Earth Sciences Commons^™

Recent Precipitation Decrease Across The Western Greenland Ice Sheet Percolation Zone, Hans-Peter Marshall, Tate Meehan

Geosciences Faculty Publications and Presentations

The mass balance of the Greenland Ice Sheet (GrIS) in a warming climate is of critical interest in the context of future sea level rise. Increased melting in the GrIS percolation zone due to atmospheric warming over the past several decades has led to increased mass loss at lower elevations. Previous studies have hypothesized that this warming is accompanied by a precipitation increase, as would be expected from the Clausius–Clapeyron relationship, compensating for some of the melt-induced mass loss throughout the western GrIS. This study tests that hypothesis by calculating snow accumulation rates and trends across the western GrIS percolation …

Exploring The Law Of Detrital Zircon: La-Icp-Ms And Ca-Tims Geochronology Of Jurassic Forearc Strata, Cook Inlet, Alaska, Usa, Trystan M. Herriott, James L. Crowley, Mark D. Schmitz, Marwan A. Wartes, Robert J. Gillis

Geosciences Faculty Publications and Presentations

Uranium-lead (U-Pb) geochronology studies commonly employ the law of detrital zircon: A sedimentary rock cannot be older than its youngest zircon. This premise permits maximum depositional ages (MDAs) to be applied in chronostratigraphy, but geochronologic dates are complicated by uncertainty. We conducted laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and chemical abrasion-thermal ionization mass spectrometry (CA-TIMS) of detrital zircon in forearc strata of southern Alaska (USA) to assess the accuracy of several MDA approaches. Six samples from Middle–Upper Jurassic units are generally replete with youthful zircon and underwent three rounds of analysis: (1) LA-ICP-MS of ∼115 grains, with one date per …

Spatially Extensive Ground‐Penetrating Radar Snow Depth Observations During Nasa's 2017 Snowex Campaign: Comparison With In Situ, Airborne, And Satellite Observations, Hans-Peter Marshall

Geosciences Faculty Publications and Presentations

Seasonal snow is an important component of Earth's hydrologic cycle and climate system, yet it remains challenging to consistently and accurately measure snow depth and snow water equivalent (SWE) across the range of diverse snowpack conditions that exist on Earth. The NASA SnowEx campaign is focused on addressing the primary gaps in snow remote sensing in order to gain an improved spatiotemporal understanding of this important resource and to further efforts toward a future satellite‐based snow remote sensing mission. Ground‐penetrating radar (GPR) is an efficient and mature approach for measuring snow depth and SWE. We collected ~1.3 million GPR snow …

Snow Depth Variability In The Northern Hemisphere Mountains Observed From Space, Hans-Peter Marshall

Geosciences Faculty Publications and Presentations

Accurate snow depth observations are critical to assess water resources. More than a billion people rely on water from snow, most of which originates in the Northern Hemisphere mountain ranges. Yet, remote sensing observations of mountain snow depth are still lacking at the large scale. Here, we show the ability of Sentinel-1 to map snow depth in the Northern Hemisphere mountains at 1 km² resolution using an empirical change detection approach. An evaluation with measurements from ~4000 sites and reanalysis data demonstrates that the Sentinel-1 retrievals capture the spatial variability between and within mountain ranges, as well as their inter-annual …

The Alleghanian Isthmus As The Trigger Of The Onset Of The Bashkirian Glaciation: Constraints From Warm-Water Benthic Foraminifera, Vladimir I. Davydov, Pedro Cózar

Geosciences Faculty Publications and Presentations

The timing of the final collision and particularly the disappearance of the gateway between the Rheic and Tethyan oceans is quite controversial and poorly established. The accurate timing on the gateway closure is vitally important for the understanding of global sea-level fluctuations, ocean circulation, regional and global environments, salinity and reorganization of the thermohaline circulation, enhanced deep water organic carbon production in the western Tethys and the overall decline of atmospheric CO₂ concentrations. Here we present a new approach by applying warm-water benthic foraminifera (WWBF) data to precisely constraint the Rheic-Tethys gateway (RTG) closure, utilizing taxonomic and statistical methods. …

Melpf Version 1: Modeling Error Learning Based Post-Processor Framework For Hydrologic Models Accuracy Improvement, Rui Wu, Lei Yang, Chao Chen, Sajjad Ahmad, Sergiu M. Dascalu, Frederick C. Harris Jr.

