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Department of Earth and Atmospheric Sciences: Faculty Publications

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Articles 181 - 210 of 670

Full-Text Articles in Earth Sciences

Coastal Geology And Recent Origins For Sand Point, Lake Superior, Timothy G. Fisher, David E. Krantz, Mario R. Castaneda, Walter L. Loope, Harry M. Jol, Ronald J. Goble, Melinda C. Higley, Samantha Dewald, Paul R. Hanson Jan 2014

Coastal Geology And Recent Origins For Sand Point, Lake Superior, Timothy G. Fisher, David E. Krantz, Mario R. Castaneda, Walter L. Loope, Harry M. Jol, Ronald J. Goble, Melinda C. Higley, Samantha Dewald, Paul R. Hanson

Department of Earth and Atmospheric Sciences: Faculty Publications

Sand Point is a small cuspate foreland located along the southeastern shore of Lake Superior within Pictured Rocks National Lakeshore near Munising, Michigan. Park managers’ concerns for the integrity of historic buildings at the northern periphery of the point during the rising lake levels in the mid-1980s greatly elevated the priority of research into the geomorphic history and age of Sand Point. To pursue this priority, we recovered sediment cores from four ponds on Sand Point, assessed subsurface stratigraphy onshore and offshore using geophysical techniques, and interpreted the chronology of events using radiocarbon and luminescence dating. Sand Point formed at …

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Toward Enhanced Understanding And Projections Of Climate Extremes Using Physics-Guided Data Mining Techniques, A. R. Ganguly, E. A. Kodra, A. Agrawal, A. Banerjee, S. Boriah, Sn. Chatterjee, So. Chatterjee, A. Choudhary, D. Das, J. Faghmous, P. Ganguli, S. Ghosh, K. Hayhoe, C. J. Hays, W. Hendrix, Q. Fu, J. Kawale, D. Kumar, V. Kumar, W. Liao, S. Liess, R. Mawalagedara, V. Mithal, R. Oglesby, K. Salvi, P. K. Snyder, K. Steinhaeuser, D. Wang, D. Wuebbles Jan 2014

Toward Enhanced Understanding And Projections Of Climate Extremes Using Physics-Guided Data Mining Techniques, A. R. Ganguly, E. A. Kodra, A. Agrawal, A. Banerjee, S. Boriah, Sn. Chatterjee, So. Chatterjee, A. Choudhary, D. Das, J. Faghmous, P. Ganguli, S. Ghosh, K. Hayhoe, C. J. Hays, W. Hendrix, Q. Fu, J. Kawale, D. Kumar, V. Kumar, W. Liao, S. Liess, R. Mawalagedara, V. Mithal, R. Oglesby, K. Salvi, P. K. Snyder, K. Steinhaeuser, D. Wang, D. Wuebbles

Department of Earth and Atmospheric Sciences: Faculty Publications

Extreme events such as heat waves, cold spells, floods, droughts, tropical cyclones, and tornadoes have potentially devastating impacts on natural and engineered systems and human communities worldwide. Stakeholder decisions about critical infrastructures, natural resources, emergency preparedness and humanitarian aid typically need to be made at local to regional scales over seasonal to decadal planning horizons. However, credible climate change attribution and reliable projections at more localized and shorter time scales remain grand challenges. Long-standing gaps include inadequate understanding of processes such as cloud physics and ocean–land–atmosphere interactions, limitations of physics-based computer models, and the importance of intrinsic climate system variability …

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Combining Limnology And Palaeolimnology To Investigate Recent Regime Shifts In A Shallow, Eutrophic Lake, Linda Randsalu-Wendrup, Daniel J. Conley, Jacob Carstensen, Lars-Anders Hansson, Christer Brönmark, Sherilyn C. Fritz, Preetam Choudhary, Joyanto Routh, Dan Hammarlund Jan 2014

