• A Solid Interpretation of Bright Radar Reflectors Under the Mars South Polar Ice

      Smith, I.B.; Lalich, D.E.; Rezza, C.; Horgan, B.H.N.; Whitten, J.L.; Nerozzi, S.; Holt, J.W.; Lunar and Planetary Laboratory, University of Arizona; Department of Geosciences, University of Arizona (John Wiley and Sons Inc, 2021)
      Bright radar reflections observed beneath the south polar layered deposits (SPLD) by the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument were interpreted to represent liquid water, but the required amounts of salt and heat to form and maintain liquids in this location are implausible given what is known about Mars. Here, we present another hypothesis that accounts for the bright reflections: hydrated and cold clay-rich deposits at the base of the SPLD create the observed radar response. To support this hypothesis, we present experimental measurements and wave propagation modeling that show that smectites, cooled to 230 K, have real and imaginary parts of the dielectric permittivity large enough to cause the bright reflections, even when mixed with other materials. Further, we find that absorptions attributable to these minerals are present in south polar orbital visible-near infrared reflectance spectra. Because these minerals are present at the south pole and can cause the reflections, we believe this to be a more viable scenario than the liquid water interpretation. © 2021. American Geophysical Union. All Rights Reserved.
    • Accurate Simulation of Both Sensitivity and Variability for Amazonian Photosynthesis: Is It Too Much to Ask?

      Gallup, S.M.; Baker, I.T.; Gallup, J.L.; Restrepo-Coupe, N.; Haynes, K.D.; Geyer, N.M.; Denning, A.S.; Department of Ecology and Evolutionary Biology, University of Arizona (John Wiley and Sons Inc, 2021)
      Estimates of Amazon rainforest gross primary productivity (GPP) differ by a factor of 2 across a suite of three statistical and 18 process models. This wide spread contributes uncertainty to predictions of future climate. We compare the mean and variance of GPP from these models to that of GPP at six eddy covariance (EC) towers. Only one model's mean GPP across all sites falls within a 99% confidence interval for EC GPP, and only one model matches EC variance. The strength of model response to climate drivers is related to model ability to match the seasonal pattern of the EC GPP. Models with stronger seasonal swings in GPP have stronger responses to rain, light, and temperature than does EC GPP. The model to data comparison illustrates a trade-off inherent to deterministic models between accurate simulation of a mean (average) and accurate responsiveness to drivers. The trade-off exists because all deterministic models simplify processes and lack at least some consequential driver or interaction. If a model's sensitivities to included drivers and their interactions are accurate, then deterministically predicted outcomes have less variability than is realistic. If a GPP model has stronger responses to climate drivers than found in data, model predictions may match the observed variance and seasonal pattern but are likely to overpredict GPP response to climate change. High or realistic variability of model estimates relative to reference data indicate that the model is hypersensitive to one or more drivers. © 2021. The Authors. Journal of Advances in Modeling Earth Systems published by Wiley Periodicals LLC on behalf of American Geophysical Union.
    • Climate Impacts on Source Contributions and Evaporation to Flow in the Snake River Basin Using Surface Water Isoscapes (δ2H and δ18O)

      Windler, G.; Brooks, J.R.; Johnson, H.M.; Comeleo, R.L.; Coulombe, R.; Bowen, G.J.; Department of Geosciences, University of Arizona (John Wiley and Sons Inc, 2021)
      Rising global temperatures are expected to decrease the precipitation amount that falls as snow, causing greater risk of water scarcity, groundwater overdraft, and fire in areas that rely on mountain snowpack for their water supply. Streamflow in large river basins varies with the amount, timing, and type of precipitation, evapotranspiration, and drainage properties of watersheds; however, these controls vary in time and space making it difficult to identify the areas contributing most to flow and when. In this study, we separate the evaporative influences from source values of water isotopes from the Snake River basin in the western United States to relate source area to flow dynamics. We developed isoscapes (δ2H and δ18O) for the basin and found that isotopic composition of surface water in small watersheds is primarily controlled by longitude, latitude, and elevation. To examine temporal variability in source contributions to flow, we present a 6-years record of Snake River water isotopes from King Hill, Idaho, after removing evaporative influences. During periods of low flow, source water values were isotopically lighter indicating a larger contribution to flow from surface waters in the highest elevation, eastern portion of the basin. River evaporation increases were evident during summer likely reflecting climate, changing water availability, and management strategies within the basin. Our findings present a potential tool for identifying critical portions of basins contributing to river flow as climate fluctuations alter flow dynamics. This tool can be applied in other continental-interior basins where evaporation may obscure source water isotopic signatures. © 2021. American Geophysical Union. All Rights Reserved.
    • Cloud, Aerosol, and Radiative Properties Over the Western North Atlantic Ocean