Geosciences Faculty Publications and Presentations

This paper studies how to improve the accuracy of hydrologic models using machine-learning models as post-processors and presents possibilities to reduce the workload to create an accurate hydrologic model by removing the calibration step. It is often challenging to develop an accurate hydrologic model due to the time-consuming model calibration procedure and the nonstationarity of hydrologic data. Our findings show that the errors of hydrologic models are correlated with model inputs. Thus motivated, we propose a modeling-error-learning-based post-processor framework by leveraging this correlation to improve the accuracy of a hydrologic model. The key idea is to predict the differences (errors) …

Regional Scale Dryland Vegetation Classification With An Integrated Lidar-Hyperspectral Approach, Hamid Dashti, Nancy F. Glenn, Nayani Ilangakoon, Josh Enterkine, Alejandro N. Flores

Geosciences Faculty Publications and Presentations

The sparse canopy cover and large contribution of bright background soil, along with the heterogeneous vegetation types in close proximity, are common challenges for mapping dryland vegetation with remote sensing. Consequently, the results of a single classification algorithm or one type of sensor to characterize dryland vegetation typically show low accuracy and lack robustness. In our study, we improved classification accuracy in a semi-arid ecosystem based on the use of vegetation optical (hyperspectral) and structural (lidar) information combined with the environmental characteristics of the landscape. To accomplish this goal, we used both spectral angle mapper (SAM) and multiple endmember spectral …

High-Precision Radioisotopic Ages For The Lower Midian (Upper Wordian) Stage Of The Tethyan Time Scale, Shigeyasu Quarry, Yamaguchi Prefecture, Japan, V. I. Davydov, M. D. Schmitz

Geosciences Faculty Publications and Presentations

Global correlation of strata to the Guadalupian Series (Permian Period) of the International Geologic Time Scale remains provisional due to a lack of the sufficient biostratigraphically constrained radioisotopic ages. Five new high-precision U–Pb radioisotopic ages were obtained from tuffs in the lower Midian (upper Wordian) volcano-siliciclastic succession of the Akiyoshi Plateau, southwestern Japan. Two undisturbed and continuous tuffs occur within fusulinid-bearing laminated limestone turbidites, with precise biostratigraphic control. The Colania douvillei and Lepidolina shiraiwensis fusulinid Zones in the Akiyoshi succession provide an early Midian age in the Tethyan provincial time scale. The range of ages (267.46 ± 0.04 Ma to …

Comparing Aerial Lidar Observations With Terrestrial Lidar And Snow-Probe Transects From Nasa's 2017 Snowex Campaign, Zach Uhlmann, Lucas Spaete, Nancy F. Glenn

Geosciences Faculty Publications and Presentations

NASA's 2017 SnowEx field campaign at Grand Mesa, CO, generated Airborne Laser Scans (ALS), Terrestrial Laser Scans (TLS), and snow‐probe transects, which allowed for a comparison between snow depth measurement techniques. At six locations, comparisons between gridded ALS and TLS observations, at 1‐m resolution, had a median snow depth difference of 5 cm, root‐mean‐square difference of 16 cm, mean‐absolute difference of 10 cm, and 3‐cm difference in standard deviation. ALS generally had greater but similar snow depth values to TLS, and results were not sensitive to the gridded cell size between 0.5 and 5 m. The greatest disagreements were where …

Approximating Input Data To A Snowmelt Model Using Weather Research And Forecasting Model Outputs In Lieu Of Meteorological Measurements, Scott Havens, Danny Marks, Katelyn Fitzgerald, Matt Masarik, Alejandro N. Flores, Patrick Kormos, Andrew Hedrick

Geosciences Faculty Publications and Presentations

Forecasting the timing and magnitude of snowmelt and runoff is critical to managing mountain water resources. Warming temperatures are increasing the rain–snow transition elevation and are limiting the forecasting skill of statistical models relating historical snow water equivalent to streamflow. While physically based methods are available, they require accurate estimations of the spatial and temporal distribution of meteorological variables in complex terrain. Across many mountainous areas, measurements of precipitation and other meteorological variables are limited to a few reference stations and are not adequate to resolve the complex interactions between topography and atmospheric flow. In this paper, we evaluate the …