Combining Limnology And Palaeolimnology To Investigate Recent Regime Shifts In A Shallow, Eutrophic Lake, Linda Randsalu-Wendrup, Daniel J. Conley, Jacob Carstensen, Lars-Anders Hansson, Christer Brönmark, Sherilyn C. Fritz, Preetam Choudhary, Joyanto Routh, Dan Hammarlund

Department of Earth and Atmospheric Sciences: Faculty Publications

In this study, we demonstrate that an integrated approach, combining palaeolimnological records and limnological monitoring data, can increase our understanding of changing ecological patterns and processes in shallow lakes. We focused on recent regime shifts in shallow Lake Krankesjön, southern Sweden, including the collapse of the clear-water state in 1975 and its subsequent recovery in the late 1980s. We used diatom, hydrocarbon, and biogenic silica sediment records, in concert with limnological data sets on nutrient concentrations, water clarity, chlorophyll-a and water depth, to investigate the shifts. The shift from clear to turbid conditions was abrupt and occurred over 1 to …

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Lithologic Influences On Groundwater Recharge Through Incised Glacial Till From Profile To Regional Scales: Evidence From Glaciated Eastern Nebraska, John B. Gates, Gregory V. Steele, Paolo Nasta, Jozsef Szilagyi Jan 2014

Lithologic Influences On Groundwater Recharge Through Incised Glacial Till From Profile To Regional Scales: Evidence From Glaciated Eastern Nebraska, John B. Gates, Gregory V. Steele, Paolo Nasta, Jozsef Szilagyi

Department of Earth and Atmospheric Sciences: Faculty Publications

Variability in sediment hydraulic properties associated with landscape depositional and erosional features can influence groundwater recharge processes by affecting soil-water storage and transmission. This study considers recharge to aquifers underlying river-incised glaciated terrain where the distribution of clay-rich till is largely intact in upland locations but has been removed by alluvial erosion in stream valleys. In a stream-dissected glacial region in eastern Nebraska (Great Plains region of the United States), recharge estimates were developed for nested profile, aquifer, and regional scales using unsaturated zone profile measurements (matric potentials, Cl- and 3H), groundwater tracers (CFC-12 and SF6), …

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Architecture, Heterogeneity, And Origin Of Late Miocene Fluvial Deposits Hosting The Most Important Aquifer In The Great Plains, Usa, R. Matthew Joeckel, Steve R. Wooden Jr., Jesse T. Korus, Jon Garbisch Jan 2014

Architecture, Heterogeneity, And Origin Of Late Miocene Fluvial Deposits Hosting The Most Important Aquifer In The Great Plains, Usa, R. Matthew Joeckel, Steve R. Wooden Jr., Jesse T. Korus, Jon Garbisch

Department of Earth and Atmospheric Sciences: Faculty Publications

The Ash Hollow Formation (AHF) of the Ogallala Group is an important sedimentary archive of the emergence of the Great Plains and it contains major groundwater resources. Stratal patterns of constituent alluvial lithofacies demonstrate that the AHF is much more heterogeneous than is commonly assumed. Very fine- to fine-grained sandstone dominate overall, chiefly lithofacies Sm (massive to locally stratified sandstone). Stacked, thin sheets of Sm with accretionary macroform surfaces are common, indicating that many sandstone architectural elements originated as compound-bar deposits in dominantly sand-bed streams. Channel forms are difficult to identify and steep cutbanks are absent. Multiple units of lithofacies …

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A 60,000-Year Record Of Hydrologic Variability In The Central Andes From The Hydrogen Isotopic Composition Of Leaf Waxes In Lake Titicaca Sediments, Kyrstin L. Fornace, Konrad A. Hughen, Timothy M. Shanahan, Sherilyn C. Fritz, Paul A. Baker, Sean P. Sylva Jan 2014

A 60,000-Year Record Of Hydrologic Variability In The Central Andes From The Hydrogen Isotopic Composition Of Leaf Waxes In Lake Titicaca Sediments, Kyrstin L. Fornace, Konrad A. Hughen, Timothy M. Shanahan, Sherilyn C. Fritz, Paul A. Baker, Sean P. Sylva