      Braun, R.A.; McComiskey, A.; Tselioudis, G.; Tropf, D.; Sorooshian, A.; Department of Chemical and Environmental Engineering, University of Arizona; Department of Hydrology and Atmospheric Sciences, University of Arizona (John Wiley and Sons Inc, 2021)
      This study examines the atmospheric properties of weather states (WSs) derived from the International Satellite Cloud Climatology Project over the Western North Atlantic Ocean. In particular, radiation and aerosol data corresponding to two sites in the study domain, Pennsylvania State University and Bermuda, were examined to characterize the atmospheric properties of the various satellite-derived WSs. At both sites, the fair weather WS was most prevalent, followed by the cirrus WS. Differences in the seasonality of the various WSs were observed at the two sites. Fractional sky cover and effective shortwave cloud transmissivity derived from ground-based radiation measurements were able to capture differences among the satellite-derived WSs. Speciated aerosol optical thicknesses (AOT) from the Modern-Era Retrospective Analysis for Research and Applications, version 2 were used to investigate potential differences in aerosol properties among the WSs. The clear sky WS exhibited below-average seasonal values of AOT at both sites year-round, as well as relatively high rates of occurrence with low AOT events. In addition, the clear sky WS showed above-average contributions from dust and black carbon to the total AOT year-round. Finally, transitions between various WSs were examined under low, high, and mid-range AOT conditions. The most common pathway was for the WSs to remain in the same state after a 3 h interval. Some WSs, such as mid latitude storms, deep convection, middle top, and shallow cumulus, were more prevalent as ending states under high AOT conditions. This work motivates examining differences in aerosol properties between WSs in other regions. © 2021. American Geophysical Union. All Rights Reserved.
    • Conservatism and infrequent mask usage: A study of US counties during the novel coronavirus (COVID‐19) pandemic

      Gonzalez, Kelsey E.; James, Rina; Bjorklund, Eric T.; Hill, Terrence D.; School of Sociology, The University of Arizona (John Wiley and Sons Inc, 2021-08-27)
      Objective: Although the Centers for Disease Control and Prevention eventually recommended wearing masks in public to slow the spread of the Coronavirus, the practice has been unevenly distributed in the United States. Methods: In this article, we model county‐level infrequent mask usage as a function of three pillars of conservatism: (1) Republican political leadership (percentage of votes for Donald Trump in the 2016 presidential election), (2) conservative Protestantism (percentage evangelical Christian), and (3) right‐wing media consumption (Google searches for Fox News). Results: Our analyses indicate that mask usage tends to be lower in counties with greater support for President Trump (in majority Trump counties), counties with more evangelical Christians, and areas with greater interest in Fox News. Conclusion: Given the effectiveness of masks in limiting the transmission of respiratory droplets, conservative ideological resistance to public health and recommended pandemic lifestyles may indirectly support the spread of the coronavirus.
    • Continental Hydrologic Intercomparison Project, Phase 1: A Large-Scale Hydrologic Model Comparison Over the Continental United States