Leveraging Environmental Research And Observation Networks To Advance Soil Carbon Science, Alejandro N. Flores

Geosciences Faculty Publications and Presentations

Soil organic matter (SOM) is a critical ecosystem variable regulated by interacting physical, chemical, and biological processes. Collaborative efforts to integrate perspectives, data, and models from interdisciplinary research and observation networks can significantly advance predictive understanding of SOM. We outline how integrating three networks—the Long‐Term Ecological Research with a focus on ecological dynamics, the Critical Zone Observatories with strengths in landscape/geologic context, and the National Ecological Observatory Network with standardized multiscale measurements—can advance SOM knowledge. This integration requires improved data dissemination and sharing, coordinated data collection activities, and enhanced collaboration between empiricists and modelers within and across networks.

First-Order Estimates Of Coastal Bathymetry In Ilulissat And Naajarsuit Fjords, Greenland, From Remotely Sensed Iceberg Observations, Jessica Scheick, Ellyn M. Enderlin, Emily E. Miller, Gordon Hamilton

Geosciences Faculty Publications and Presentations

Warm water masses circulating at depth off the coast of Greenland play an important role in controlling rates of mass loss from the Greenland Ice Sheet through feedbacks associated with the melting of marine glacier termini. The ability of these warm waters to reach glacier termini is strongly controlled by fjord bathymetry, which was unmapped for the majority of Greenland’s fjords until recently. In response to the need for bathymetric measurements in previously uncharted areas, we developed two companion methods to infer fjord bathymetry using icebergs as depth sounders. The main premise of our methods centers around the idea that …

Permeability Prediction In Rocks Experiencing Mineral Precipitation And Dissolution: A Numerical Study, Qifei Niu, Chi Zhang

Geosciences Faculty Publications and Presentations

In this study, we focus on the electrical tortuosity-based permeability model k = r_eff²/8F (r_eff is an effective pore size, and F is the formation factor) and analyze its applicability to rocks experiencing mineral precipitation and dissolution. Two limiting cases of advection-dominated water-rock reactions are simulated, that is, the reaction-limited and transport-limited cases. At the pore scale, the two precipitation/dissolution patterns are simulated with a geometrical model and a phenomenological model. The fluid and electric flows in the rocks are simulated by directly solving the linear Stokes equation and Laplace equation on the representative …

Examining Interactions Between And Among Predictors Of Net Ecosystem Exchange: A Machine Learning Approach In A Semi-Arid Landscape, Qingtao Zhou, Aaron Fellows, Gerald N. Flerchinger, Alejandro N. Flores

Geosciences Faculty Publications and Presentations

Net ecosystem exchange (NEE) is an essential climate indicator of the direction and magnitude of carbon dioxide (CO₂) transfer between land surfaces and the atmosphere. Improved estimates of NEE can serve to better constrain spatiotemporal characteristics of terrestrial carbon fluxes, improve verification of land models, and advance monitoring of Earth’s terrestrial ecosystems. Spatiotemporal NEE information developed by combining ground-based flux tower observations and spatiotemporal remote sensing datasets are of potential value in benchmarking land models. We apply a machine learning approach (Random Forest (RF)) to develop spatiotemporally varying NEE estimates using observations from a flux tower and several …

Hillslope Hydrology In Global Change Research And Earth System Modeling, A. Flores, J. Mcnamara

Geosciences Faculty Publications and Presentations

Earth System Models (ESMs) are essential tools for understanding and predicting global change, but they cannot explicitly resolve hillslope‐scale terrain structures that fundamentally organize water, energy, and biogeochemical stores and fluxes at subgrid scales. Here we bring together hydrologists, Critical Zone scientists, and ESM developers, to explore how hillslope structures may modulate ESM grid‐level water, energy, and biogeochemical fluxes. In contrast to the one‐dimensional (1‐D), 2‐ to 3‐m deep, and free‐draining soil hydrology in most ESM land models, we hypothesize that 3‐D, lateral ridge‐to‐valley flow through shallow and deep paths and insolation contrasts between sunny and shady slopes are the …

