bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Future Climate and Air Quality Response From Different Near‐Term Climate Forcer, Climate, and Land‐Use Scenarios Using UKESM1
Authors: Turnock Steven T. , Allen Robert , Archibald Alex T. , Dalvi Mohit , Folberth Gerd , Griffiths Paul T. , Keeble James , Robertson Eddy , O’Connor Fiona M. 
Published: August 2022

AbstractNear‐term climate forcers (NTCFs) can influence climate via interaction with the Earth's radiative balance and include both aerosols and trace gas constituents of the atmosphere (such as methane and ozone). Two of the principal NTCFs, aerosols (particulate matter) and tropospheric ozone (O3), can also affect local air quality when present in the lower levels of the atmosphere. Previous studies have shown that mitigation of NTCFs has the potential to improve air quality and reduce the rate of surface warming induced by long‐lived greenhouse gases. Here, we assess the combined air quality and climate impacts from changes in NTCFs under numerous different future mitigation scenarios, relative to a future reference scenario, that were conducted by a single Earth system model (UKESM1) as part of the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP). Co‐benefits to both global air quality and climate are only achieved in the future scenario with strong mitigation measures applied to all NTCFs, particularly aerosols and methane, with penalties identified for inaction. When compared to the combined NTCF mitigation scenario, analysis of individual mitigation scenarios shows that there are important non‐linearities and interactions between NTCFs (e.g., aerosols and clouds). If only aerosol components are mitigated, there are still benefits to air quality but detrimental impacts on climate, particularly at the regional scale. In addition, other changes in future land‐use and climate could have important impacts on regional NTCFs, which should be considered when designing future mitigation measures to anthropogenic emissions.
Extratropical Climate Change During Periods Before and After an Arctic Ice‐Free Summer
Authors: Xie Yongkun , Nie Hanbin , He Yongli 
Published: August 2022

AbstractThe temperature of a well‐mixed ice‐water mixture stays constant until the ice melts due to external heat. Whether the temperature over the Arctic Ocean exhibits an analogous stagewise evolution to reach an ice‐free point remains unclear. Therefore, this study explored the characteristics of extratropical climate change before and after a period during which the Arctic Ocean was ice‐free in summer using multimodel simulations. Here, we show that the seasonality of Arctic warming varies between the two periods separated by an ice‐free summer. The warming maximum in the cold season delayed for a month after becoming ice‐free than before. In addition, the warming maximum lagged behind the sea‐ice decline maximum before becoming ice‐free, whereas the maximums of the two became coordinated after becoming ice‐free. The closed cross‐season energy cycle demonstrated that the capacitor effect of the Arctic Ocean with delayed release of the energy taken up in spring and summer due to sea‐ice decline and seawater absorption is crucial for the seasonality observed in Arctic climate change. Moreover, we found that although Arctic amplification induced general weakening in high‐frequency weather variability in the mid‐high latitudes via decreased meridional temperature gradients, significant weakening was induced only after becoming ice‐free under high emission. Our findings suggest that the two stages of Arctic sea‐ice decline should be taken into consideration when dealing with global warming.
Contrasting Sea‐Air CO2 Exchanges in the Western Tropical Atlantic Ocean
Authors: Monteiro Thiago , Batista Matheus , Henley Sian , Machado Eunice da Costa , Araujo Moacyr , Kerr Rodrigo 
Published: August 2022

AbstractThe western Tropical Atlantic Ocean is a biogeochemically complex region due to the structure of the surface current system and the large freshwater input from the Amazon River coupled with the dynamics of precipitation. Such features make it difficult to understand the dynamics of the carbon cycle, leading to contrasting estimates in sea‐air CO2 exchanges in this region. Here, we demonstrate that these contrasting estimates occur because the western Tropical Atlantic Ocean can be split into three distinct sub‐regions in terms of the sea‐air CO2 exchanges. The sub‐region under the North Brazil Current domain acts as a weak annual CO2 source to the atmosphere, with low interannual variability. The sub‐region under the North Equatorial Current influence acts as an annual CO2 sink, with great temporal variability. The third sub‐region under the Amazon River plume influence shows greater interannual variability of CO2 exchanges, but it always acts as a net oceanic sink for CO2. Despite this large spatial variability, the entire region acts as a net annual CO2 sink of −1.6 ± 1.0 mmol m−2 day−1. Importantly, the Amazon River plume waters drive 87% of the CO2 uptake in the western Tropical Atlantic Ocean. In addition, we found a significant increasing trend in sea surface CO2 partial pressure in the North Brazil Current and North Equatorial Current waters. Such trends are more pronounced than the increase in atmospheric CO2 partial pressure, revealing the sensitivity of carbon dynamics in these sub‐regions to global climate change.
Asthenospheric Flow From East Asia to the Philippine Sea Plate Revealed by Rj‐MCMC Inversion of Surface Waves
Authors: Zhao Yanzhe , Guo Zhen , Wang Yanbin 
Published: August 2022

