bluuebunny/crossref_metadata_2025_split huggingface dataset:
Response of dry beans to tiafenacil applied preemergence
Authors: Soltani Nader , Shropshire Christy , Sikkema Peter H. 
Published: August 2021

AbstractTiafenacil is a new nonselective, protoporphyrinogen IX oxidase–inhibiting pyrimidinedione herbicide that is under consideration for registration to control grass and broadleaf weeds in corn, soybean, wheat, cotton, and other crops prior to crop emergence. The sensitivity of dry beans to tiafenacil is not known. Four field experiments were completed at Exeter and Ridgetown, ON, Canada, during the 2019 and 2020 growing seasons, to determine the sensitivity of azuki, kidney, small red, and white beans to tiafenacil applied preemergence (PRE) at 12.5, 25, 50, and 100 g ai ha−1. Tiafenacil applied at 100 g ai ha−1 caused 5% or less injury to azuki, kidney, small red, and white beans: 0% to 3% injury to azuki bean; 1% to 5% injury to kidney bean; and 1% to 4% injury to both small red bean and white bean. Tiafenacil applied PRE at 12.5, 25, 50, and 100 g ai ha−1 caused up to 1%, 4%, 4%, and 5% visible dry bean injury, respectively, but had no negative effect on other measured growth parameters including seed yield. Crop injury was generally greatest when tiafenacil was appled at the 100 g ai ha−1 rate in dry beans. Generally, kidney, small red, and white bean were more sensitive to tiafenacil than azuki bean. Dry bean injury was persistent and increased with time with the greatest injury observed 8 wk after emergence. Tiafenacil applied PRE can be a useful addition to the current strategies to control grass and broadleaf weeds, especially glyphosate-resistant horseweed and amaranth species prior to bean emergence.
Herbicide diagnostics reveal multiple patterns of synthetic auxin resistance in kochia (Bassia scoparia)
Authors: Geddes Charles M. , Owen Mallory L. , Ostendorf Teandra E. , Leeson Julia Y. , Sharpe Shaun M. , Shirriff Scott W. , Beckie Hugh J. 
Published: August 2021

AbstractHerbicide-resistant (HR) kochia is a growing problem in the Great Plains region of Canada and the United States. Resistance to up to four herbicide sites of action, including photosystem II inhibitors, acetolactate synthase inhibitors, synthetic auxins, and the 5-enolpyruvylshikimate-3-phosphate synthase inhibitor glyphosate have been reported in many areas of this region. Despite being present in the United States since 1993/1994, auxinic-HR kochia is a recent and growing phenomenon in Canada. This study was designed to characterize 1) the level of resistance and 2) patterns of cross-resistance to dicamba and fluroxypyr in 12 putative auxinic-HR kochia populations from western Canada. The incidence of dicamba-resistant individuals ranged among populations from 0% to 85%, while fluroxypyr-resistant individuals ranged from 0% to 45%. In whole-plant dose-response bioassays, the populations exhibited up to 6.5-fold resistance to dicamba and up to 51.5-fold resistance to fluroxypyr based on visible injury 28 d after application. Based on plant survival estimates, the populations exhibited up to 3.7-fold resistance to dicamba and up to 72.5-fold resistance to fluroxypyr. Multiple patterns of synthetic auxin resistance were observed, in which one population from Cypress County, Alberta, was resistant to dicamba but not fluroxypyr, whereas another from Rocky View County, Alberta, was resistant to fluroxypyr but not dicamba based on single-dose population screening and dose-response bioassays. These results suggest that multiple mechanisms may confer resistance to dicamba and/or fluroxypyr in Canadian kochia populations. Further research is warranted to determine these mechanisms. Farmers are urged to adopt proactive nonchemical weed management practices in an effort to preserve efficacy of the remaining herbicide options available for control of HR kochia.
Mechanisms that may lead to high genetic divergence and to the invasive success of tall fleabane (Conyza sumatrensis; Asteraceae)
Authors: Ruiz Maycon Rodrigo , Mangolin Claudete Aparecida , de Oliveira Rubem Silvério , Mendes Rafael Romero , Takano Hudson Kagueyama , Eisele Tauana Gibim , Machado Maria de Fátima P. S. 
Published: August 2021