Including Variability Across Climate Change Projections In Assessing Impacts On Water Resources In An Intensively Managed Landscape, Bangshuai Han, Shawn G. Benner, Alejandro N. Flores

Geosciences Faculty Publications and Presentations

In intensively managed watersheds, water scarcity is a product of interactions between complex biophysical processes and human activities. Understanding how intensively managed watersheds respond to climate change requires modeling these coupled processes. One challenge in assessing the response of these watersheds to climate change lies in adequately capturing the trends and variability of future climates. Here we combine a stochastic weather generator together with future projections of climate change to efficiently create a large ensemble of daily weather for three climate scenarios, reflecting recent past and two future climate scenarios. With a previously developed model that captures rainfall-runoff processes and …

Probability Of Streamflow Permanence Model (Prosper): A Spatially Continuous Model Of Annual Streamflow Permanence Throughout The Pacific Northwest, K. E. Kaiser

Geosciences Faculty Publications and Presentations

The U.S. Geological Survey (USGS) has developed the PRObability of Streamflow PERmanence (PROSPER) model, a GIS raster-based empirical model that provides streamflow permanence probabilities (probabilistic predictions) of a stream channel having year-round flow for any unregulated and minimallyimpaired stream channel in the Pacific Northwest region, U.S. The model provides annual predictions for 2004–2016 at a 30-m spatial resolution based on monthly or annually updated values of climatic conditions and static physiographic variables associated with the upstream basin. Predictions correspond to any pixel on the channel network consistent with the medium resolution National Hydrography Dataset channel network stream grid. Total annual …

Late Permian And Early Triassic Conchostracans From The Babii Kamen Section (Kuznetsk Coal Basin), V. I. Davydov, V. V. Zharinova, V. V. Silantiev

Geosciences Faculty Publications and Presentations

The Late Permian and Early Triassic conchostracans from the Babii Kamen section (Western Siberia) were studied. The conchostracans were collected from the section during the field work in 2015–2018. It was found that the conchostracans from the Babii Kamen section are characterized by a rather high taxonomical diversity: we identified five Late Permian conchostracan species (Pseudestheria novacastrensis (Mitchell, 1927), Cornia papillaria (Lutkevich, 1937), Megasitum harmonicum Novojilov, 1970, Megasitum lopokolense Novojilov, 1970, and Echinolimnadia mattoxi Novojilov, 1965) and two Early Triassic species (Concherisma tomensis Novojilov, 1958, Cyclotunguzites gutta (Lutkevich, 1938). The discovered conchostracan species occur frequently in the …

Applying Cloud-Based Computing And Emerging Remote Sensing Technologies To Inform Land Management Decisions, Monica Vermillion, Josh Enterkine, Lucas Spaete, Nancy Glenn

Geosciences Faculty Publications and Presentations

Who: Boise State University and Mountain Home Air Force Base

What: Creating a species level classification map through the use of Google Earth Engine (GEE), a cloud-based computing platform, to map invasive species

When: In-situ data collected in Summer 2018, a continuation of data collected in Summer 2016. Classification was created in Fall 2018. Unmanned aerial vehicles (UAV) flights in August 2018.

Where: Mountain Home Air Force Base (MHAFB) in southwest Idaho, ecosystem is in the Great Basin Range (GBR)

Why: The introduction of exotic species like cheatgrass (Bromus tectorum) has drastically altered the fire cycle of the …

Precaspian Isthmus Emergence Triggered The Early Sakmarian Glaciation (Paleontologic, Sedimentologic And Geochemical Proxies), Vladimir I. Davydov

Geosciences Faculty Publications and Presentations

The sub-meridional seaway that connected Paleo-Arctic and Paleo-Tethys basins was one of the most important geographical attributes of the Late Paleozoic Pangea landscape, paleogeography and paleoclimate. Existing models about the timing of the disconnection of the Paleo-Arctic and the Paleo-Tethyan oceans is very controversial and poorly documented. Warm-water benthic foraminifera (WWBF) were utilized to establish the precise timing of the closure of the Urals-Precaspian-Paleo-Tethys Seaway (UPTS) during Cisuralian time. The WWBF of Paleo-Tethys and those of the Ural-Precaspian Basins during the Gzhelian-Asselian, display a considerably high level of similarity. Beginning from the Sakmarian, the faunas of these two regions became …