Department of Earth and Atmospheric Sciences: Faculty Publications

A record of the hydrogen isotopic composition of terrestrial leaf waxes (δDwax) in sediment cores from Lake Titicaca provides new insight into the precipitation history of the Central Andes and controls of South American Summer Monsoon (SASM) variability since the last glacial period. Comparison of the δDwax record with a 19-kyr δD record from the nearby Illimani ice core supports the interpretation that precipitation δD is the primary control on δDwax with a lesser but significant role for local evapotranspiration and other secondary influences on δDwax. The Titicaca δDwax record con-firms overall wetter conditions in the Central Andes during the …

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The Emerging Field Of Geogenomics: Constraining Geological Problems With Genetic Data, Paul A. Baker, Sherilyn C. Fritz, Christopher W. Dick, Andrew J. Eckert, Brian K. Horton, Stefano Manzoni, Camila C. Ribas, Carmala N. Garzione, David S. Battisti Jan 2014

The Emerging Field Of Geogenomics: Constraining Geological Problems With Genetic Data, Paul A. Baker, Sherilyn C. Fritz, Christopher W. Dick, Andrew J. Eckert, Brian K. Horton, Stefano Manzoni, Camila C. Ribas, Carmala N. Garzione, David S. Battisti

Department of Earth and Atmospheric Sciences: Faculty Publications

The development of a genomics-derived discipline within geology is timely, as a result of major advances in acquiring and processing geologically relevant genetic data. This paper articulates the emerging field of “geogenomics,” which involves the use of large-scale genetic data to constrain geological hypotheses. The paper introduces geogenomics and discusses how hypotheses can be ad-dressed through collaboration between geologists and evolutionary biologists. As an example, geogenomic methods are applied to evaluate competing hypotheses regarding the timing of the Andean uplift, the closure of the Isthmus of Panama, the onset of trans-Amazon drainage, and Quaternary climate variation in the Neotropics.

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Daily Area Of Snow Melt Onset On Arctic Sea Ice From Passive Microwave Satellite Observations 1979–2012, Angela C. Bliss, Mark R. Anderson Jan 2014

Daily Area Of Snow Melt Onset On Arctic Sea Ice From Passive Microwave Satellite Observations 1979–2012, Angela C. Bliss, Mark R. Anderson

Department of Earth and Atmospheric Sciences: Faculty Publications

Variability in snow melt onset (MO) on Arctic sea ice since 1979 is examined by determining the area of sea ice experiencing the onset of melting during the melt season on a daily basis. The daily MO area of the snow and ice surface is determined from passive microwave satellite-derived MO dates for the Arctic Ocean and sub-regions. Annual accumulations of MO area are determined by summing the time series of daily MO area through the melt season. Daily areas and annual accumulations of MO area highlight inter-annual and regional variability in the timing of MO area, which is sensitive …

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Mesoscale Modeling Of Smoke Transport Over The Southeast Asian Maritime Continent: Coupling Of Smoke Direct Radiative Effect Below And Above The Low-Level Clouds, C. Ge, J. Wang, J. S. Reid Jan 2014

Mesoscale Modeling Of Smoke Transport Over The Southeast Asian Maritime Continent: Coupling Of Smoke Direct Radiative Effect Below And Above The Low-Level Clouds, C. Ge, J. Wang, J. S. Reid

Department of Earth and Atmospheric Sciences: Faculty Publications

The online-coupled Weather Research and Forecasting model with Chemistry (WRF-Chem) is used to simulate the direct and semi-direct radiative impacts of smoke particles over the Southeast Asian Maritime Continent (MC, 10◦ S–10◦ N, 90–150◦ E) during October 2006 when a significant El Niño event caused the highest biomass burning activity since 1997. With the use of an OC (organic carbon) / BC (black carbon) ratio of 10 in the smoke emission inventory, the baseline simulation shows that the clouds can reverse the negative smoke forcing in cloud-free conditions to a positive value. The net absorption of the …

