bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ongoing (2015‐) Magma Surge in the Upper Mantle Beneath the Island of Hawaiʻi
Authors: Burgess Matthew K. , Roman Diana C. 
Published: March 2021

Abstract“Surges” in magma supply from the mantle can lead to significant changes in eruptive behavior, thus their early identification is critical to long‐term eruption forecasting. Here, we document and analyze two order‐of‐magnitude increases in seismicity in the upper mantle beneath southern Hawaiʻi between 2015 and 2020. We interpret the anomalous seismicity, which involved the rapid formation of new multiplets and a change in fault‐plane solution orientations relative to pre‐2015 events, as reflecting a substantial increase, or “surge” in mantle‐derived magma, and we suggest that the intruded magma has been driving concurrent unrest at Mauna Loa, Kīlauea, and Lōʻihi Volcanoes through mechanical stress transfer.
Meteorological Aspects of Gamma‐Ray Glows in Winter Thunderstorms
Authors: Wada Y. , Enoto T. , Kubo M. , Nakazawa K. , Shinoda T. , Yonetoku D. , Sawano T. , Yuasa T. , Ushio T. , Sato Y. , Diniz G. S. , Tsuchiya H. 
Published: March 2021

AbstractDuring three winter seasons from November 2016 to March 2019, 11 gamma‐ray glows were detected at a single observation site of our ground‐based gamma‐ray monitoring network in Kanazawa, Japan. These events are analyzed with observations of an X‐band radar network, a ceilometer, a disdrometer, and a weather monitor. All the detected glows were connected to convective high‐reflectivity regions of more than 35 dBZ, developed up to an altitude of >2 km. They were also accompanied by heavy precipitation of graupels. Therefore, graupels in the lower layer of thunderclouds that correspond to high‐reflectivity regions can form strong electric fields producing gamma‐ray glows. Also, these events are compared with a limited sample of nondetection cases, but no significant differences in meteorological conditions were found between detection and nondetection cases in the present study.
Larger Spatial Footprint of Wintertime Total Precipitation Extremes in a Warmer Climate
Authors: Bevacqua Emanuele , Shepherd Theodore G. , Watson Peter A. G. , Sparrow Sarah , Wallom David , Mitchell Dann 
Published: March 2021

AbstractThe simultaneous occurrence of extremely wet winters at multiple locations in the same region can contribute to widespread flooding and associated socio‐economic losses. However, the spatial extent of precipitation extremes (i.e., the area in which nearby locations experience precipitation extremes simultaneously) and its future changes are largely overlooked in climate assessments. Employing new multi‐thousand‐year climate model simulations, we show that under both 2.0 °C and 1.5 °C warming scenarios, wintertime total precipitation extreme extents would increase over about 80%–90% of the Northern Hemisphere extratropics (i.e., of the latitude band 28°–78°N). Stabilizing at 1.5 °C rather than 2.0 °C would reduce the average magnitude of the increase by 1.7–2 times. According to the climate model, the increased extents are caused by increases in precipitation intensity rather than changes in the spatial organization of the events. Relatively small percentage increases in precipitation intensities (e.g., by 4%) can drive disproportionately larger, by 1–2 orders of magnitude, growth in the spatial extents (by 93%).
Effect of Resolving Ocean Eddies on the Transient Response of Global Mean Surface Temperature to Abrupt 4xCO2 Forcing
Authors: Putrasahan D. A. , Gutjahr O. , Haak H. , Jungclaus J. H. , Lohmann K. , Roberts M. J. , von Storch J.‐S. 
Published: March 2021

AbstractThe magnitude of global mean surface temperature (GMST) response to increasing atmospheric CO2 concentrations is affected by the efficiency of ocean heat uptake, which in turn can be affected by oceanic mesoscale eddies. Using the Max Planck Institute ‐ Earth System Model (MPI‐ESM1.2), we find that resolving eddies leads to a −0.1°C cooler response of GMST to an abrupt CO2 quadrupling, which is related to a larger rate of heat uptake by an eddying ocean. This is consistent with changes in the energy budget of the whole climate system induced by increasing ocean resolution under the same radiative forcing and climate feedback. As a fast response, heat is taken up by the deep ocean, independent of resolution. The change in deep ocean heat uptake due to resolved eddies is an amplification in the magnitude of the responses of all heat processes, including eddy heat advection, mean heat advection, and diffusive processes.
Connection Between Mass Flux Transport and Eddy Diffusivity in Convective Atmospheric Boundary Layers
Authors: Li Qi , Cheng Yu , Gentine Pierre 
Published: March 2021