      Tijerina, D.; Condon, L.; FitzGerald, K.; Dugger, A.; O’Neill, M.M.; Sampson, K.; Gochis, D.; Maxwell, R.; University of Arizona (John Wiley and Sons Inc, 2021)
      High-resolution, coupled, process-based hydrology models, in which subsurface, land-surface, and energy budget processes are represented, have been applied at the basin-scale to ask a wide range of water science questions. Recently, these models have been developed at continental scales with applications in operational flood forecasting, hydrologic prediction, and process representation. As use of large-scale model configurations increases, it is exceedingly important to have a common method for performance evaluation and validation, particularly given challenges associated with accurately representing large domains. Here, we present phase 1 of a comparison project for continental-scale, high-resolution, processed-based hydrologic models entitled the Continental Hydrologic Intercomparison Project (CHIP). The first phase of CHIP is based on past Earth System Model intercomparisons and comprised of a two-model proof of concept comparing the ParFlow-CONUS hydrologic model, version 1.0 and a NOAA US National Water Model configuration of WRF-Hydro, version 1.2. The objectives of CHIP phase 1 are: (a) describe model physics and components, (b) design an experiment to ensure a fair comparison, and (b) assess simulated streamflow with observations to better understand model bias. To our knowledge, this is the first comparison of continental-scale, high-resolution, physics-based models which incorporate lateral subsurface flow. This model intercomparison is an initial step toward a continued effort to unravel process, parameter, and formulation differences in current large-scale hydrologic models and to engage the hydrology community in improving hydrology model configuration and process representation. © 2021. The Authors.
    • Coupling Between Lithosphere Removal and Mantle Flow in the Central Andes

      Wang, H.; Currie, C.A.; DeCelles, P.G.; Department of Geosciences, University of Arizona (John Wiley and Sons Inc, 2021)
      The central Andes is part of a Cordilleran orogen formed through continent-ocean convergence. In contrast to the thickened crust, the mantle lithosphere below much of the orogen is anomalously thin. Additionally, the surface is characterized by widespread backarc magmatism and transient ∼100-km-wide basins that developed the over last 30 million years, with basins located systematically seaward of major backarc ignimbrite centers and basin formation predating the late Miocene magma/ignimbrite flare-up. Using numerical models, we propose a novel mechanism whereby lithosphere removal is coupled with mantle flow. First, a small area of high-density eclogitized lower crust initiates a gravitational instability, causing a localized basin at the surface that subsides and then uplifts. Foundering crust and adjacent lithosphere are entrained by subduction-induced mantle flow, driving regional lithosphere removal and magmatism. The models demonstrate that mantle flow can amplify a local lithosphere instability to orogen-wide lithosphere removal, rapidly eliminating accumulated mass in the orogen. © 2021. American Geophysical Union. All Rights Reserved.
    • Crustal Groundwater Volumes Greater Than Previously Thought

      Ferguson, G.; McIntosh, J.C.; Warr, O.; Sherwood Lollar, B.; Ballentine, C.J.; Famiglietti, J.S.; Kim, J.-H.; Michalski, J.R.; Mustard, J.F.; Tarnas, J.; et al. (John Wiley and Sons Inc, 2021)
      Global groundwater volumes in the upper 2 km of the Earth's continental crust—critical for water security—are well estimated. Beyond these depths, a vast body of largely saline and non-potable groundwater exists down to at least 10 km—a volume that has not yet been quantified reliably at the global scale. Here, we estimate the amount of groundwater present in the upper 10 km of the Earth's continental crust by examining the distribution of sedimentary and crystalline rocks with depth and applying porosity-depth relationships. We demonstrate that groundwater in the 2–10 km zone (what we call “deep groundwater”) has a volume comparable to that of groundwater in the upper 2 km of the Earth's crust. These new estimates make groundwater the largest continental reservoir of water, ahead of ice sheets, provide a basis to quantify geochemical cycles, and constrain the potential for large-scale isolation of waste fluids. © 2021. American Geophysical Union. All Rights Reserved.
    • Discerning Changes in High-Frequency Climate Variability Using Geochemical Populations of Individual Foraminifera

