bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functionally diverse flax-based rotations improve wild oat (Avena fatua) and cleavers (Galium spurium) management
Authors: Benaragama Dilshan I. , May William E. , Gulden Robert H. , Willenborg Christian J. 
Published: January 2022

AbstractWild oat (Avena fatua L.) and false cleavers (Galium spurium L.) are currently a challenge to manage in less competitive crops such as flax (Linum usitatissimum L.). Increasing the functional diversity in crop rotations can be an option to improve weed management. Nonetheless, this strategy had not been tested in flax in western Canada. A 5-yr (2015 to 2019) crop rotation study was carried at three locations in western Canada to determine the effect of diverse flax-based crop rotations with differences in crop species, crop life cycles, harvesting time, and reduced herbicides on managing A. fatua and G. spurium. The perennial rotation (flax–alfalfa [Medicago sativa L.]–alfalfa–alfalfa–flax) under reduced herbicide use was found to be the most consistent cropping system, providing A. fatua and G. spurium control similar to the conventional annual flax crop rotation (flax–barley [Hordeum vulgare L.]–flax–oat [Avena sativa L.]–flax) with standard herbicides. At Carman, this alfalfa rotation provided even better weed control (80% A. fatua, 75% G. spurium) than the conventional rotation. Furthermore, greater A. fatua control was identified compared with a conventional rotation in which two consecutive winter cereal crops were grown successfully in rotation (flax–barley–winter triticale [×Triticosecale Wittm. ex A. Camus (Secale × Triticum)]–winter wheat [Triticum aestivum L.]–flax). Incorporation of silage oat crops did not show consistent management benefits compared with the perennial alfalfa rotation but was generally similar to the conventional rotation with standard herbicides. The results showed that perennial alfalfa in the rotation minimized G. spurium and A. fatua in flax-cropping systems, followed by rotations with two consecutive winter cereal crops.
Flooding depths and burial effects on seedling emergence of five California weedy rice (Oryza sativa spontanea) accessions
Authors: Galvin Liberty B. , Inci Deniz , Mesgaran Mohsen , Brim-DeForest Whitney , Al-Khatib Kassim 
Published: January 2022

AbstractWeedy rice (Oryza sativa f. spontanea Roshev.) has recently become a significant botanical pest in California rice (Oryza sativa L.) production systems. The conspecificity of this pest with cultivated rice negates the use of selective herbicides, rendering the development of nonchemical methods a necessary component of creating management strategies for this weed. Experiments were conducted to determine the emergence and early growth responses of O. sativa spontanea to flooding soil and burial conditions. Treatment combinations of four flooding depths (0, 5, 10, and 15 cm) and four burial depths (1.3, 2.5, 5, and 10 cm) were applied to test the emergence of five O. sativa spontanea accessions as well as ‘M-206’, a commonly used rice cultivar in California, for comparison. Results revealed that burial depth had a significant effect on seedling emergence. A 43% to 91% decrease in emergence between seedlings buried at 1.3 and 2.5 cm depending on the flooding depth and accession and an absence of emergence from seedlings buried at or below 5 cm were observed. Flooding depth did not affect emergence, but there was a significant interaction between burial and flooding treatments. There was no significant difference between total O. sativa spontanea emergence from the soil and water surfaces regardless of burial or flooding depths, implying that once the various accessions have emerged from the soil they will also emerge from the floodwater. Most accessions had similar total emergence compared with M-206 cultivated rice but produced more dry weight than M-206 when planted at 1.3 cm in the soil. The results of this experiment can be used to inform stakeholders of the flooding conditions necessary as well as soil burial depths that will promote or inhibit the emergence of California O. sativa spontanea accessions from the weed seedbank.
Ambivalence and Self-Reported Adherence to Recommendations to Reduce	the Spread of COVID-19
Authors: Schneider Iris K. , Dorrough Angela R. , Frank Celine 
Published: January 2022