Climate Change And Curtailment: Evaluating Water Management Practices In The Context Of Changing Runoff Regimes In A Snowmelt-Dominated Basin, Amy L. Steimke, Bangshuai Han, Jodi S. Brandt, Alejandro N. Flores

Geosciences Faculty Publications and Presentations

Hydrologic scientists and water resource managers often focus on different facets of flow regimes in changing climates. The objective of this work is to examine potential hydrological changes in the Upper Boise River Basin, Idaho, USA in the context of biophysical variables and their impacts a key variable governing administration of water resources in the region in an integrated way. This snowmelt-dominated, mountainous watershed supplies water to a semi-arid, agriculturally intensive, but rapidly urbanizing, region. Using the Envision integrated modeling framework, we created a hydrological model to simulate hydrological response to the year 2100 using six alternative future climate trajectories. …

Imaging Spectroscopic Analysis Of Biochemical Traits For Shrub Species In Great Basin, Usa, Yi Qi, Susan L. Ustin, Nancy F. Glenn

Geosciences Faculty Publications and Presentations

The biochemical traits of plant canopies are important predictors of photosynthetic capacity and nutrient cycling. However, remote sensing of biochemical traits in shrub species in dryland ecosystems has been limited mainly due to the sparse vegetation cover, manifold shrub structures, and complex light interaction between the land surface and canopy. In order to examine the performance of airborne imaging spectroscopy for retrieving biochemical traits in shrub species, we collected Airborne Visible Infrared Imaging Spectrometer—Next Generation (AVIRIS-NG) images and surveyed four foliar biochemical traits (leaf mass per area, water content, nitrogen content and carbon) of sagebrush (Artemesia tridentata) and …

Reverse-Time Migration From Rugged Topography To Image Ground-Penetrating Radar Data In Complex Environments, John H. Bradford, Janna Privette, David Wilkins, Richard Ford

Geosciences Faculty Publications and Presentations

In ground-penetrating radar (GPR) imaging, it is common for the depth of investigation to be on the same order as the variability in surface topography. In such cases, migration fails when it is carried out from a datum after the application of elevation statics. We introduce a reverse-time migration (RTM) algorithm based on the second-order decoupled form of Maxwell’s equations, which requires computation of only the electric field. The wavefield extrapolation is computed directly from the acquisition surface without the need for datuming. In a synthetic case study, the algorithm significantly improves image accuracy over a processing sequence in which …

Nested Scales Of Spatial And Temporal Variability Of Soil Water Content Across A Semiarid Montane Catchment, Kendra E. Kaiser, Brian L. Mcglynn

Geosciences Faculty Publications and Presentations

Topographic redistribution of water has been represented by various terrain metrics (e.g., topographic wetness index, slope, and upslope accumulated area). This type of landscape characterization has promoted the use of terrain metrics to inform how spatial patterns of soil volumetric water content (VWC) influence streamflow, ecological processes, and associated nutrient fluxes. However, evaluation of what these static terrain metrics reflect has only been accomplished in a few catchments. Additionally, previous research suggests that relationships between topographic metrics and VWC could be different across catchments through time. Here we measured VWC from snowmelt through summer drydown across a semiarid montane catchment. …

Submarine Deep-Water Lava Flows At The Base Of The Western Galápagos Platform, Molly Anderson, V. Dorsey Wanless, Darin M. Schwartz, Emma Mccully, Daniel J. Fornari, Meghan R. Jones, S. Adam Soule

Geosciences Faculty Publications and Presentations

To investigate the initial phases of magmatism at the leading edge of the upwelling mantle plume, we mapped, photographed, and collected samples from two long, deep-water lava flows located at the western base of the Galápagos Platform using the remotely operated vehicle Hercules. Lavas were recovered from four areas on the seafloor west of Fernandina volcano, including the western flow fronts of two deep-water flows, heavily sedimented terrain between the two flows, and the eastern, shallower end of one flow. The sediment cover and morphologies are distinct between the western flow fronts and the eastern region based on seafloor …