      Glaubke, R.H.; Thirumalai, K.; Schmidt, M.W.; Hertzberg, J.E.; Department of Geosciences, University of Arizona (John Wiley and Sons Inc, 2021)
      Individual foraminiferal analysis (IFA) has proven to be a useful tool in reconstructing the amplitude of high-frequency climate signals such as the annual cycle and the El Niño-Southern Oscillation (ENSO). However, using IFA to evaluate past changes in climate variability is complicated by many factors including geographic location, foraminiferal ecology, methods of sample processing, and the influence of multiple, superimposed high-frequency climate signals. Robust statistical tools and rigorous uncertainty analysis are therefore required to ensure the reliability of IFA-based interpretations of paleoclimatic change. Here, we present a new proxy system model—called the Quantile Analysis of Temperature using Individual Foraminiferal Analyses (QUANTIFA)—that combines methods for assessing IFA detection sensitivity with analytical tools for processing and interpreting IFA data to standardize and streamline reconstructions employing IFA-Mg/Ca measurements. Model exercises with simulated and real IFA data demonstrate that the dominant signal retained by IFA populations is largely determined by the annual-to-interannual ratio of climate variability at a given location and depth and can be impacted by seasonal biases in foraminiferal productivity. In addition, our exercises reveal that extreme quantiles can be reliable indicators of past changes in climate variability, are often more sensitive to climate change than quantiles within the distributional interior, and can be used to distinguish changes in interannual phenomena like ENSO from seasonality. Altogether, QUANTIFA provides a useful tool for modeling IFA uncertainties and processing IFA data that can be leveraged to establish a history of past climate variability. © 2021. American Geophysical Union. All Rights Reserved.
    • Efficacy of personal pharmacogenomic testing as an educational tool in the pharmacy curriculum: A nonblinded, randomized controlled trial

      Grace, C.; Larriva, M.M.; Steiner, H.E.; Marupuru, S.; Campbell, P.J.; Patterson, H.; Cropp, C.D.; Quinn, D.; Klimecki, W.; Nix, D.E.; et al. (John Wiley and Sons Inc, 2021)
      Personal genomic educational testing (PGET) has been suggested as a strategy to improve student learning for pharmacogenomics (PGx), but no randomized studies have evaluated PGET’s educational benefit. We investigated the effect of PGET on student knowledge, comfort, and attitudes related to PGx in a nonblinded, randomized controlled trial. Consenting participants were randomized to receive PGET or no PGET (NPGET) during 4 subsequent years of a PGx course. All participants completed a pre-survey and post-survey designed to assess (1) PGx knowledge, (2) comfort with PGx patient education and clinical skills, and (3) attitudes toward PGx. Instructors were blinded to PGET assignment. The Wilcoxon Rank Sum test was used to compare pre-survey and post-survey PGx knowledge, comfort, and attitudes. No differences in baseline characteristics were observed between PGET (n = 117) and NPGET (n = 116) participants. Among all participants, significant improvement was observed in PGx knowledge (mean 57% vs. 39% correct responses; p < 0.001) with similar results for student comfort and attitudes. Change in pre/post-PGx knowledge, comfort, and attitudes were not significantly different between PGET and NPGET groups (mean 19.5% vs. 16.7% knowledge improvement, respectively; p = 0.41). Similar results were observed for PGET participants carrying a highly actionable PGx variant versus PGET participants without an actionable variant. Significant improvement in Likert scale responses were observed in PGET versus NPGET for questions that assessed student engagement (p = 0.020) and reinforcement of course concepts (p = 0.006). Although some evidence of improved engagement and participation was observed, the results of this study suggest that PGET does not directly improve student PGx knowledge, comfort, and attitudes. © 2021 The Authors. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.
    • Evolution of the Oligotrophic West Pacific Warm Pool During the Pliocene-Pleistocene Boundary

      Bali, H.; Gupta, A.K.; Mohan, K.; Thirumalai, K.; Tiwari, S.K.; Panigrahi, M.K.; Department of Geosciences, University of Arizona (John Wiley and Sons Inc, 2020)
      This study investigates the development of oligotrophic conditions, thickening, and zonal and meridional contraction of the West Pacific Warm Pool (WPWP) during the Pliocene. It has been hypothesized that the evolution of the WPWP and the establishment of strong equatorial Pacific zonal gradients are closely related to the narrowing of the Indonesian Gateway (IG) as well as the closure of the Central American Seaway (CAS). However, the timing of the development of these events remains unclear. Here we report Pliocene-to-Recent relative abundances of planktic foraminifera at Deep Sea Drilling Project (DSDP) Site 214 in the eastern Indian Ocean and at Ocean Drilling Program (ODP) Site 807, in the western Pacific. A comparison of the abundance of mixed-layer species (MLS) from both sites indicates a pronounced increase in their population between ~3.15 and 1.6 Ma. There is a contemporaneous decrease in the Globigerinita glutinata population during this time, which together with the MLS data suggest the development of oligotrophic conditions in the western tropical Pacific. Our data suggest that the oligotrophic WPWP, resembling present-day conditions, developed around 3.15 Ma and was closely linked to the gradual constriction of the IG. ©2020. American Geophysical Union. All Rights Reserved.
    • Exploring GPS Observations of Postseismic Deformation Following the 2012 MW7.8 Haida Gwaii and 2013 MW7.5 Craig, Alaska Earthquakes: Implications for Viscoelastic Earth Structure

