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University of Nebraska - Lincoln

Department of Earth and Atmospheric Sciences: Faculty Publications

2012

Articles 1 - 17 of 17

Full-Text Articles in Physical Sciences and Mathematics

Spatial Filter Approach To Evaluating The Role Of Convection On The Evolution Of A Mesoscale Vortex, Glenn A. Creighton, Robert E. Hart, Philip Cunningham Dec 2012

Spatial Filter Approach To Evaluating The Role Of Convection On The Evolution Of A Mesoscale Vortex, Glenn A. Creighton, Robert E. Hart, Philip Cunningham

Department of Earth and Atmospheric Sciences: Faculty Publications

A new spatial filter is proposed that exploits a spectral gap in power between the convective scale and the system (‘‘vortex’’) scale during tropical cyclone (TC) genesis simulations. Using this spatial separation, this study analyzes idealized three-dimensional numerical simulations of deep moist convection in the presence of a symmetric midlevel vortex to quantify and understand the energy cascade between the objectively defined convective scale and system scale during the early stages of tropical cyclogenesis. The simulations neglect surface momentum, heat, and moisture fluxes to focus on generation and enhancement of vorticity within the interior to more completely close off the …

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Reservoir Potential Of Sands Formed In Glaciomarine Environments: An Analog Study Based On Cenozoic Examples From Mcmurdo Sound, Antarctica, Christopher R. Fielding, Brian A. Blackstone, Tracy D. Frank, Zi Gui Apr 2012

Reservoir Potential Of Sands Formed In Glaciomarine Environments: An Analog Study Based On Cenozoic Examples From Mcmurdo Sound, Antarctica, Christopher R. Fielding, Brian A. Blackstone, Tracy D. Frank, Zi Gui

Department of Earth and Atmospheric Sciences: Faculty Publications

This paper provides documentation of unexpectedly high-reservoir-quality glaciomarine sands found in the Cenozoic succession beneath McMurdo Sound, Antarctica, as an analogue study for evaluations of hydrocarbon prospectivity in basins elsewhere. The Oligocene to Lower Miocene succession of the Victoria Land Basin, an extant portion of the West Antarctic Rift System, comprises diamictites, mudrocks, and sandstones with minor conglomerates. These lithologies are arranged in repetitive stacking patterns (cycles), interpreted to record repeated advance and retreat of glaciers into and out of the basin, with attendant eustatic and isostatic effects. Phases of ice retreat within the cycles comprise an array of mudrocks, …

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Evolution Of The Earliest Horses Driven By Climate Change In The Paleocene-Eocene Thermal Maximum, Ross Secord, Jonathan I. Bloch, Stephen G. B. Chester, Doug M. Boyer, Aaron R. Wood, Scott L. Wing, Mary J. Kraus, Francesca A. Mcinerney, John Krigbaum Feb 2012

Evolution Of The Earliest Horses Driven By Climate Change In The Paleocene-Eocene Thermal Maximum, Ross Secord, Jonathan I. Bloch, Stephen G. B. Chester, Doug M. Boyer, Aaron R. Wood, Scott L. Wing, Mary J. Kraus, Francesca A. Mcinerney, John Krigbaum

Department of Earth and Atmospheric Sciences: Faculty Publications

Body size plays a critical role in mammalian ecology and physiology. Previous research has shown that many mammals became smaller during the Paleocene-Eocene Thermal Maximum (PETM), but the timing and magnitude of that change relative to climate change have been unclear. A high-resolution record of continental climate and equid body size change shows a directional size decrease of ~30% over the first ~130,000 years of the PETM, followed by a ~76% increase in the recovery phase of the PETM. These size changes are negatively correlated with temperature inferred from oxygen isotopes in mammal teeth and were probably driven by shifts …

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Evolution Of The Lake Titicaca Basin And Its Diatom Flora Over The Last ~ 370,000 Years, Sherilyn C. Fritz, P. A. Baker, Pedro M. Tapia, Trisha L. Spanbauer, Karlyn S. Westover Feb 2012