Abstract. Governments worldwide still, to some extent, rely on behavioral recommendations to reduce the spread of COVID-19. We examine the role of ambivalence toward both the specific recommendations (micro-ambivalence) and the pandemic as a whole (macro-ambivalence) about compliance. We predict that micro ambivalence relates negatively, whereas macro ambivalence relates positively to self-reported adherence to recommendations. We present two studies ( N = 691) supporting our hypotheses: the more ambivalent people are toward the behavioral recommendations (micro-level), the less they report following them. Conversely, the more ambivalent people are about the pandemic as a whole (macro-level), the more they report following recommendations. Our findings were replicated in a US sample and a representative German sample.
Propagation Direction Analyses of Medium‐Scale Traveling Ionospheric Disturbances Observed Over North America With GPS‐TEC Perturbation Maps by Three‐Dimensional Spectral Analysis Method
Authors: Perwitasari Septi , Nakamura Takuji , Tsugawa Takuya , Nishioka Michi , Tomikawa Yoshihiro , Ejiri Mitsumu K. , Kogure Masaru , Otsuka Yuichi , Shinbori Atsuki , Jin Hidekatsu , Tao Chihiro 
Published: January 2022

AbstractWe applied a novel three‐dimensional spectral analysis method to GPS‐TEC perturbation (GPS‐TECP) maps to study the propagation direction of daytime and nighttime medium‐scale traveling ionospheric disturbances (MSTIDs) over North America. By this method, we can automatically calculate the phase velocity spectrum and directionality of MSTIDs. We focused on the periods of high MSTIDs occurrence, namely, June–July 2006 and November–December 2006, to study nighttime and daytime MSTIDs. We divided North America into the west (100°–130°W, 25°–55°N) and east (70°–100°W, 25°–55°N) parts. Our results show that both daytime and nighttime MSTID propagations exhibit strong longitudinal variations as a function of local time and day‐to‐day variations. The power peaks of daytime MSTIDs are from 10:00–16:00 LT in the west part and 10:00–14:00 LT in the east part. The predominant propagation directions of daytime MSTIDs are southward (southeastward) in the west (east). The daytime local time variations demonstrate that the MSTIDs display directional change in the west part; however, a similar directional change is not very pronounced in the east part. The local time variations of nighttime MSTIDs shows the power peaks from 22:00–02:00 LT in the west and 20:00–00:00 LT in the east. We found that the predominant propagation direction in the west part is westward with a wider azimuthal band (∼210°–300°) than the east part (∼210°–240°). By comparing nighttime propagation directions between the western and eastern parts, we reached the conclusion that the magnetic declination angle affects the propagation direction.
Deep to Shallow Sulfide Saturation at Nisyros Active Volcano
Authors: Georgatou A. , Chiaradia M. , Klaver M. 
Published: January 2022

AbstractWe report new petrographic and geochemical observations on magmatic sulfides occurring in different enclave types, including hornblende and/or clinopyroxene‐rich cumulates, and in the host lavas, in Nisyros (South Aegean volcanic arc). We discuss our findings in the context of pre‐existing petrological and thermobarometry studies. Our results indicate that sulfides become less abundant and Cu‐richer (Cu median values) with magma differentiation at progressively lower pressure/P‐temperature/T‐depth conditions. Starting with high T‐P sulfide‐free pillow lavas and wehrilitic cumulates still representing a sulfide undersaturated system, passing to high T and lower P, deep‐forming sulfide‐rich and hornblende‐rich gabbroic enclaves (SiO2 = 53–55 wt.%, 4–5 × 10−5 area %, Cu = 260 μg/g) at the base of the crust (∼25–30 km), then to clinopyroxene‐rich gabbroic micro‐cumulates (2–3 × 10−5 area %, Cu = 570 μg/g) forming in shallower crustal levels (∼10 km), then to more evolved sulfide‐poor hybrid enclaves (SiO2 = 56–70 wt.%, 1 × 10−5 area %, Cu = 602 μg/g), and finally to even more sulfide‐poor rhyodacitic host lavas (SiO2 = 66–76 wt.%, <0.5 × 10−5 area %, Cu = 6.4 wt.%) differentiating at even shallower crustal levels (∼7 km). Sulfide‐free quenched basaltic andesitic enclaves differentiating near surface levels, carry no textural evidence of pre‐existing magmatic sulfides suggesting that the system returned to a sulfide‐undersaturated state. Finally, we point out two important processes for sulfide evolution, a reaction replacement of clinopyroxene by amphibole observed in the deep‐forming hornblende‐rich gabbroic enclaves triggering the onset of sulfide saturation, and an increased mafic input followed by magma mingling and enclave disaggregation leading to sulfide dissolution and Cu‐enrichment of the magmas.
Decreasing Wintertime Mixed‐Layer Depth in the Northwestern North Pacific Subtropical Gyre
Authors: Sugimoto S. 
Published: January 2022