      Guns, K.A.; Pollitz, F.F.; Lay, T.; Yue, H.; Department of Geosciences, University of Arizona (John Wiley and Sons Inc, 2021)
      The Queen Charlotte-Fairweather Fault (QC-FF) system off the coast of British Columbia and southeast Alaska is a highly active dextral strike-slip plate boundary that accommodates ∼50 mm/yr of relative motion between the Pacific and North America plates. Nine MW ≥ 6.7 earthquakes have occurred along the QC-FF system since 1910, including a MS(G-R)8.1 event in 1949. Two recent earthquakes, the October 28, 2012 Haida Gwaii (MW7.8) and January 5, 2013 Craig, Alaska (MW7.5) events, produced postseismic transient deformation that was recorded in the motions of 25 nearby continuous Global Positioning System (cGPS) stations. Here, we use 5+ yr of cGPS measurements to characterize the underlying mechanisms of postseismic deformation and to constrain the viscosity structure of the upper mantle surrounding the QC-FF. We construct forward models of viscoelastic deformation driven by coseismic stress changes from these two earthquakes and explore a large set of laterally heterogeneous viscosity structures that incorporate a relatively weak back-arc domain; we then evaluate each model based on its fit to the postseismic signals in our cGPS data. In determining best-fit model structures, we additionally incorporate the effects of afterslip following the 2012 event. Our results indicate the occurrence of a combination of temporally decaying afterslip and vigorous viscoelastic relaxation of the mantle asthenosphere. In addition, our best-fit viscosity structure (transient viscosity of 1.4–2.0 × 1018 Pa s; steady-state viscosity of 1019 Pa s) is consistent with the range of upper mantle viscosities determined in previous studies of glacial isostatic rebound and postseismic deformation. © 2021. American Geophysical Union. All Rights Reserved.
    • Glacial-Interglacial Shifts Dominate Tropical Indo-Pacific Hydroclimate During the Late Pleistocene

      Windler, G.; Tierney, J.E.; Anchukaitis, K.J.; Department of Geosciences, University of Arizona; School of Geography, Development, and Environment, University of Arizona; Laboratory of Tree-Ring Research, University of Arizona (John Wiley and Sons Inc, 2021)
      The climatic drivers of tropical rainfall and atmospheric circulation in the late Pleistocene are still debated. Some studies suggest that tropical precipitation primarily responded to precession (23–19 ky cycle), whereas others propose that glacial-interglacial (100 ky) changes in ice sheets and sea level dominate. Here, we reexamine orbital influences on tropical-to-subtropical precipitation isotopes using singular spectrum analysis to isolate leading oscillatory modes from proxy records across the Indo-Pacific Warm Pool (IPWP) and Asian monsoon domain. We find that the IPWP, Bay of Bengal, and South China Sea are dominated by the 100 ky glacial-interglacial mode of variability, whereas eastern China clearly follows precession, suggesting that precipitation isotopes over the mid-latitude Asian continent respond to different mechanisms than those in the IPWP or Indian and East Asian monsoon regions. This study demonstrates that glacial cycles, rather than changes in local insolation, are the dominant drivers of Pleistocene IPWP hydroclimate. © 2021. American Geophysical Union. All Rights Reserved.
    • Holocene Evolution of Sea-Surface Temperature and Salinity in the Gulf of Mexico