AbstractTall fleabane [Conyza sumatrensis (Retz.) E. Walker] is commonly invasive in agricultural fields, reducing yield in various infested crops. The current study investigates the genetic diversity within and between a significant number of invasive C. sumatrensis biotypes in soybean fields in southern, southeastern, and midwestern Brazil, using microsatellites as molecular markers. High and low observed and expected heterozygosity estimated in microsatellite loci supported our hypothesis that different levels of genetic diversity may be detected within biotypes from different invaded fields. Analysis of a significant number of biotypes in several fields showed high and low genetic diversity not associated with geographic distribution, bottleneck effect, or susceptibility to glyphosate. A deficit of heterozygous plants, high genetic divergence, and moderate allelic transference were also observed. Allelic fixation was different in the different biotypes. The bottleneck effect was seen in biotypes with reduced genetic diversity and in biotypes with the highest genetic diversity. Data on genetic diversity, bottleneck effect, and glyphosate resistance showed contrasts in biotypes from nearby invaded fields. Our study showed different genetic diversity levels in biotypes from invaded areas under the same climatic conditions.
Impacts of Tropical Cyclones on the Caribbean Under Future Climate Conditions
Authors: Kleptsova Olga S. , Dijkstra Henk A. , van Westen René M. , van der Boog Carine G. , Katsman Caroline A. , James Rebecca K. , Bouma Tjeerd J. , Klees Roland , Riva Riccardo E. M. , Slobbe D. Cornelis , Zijlema Marcel , Pietrzak Julie D. 
Published: August 2021

AbstractJoint effects of the dynamic sea‐level rise projected changes in the large‐scale atmosphere/ocean circulation, and wave climate on hurricane‐induced extreme water levels in the Caribbean region are assessed. We use the 2D‐depth integrated ADCIRC + SWAN wave‐ocean model, baroclinically coupled to an ocean‐eddying version of the Community Earth System Model, to compare impacts of the September 2017 hurricanes with projected impacts of similar hypothetical tropical storms occurring in the future. The model predicts only minor changes in the hurricane‐induced extreme water levels for those Caribbean islands which were severely devastated by the 2017 tropical storms (Irma and Maria). That is, provided that the hurricane intensity remains at the present‐day level, the global mean sea‐level rise is the main future coastal flood risk factor.
A New Unconstrained Approach to GNSS Atmospheric Water Vapor Tomography
Authors: Miranda P. M. A. , Mateus P. 
Published: August 2021

AbstractA new atmospheric tomographic model totally based on Global Navigation Satellite System (GNSS) observations is proposed and tested against field observations. The method does not require a first guess, does not contain specific constraints on the variability of water vapor density inside the tomographic domain, and is able to produce reasonable results at 6 km horizontal and 500 m vertical resolutions, from short (30 min) GNSS data samples. The inversion method uses the Moore‐Penrose pseudoinverse, which is made possible by increasing the rank of the design matrix through angular interpolation and extrapolation of the observations. Comparisons against 30 consecutive 4‐h radiosonde observations and model simulations suggest the ability of the method to detect inversions and local maxima aloft, and behave sensibly in the far‐field. Further improvements from this method may be expected from higher density and multi‐constellation networks.
Low‐Temperature Magnetic Properties of Marine Sediments—Quantifying Magnetofossils, Superparamagnetism, and Maghemitization: Eastern Mediterranean Examples
Authors: Qian Yao , Heslop David , Roberts Andrew P. , Hu Pengxiang , Zhao Xiang , Liu Yan , Li Jinhua , Grant Katharine M. , Rohling Eelco J. 
Published: August 2021