AbstractThe Pacific and Philippine Sea Plate subductions have resulted in and controlled the development of a typical trench‐arc‐back‐arc system in NE Asia since the Cenozoic. The formation of widely distributed intraplate volcanoes and the dynamic pattern of the entire region are still debated. Here we constructed a three‐dimensional anisotropic S‐wave velocity model of NE Asia by inverting Rayleigh wave dispersion using a modified reversible‐jump Markov Chain Monte Carlo (rj‐MCMC) algorithm. The resulting model revealed a localized mantle upwelling beneath intraplate volcanoes in NE Asia and an ongoing lithospheric downwelling beneath the central Korean Peninsula. This suggests vigorous asthenosphere and lithosphere interactions, which is likely to control the spatial distribution of Cenozoic volcanoes. The fast directions show clockwise rotation beneath NE Asia, which eventually points to the Nankai Trough. This observation is broadly consistent with shear wave splitting and suggests the presence of mantle flow from East China to the Philippine Sea Plate. The slab window beneath the Nankai Trough within the Philippine Sea Plate subduction system may accommodate the mantle flow from East China. Our study indicates that the interaction of the Philippine, Pacific Sea Plates, and Eurasian Plates plays an essential role in controlling the mantle flow and intraplate volcanism of NE Asia.
Fluvial Sedimentary Response to Late Quaternary Climate and Tectonics at the Himalayan Frontal Thrust, Central Nepal
Authors: Hamahashi Mari , Hubbard Judith A. , Almeida Rafael V. , Haines Samuel H. , Owen Lewis A. , Mishra Sanjita , Sapkota Soma Nath 
Published: August 2022

AbstractTo investigate the subsurface structure surrounding the Main Frontal Thrust (MFT) in central Nepal, we drilled and cored sediments to depths of 45–100 m at 10 sites. Our boreholes were located along previously acquired high‐resolution seismic profiles across the MFT imaging the upper 1–2 km of the subsurface, which revealed a beveled erosional surface in the hanging wall above a broad, gentle anticline, as well as growth strata in the footwall. The boreholes exhibit interlayered clays, silts, sands, and gravels, dated with optically stimulated luminescence and radiocarbon to <72.5 ± 4.3 ka, with a transition from finer to coarser sediments at ∼13.5 ± 0.1 ka. Near the fault tip, the deposits exhibit steeper dips and deformation bands. A 25‐m‐thick section of silt and clay above the south end of the buried anticline is interpreted as a temporary lacustrine depocenter formed due to uplift near the fault tip. Based on the distribution of marker beds and sediment ages, we interpret a shortening rate of 3.1–12.1 m/ka on the MFT. Three major transitions between fluvial‐lacustrine and coarse fluvial channel facies are inferred from the boreholes, and the timings of these transitions correlate with Indian monsoonal intensity variations linked to Earth's precession. We infer that a strengthened monsoon led to increased river discharge and advance of coarse bedload‐dominant braided channels, whereas a weak monsoon formed a finer‐grained channel environment. These monsoonal climate variations have affected the depositional environment and river base levels in this region, influencing the formation and apparent relative uplift of nearby river terraces.
Evolution of the Northern Part of the Lesser Antilles Arc—Geochemical Constraints From St. Barthélemy Island Lavas
Authors: Bosch Delphine , Zami Fabienne , Philippon Mélody , Lebrun Jean‐Frédéric , Münch Philippe , Cornée Jean‐Jacques , Legendre Lucie , Lemoyne Alexandre 
Published: August 2022