AbstractThe deep winter mixed layer (ML), ∼240 m, in the northwestern North Pacific subtropical gyre exchanges heat and absorbs carbon dioxide from the atmosphere, and receives nutrients through the Kuroshio. The ML water spreads broadly in the subsurface ocean over the subtropical gyre. Compiling historical temperature measurements, we show that the winter ML depth (MLD) has decreased by ∼6% over the last six decades. Observations, atmospheric reanalyzes, simulation outputs from a one‐dimensional turbulent closure model, and climate projections reveal that the strengthening of the upper‐ocean stratification due to surface warming under global warming is responsible for the MLD decrease. Climate models project further decrease of winter MLD attributable to the marked strengthening of ocean stratification with climate warming, of up to 27%–40% by 2100 under the highest emission scenario. A monitoring system for winter ML should be established so that important changes for marine ecosystems can be foreseen.
Energy Transfer From PSI‐Generated M1 Subharmonic Waves to High‐Frequency Internal Waves
Authors: Yang Wei , Wei Hao , Zhao Liang 
Published: January 2022

AbstractInternal tides (ITs) represent one of the major energy sources available for small‐scale mixing in the ocean. Here, the energy pathway associated with ITs is examined based on measurements obtained at the East China Sea shelf slope. We reveal that after the occurrence of parametric subharmonic instability (PSI), energy can be further transferred from the PSI‐generated subharmonic waves to high‐frequency internal waves (HFIWs) through nonlinear interactions between them. This interprets the observed similar varying trends of magnitude between internal waves at near‐inertial and high‐frequency bands. Bispectrum and bicoherence estimates confirm that the M1 subharmonic wave interacts with a pair of HFIW which have larger vertical scales and a broad range of frequencies. The averaged net value of the energy transfer rate reaches 2 10−7 W kg−1, which has implications for a further significant role of this energy pathway on the spatial distribution of ocean mixing.
Prospects for Detecting Accelerated Global Warming
Authors: Richardson Mark T. 
Published: January 2022

AbstractWith global temperatures approaching Paris climate agreement targets and a wide spread in modeled future warming, it is critical to rapidly identify any changes in warming rate. Here, I address the question of when we would be able to detect acceleration of warming in global‐mean temperature. Some standard techniques report significantly (p < 0.05) accelerated warming over 1980–2020 in the latest versions of the three main data sets used in the The Intergovernmental Panel on Climate Change 5th Assessment Report, with a mean acceleration of 49 m°C/decade2, which would add about 0.5°C additional warming over 50 years compared with linear warming. Accounting for El Nino, volcanism, and solar activity using a published method, the acceleration is 36 ± 30m°C/decade2. Using large ensemble output, I show that statistical uncertainties are underestimated by several common approaches. I recommend a better‐performing method and show that with these techniques 49m°C/decade2 acceleration would likely not be detectable with robust confidence until at least 2026.
A Multivariate Flash Drought Indicator for Identifying Global Hotspots and Associated Climate Controls
Authors: Mukherjee Sourav , Mishra Ashok Kumar 
Published: January 2022