Evolution Of The Lake Titicaca Basin And Its Diatom Flora Over The Last ~ 370,000 Years, Sherilyn C. Fritz, P. A. Baker, Pedro M. Tapia, Trisha L. Spanbauer, Karlyn S. Westover

Department of Earth and Atmospheric Sciences: Faculty Publications

In recent years, deep drilling undertaken as part of the International Continental Drilling Program has generated multiple long lacustrine sedimentary records to reconstruct continental paleoclimate. In many cases, the tectonic and geomorphic history of these basins is under-constrained and poorly known, which affects the interpretation of climate history from geophysical, geochemical, and paleobiotic proxies in the sedimentary record. In addition, non-analog biotic assemblages that reflect evolutionary processes may constrain the reconstruction of past environments. In the drill-core record of Lake Titicaca, spanning the last ~ 370 ka, the diatom stratigraphy reflects both the influence of climate and the longterm evolution …

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Hydraulic Conductivity Of The High Plains Aquifer Re-Evaluated Using Surface Drainage Patterns, Wei Luo, Darryll T. Pederson Jan 2012

Hydraulic Conductivity Of The High Plains Aquifer Re-Evaluated Using Surface Drainage Patterns, Wei Luo, Darryll T. Pederson

Department of Earth and Atmospheric Sciences: Faculty Publications

The High Plains Aquifer (HPA), underlying parts of 8 states from South Dakota to Texas, is one of the largest fresh water aquifers in the world and accounts for 30% of the groundwater used for irrigation in the US. Determining the distribution of HPA’s hydraulic conductivity (K) is critical for water management and addressing water quality issues. K is traditionally estimated from well pumping data coupled with computer modeling and is known to be highly variable, spanning several orders of magnitude for the same type of rock. Here we show that applying our innovative method of determining effective …

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Progressive Abandonment And Planform Changes Of The Central Platte River In Nebraska, Central Usa, Over Historical Timeframes, John D. Horn, R. Matthew Joeckel, Christopher R. Fielding Jan 2012

Progressive Abandonment And Planform Changes Of The Central Platte River In Nebraska, Central Usa, Over Historical Timeframes, John D. Horn, R. Matthew Joeckel, Christopher R. Fielding

Department of Earth and Atmospheric Sciences: Faculty Publications

This paper presents data compiled from aerial photography, General Land Office maps (GLOs), and discharge data from the central Platte River in Nebraska that quantify and provide a new understanding of channel evolution and abandonment in a braided stream. Analyses of aerial photographs and GLOs in ArcMap™ show that channel area decreased by an average of 46% from 1938 to 2006 and that channel widths in 1858 were an average of 539% greater than in 2006. Annual discharge during 1942–2006 does not show a clear long-term relationship with the decrease in channel width and area. Rather, stabilization through vegetation of …

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Holocene Seasonal Variability Inferred From Multiple Proxy Records From Crevice Lake, Yellowstone National Park, Usa, Cathy Whitlock, Walter E. Dean, Sherilyn C. Fritz, Lora R. Stevens, Jeffery R. Stone, Mitchell J. Power, Joseph R. Rosenbaum, Kenneth L. Pierce, Brandi B. Bracht-Flyr Jan 2012

Holocene Seasonal Variability Inferred From Multiple Proxy Records From Crevice Lake, Yellowstone National Park, Usa, Cathy Whitlock, Walter E. Dean, Sherilyn C. Fritz, Lora R. Stevens, Jeffery R. Stone, Mitchell J. Power, Joseph R. Rosenbaum, Kenneth L. Pierce, Brandi B. Bracht-Flyr