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Cenomanian Through Basal Coniacian Calcareous Nannofossil Biostratigraphy Of Themancos Shale Reference Section, Mesa Verde National Park, Co, Matthew J. Corbett, David K. Watkins Jan 2014

Cenomanian Through Basal Coniacian Calcareous Nannofossil Biostratigraphy Of Themancos Shale Reference Section, Mesa Verde National Park, Co, Matthew J. Corbett, David K. Watkins

Department of Earth and Atmospheric Sciences: Faculty Publications

Upper Cenomanian through lower Coniacian calcareous nannofossil biostratigraphy is integrated with macrofossil and lithostratigraphic correlations at the reference section for the Mancos Shale in Mesa Verde National Park, CO. Interpretations of key biostratigraphic events and δ13C values from bulk-rock carbonate fit well with the placement of stage boundaries by Leckie et al. (1997) and observations of nannofossil biostratigraphy in equivalent successions in the Western Interior. Tethyan nannofossil zone CC10b brackets the Cenomanian-Turonian boundary between 22.7–27.6m. Anannofossil zonal boundary between CC13 and CC14 is placed at 200.4-201m supporting the existence of an unconformity in the basal Smoky Hill Member …

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A Numerical Testbed For Remote Sensing Of Aerosols, And Its Demonstration For Evaluating Retrieval Synergy From A Geostationary Satellite Constellation Of Geo-Cape And Goes-R, Jun Wang, Xiaoguang Xu, Shouguo Ding, Jing Zeng, Robert Spurr, Xiong Liu, Kelly Chance, Michael I. Mishchenko Jan 2014

A Numerical Testbed For Remote Sensing Of Aerosols, And Its Demonstration For Evaluating Retrieval Synergy From A Geostationary Satellite Constellation Of Geo-Cape And Goes-R, Jun Wang, Xiaoguang Xu, Shouguo Ding, Jing Zeng, Robert Spurr, Xiong Liu, Kelly Chance, Michael I. Mishchenko

Department of Earth and Atmospheric Sciences: Faculty Publications

We present a numerical testbed for remote sensing of aerosols, together with a demonstration for evaluating retrieval synergy from a geostationary satellite constellation. The testbed combines inverse (optimal-estimation) software with a forward model containing linearized code for computing particle scattering (for both spherical and non-spherical particles). a kernel-based (land and ocean) surface bi-directional reflectance facility, and a linearized radiative transfer model for polarized radiance. Calculation of gas absorption spectra uses the HITRAN (HIgh-resolution TRANsmission molecular absorption) database of spectroscopic line parameters and other trace species cross-sections. The outputs of the testbed include not only the Stokes 4-vector elements and their …

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Prolonged Instability Prior To A Regime Shift, Trisha L. Spanbauer, Craig R. Allen, David G. Angeler, Tarsha Eason, Sherilyn C. Fritz, Ahjond S. Garmestani, Kirsty L. Nash, Jeffrey R. Stone Jan 2014

Prolonged Instability Prior To A Regime Shift, Trisha L. Spanbauer, Craig R. Allen, David G. Angeler, Tarsha Eason, Sherilyn C. Fritz, Ahjond S. Garmestani, Kirsty L. Nash, Jeffrey R. Stone

Department of Earth and Atmospheric Sciences: Faculty Publications

Regime shifts are generally defined as the point of ‘abrupt’ change in the state of a system. However, a seemingly abrupt transition can be the product of a system reorganization that has been ongoing much longer than is evident in statistical analysis of a single component of the system. Using both univariate and multivariate statistical methods, we tested a longterm high-resolution paleoecological dataset with a known change in species assemblage for a regime shift. Analysis of this dataset with Fisher Information and multivariate time series modeling showed that there was a ~2000 year period of instability prior to the regime …

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Dune Formation On Late Holocene Sandy Bay Barriers Along Lake Michigan’S Door Peninsula: The Importance Of Increased Sediment Supply Following The Nipissing And Algoma High Lake-Level Phases, J. Elmo Rawling Iii, Paul R. Hanson Jan 2014