AbstractTurbulence parameterizations for convective boundary layer in coarse‐scale atmospheric models usually consider a combination of the eddy‐diffusive transport and a non‐local transport, typically in the form of a mass flux term, such as the widely adopted eddy‐diffusivity mass‐flux (EDMF) approach. These two types of turbulent transport are generally considered to be independent of each other. Using results from large‐eddy simulations, here, we show that a Taylor series expansion of the updraft and downdraft mass‐flux transport can be used to approximate the eddy‐diffusivity transport in the atmospheric surface layer and the lower part of the mixed layer, connecting both eddy‐diffusivity and mass‐flux transport theories in convective conditions, which also quantifies departure from the Monin‐Obukhov similarity (MOS) in the surface layer. This study provides a theoretical support for a unified EDMF parameterization applied to both the surface layer and mixed layer and highlights important correction required for surface models relying on MOS.
Water Depth Dependence of Long‐Range Correlation in Nontidal Variations in Seafloor Pressure
Authors: Inoue Tomohiro , Ito Yoshihiro , Wallace Laura M. , Yoshikawa Yutaka , Inazu Daisuke , Garcia Emmanuel Soliman M. , Muramoto Tomoya , Webb Spahr C. , Ohta Kazuaki , Suzuki Syuichi , Hino Ryota 
Published: March 2021

AbstractIsolating the source of nontidal oceanographic noise in seafloor pressure data is critical for improving the use of these data for seafloor geodetic applications. Residuals between nearby bottom pressure records have typically been used to remove the nontidal components, as these are largely common‐mode. To evaluate the similarities between pairs of observed bottom pressure records at a range of water depths, we calculate the standard deviations of the time series of residuals between data from all site pairs, installed in the Hikurangi subduction zone offshore New Zealand. We find that the magnitude of the standard deviation depends more on relative water depth than the distance between sites. This confirms the result of previous studies from Cascadia that nontidal components are more similar along isobaths even if the distance between sites is large. Furthermore, in order to reduce noises, the required depth difference between site pairs also varies with site depths.
Topography as a Major Influence on Geothermal Circulation in the Taupo Volcanic Zone, New Zealand
Authors: Pearson‐Grant S. C. , Bertrand E. A. 
Published: March 2021

AbstractGeothermal systems are an important resource in the global effort to reduce fossil fuel use. They are formed by convection of water heated at depth, but without external controls convection is unstable and upflows move or dissipate. In the central Taupo Volcanic Zone in New Zealand, the geothermal systems have been in the same locations for more than 50 kyr. We created heat and fluid flow models with uniform geology and basal heat which showed that the known topography localizes convective upflows. Fourteen out of 19 known geothermal systems in the model area were correctly located beneath topographic lows. Even at 3 km depth, inclusion of topography in our models improved agreement between the locations of upflows and low‐resistivity zones derived from 3‐D inversion of magnetotelluric data. Therefore, while topography is not the only factor that influences geothermal convection, its contribution is on a larger scale than is generally assumed.
Present and Future of Rainfall in Antarctica
Authors: Vignon É. , Roussel M.‐L. , Gorodetskaya I. V. , Genthon C. , Berne A. 
Published: March 2021

AbstractWhile most precipitation in Antarctica falls as snow, little is known about liquid precipitation, although it can have ecological and climatic impacts. This study combines meteorological reports at 10 stations with the ERA5 reanalysis to provide a climatological characterization of rainfall occurrence over Antarctica. Along the East Antarctic coast, liquid precipitation occurs 22 days per year at most and coincides with maritime intrusions and blocking anticyclones. Over the north‐western Antarctic Peninsula, rainfall occurs more than 50 days per year on average and the recent summer cooling was accompanied by a decrease of −35 annual rainy days per decade between 1998 and 2015 at Faraday‐Vernadsky. Projections from seven latest‐generation climate models reveal that Antarctic coasts will experience a warming and more frequent and intense rainfall by the end of the century. Rainfall is expected to impact new regions of the continent, increasing their vulnerability to melting by the preconditioning of surface snow.
Arctic Warming and Associated Sea Ice Reduction in the Early 20th Century Induced by Natural Forcings in MRI‐ESM2.0 Climate Simulations and Multimodel Analyses
Authors: Aizawa Takuro , Ishii Masayoshi , Oshima Naga , Yukimoto Seiji , Hasumi Hiroyasu 
Published: March 2021

AbstractDuring the early 20th century, the Arctic experienced a period of remarkable warming, often called the early 20th century warming (ETCW). However, the degree of the response to external climate forcing on the Arctic surface air temperature is not well understood. Climate simulations using a state‐of‐the‐art climate model of Meteorological Research Institute (MRI‐ESM2.0) and multimodel analyses were conducted to better understand ETCW. The MRI‐ESM2.0 historical simulations successfully reproduced the observed ETCW and the corresponding decreases in sea ice extent. Detection and attribution experiments using MRI‐ESM2.0 suggest that internal climate variability and external natural forcings by solar and volcanic activities had major influences on the model‐simulated ETCW, rather than external anthropogenic forcings. Multimodel analyses indicate that the Arctic warming trend during 1911–1940 induced by natural forcings is comparable to the unforced multidecadal internal variability, suggesting major contributions of the internal dynamics and natural forcings to ETCW.
Heterotrophic Respiration and the Divergence of Productivity and Carbon Sequestration
Authors: Noormets Asko , Bracho Rosvel , Ward Eric , Seiler John , Strahm Brian , Lin Wen , McElligott Kristin , Domec Jean‐Christophe , Gonzalez‐Benecke Carlos , Jokela Eric J. , Markewitz Daniel , Meek Cassandra , Miao Guofang , McNulty Steve G. , King John S. , Samuelson Lisa , Sun Ge , Teskey Robert , Vogel Jason , Will Rodney , Yang Jinyan , Martin Timothy A. 
Published: March 2021