Department of Earth and Atmospheric Sciences: Faculty Publications

A 9400-yr-old record from Crevice Lake, a semi-closed alkaline lake in northern Yellowstone National Park, was analyzed for pollen, charcoal, geochemistry, mineralogy, diatoms, and stable isotopes to develop a nuanced understanding of Holocene environmental history in a region of northern Rocky Mountains that receives both summer and winter precipitation. The limited surface area, conical bathymetry, and deep water (>31 m) of Crevice Lake create oxygen-deficient conditions in the hypolimnion and preserve annually laminated sediment (varves) for much of the record. Pollen data indicate that the watershed supported a closed Pinus-dominated forest and low fire frequency prior to 8200 …

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Calcareous Nannofossil Assemblage Changes Across The Paleocene–Eocene Thermal Maximum: Evidence From A Shelf Setting, Jean M. Self-Trail, David S. Powars, David K. Watkins, Gregory A. Wandless Jan 2012

Calcareous Nannofossil Assemblage Changes Across The Paleocene–Eocene Thermal Maximum: Evidence From A Shelf Setting, Jean M. Self-Trail, David S. Powars, David K. Watkins, Gregory A. Wandless

Department of Earth and Atmospheric Sciences: Faculty Publications

Biotic response of calcareous nannoplankton to abrupt warming across the Paleocene/Eocene boundary reflects a primary response to climatically induced parameters including increased continental runoff of freshwater, global acidification of seawater, high sedimentation rates, and calcareous nannoplankton assemblage turnover. We identify ecophenotypic nannofossil species adapted to low pH conditions (Discoaster anartios, D. araneus, Rhomboaster spp.), excursion taxa adapted to the extremely warm climatic conditions (Bomolithus supremus and Coccolithus bownii), three species of the genus Toweius (T. serotinus, T. callosus, T. occultatus) adapted to warm, rather than cool, water conditions, opportunists adapted to high productivity conditions (Coronocyclus bramlettei, …

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Trends In Record-Breaking Temperatures For The Conterminous United States, Clinton M. Rowe, Logan E. Derry Jan 2012

Trends In Record-Breaking Temperatures For The Conterminous United States, Clinton M. Rowe, Logan E. Derry

Department of Earth and Atmospheric Sciences: Faculty Publications

In an unchanging climate, record-breaking temperatures are expected to decrease in frequency over time, as established records become increasingly more difficult to surpass. This inherent trend in the number of record-breaking events confounds the interpretation of actual trends in the presence of any underlying climate change. Here, a simple technique to remove the inherent trend is introduced so that any remaining trend can be examined separately for evidence of a climate change. As this technique does not use the standard definition of a broken record, our records* are differentiated by an asterisk. Results for the period 1961– 2010 indicate that …

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Climate-Induced Changes In Lake Ecosystem Structure Inferred From Coupled Neo- And Paleoecological Approaches, Jasmine E. Saros, Jeffery R. Stone, Gregory T. Pederson, Krista E.H. Slemmons, Trisha Spanbauer, Anna Schliep, Douglas Cahl, Craig E. Williamson, Daniel R. Engstrom Jan 2012

Climate-Induced Changes In Lake Ecosystem Structure Inferred From Coupled Neo- And Paleoecological Approaches, Jasmine E. Saros, Jeffery R. Stone, Gregory T. Pederson, Krista E.H. Slemmons, Trisha Spanbauer, Anna Schliep, Douglas Cahl, Craig E. Williamson, Daniel R. Engstrom

Department of Earth and Atmospheric Sciences: Faculty Publications

Over the 20th century, surface water temperatures have increased in many lake ecosystems around the world, but long-term trends in the vertical thermal structure of lakes remain unclear, despite the strong control that thermal stratification exerts on the biological response of lakes to climate change. Here we used both neo- and paleoecological approaches to develop a fossil-based inference model for lake mixing depths and thereby refine understanding of lake thermal structure change. We focused on three common planktonic diatom taxa, the distributions of which previous research suggests might be affected by mixing depth. Comparative lake surveys and growth rate experiments …