Dune Formation On Late Holocene Sandy Bay Barriers Along Lake Michigan’S Door Peninsula: The Importance Of Increased Sediment Supply Following The Nipissing And Algoma High Lake-Level Phases, J. Elmo Rawling Iii, Paul R. Hanson

Department of Earth and Atmospheric Sciences: Faculty Publications

This study focuses on the geomorphology and geochronology of dunes formed on three sandy barrier systems at Clark, Europe and Kangaroo Lakes in Wisconsin’s Door Peninsula. The Lake Michigan shoreline in the peninsula contains abundant evidence for fluctuations in lake level with paleo-shoreline features that lie up to ~7 m above the present shoreline. Dunes are not very common along the Lake Michigan shoreline in Wisconsin, but the three bay barriers studied contain beach ridges that were buried by varying depths of eolian sand in the form of low relief sandsheets as well as parabolic and transverse dunes that have …

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Optimal Estimation For Global Ground-Level Fine Particulate Matter Concentrations, Aaron Van Donkelaar, Randall V. Martin, Robert J. D. Spurr, Easan Drury, Lorraine A. Remer, Robert C. Levy, Jun Wang Jan 2013

Optimal Estimation For Global Ground-Level Fine Particulate Matter Concentrations, Aaron Van Donkelaar, Randall V. Martin, Robert J. D. Spurr, Easan Drury, Lorraine A. Remer, Robert C. Levy, Jun Wang

Department of Earth and Atmospheric Sciences: Faculty Publications

We develop an optimal estimation (OE) algorithm based on top-of-atmosphere reflectances observed by the MODIS satellite instrument to retrieve near-surface fine particulatematter (PM2.5). The GEOS-Chem chemical transport model is used to provide prior information for the Aerosol Optical Depth (AOD) retrieval and to relate total column AOD to PM2.5. We adjust the shape of the GEOS-Chem relative vertical extinction profiles by comparison with lidar retrievals from the CALIOP satellite instrument. Surface reflectance relationships used in the OE algorithm are indexed by land type. Error quantities needed for this OE algorithm are inferred by comparison with AOD observations taken by a …

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Effect Of The Strengthened Western Pacific Subtropical High On Summer Visibility Decrease Over Eastern China Since 1973, Wenjun Qu, Jun Wang, Shanhong Gao, Tongwen Wu Jan 2013

Effect Of The Strengthened Western Pacific Subtropical High On Summer Visibility Decrease Over Eastern China Since 1973, Wenjun Qu, Jun Wang, Shanhong Gao, Tongwen Wu

Department of Earth and Atmospheric Sciences: Faculty Publications

Daily visibility (Vis) data from 354 meteorological stations are used to evaluate the seasonal Vis trends over China from 1973 to 2009, which show that Vis decline is most distinct over eastern China in summer, with a trend of -1.4 km per decade or -34% in the 37 years. This rapid decline of summertime Vis is found to be partially associated with the intensification and westward extension of the western Pacific subtropical high (WPSH) that has occurred in recent years. Such a change in the strength and breadth of WPSH has resulted in more days with stable, hot, and humid …

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Potential Climate Change Effects On Groundwater Recharge In The High Plains Aquifer, Usa, Russell S. Crosbie, Bridget R. Scanlon, Freddie S. Mpelasoka, Robert C. Reedy, John B. Gates, Lu Zhang Jan 2013

Potential Climate Change Effects On Groundwater Recharge In The High Plains Aquifer, Usa, Russell S. Crosbie, Bridget R. Scanlon, Freddie S. Mpelasoka, Robert C. Reedy, John B. Gates, Lu Zhang