AbstractThis study presents an extensive geochemical data set of 23 samples from St. Barthélemy Island, which belongs to the extinct branch of the Lesser Antilles arc and is currently exposed in the northern part of the subduction forearc. Samples were selected to represent all lithologies and main periods of magmatism, that is, Middle‐Late Eocene, Early Oligocene and Late Oligocene. They show enrichment in light rare earth element/medium rare earth element, large ion lithophile elements (Rb and Ba) and isotopic characteristics, suggesting mixing between the mantle and a subduction component (oceanic crust + sediments). Trace element ratios suggest that primary magmas were generated in a normal mid‐oceanic ridge basalt‐type mantle‐wedge that underwent 8%–18% partial melting in the spinel‐stability field. The sediment contribution was low (0.1%–1%) irrespective of the age of the samples. This is similar to what is observed for the northern Lesser Antilles active branch. St. Barthélemy Island shares strong similarities with St. Martin Island, located on the same extinct arc branch, which suggests a similar geodynamic evolution. Oligocene samples displayed an increase in incompatible elements in the magma source, suggesting an increase in sediment melts, which could be correlated with a drastic change in the tectonic regime at that time, characterized by stretching perpendicular to the trench and subsequent basin opening. On Δ7/4Pb versus206Pb/204Pb, the samples showed a similar trend for both active and extinct islands of the northern Lesser Antilles, suggesting negligible changes in the nature of the magma sources.
Polarization Characteristics of a Single Mode Radio Wave Traversing Through the Ionosphere: A Unique Observation From the RRI on ePOP/SWARM‐E
Authors: Pandey Kuldeep , Eyiguler E. C. Kalafatoglu , Gillies Robert G. , Hussey Glenn C. , Danskin Donald W. , Yau Andrew W. 
Published: August 2022

AbstractThe polarization characteristics of radio waves traversing the ionosphere can be determined using the cross‐dipole antennas of Radio Receiver Instrument (RRI) onboard the Enhanced Polar Outflow Probe payload on the CAScade, Smallsat, and Ionospheric Polar Explorer/Swarm‐E satellite. Numerous coordinated ground‐RRI transionospheric propagation experiments have been executed, with the present study using transmitted radio waves from a High Frequency (HF) ground transmitter located in Ottawa, Canada (45.41°N, 75.55°W). Most of these experiments have shown the HF radio waves to propagate with both magnetoionic propagation modes, the O‐ and X‐modes, combined. However, the coordinated ground‐RRI experiment on 12 May 2017 showed only one magnetoionic propagation mode. The observed polarization state had a stable orientation angle, but the ellipticity angle changed from −19° to linear (0°) and finally 30° within a latitude span of 15°. A detailed investigation using magnetoionic ray trace modeling and ground‐based ionogram observations revealed that the HF transmitted frequency and ionospheric conditions were such that only the O‐mode radio waves reached the satellite for the entire pass. This distinct observation is a unique opportunity to examine the radio wave polarization state during a transionospheric propagation of only O‐mode waves.
The Fate of Oxygen in the Ocean and Its Sensitivity to Local Changes in Biological Production
Authors: Holzer Mark 
Published: August 2022

AbstractWe investigate the sensitivity of the oxygen content and true oxygen utilization of key low‐oxygen regions Ω to pointwise changes in biological production. To understand how the combined water and biogenic particle transport controls the sensitivity patterns and the fate of oxygen in the ocean, we develop new relationships that link the steady‐state oxygen content and deficit of Ω to the downstream and upstream oxygen utilization rate (OUR), respectively. We find that the amount of oxygen from Ω that will be lost per unit volume at point r is linked to OUR(r) through the mean oxygen age accumulated in Ω. The geographic sensitivity pattern of the Ω‐integrated oxygen deficit is shaped by where the utilization occurs that causes this deficit. The contribution to the oxygen deficit of Ω from utilization at r is controlled by the mean time that water at r spends in Ω before next ventilation at the surface. We illustrate these relationships and the new transport timescales using a simple steady‐state data‐constrained carbon and oxygen model. We focus on Ω being the global ocean, the Pacific Hypoxic Zone (PHZ, [O2] < 62.5 µM), and the North Pacific oxygen minimum zone. The oxygen deficit of the PHZ is most sensitive where mode and intermediate waters form and where increased organic‐matter production directly increases the PHZ's oxygen demand. The fraction of the local oxygen concentration that will be utilized in respiration is as high as 90% in the PHZ and up to 70% in the water column beneath it.
Monitoring Surface 10Be/7Be Directly Reveals Stratospheric Air Intrusion in Sichuan Basin, China
Authors: Liu Xuke , Fu Yunchong , Bi Yanting , Zhang Li , Zhao Guoqing , Xian Feng , Zhou Weijian 
Published: August 2022

