2008
Van Buren, 2014
Dunes Are Stabilizing
Nu
mb
er
of
Even
ts
Year
Dunes Stabilizing
Source: State of Michigan Climate Center
0
1
2
3
4
5
6
7
8
19801982 1984 1986 1988 1990 1992 19941996 1998 2000 2002 2004 2006 20082010 2012 2014
Days With Average Winds > 30 Knots
Dunes Stabilizing
Questions:
1) What role do lake-level fluctuations play in dune evolution?
2) How do local site conditions influence dune evolution?
3) Storminess (strong winds) certainly plays a role,but in what way?
-dun
ebu
ildin
g+
Great Lakes (162)
• What are the drivers and forcingvariables that promote (basin-wideor world-wide) dune growth,
• Can we integrate the large-scalecycles & hemisphericteleconnections by comparing dunecycles from the mid-continent/northeast North Americawith northern European coastaldunes.
GreatLakes Cape
Cod
N. Europe-British Isles
Cape Cod (27)
01 ka5 ka6 ka 2 ka3 ka4 ka
-dun
ebu
ildin
g+
-dun
ebu
ildin
g+
N. Europe (79)H
olla
ndPa
leos
ol?
Linked dune cyclessince ~2000 ya?
Even Broader Linkages??
4 ka 3 ka 2 ka 1 ka 0
15
30
5
<5 eventsEl Nino events/century
N. Europe
(n=79) Cape Cod
(n=27)
Dune OSLPDD (5000-
200 ya)
LIA During the lateHolocene, majorhemispheric-scaleddrivers apparentlybecome connectedacross the atlanticand drive dunebuilding in Europeand NorthAmerica. Whilethese are probablyrelated to ENSO,NAO, PNA, etc.the why and howremain unclear
El Niño summer
The El Niño-Southern Oscillation (ENSO)describes fluctuating ocean temperatures in equatorialPacific. Warmer waters oscillate back and forth across thePacific, controlling North American (and global)variations climate patterns because of wind (jet stream)flow patterns. Two main phases are:
El Nino (warm pacific) and La Nina (cold pacific)
La Niña winter La Niña summer
In the Great Lakes/Northeast:
El Nino are oftencharacterized by mild andwarm winters with fewerwinter storms
La Nina are oftencharacterized by colderwinters and more commonautumn and winter storms,particularly low pressuresystems that originate in theSW USA and track into theGreat Lakes region
El Niño winter
Current Conditions
& LessStormy!
Acknowledgments
Antrim County ParksFederal Highway AdministrationFriends of Sleeping Bear Dunes National LakeshoreHiawatha National ForestIndiana Geological SurveyMichigan Department of Environmental QualityMichigan Department of Natural ResourcesMichigan Department of TransportationMichigan State UniversityNational Science FoundationTorch Bay Township
& Many Individual Property Owners
Thanks for Listening!