The Final Stages Of Slip And Volcanism On An Oceanic Detachment Fault At 13°48′N, Mid-Atlantic Ridge, V. D. Wanless

Geosciences Faculty Publications and Presentations

While processes associated with initiation and maintenance of oceanic detachment faults are becoming better constrained, much less is known about the tectonic and magmatic conditions that lead to fault abandonment. Here we present results from near‐bottom investigations using the submersible Alvin and autonomous underwater vehicle Sentry at a recently extinct detachment fault near 13°48′N, Mid‐Atlantic Ridge, that allow documentation of the final stages of fault activity and magmatism. Seafloor imagery, sampling, and near‐bottom magnetic data show that the detachment footwall is intersected by an ~850 m‐wide volcanic outcrop including pillow lavas. Saturation pressures in these vesicular basalts, based on dissolved …

Tephra From The 3 March 2015 Sustained Column Related To Explosive Lava Fountain Activity At Volcán Villarrica (Chile), Jeffrey B. Johnson

Geosciences Faculty Publications and Presentations

Exceptionally intense lava fountains at open conduit volcanoes are infrequent, hazardous and little-warned events. Studying their tephra falls may reveal conduit dynamics, eruption source parameters and fragmentation mechanisms. Villarrica Volcano (Southern Andes of Chile) has sustained persistent open conduit activity, associated with a dynamic lava lake since at least 1984–85. Increased seismicity and degassing in August 2014 were followed by Strombolian activity starting in February 2015 and culminated with a 1.5 km-high lava fountain on 3 March 2015. This eruption produced tephra fallout, spatter agglutination, clastogenic lavas and mixed avalanche deposits. Here we characterized for first time Villarrica's 3 March …

Identification Of Erosional Terraces On Seamounts: Implications For Interisland Connectivity And Subsidence In The Galápagos Archipelago, Darin M. Schwartz, S. Adam Soule, V. Dorsey Wanless, Meghan R. Jones

Geosciences Faculty Publications and Presentations

Shallow seamounts at ocean island hotspots and in other settings may record emergence histories in the form of submarine erosional terraces. Exposure histories are valuable for constraining paleo-elevations and sea levels in the absence of more traditional markers, such as drowned coral reefs. However, similar features can also be produced through primary volcanic processes, which complicate the use of terraced seamounts as an indicator of paleo-shorelines. In the western Galápagos Archipelago, we utilize newly collected bathymetry along with seafloor observations from human-occupied submersibles to document the location and depth of erosional terraces on seamounts near the islands of Santiago, Santa …

Eleven Years Of Mountain Weather, Snow, Soil Moisture And Streamflow Data From The Rain–Snow Transition Zone – The Johnston Draw Catchment, Reynolds Creek Experimental Watershed And Critical Zone Observatory, Usa, James P. Mcnamara

Geosciences Faculty Publications and Presentations

Detailed hydrometeorological data from the rain-to-snow transition zone in mountain regions are limited. As the climate warms, the transition from rain to snow is moving to higher elevations, and these changes are altering the timing of downslope water delivery. To understand how these changes impact hydrological and biological processes in this climatologically sensitive region, detailed observations from the rain-to-snow transition zone are required. We present a complete hydrometeorological dataset for water years 2004 through 2014 for a watershed that spans the rain-to-snow transition zone (https://doi.org/10.15482/usda.adc/1402076). The Johnston Draw watershed (1.8km²), ranging from 1497 to 1869m in elevation, is …

Hyporheic Source And Sink Of Nitrous Oxide, W. Jeffery Reeder, Annika M. Quick, Tiffany B. Farrell, Shawn G. Benner, Kevin P. Feris, Alessandra Marzadri, Daniele Tonina

Geosciences Faculty Publications and Presentations

Nitrous oxide (N₂O) is a potent greenhouse gas with an estimated 10% of anthropogenic N₂O coming from the hyporheic zone of streams and rivers. However, difficulty in making accurate fine-scale field measurements has prevented detailed understanding of the processes of N₂O production and emission at the bedform and flowline scales. Using large-scale, replicated flume experiments that employed high-density chemical concentration measurements, we have been able to refine the current conceptualization of N₂O production, consumption, and emission from the hyporheic zone. We present a predictive model based on a Damköhler-type transformation (τ̃) in …