AbstractStratospheric air intrusion can break the balance of atmospheric properties such as chemicals and radiation affecting the atmosphere. The meteoric cosmogenic 7Be and 10Be are mainly produced between the lower stratosphere and the upper troposphere and then adsorbed on aerosols for transport, they are good tracers of the atmospheric mass transport. Here, 7Be and 10Be in aerosols were measured simultaneously by accelerator mass spectrometry, and after removing dust 10Be interference, daily resolution 7Be and 10Be for the whole year in Chengdu (a major city in the Sichuan Basin of China) was obtained. The long‐period tracing of stratospheric air intrusion in the Sichuan Basin area is realized by directly observing the surface 10Be/7Be ratio. This work confirms the influence of stratospheric air intrusion on the surface O3 and atmospheric water vapor in the Sichuan Basin and finds that the stratospheric air intrusion degree in spring and summer is significantly higher than that in autumn and winter. The results indicate that high‐resolution 10Be/7Be can provide effective and refined tracers for the atmospheric vertical motion. The new 7Be and 10Be observation records contribute to evaluating the impact on the environment and climate during the stratospheric air intrusion in the Sichuan Basin.
A Revision of the Formation Conditions of the Vredefort Crater
Authors: Allen Natalie H. , Nakajima Miki , Wünnemann Kai , Helhoski Søren , Trail Dustin 
Published: August 2022

AbstractThe Vredefort impact structure, located in South Africa and formed 2.02 Ga, is the largest confirmed remnant impact crater on Earth. The widely accepted impactor diameter and velocity to form this crater are 15 km and 15 km/s, respectively, which produce a crater diameter of 172 km. This is much smaller than the most commonly cited estimates (250–280 km), and while previous results were able to match the geologic evidence known at that time, these impact parameters are not consistent with more recent geological constraints. Here, we conduct impact simulations to model the Vredefort crater formation with the shock physics code impact Simplified Arbitrary Lagrangian Eulerian (iSALE). Our numerical simulations show that combinations of the impactor diameter and impact velocity of 25 km and 15 km/s or 20 km and 25 km/s are able to recreate the larger crater size of ∼250 km. Moreover, these configurations can reproduce shock‐metamorphic features present in the impact structure today, including the distributions of breccia, shatter cones, planar deformation features in quartz and zircon, and melt. Our model also predicts that Vredefort and Karelia, Russia, where an ejecta layer from the impact was found, were approximately 2,000–2,500 km apart based on the layer thickness. Additionally, we use this model to predict the potential global effects of such a large impact by estimating the amount of climatically important gases released to the atmosphere at the time. Our work demonstrates the need to revisit previously estimated impactor parameters for large terrestrial craters in order to better characterize impact events on Earth and elsewhere.
Hot Moments of N2O Emission Under Water and Nitrogen Management in Three Types of Steppe
Authors: Liu Wei , Lü Xiao‐Tao , Yang Yong , Hou Longyu , Shao Changliang , Yuan Wenping , Pan Qingmin , Li Linghao 
Published: August 2022