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Rinded Iron-Oxide Concretions: Hallmarks Of Altered Siderite Masses Of Both Early And Late Diagenetic Origin, David Loope, Richard Kettler, Karrie A. Weber, Nathan L. Hinrichs, Derek T. Burgess Jan 2012

Rinded Iron-Oxide Concretions: Hallmarks Of Altered Siderite Masses Of Both Early And Late Diagenetic Origin, David Loope, Richard Kettler, Karrie A. Weber, Nathan L. Hinrichs, Derek T. Burgess

Department of Earth and Atmospheric Sciences: Faculty Publications

Iron-bearing concretions are valuable records of oxidation states of subsurface waters, but the first concretions to form can be altered drastically during later diagenetic events. Distinctive concretions composed of heavy rinds of iron oxide that surround iron-poor, mud-rich cores are common along bases of fluvial cross-bed sets of the Cretaceous Dakota Formation, Nebraska, USA. Concretion rinds thicken inward and cores contain 46 to 89% void space. Millimeter-scale spherosiderites are abundant in palaeosols that developed in floodplain facies. Evolution of rinded concretions began when intraformational clasts were eroded from sideritic soils, transported, abraded and deposited in river channels. Alteration of siderite …

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Improving Student Attitudes About Learning Science And Student Scientific Reasoning Skills, Douglas K. Duncan, Leilani Arthurs Jan 2012

Improving Student Attitudes About Learning Science And Student Scientific Reasoning Skills, Douglas K. Duncan, Leilani Arthurs

Department of Earth and Atmospheric Sciences: Faculty Publications

Student attitudes about learning science and student ideas about the nature of science were compared at the end of two astronomy courses taught in Fall 2007, a course with a traditional astronomy curriculum and a transformed course, whose traditional astronomy curriculum was supplemented by an embedded curriculum that explicitly addressed the nature of science and student metacognition (i.e., thinking about one’s own thinking.) The embedded curriculum in the transformed course gave students practice at evaluating examples of valid science and pseudoscience found on the internet; it also provided students opportunities to discuss what they think about learning science. Student attitudes …

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Berino Paleosol, Late Pleistocene Argillic Soil Development On The Mescalero Sand Sheet In New Mexico, Stephen A. Hall, Ronald J. Goble Jan 2012

Berino Paleosol, Late Pleistocene Argillic Soil Development On The Mescalero Sand Sheet In New Mexico, Stephen A. Hall, Ronald J. Goble

Department of Earth and Atmospheric Sciences: Faculty Publications

The Berino paleosol is the first record of a directly dated Aridisol in the American Southwest where paleoclimatic conditions during the time of pedogenesis can be estimated. The noncalcic, argillic paleosol formed in eolian sand during the cool, wet climate of the mid- and late Wisconsin, marine isotope stages 3 and 2, in presently semiarid southeastern New Mexico. Optically stimulated luminescence dating of the Mescalero sand sheet and the Berino indicates that soil formation occurred during the period 50–18 ka. The paleosol is a red 2.5YR hue Bt horizon, 120 cm thick, with 25% clay, 0.36% Fe, and an absence …

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Quantification Of Salt Dust Pathways From A Groundwater-Fed Lake: Implications For Solute Budgets And Dust Emission Rates, Vitaly A. Zlotnik, John B. Ong, John D. Lenters, Jens Schmieder, Sherilyn C. Fritz Jan 2012

Quantification Of Salt Dust Pathways From A Groundwater-Fed Lake: Implications For Solute Budgets And Dust Emission Rates, Vitaly A. Zlotnik, John B. Ong, John D. Lenters, Jens Schmieder, Sherilyn C. Fritz

Department of Earth and Atmospheric Sciences: Faculty Publications

Emissions of salt dust from the shores of saline lakes significantly impact lake chemistry, air quality, transportation, human health, and climate. Quantitative methods for assessing these emissions, however, are still in the developmental stage. We investigate salt pathways from groundwater to dust using an approach that takes advantage of opportune conditions at a groundwater-fed, saline lake in the Nebraska Sand Hills region. The mass of salt in the lakeshore surface crust and soil was measured, as well as in the dust on the surrounding dune field. These data, together with information on the lake hydrology, show that dust emission is …