      Thirumalai, K.; Richey, J.N.; Quinn, T.M.; Department of Geosciences, University of Arizona (John Wiley and Sons Inc, 2021)
      Flows into and out of the Gulf of Mexico (GoM) are integral to North Atlantic Ocean circulation and help facilitate poleward heat transport in the Western Hemisphere. The GoM also serves as a key source of moisture for most of North America. Modern patterns of sea-surface temperature (SST) and salinity in the GoM are influenced by the Loop Current, its eddy-shedding dynamics, and the ensuing interplay with coastal processes. Here, we present sub-centennial-scale records of SST and stable oxygen isotope composition of seawater ((Formula presented.) 18Osw; a proxy for salinity) over the past 11,700 years using planktic foraminiferal geochemistry in sediments from the Garrison Basin, northwestern GoM. We measured (Formula presented.) O and magnesium-to-calcium ratios in tests of Globigerinoides ruber (white) to generate quantitative estimates of past sea-surface conditions. Our results replicate and extend late Holocene reconstructions from the Garrison Basin, using which we then create composites of SST and (Formula presented.) 18Osw. We find considerable centennial and millennial-scale variability in both SST and (Formula presented.) 18Osw, although their evolution over the Holocene is distinct. Whereas mean-annual SSTs display pronounced millennial-scale variability, (Formula presented.) 18Osw exhibits a secular trend spanning multiple millennia and points to increasing northwestern GoM surface salinity since the early Holocene. We then synthesize the available Holocene records from across the GoM and alongside the Garrison Basin composite uncover substantial, yet regionally consistent, spatiotemporal variability. Finally, we discuss the role of the Loop Current and coastal influx of freshwater in imposing these heterogeneities. We conclude that dynamic surface-ocean changes occurred across the GoM over the Holocene. © 2021. American Geophysical Union. All Rights Reserved.
    • Imaging the dynamics and microstructure of fibrin clot polymerization in cardiac surgical patients using spectrally encoded confocal microscopy

      Tshikudi, Diane M; Simandoux, Olivier; Kang, Dongkyun; Van Cott, Elizabeth M; Andrawes, Michael N; Yelin, Dvir; Nadkarni, Seemantini K; College of Optical Sciences and Department of Biomedical Engineering, University of Arizona (John Wiley and Sons Inc, 2021-05-10)
      During cardiac surgery with cardiopulmonary bypass (CPB), altered hemostatic balance may disrupt fibrin assembly, predisposing patients to perioperative hemorrhage. We investigated the utility of a novel device termed spectrally-encoded confocal microscopy (SECM) for assessing fibrin clot polymerization following heparin and protamine administration in CPB patients. SECM is a novel, high-speed optical approach to visualize and quantify fibrin clot formation in three dimensions with high spatial resolution (1.0 μm) over a volumetric field-of-view (165 × 4000 × 36 μm). The measurement sensitivity of SECM was first determined using plasma samples from normal subjects spiked with heparin and protamine. Next, SECM was performed in plasma samples from patients on CPB to quantify the extent to which fibrin clot dynamics and microstructure were altered by CPB exposure. In spiked samples, prolonged fibrin time (4.4 ± 1.8 to 49.3 ± 16.8 min, p < 0.001) and diminished fibrin network density (0.079 ± 0.010 to 0.001 ± 0.002 A.U, p < 0.001) with increasing heparin concentration were reported by SECM. Furthermore, fibrin network density was not restored to baseline levels in protamine-treated samples. In CPB patients, SECM reported lower fibrin network density in protaminized samples (0.055 ± 0.01 A.U. [Arbitrary units]) vs baseline values (0.066 ± 0.009 A.U.) (p = 0.03) despite comparable fibrin time (baseline = 6.0 ± 1.3, protamine = 6.4 ± 1.6 min, p = 0.5). In these patients, additional metrics including fibrin heterogeneity, length and straightness were quantified. Note, SECM revealed that following protamine administration with CPB exposure, fibrin clots were more heterogeneous (baseline = 0.11 ± 0.02 A.U, protamine = 0.08 ± 0.01 A.U, p = 0.008) with straighter fibers (baseline = 0.918 ± 0.003A.U, protamine = 0.928 ± 0.0006A.U. p < 0.001). By providing the capability to rapidly visualize and quantify fibrin clot microstructure, SECM could furnish a new approach for assessing clot stability and hemostasis in cardiac surgical patients. © 2021 Wiley Periodicals LLC.
    • Impacts of Coral Growth on Geochemistry: Lessons From the Galápagos Islands