Department of Earth and Atmospheric Sciences: Faculty Publications

Considering that past climate changes have significantly impacted groundwater resources, quantitative predictions of climate change effects on groundwater recharge may be valuable for effective management of future water resources. This study used 16 global climate models (GCMs) and three global warming scenarios to investigate changes in groundwater recharge rates for a 2050 climate relative to a 1990 climate in the U.S. High Plains region. Groundwater recharge was modeled using the Soil-Vegetation-Atmosphere- Transfer model WAVES for a variety of soil and vegetation types representative of the High Plains. The median projection under a 2050 climate includes increased recharge in the Northern …

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Prelude To Seven Slots: Filling And Subsequent Modification Of Seven Broad Canyons In The Navajo Sandstone, South-Central Utah, David B. Loope, Ronald J. Goble, Joel P. L. Johnson Jan 2013

Prelude To Seven Slots: Filling And Subsequent Modification Of Seven Broad Canyons In The Navajo Sandstone, South-Central Utah, David B. Loope, Ronald J. Goble, Joel P. L. Johnson

Department of Earth and Atmospheric Sciences: Faculty Publications

Within a four square kilometer portion of Grand Staircase-Escalante National Monument, seven distinct slot canyons cut the Jurassic Navajo Sandstone. Four of the slots developed along separate reaches of a trunk stream (Dry Fork of Coyote Gulch), and three (including canyons locally known as “Peekaboo” and “Spooky”) are at the distal ends of south-flowing tributary drainages. All these slot canyons are examples of epigenetic gorges—bedrock channel reaches shifted laterally from previous reach locations. The previous channels became filled with alluvium, allowing active channels to shift laterally in places and to subsequently re-incise through bedrock elsewhere. New evidence, based on optically …

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Jurassic Earthquake Sequence Recorded By Multiple Generations Of Sand Blows, Zion National Park, Utah, David Loope, James F. Elder, Vitaly A. Zlotnik, Richard M. Kettler, Darryll T. Pederson Jan 2013

Jurassic Earthquake Sequence Recorded By Multiple Generations Of Sand Blows, Zion National Park, Utah, David Loope, James F. Elder, Vitaly A. Zlotnik, Richard M. Kettler, Darryll T. Pederson

Department of Earth and Atmospheric Sciences: Faculty Publications

Earthquakes along convergent plate boundaries commonly occur in sequences that are complete within 1 yr, and may include 8–10 events strong enough to generate sand blows. Dune crossbeds within the Jurassic Navajo Sandstone of Utah (western United States) enclose intact and truncated sand blows, and the intrusive structures that fed them. We mapped the distribution of more than 800 soft-sediment dikes and pipes at two small sites. All water-escape structures intersect a single paleo-surface, and are limited to the upper portion of the underlying set of cross-strata and the lower portion of the overlying set. A small portion of one …

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The Freshwater System West Of The Antarctic Peninsula: Spatial And Temporal Changes, Michael P. Meredith, Hugh J. Venables, Andrew Clarke, Hugh W. Ducklow, Matthew Erickson, Melanie J. Leng, Jan T. M. Lenaerts, Michiel R. Van Den Broeke Jan 2013

The Freshwater System West Of The Antarctic Peninsula: Spatial And Temporal Changes, Michael P. Meredith, Hugh J. Venables, Andrew Clarke, Hugh W. Ducklow, Matthew Erickson, Melanie J. Leng, Jan T. M. Lenaerts, Michiel R. Van Den Broeke

Department of Earth and Atmospheric Sciences: Faculty Publications

Climate change west of the Antarctic Peninsula is the most rapid of anywhere in the Southern Hemisphere, with associated changes in the rates and distributions of freshwater inputs to the ocean. Here, results from the first comprehensive survey of oxygen isotopes in seawater in this region are used to quantify spatial patterns of meteoric water (glacial discharge and precipitation) separately from sea ice melt. High levels of meteoric water are found close to the coast, due to orographic effects on precipitation and strong glacial discharge. Concentrations decrease offshore, driving significant southward geostrophic flows (up to ;30 cm s21). These produce …

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Salinity And Climate Reconstructions From Continental Lakes, Sherilyn C. Fritz Jan 2013

Salinity And Climate Reconstructions From Continental Lakes, Sherilyn C. Fritz

Department of Earth and Atmospheric Sciences: Faculty Publications

Diatoms are widely used to reconstruct past environments because of their sensitivity to a range of environmental variables. Among the variables that exert a strong influence on diatoms are ionic concentration, expressed as salinity or conductivity, and ionic composition. Because the ionic concentration and composition of inland water bodies is affected by changes in effective moisture (precipitation minus evaporation, P – E), changes in the abundance of diatom species that vary in their salinity tolerances provide a tool for the reconstruction of past climate.