AbstractHot moments of soil nitrous oxide (N2O) emission contribute to large fractions of total annual emissions. Magnitudes of N2O emission during hot moments to increasing water and nitrogen (N) availabilities in different steppe types were not well understood. Based on soil monoliths collected from three steppes (meadow, typical, and desert steppes) in northern China, we found that the typical steppe held the lowest N2O emission among the three steppes. Water and N co‐addition could increase soil N2O emission by up to 245‐fold. Water addition significantly enhanced soil N2O emission in all the three steppes, but the sensitivity of soil N2O emission to water addition decreased from desert steppe (r2 = 0.83) to typical (r2 = 0.73) and meadow (r2 = 0.66) steppes. Nitrogen addition significantly promoted soil N2O emission only in the meadow steppe where soil C:N was relatively higher than the other two steppes. Water and N addition displayed strong positive interaction on soil N2O emission in the meadow steppe while negative interaction in the typical steppe. Different responses of plants, microorganisms and soil NO3− concentration drove the variation in magnitude of soil N2O emission between the two steppes. Our results illustrate different interactions of water and N addition on hot moments of soil N2O emission in the three steppes. We suggest that the pulsed feature of N2O emission should be taken into account in prediction of greenhouse gas emission in the global arid and semiarid grasslands.
A Tempered Particle Filter to Enhance the Assimilation of SAR‐Derived Flood Extent Maps Into Flood Forecasting Models
Authors: Di Mauro Concetta , Hostache Renaud , Matgen Patrick , Pelich Ramona , Chini Marco , van Leeuwen Peter Jan , Nichols Nancy , Blöschl Günter 
Published: August 2022

AbstractData assimilation (DA) is a powerful tool to optimally combine uncertain model simulations and observations. Among DA techniques, the particle filter (PF) has gained attention for its capacity to deal with nonlinear systems and for its relaxation of the Gaussian assumption. However, the PF may suffer from degeneracy and sample impoverishment. In this study, we propose an innovative approach, based on a tempered particle filter (TPF), aiming at mitigating PFs issues, thus extending over time the assimilation benefits. Probabilistic flood maps derived from synthetic aperture radar data are assimilated into a flood forecasting model through an iterative process including a particle mutation in order to keep diversity within the ensemble. Results show an improvement of the model forecasts accuracy, with respect to the Open Loop: on average the root mean square error (RMSE) of water levels decrease by 80% at the assimilation time and by 60% 2 days after the assimilation. A comparison with the Sequential Importance Sampling (SIS) is carried out showing that although SIS performances are generally comparable to the TPF ones at the assimilation time, they tend to decrease more quickly. For instance, on average TPF‐based RMSE are 20% lower compared to the SIS‐based ones 2 days after the assimilation. The application of the TPF determines higher critical success index values compared to the SIS. On average the increase in performances lasts for almost 3 days after the assimilation. Our study provides evidence that the application of the variant of the TPF enables more persistent benefits compared to the SIS.
Understanding the Hydrogeochemical Response of a Mountainous Watershed Using Integrated Surface‐Subsurface Flow and Reactive Transport Modeling
Authors: Xu Zexuan , Molins Sergi , Özgen‐Xian Ilhan , Dwivedi Dipankar , Svyatsky Daniil , Moulton J. David , Steefel Carl 
Published: August 2022

AbstractClimate change and other disturbances significantly impact hydrogeochemical exports from mountainous headwater catchments such as the Upper Colorado River Basin. Developing a mechanistic understanding of how the physical and chemical processes interact in time and space in an integrated manner is key to quantifying the future impacts of such disturbances. The hydrogeochemical response of a mountainous catchment in the 2010–2019 period is evaluated quantitatively using a high‐resolution model that simulates integrated hydrology, and transport and reactions for selected solutes and minerals. The model assumes that pyrite is present only at depth while calcite is distributed uniformly, and captures the observed C‐Q reasonably well. Distinct C‐Q dynamics are observed in an average (WY16), a wet (WY17), and a dry (WY18) water year. The model also quantifies the water fraction from surface, shallow and deep groundwater compartments using tracers, and suggests greater groundwater contributions to peak stream discharge in the dry WY18. Results demonstrate that calcium concentrations do not change significantly from year to year, while sulfate shows significant temporal variability. Pyrite dissolution is affected by the changing hydrological drivers where it is enhanced in the dry WY18; calcite dissolution supplements calcium dilution under high flow conditions. The model simulates the reaction hotspots controlled by hydrological conditions, and the spatially‐resolved results show that higher soil saturation and less snowpack occur earlier on the south‐facing side than on the north‐facing side. This is a first‐of‐its‐kind demonstration of a model that integrates hydrologic processes, including evapotranspiration, and reactive transport to enable a predictive understanding of hydrogeochemical exports.