      Reed, E.V.; Thompson, D.M.; Cole, J.E.; Lough, J.M.; Cantin, N.E.; Cheung, A.H.; Tudhope, A.; Vetter, L.; Jimenez, G.; Edwards, R.L.; et al. (John Wiley and Sons Inc, 2021)
      Coral geochemical climate reconstructions can extend our knowledge of global climate variability and trends over time scales longer than those of instrumental data. However, such reconstructions can be biased by coral growth and skeletal architecture, such as growth troughs, off-axis corallite orientation, and changing growth direction. This study quantifies the impact of skeletal architecture and growth on geochemistry using measurements of coral skeletal density, extension rate, and calcification rate, and uses these metrics to improve paleoclimate reconstructions. We present paired geochemistry-density records at Wolf Island, Galápagos, from three Porites lobata corals: two new paired density and geochemistry records from one fossil coral, and new density data from two previously published modern geochemistry records. We categorize each sampling transect used in this record by the quality of its orientation with respect to skeletal architecture. We observe relationships between geochemistry and density that are not detected using extension or calcification rate alone. These density-geochemistry relationships likely reflect both the response of coral growth to environmental conditions and the nonclimatic impact of skeletal architecture on geochemistry in suboptimal sampling transects. Correlations of density with Sr/Ca, Ba/Ca, and Mg/Ca are consistent with the Rayleigh fractionation model of trace element incorporation into coral skeletons. Removing transects with suboptimal skeletal architecture increases mean reconstructed SST closer to instrumental mean SST, and lowers errors of reconstruction by up to 20%. These results demonstrate the usefulness of coral density data for assessing skeletal architecture and growth when generating coral paleoclimate records. © 2021. American Geophysical Union. All Rights Reserved.
    • In-Situ Measurements of Electron Temperature and Density in Mars' Dayside Ionosphere

      Ergun, R.E.; Andersson, L.A.; Fowler, C.M.; Thaller, S.A.; Yelle, R.V.; Lunar and Planetary Laboratory, University of Arizona (John Wiley and Sons Inc, 2021)
      We present dayside electron temperature (Te) and density altitude profiles at Mars from MAVEN satellite deep-dip orbits. The data are after recalibration of the Langmuir Probe and Waves instrument that results in reduced uncertainties to as low as ±82°K. At MAVEN's lowest altitudes, (∼120–∼135 km), the measured values of Te are, after uncertainties, higher than those predicted by several modeling efforts. To better understand this discrepancy, we perform a basic heat-transfer analysis for two specific dayside deep dips. The analysis supports that CO2 excitation/de-excitation of its lowest-energy vibrational states dominates energy transfer to and from electrons. We hypothesize that the discrepancy between the measured and modeled Te is due to (a) the coupling of Te to CO2 vibrational temperatures combined with a non-LTE (local thermal equilibrium) excess of excited CO2 and/or (b) a non-Maxwellian electron distribution that moderates CO2 cooling. © 2021. American Geophysical Union. All Rights Reserved.
    • Innovations to expand drone data collection and analysis for rangeland monitoring

      Gillan, J.K.; Ponce-Campos, G.E.; Swetnam, T.L.; Gorlier, A.; Heilman, P.; McClaran, M.P.; School of Natural Resources & Environment, University of Arizona; BIO5 Institute, University of Arizona (John Wiley and Sons Inc, 2021)
      In adaptive management of rangelands, monitoring is the vital link that connects management actions with on-the-ground changes. Traditional field monitoring methods can provide detailed information for assessing the health of rangelands, but cost often limits monitoring locations to a few key areas or random plots. Remotely sensed imagery, and drone-based imagery in particular, can observe larger areas than field methods while retaining high enough spatial resolution to estimate many rangeland indicators of interest. However, the geographic extent of drone imagery products is often limited to a few hectares (for resolution ≤1 cm) due to image collection and processing constraints. Overcoming these limitations would allow for more extensive observations and more frequent monitoring. We developed a workflow to increase the extent and speed of acquiring, processing, and analyzing drone imagery for repeated monitoring of two common indicators of interest to rangeland managers: vegetation cover and vegetation heights. By incorporating a suite of existing technologies in drones (real-time kinematic GPS), data processing (automation with Python scripts, high performance computing), and cloud-based analysis (Google Earth Engine), we greatly increased the efficiency of collecting, analyzing, and interpreting high volumes of drone imagery for rangeland monitoring. End-to-end, our workflow took 30 d, while a workflow without these innovations was estimated to require 141 d to complete. The technology around drones and image analysis is rapidly advancing which is making high volume workflows easier to implement. Larger quantities of monitoring data will significantly improve our understanding of the impact management actions have on land processes and ecosystem traits. © 2021 The Authors.
    • Late Eocene Record of Hydrology and Temperature From Prydz Bay, East Antarctica