AbstractPeriodic and marked redox changes in eastern Mediterranean marine sediments drive environmental and diagenetic changes to which magnetic minerals are sensitive. Magnetic property changes, therefore, provide useful indications of paleoceanographic conditions during and after periods of organic‐rich sediment (sapropel) deposition. Magnetic properties of eastern Mediterranean sediments at room temperature have been studied for decades; however, few studies have considered low‐temperature magnetic properties. Here, we investigate the low‐temperature (10–300 K) magnetic properties of different eastern Mediterranean sediment types combined with room temperature (∼300 K) magnetic properties, transmission electron microscopy, and calibrated X‐ray fluorescence elemental data to illustrate the valuable information that can be obtained from low‐temperature magnetic analysis of sediments. Our low‐temperature magnetic results suggest that magnetite magnetofossils and superparamagnetic (SP) particles occur widely in eastern Mediterranean sediments. SP particle contents are highest in diagenetically reduced intervals associated with sapropels. In contrast, magnetite magnetofossils are most abundant in oxidation fronts at the tops of sapropels, where strong redox gradients formed, but are also widespread throughout other sedimentary intervals that have not been subjected to extensive reductive diagenesis. Moreover, the surfaces of magnetite particles are maghemitized (i.e., partially oxidized) in oxidation fronts at the tops of sapropels, and in other oxic sediment intervals. Our results demonstrate the value of LT magnetic measurements for quantifying diverse sedimentary magnetic signals of interest in environmental magnetism when studying paleoceanographic and paleoenvironmental processes.
Error Assessment of GRACE and GRACE Follow‐On Mass Change
Authors: Chen Jianli , Tapley Byron , Tamisiea Mark E. , Save Himanshu , Wilson Clark , Bettadpur Srinivas , Seo Ki‐Weon 
Published: August 2021

AbstractWe carry out a comprehensive error assessment of Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow‐On (GFO) Release‐6 (RL06) solutions from the Center for Space Research (CSR) at the University of Texas at Austin, NASA Jet Propulsion Laboratory (JPL), and Geoforschungszentrum (GFZ). The study covers the period April 2002 to August 2020 and uses two different methods, one based upon open ocean residuals (OOR) and the other a Three‐Cornered Hat (TCH) calculation. General results from the two methods are similar. With 300 km Gaussian smoothing OOR RMS errors for CSR, JPL, and GFZ solutions are ∼2.01, 3.19, and 3.67 cm, respectively. With additional decorrelation filtering OOR RMS values are reduced to ∼1.24, 1.53, and 1.69 cm, respectively. TCH analysis also shows that CSR has the lowest noise levels with similar RMS values, and additional decorrelation filtering reduces error levels. TCH may underestimate errors if there are common errors among geophysical background models. Errors in GFO's first two years (25 solutions for 2018.06 to 2020.08) are comparable to those of GRACE when zonal degree 2 and 3 coefficients are replaced by Satellite Laser Ranging estimates. The OOR method reveals mismodeled intra‐seasonal dynamic ocean signals associated with the Argentine Gyre during de‐aliasing, while the TCH method shows differences between ocean tide models near Australia and Antarctica. Both OOR and TCH RMS analysis offer a means to assess the noise level of GRACE/GFO estimated mass change. The actual uncertainty of GRACE/GFO estimate averaged (or totaled) over a given region is also affected by other error sources.
Mechanism of the Centennial Subpolar North Atlantic Cooling Trend in the FGOALS‐g2 Historical Simulation
Authors: Fan Yifei , Lu Jianhua , Li Laifang 
Published: August 2021

AbstractA cold blob, manifested as a centennial cooling trend in sea surface temperature (SST), is observed in the mid‐latitude North Atlantic. The presence of the cold blob is hypothesized as an evidence of a slowdown of Atlantic Meridional Overturning Circulation (AMOC), based on paleoclimate proxies and global climate models (GCMs). However, the performance of GCMs in simulating the cold blob remains unsatisfactory in terms of the SST cooling rate and the spatial extent. This study investigates the forcing mechanism of the cold blob using the Flexible Global Ocean‐Atmosphere‐Land System Model Grid‐point version 2 (FGOALS‐g2), a GCM that reasonably simulates the observed cooling trend in the subpolar North Atlantic and its spatial pattern. Surface heat budget analysis suggests that the cold blob is largely a result of the imbalance between changes in the heat storage and surface turbulent heat fluxes, exhibiting a cooling and warming effect, respectively. Investigation of ocean heat content indicates that heat advection into the cold blob region has decreased, mainly due to ocean circulation changes. However, in the FGOALS‐g2, both the AMOC slowdown and the reduced meridional heat transport explain a limited portion (less than 50%) of the cold blob sea surface temperature anomaly trend. Overall, complementing existing studies that attribute the cold blob to an AMOC slowdown, our results suggest that additional processes, including subpolar gyre circulation and a synergy between the atmosphere and the ocean, are at work in the formation of the cold blob.
Observations of Nighttime Clouds Over Chiba, Japan, Using Digital Cameras and Satellite Images
Authors: Lagrosas N. , Shiina T. , Kuze H. 
Published: August 2021