AbstractThe significant impact of flash droughts (FDs) on society can vary based on a combination of FD characteristics (event counts, mean severity, and rate of intensification), which is largely unexplored. We employed root‐zone soil‐moisture for 1980–2018 to calculate the FD characteristics and integrated them to formulate a novel multivariate FD indicator for mapping the global FD hotspot regions. The potential influence of climate characteristics (i.e., anomalies, aridity, and evaporative fractions) and land‐climate feedbacks on the evolution of multivariate FD indicator is investigated. Our results indicate that precipitation is the primary driver of FD evolution, while the effect of temperature, vapor pressure deficit, and land‐climate interaction varies across the climate divisions after the onset of the events. The magnitude of multivariate FD indicator decreases with increased climate aridity, and it is significant in the global humid regimes, underscoring the importance of water and energy supply as limiting factors regulating FD‐risk.
Impacts of Sudden Stratospheric Warming on Extreme Cold Events in Early 2021: An Ensemble‐Based Sensitivity Analysis
Authors: Zhang Murong , Yang Xiao‐Yi , Huang Yipeng 
Published: January 2022

AbstractImpacts of sudden stratospheric warming (SSW) on three severe cold events (C1–C3) over Northern Hemisphere in early 2021 were investigated using subseasonal‐to‐seasonal ensemble forecasts. The SSW was characterized by successive displacement and split of the stratospheric polar vortex (SPV). Ensemble‐based sensitivity analyses showed that C1 over Siberia and C2 over western Canada were more related to SPV variations at a lead time of 1–2 weeks than C3 over central U.S. Within ensemble forecasts, a more elongated SPV with higher geopotential height over northern Eurasia were conducive to C1, whereas a SPV with the more poleward retreat from displacement contributed to C2. The forecast accuracy of stratospheric heights over the sensitive region at 2 weeks lead was significantly correlated with the forecast skill of the tropospheric circulation pattern preceding C1, implying that prediction of specific cold weather events may be improved by a better forecast of key features in SPV variations.
Ekman Transport as the Driver of Extreme Interannual Formation Rates of Eighteen Degree Water
Authors: Li Ke , Maze Guillaume , Mercier Herlé 
Published: January 2022

AbstractIn the North Atlantic subtropical gyre, the Eighteen Degree Water (EDW) is a voluminous heat reservoir, submerged under a seasonal pycnocline that can be progressively removed through the winter, allowing EDW ventilation in the early spring. We target the EDW formation extremes, namely 2004–2005, 2009–2010, and 2012–2013 for the strong years, and 2007–2008, 2008–2009, 2011–2012, and 2013–2014 for the weak years. We employ gridded hydrographic datasets mainly measured by Argo floats over the last 20 years, and provide a synthetic study on the extreme events of strong and weak EDW formation of this time period. We found that the Ekman transport is the indicator and driving mechanism explaining these extremes. Strong (Weak) EDW formation years correspond with atmospheric patterns resembling NAO− (NAO+), attributed to a strong (weak) winter air‐sea surface heat loss, and a strong (weak) winter heat loss due to Ekman transport. Further, we show that such extreme Ekman advection patterns can be linked to mid‐latitude storms, of which both intensity and duration have an impact on the extreme of EDW ventilation in the western subtropical North Atlantic. To yield a strong EDW formation, it requires a large winter heat deficit due to Ekman divergence, which can be sufficiently represented by numbers of strong winter storms, most notably, remnants of hurricanes and US east coast snowstorms. Meanwhile, to yield a weak EDW formation, apart from weak atmospheric forcings, a remnant positive heat content anomaly carried through from previous years would serve as an unfavorable preconditioning, hindering the EDW formation.
Three‐Dimensional Physical Modeling of Tsunamis Generated by Partially Submerged Landslides
Authors: Takabatake Tomoyuki , Han Dawn Chenxi , Valdez Justin Joseph , Inagaki Naoto , Mäll Martin , Esteban Miguel , Shibayama Tomoya 
Published: January 2022