      Tibbett, E.J.; Scher, H.D.; Warny, S.; Tierney, J.E.; Passchier, S.; Feakins, S.J.; Department of Geosciences, University of Arizona (John Wiley and Sons Inc, 2021)
      The Eocene-Oligocene transition (EOT) marks the onset of Antarctic glaciation at 33.7 Ma. Although the benthic oxygen isotope record defines the major continental ice sheet expansion, recent sedimentary and geochemical evidence suggests the presence of earlier ephemeral ice sheets. Sediment cores from Ocean Drilling Program Legs 119 and 188 in Prydz Bay provide an archive of conditions in a major drainage system of East Antarctica. We study biomarker and microfossil evidence to discern how the vegetation and climate shifted between 36 and 33 Ma. Pollen was dominated by reworked Permian Glossopterid gymnosperms; however, penecontemporaneous Eocene pollen assemblages indicate that some vegetation survived the glacial advances. At the EOT, brGDGT soil biomarkers indicate abrupt cooling from 13°C to 8°C and soil pH increases from 6.0 to 6.7, suggesting drying which is further supported by plant wax hydrogen and carbon isotopic shifts of 20‰ and 1.1‰, respectively, and evidence for drying from weathering proxies. Although the terrestrial soil biomarker influx mostly precludes the use of TEX86, we find sea surface temperatures of 12°C in the late Eocene cooling to 8°C at the EOT. Marine productivity undergoes a sustained increase after the glacial advance, likely promoted by enhanced ocean circulation. Between the two glacial surge events of the Priabonian Oxygen Maximum at 37.3 Ma and the EOT at 33.7 Ma, we observe warming of 2–5°C at 35.7 and 34.7 Ma, with increase in penecontemporaneous pollen and enhanced marine productivity, capturing the last flickers of Antarctic warmth. © 2021. American Geophysical Union. All Rights Reserved.
    • Leveraging the NEON Airborne Observation Platform for socio-environmental systems research

      Ordway, E.M.; Elmore, A.J.; Kolstoe, S.; Quinn, J.E.; Swanwick, R.; Cattau, M.; Taillie, D.; Guinn, S.M.; Chadwick, K.D.; Atkins, J.W.; et al. (John Wiley and Sons Inc, 2021)
      During the 21st century, human–environment interactions will increasingly expose both systems to risks, but also yield opportunities for improvement as we gain insight into these complex, coupled systems. Human–environment interactions operate over multiple spatial and temporal scales, requiring large data volumes of multi-resolution information for analysis. Climate change, land-use change, urbanization, and wildfires, for example, can affect regions differently depending on ecological and socioeconomic structures. The relative scarcity of data on both humans and natural systems at the relevant extent can be prohibitive when pursuing inquiries into these complex relationships. We explore the value of multitemporal, high-density, and high-resolution LiDAR, imaging spectroscopy, and digital camera data from the National Ecological Observatory Network’s Airborne Observation Platform (NEON AOP) for Socio-Environmental Systems (SES) research. In addition to providing an overview of NEON AOP datasets and outlining specific applications for addressing SES questions, we highlight current challenges and provide recommendations for the SES research community to improve and expand its use of this platform for SES research. The coordinated, nationwide AOP remote sensing data, collected annually over the next 30 yr, offer exciting opportunities for cross-site analyses and comparison, upscaling metrics derived from LiDAR and hyperspectral datasets across larger spatial extents, and addressing questions across diverse scales. Integrating AOP data with other SES datasets will allow researchers to investigate complex systems and provide urgently needed policy recommendations for socio-environmental challenges. We urge the SES research community to further explore questions and theories in social and economic disciplines that might leverage NEON AOP data. © 2021 The Authors.