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Drought Drove Forest Decline And Dune Building In Eastern Upper Michigan, Usa, As The Upper Great Lakes Became Closed Basins, Walter L. Loope, Henry M. Loope, Ronald J. Goble, Timothy G. Fisher, David E. Lytle, Robert J. Legg, Douglas A. Wysocki, Paul R. Hanson, Aaron R. Young Jan 2012

Drought Drove Forest Decline And Dune Building In Eastern Upper Michigan, Usa, As The Upper Great Lakes Became Closed Basins, Walter L. Loope, Henry M. Loope, Ronald J. Goble, Timothy G. Fisher, David E. Lytle, Robert J. Legg, Douglas A. Wysocki, Paul R. Hanson, Aaron R. Young

Department of Earth and Atmospheric Sciences: Faculty Publications

Current models of landscape response to Holocene climate change in midcontinent North America largely reconcile Earth orbital and atmospheric climate forcing with pollen-based forest histories on the east and eolian chronologies in Great Plains grasslands on the west. However, thousands of sand dunes spread across 12,000 km2 in eastern upper Michigan (EUM), more than 500 km east of the present forest-prairie ecotone, present a challenge to such models. We use 65 optically stimulated luminescence (OSL) ages on quartz sand deposited in silt caps (n = 8) and dunes (n = 57) to document eolian activity in EUM. Dune building …

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Nitrogen Loss From Soil Through Anaerobic Ammonium Oxidation Coupled To Iron Reduction, Wendy H. Yang, Karrie A. Weber, Whendee L. Silver Jan 2012

Nitrogen Loss From Soil Through Anaerobic Ammonium Oxidation Coupled To Iron Reduction, Wendy H. Yang, Karrie A. Weber, Whendee L. Silver

Department of Earth and Atmospheric Sciences: Faculty Publications

The oxidation of ammonium is a key step in the nitrogen cycle, regulating the production of nitrate, nitrous oxide and dinitrogen. In marine and freshwater ecosystems, anaerobic ammonium oxidation coupled to nitrite reduction, termed anammox, accounts for up to 67% of dinitrogen production. Dinitrogen production through anaerobic ammonium oxidation has not been observed in terrestrial ecosystems, but the anaerobic oxidation of ammonium to nitrite has been observed in wetland soils under iron-reducing conditions. Here, we incubate tropical upland soil slurries with isotopically labelled ammonium and iron(iii) to assess the potential for anaerobic ammonium oxidation coupled to iron(iii) reduction, otherwise known …

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Top-Down Estimate Of Dust Emissions Through Integration Of Modis And Misr Aerosol Retrievals With The Geos-Chem Adjoint Model, Jun Wang, Xiaoguang Xu, Daven K. Henze, Jing Zeng, Qiang Ji, Si-Chee Tsay, Jianping Huang Jan 2012

Top-Down Estimate Of Dust Emissions Through Integration Of Modis And Misr Aerosol Retrievals With The Geos-Chem Adjoint Model, Jun Wang, Xiaoguang Xu, Daven K. Henze, Jing Zeng, Qiang Ji, Si-Chee Tsay, Jianping Huang

Department of Earth and Atmospheric Sciences: Faculty Publications

Predicting the influences of dust on atmospheric composition, climate, and human health requires accurate knowledge of dust emissions, but large uncertainties persist in quantifying mineral sources. This study presents a new method for combined use of satellite-measured radiances and inverse modeling to spatially constrain the amount and location of dust emissions. The technique is illustrated with a case study in May 2008; the dust emissions in Taklimakan and Gobi deserts are spatially optimized using the GEOSChem chemical transport model and its adjoint constrained by aerosol optical depth (AOD) that are derived over the downwind dark-surface region in China from MODIS …

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