AbstractMassive landslides can generate large tsunamis and endanger human lives and properties. While a number of laboratory experiments on either subaerial or submarine landslide‐tsunamis have been conducted, few studies have focused on partially submerged events. The present study aimed to investigate the characteristics of partially submerged landslide‐tsunamis and to develop a predictive equation that can estimate their heights through three‐dimensional laboratory experiments that used 114 different conditions. The experimental results showed that, while waves generated in the landslide sliding direction had around 1.7 times higher amplitude than those propagating laterally in the near‐field region, the wave period, celerity, and wavelength did not alter significantly according to the propagation angles. The effects of wave dispersion were also shown to be significant during the propagation process. Such wave characteristics were consistent with those reported in existing subaerial landslide tsunami experiments conducted by other researchers. Based on the data set obtained, the authors also derived a predictive equation which was confirmed to be able to estimate the results of other experimental studies on partially submerged landslide‐tsunamis with an error of around ±30%, and thus can be helpful for a rapid tsunami hazard assessment. The developed equation indicated that the volume of a landslide could have more than twice the impact on the height of a partially submerged landslide‐tsunami than other parameters. The effects of the landslide size were also shown to be more significant than in the case of a subaerial landslide‐tsunami, though the wave attenuation process was similar in both types.
Exploring Seasonal and Annual Nitrogen Transfer and Ecological Response in River‐Coast Continuums Based on Spatially Explicit Models
Authors: Chen Nengwang , Wang Jia , Liu Xiaochen , Zhang Caiyun , Huang Bangqin , Beusen Arthur H. W. , Middelburg Jack J. , Bouwman Alexander F. 
Published: January 2022

AbstractPerturbed nutrient balances in watersheds may eventually impact the marine ecosystem, but this river‐coast coupling is poorly understood. Monthly dissolved inorganic nitrogen (DIN) fluxes from seven major rivers in China were calculated by a global river nutrient model (IMAGE‐GNM), and then used in a regional ocean model system (ROMS) to explore changes in surface chlorophyll a (Chla) in the plume area (salinity <33) of the Taiwan Strait (TWS) in 2001–2010. Model results showed that river N input increased surface Chla by a factor of 2.1–2.7, revealing a clear eutrophic response. Without river N input, there was only one Chla peak in fall driven by current upwelling N. In contrast, sufficient river N supply and optimum temperature (above 20°C) likely caused another Chla peak (spring bloom) in the northern TWS (NTWS). The difference in the timing of spring blooms (Chla maxima) between the southern TWS (STWS) and the NTWS (April and May, respectively) may be explained by faster growth of phytoplankton at higher temperatures. Diagnostic analysis suggested that DIN was the main factor controlling interannual variation of Chla in the STWS, but only in the wet season in the NTWS. In the NTWS, reduced Chla in winter was mainly due to mixing by the strong northeast monsoon and lower temperatures. This study implies that the STWS is more sensitive to further increases in riverine N export and highlights the importance of fluvial N inputs in phytoplankton dynamics and the unique phenological features in the TWS.
A Microbial‐Explicit Soil Organic Carbon Decomposition Model (MESDM): Development and Testing at a Semiarid Grassland Site
Authors: Zhang Xia , Xie Zhenghui , Ma Zhuguo , Barron‐Gafford Greg A. , Scott Russell L. , Niu Guo‐Yue 
Published: January 2022

AbstractExplicit representations of microbial processes in soil organic carbon (SOC) decomposition models have received increasing attention, because soil heterotrophic respiration remains one of the greatest uncertainties in climate‐carbon feedbacks projected by Earth system models (ESMs). Microbial‐explicit models have been developed and applied in site‐ and global‐scale studies. These models, however, lack the ability to represent microbial respiration responses to drying‐wetting cycles, and few of them have been incorporated in land surface models (LSMs) and validated against field observations. In this study, we developed a multi‐layer, microbial‐explicit soil organic carbon decomposition model (MESDM), based on two main assumptions that (a) extracellular enzymes remain active at dry reaction microsites, and (b) microbes at wet microsites are active or potentially active, while microbes at the dry microsites are dormant, by dividing the soil volume into wet and dry zones. MESDM with O2 and CO2 gas transport models was coupled with Noah‐MP LSM and tested against half‐hourly field observations at a semiarid grassland site in the southwest US characterized by pulsed precipitation. The results show MESDM can reproduce the observed soil respiration pulses of various sizes in response to discrete precipitation events (Birch effect) and thus improve the simulation of net ecosystem exchange. Here, both microbial accessibility to accumulated dissolved organic carbon and reactivation of dormant microbes at the dry microsites upon rewetting are critical to reproducing the Birch effect. This study improves our understanding of and ability to simulate complex soil carbon dynamics that experience drying‐wetting cycle in climate‐carbon feedbacks.