AbstractNighttime cloud cover (CC) is analyzed from the data observed for 34 months over Chiba, Japan, using continuously operated digital cameras. The normal camera works in the visible region, providing quantitative and temporal changes of nighttime CC. The second camera captures sky images without the near‐infrared cut filter, and by applying the thresholding method, we obtain information on the temporal changes of thin (pixel values between 72 and 115) and thick (>115) clouds. Comparing the CC from the visible camera with cloud fraction from Atmospheric Infrared Sounder (AIRS) shows that long‐term data from the camera are valuable for correcting the underestimation of the cloud fraction product from AIRS for low‐level clouds. Furthermore, a comparison between the near‐ground temperature and CC results in estimating the seasonal changes of feedback effects of upward thermal radiation from the ground. The current results reveal that thick clouds contribute to longwave cloud forcing (LWCF) below 100 Wm−2, while thin clouds with CC below 30% contribute to LWCF below 10.2 Wm−2.
The Role of Eyewall Turbulent Transport in the Pathway to Intensification of Tropical Cyclones
Authors: Zhu Ping , Hazelton Andrew , Zhang Zhan , Marks Frank D. , Tallapragada Vijay 
Published: August 2021

AbstractIn a tropical cyclone (TC), turbulence not only exists in the planetary boundary layer (PBL) but also can be generated above the PBL by the cloud processes in the eyewall and rainbands. It is found that the Hurricane Analysis and Forecast System (HAFS), a new multi‐scale operational model for TC prediction, fails to capture the intense turbulent mixing in eyewall and rainband clouds due to a poor estimation of static stability in clouds. The problem is fixed by including the effects of multi‐phase water in the stability calculation. Simulations of 21 TCs and tropical storms in the North Atlantic basin of 2016–2019 hurricane seasons totaling 118 forecast cycles show that the stability correction substantially improves HAFS's skill in predicting storm track and intensity. Analyses of HAFS's simulations of Hurricane Michael (2018) show that the positive tendency of vortex's tangential wind resulting from the radially inward transport of absolute vorticity dominates the eddy correlation tendencies induced by the model‐resolved asymmetric eddies and serves as a main mechanism for the rapid intensification of Michael. The sub‐grid scale (SGS) turbulent transport above the PBL in the eyewall plays a pivotal role in initiating a positive feedback among the eyewall convection, mean secondary overturning circulation, vortex acceleration via the inward transport of absolute vorticity, surface evaporation, and radial convergence of moisture in the PBL. Without the SGS transport above the PBL, the model‐resolved vertical transport alone may not be sufficient in initiating the positive feedback underlying the rapid intensification of TCs.
Adapting the MPAS Dynamical Core for Applications Extending Into the Thermosphere
Authors: Klemp J. B. , Skamarock W. C. 
Published: August 2021

AbstractTo extend the nonhydrostatic global Model for Prediction Across Scales (MPAS) for deep‐atmosphere (geospace) applications, we have modified the model equations and numerics to include variable atmospheric composition and (potentially large) molecular viscosity and thermal conductivity. The split‐explicit numerical integration techniques in MPAS remain stable in idealized test cases for atmospheric domains extending into the upper thermosphere and continue to provide an efficient numerical framework for nonhydrostatic simulations. Variations in the atmospheric constituents influence the dynamical equations by altering the heat capacity and ideal gas constants. These feedbacks require little alteration of the dynamical equations although our testing reveals that the amplitude of disturbances may be sensitive to even small variations in the thermodynamic coefficients. Although the potential temperature is no longer formally conserved for adiabatic flow, it remains effective as a prognostic thermodynamic variable in the model equations. Molecular viscosity and thermal conductivity are dominant influences in the upper thermosphere and are represented implicitly in the model numerics. Because of the large magnitude of these terms, their treatment, though stable, may significantly under represent the true magnitude of their damping effects. Further consideration of these deep‐atmosphere extensions to MPAS will be explored in more realistic simulations of thermospheric dynamics.
A Comparison of Data‐Driven Approaches to Build Low‐Dimensional Ocean Models
Authors: Agarwal Niraj , Kondrashov D. , Dueben P. , Ryzhov E. , Berloff P. 
Published: August 2021