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A Gridded Reconstruction Of Warm Season Precipitation For Asia Spanning The Past Half Millennium, Song Feng, Q. Steven Hu, Qianru Wu, Michael E. Mann Jan 2013

A Gridded Reconstruction Of Warm Season Precipitation For Asia Spanning The Past Half Millennium, Song Feng, Q. Steven Hu, Qianru Wu, Michael E. Mann

Department of Earth and Atmospheric Sciences: Faculty Publications

The authors reconstructed May–September precipitation over the Asian continent (5°–55°N, 60°–135°E) back to AD 1470 on the basis of tree-ring data, historical documentary records, ice core records, and the few long-term instrumental data series available in the region. They employed the method of Regularized Expectation Maximization (RegEM) and applied it to 44 subregions within the continent. Verification exercises demonstrate that the reconstruction is skillful over most of the study domain, with eastern China, India, and other regions of humid climate displaying the greatest skill. Lower reconstruction skill is observed in semiarid and arid regions, which was attributable at least in …

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Optimal Estimation For Global Ground-Level Fine Particulate Matter Concentrations, Aaron Van Donkelaar, Randall V. Martin, Robert J. D. Spurr, Eason Drury, Lorraine A. Remer, Robert C. Levy, Jun Wang Jan 2013

Optimal Estimation For Global Ground-Level Fine Particulate Matter Concentrations, Aaron Van Donkelaar, Randall V. Martin, Robert J. D. Spurr, Eason Drury, Lorraine A. Remer, Robert C. Levy, Jun Wang

Department of Earth and Atmospheric Sciences: Faculty Publications

We develop an optimal estimation (OE) algorithm based on top-of-atmosphere reflectances observed by the MODIS satellite instrument to retrieve near-surface fine particulatematter (PM2.5). The GEOS-Chem chemical transport model is used to provide prior information for the Aerosol Optical Depth (AOD) retrieval and to relate total column AOD to PM2.5. We adjust the shape of the GEOS-Chem relative vertical extinction profiles by comparison with lidar retrievals from the CALIOP satellite instrument. Surface reflectance relationships used in the OE algorithm are indexed by land type. Error quantities needed for this OE algorithm are inferred by comparison with AOD …

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Constraints On Aerosol Sources Using Geos-Chem Adjoint And Modis Radiances, And Evaluation With Multisensor (Omi, Misr) Data, Xiaoguang Xu, Jun Wang, Daven Henze, Wenjun Qu, Monika Kopacz Jan 2013

Constraints On Aerosol Sources Using Geos-Chem Adjoint And Modis Radiances, And Evaluation With Multisensor (Omi, Misr) Data, Xiaoguang Xu, Jun Wang, Daven Henze, Wenjun Qu, Monika Kopacz

Department of Earth and Atmospheric Sciences: Faculty Publications

We present a new top-down approach that spatially constrains the amount of aerosol emissions using satellite (Moderate Resolution Imaging Spectroradiometer (MODIS)) observed radiances with the adjoint of a chemistry transport model (GEOS-Chem). This paper aims to demonstrate the approach through applying it to a case study that yields the following emission estimates over China for April 2008: 1.73 Tg for SO2, 0.72 Tg for NH3, 1.38 Tg for NOx, 0.10 Tg for black carbon, and 0.18 Tg for organic carbon from anthropogenic sources, which reflects, respectively, a reduction of 33.5%, 34.5%, 18.8%, 9.1%, and 15% in comparison to the prior …

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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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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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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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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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