AbstractWe present a comprehensive inter‐comparison of linear regression (LR), stochastic, and deep‐learning approaches for reduced‐order statistical emulation of ocean circulation. The reference data set is provided by an idealized, eddy‐resolving, double‐gyre ocean circulation model. Our goal is to conduct a systematic and comprehensive assessment and comparison of skill, cost, and complexity of statistical models from the three methodological classes. The model based on LR is considered as a baseline. Additionally, we investigate its additive white noise augmentation and a multi‐level stochastic approach, deep‐learning methods, hybrid frameworks (LR plus deep‐learning), and simple stochastic extensions of deep‐learning and hybrid methods. The assessment metrics considered are: root mean squared error, anomaly cross‐correlation, climatology, variance, frequency map, forecast horizon, and computational cost. We found that the multi‐level linear stochastic approach performs the best for both short‐ and long‐timescale forecasts. The deep‐learning hybrid models augmented by additive state‐dependent white noise came second, while their deterministic counterparts failed to reproduce the characteristic frequencies in climate‐range forecasts. Pure deep learning implementations performed worse than LR and its simple white noise augmentation. Skills of LR and its white noise extension were similar on short timescales, but the latter performed better on long timescales, while LR‐only outputs decay to zero for long simulations. Overall, our analysis promotes multi‐level LR stochastic models with memory effects, and hybrid models with linear dynamical core augmented by additive stochastic terms learned via deep learning, as a more practical, accurate, and cost‐effective option for ocean emulation than pure deep‐learning solutions.
Weak Temperature Gradient Modeling of Convection in OTREC
Authors: Raymond D. J. , Fuchs‐Stone Ž. 
Published: August 2021

AbstractConvection observed in the OTREC field program in the tropical east Pacific and southwest Caribbean is simulated using a cloud‐resolving model employing the weak temperature gradient approximation. Simulations are made using reference profiles derived from three‐dimensional variational analyses of dropsonde data selected for different ranges of saturation fraction, a kind of column relative humidity. For each of these humidity ranges, two simulations are performed, one with ventilation of the model domain by the ambient wind (a new model feature) and one without this ventilation. The model results using ventilation are much closer to observation than those without ventilation, especially for drier environments. These results have strong implications for the distribution of ITCZ convection in the east Pacific and for the construction of cumulus parameterizations.
Geomagnetic Storm Occurrence and Their Relation With Solar Cycle Phases
Authors: Reyes Paula I. , Pinto Victor A. , Moya Pablo S. 
Published: August 2021

AbstractUsing a time series of geomagnetic storm events between 1957 and 2019, obtained by selecting storms where −50 nT, we have analyzed the probability of occurrence of moderate, intense, and severe events. Considering that geomagnetic storms can be modeled as stochastic processes with a log‐normal probability distribution over their minimum index, the dataset was separated according to solar cycle (SC) and SC phases, and the distributions of events were fitted through maximum likelihood method in order to characterize the occurrence of storms in each cycle and phase, and then compare those occurrences to the SC24. Our results show that there is a strong dependence between the occurrence of intense storms, with −100 nT, and the strength of the SC measured by the sunspot numbers. In particular, SC24 is very similar to SC20. However, when comparing the occurrence of storms by SC phases, events tend to show similar activity toward the minimum phase and have significant differences in the maximum phases. By looking at the value—the fit log‐normal distribution “width” parameter—characteristic of the occurrence rate of storms, we have found that the (the sigma value in the descending phase of one cycle) shows the highest correlation () with (the sigma value in the maximum phase of the next cycle) which allows us to estimate the occurrence rate of storms for SC25 to be similar to those of SC21 and SC22, suggesting a more intense cycle than the one that just ended.