AbstractNet primary productivity (NPP) and net ecosystem production (NEP) are often used interchangeably, as their difference, heterotrophic respiration (soil heterotrophic CO2 efflux, RSH = NPP−NEP), is assumed a near‐fixed fraction of NPP. Here, we show, using a range‐wide replicated experimental study in loblolly pine (Pinus taeda) plantations that RSH responds differently than NPP to fertilization and drought treatments, leading to the divergent responses of NPP and NEP. Across the natural range of the species, the moderate responses of NPP (+11%) and RSH (−7%) to fertilization combined such that NEP increased nearly threefold in ambient control and 43% under drought treatment. A 13% decline in RSH under drought led to a 26% increase in NEP while NPP was unaltered. Such drought benefit for carbon sequestration was nearly twofold in control, but disappeared under fertilization. Carbon sequestration efficiency, NEP:NPP, varied twofold among sites, and increased up to threefold under both drought and fertilization.
Satellite‐Observed Decreases in Water Turbidity in the Pearl River Estuary: Potential Linkage With Sea‐Level Rise
Authors: Wang Jun , Tong Yan , Feng Lian , Zhao Dan , Zheng Chunmiao , Tang Jing 
Published: March 2021

AbstractWater turbidity is an important indicator of water quality, which regulates primary production by changing the light field in the water column. Thus, monitoring the spatial and temporal variations in water turbidity is environmentally and biologically important. In this study, nine commonly used spectral index algorithms were tuned using in situ data collected from two field surveys in the Pearl River Estuary of China, and the spectral ratios between the red and green bands (i.e., and ) were selected as the optimal indicator to estimate water turbidity in this region. A long‐term environmental data record of water turbidity was established for the Pearl River Estuary by applying the proposed algorithm to MODIS/Aqua data covering the estuary from 2003 to 2019. Water turbidity in the Pearl River Estuary has significantly decreased at a rate of 0.11 nephelometric turbidity units (NTU) per year (R2 = 0.84, p < 0.01). The decline in water turbidity is linked with sea‐level rise in this area. Sea‐level rise may cause the longitudinal and lateral landward retreat of estuarine turbidity maxima (ETMs), directly contributing to the decline in water turbidity. Further, the sea‐level rise and the decline in water turbidity in the Pearl River Estuary are also two effects resulting from similar processes, such as urbanization. A high degree of correlation was observed between the water turbidity and salinity, which could facilitate promising monitoring of the increasingly severe saltwater intrusions in this region.
Tree Rings Reveal the Impacts of the Northern Hemisphere Temperature on Precipitation Reduction in the Low Latitudes of East Asia Since 1259 CE
Authors: Sun Changfeng , Liu Yu , Li Qiang , Song Huiming , Cai Qiufang , Fang Congxi , Liu Ruoshi , Ren Yongfei 
Published: March 2021

AbstractFrom the late 1920s to the early 21st century, meteorological observations indicate a decreasing trend of precipitation in Taiwan, an island in the low latitudes of East Asia, with global warming. However, it is still unclear whether the decreasing trend of Taiwan precipitation can be physically linked to an increase in temperature. Here, we present an annually resolved precipitation reconstruction for Taiwan for 1259–2006 CE based on tree‐ring width and oxygen isotope indices, which both reflect a high sensitivity to climatic changes. Over the past 748 years both, extremely dry and wet years accounted for 2.8% of all years and Taiwan precipitation can reflect the large‐scale precipitation in the low latitudes of East Asia. Before the onset of global warming, the precipitation reconstruction exhibited four other significant decreasing trends during the 1380s–1440s, 1640s–1700s, 1720s–1790s, and 1790s–1860s, and each decreasing trend was accompanied by an increase in Northern Hemisphere temperature. This implies that the decreasing trends in precipitation were affected by increasing temperature. We also found that large volcanic eruptions in the low latitudes of the globe played an important role in precipitation changes by influencing the El Niño/Southern Oscillation and Asian summer monsoon. Precipitation usually decreased in the second year after large tropical volcanic eruptions. Our reconstruction is the longest annual‐resolution precipitation reconstruction for the low latitudes of East Asia, and it is useful not only for understanding past hydroclimate changes but also for providing basic data to project future precipitation changes through climate modeling.
Uncertainties of Simulated Aerosol Direct Radiative Effect Induced by Aerosol Chemical Components: A Measurement‐Based Perspective From Urban‐Forest Transition Region in East China
Authors: Ma Yining , Xin Jinyuan , Zhang Wenyu , Gong Chongshui , Wen Tianxue , Wu Xiaoyan , Wang Yuesi , Wang Lili , Wu Fangkun , Ding Xiang 
Published: March 2021

AbstractDifference and uncertainty of the aerosol radiative effects were quantified using the Santa Barbara DISORT Atmospheric Radiative Transfer model and multiple aerosol observation data sets from urban‐forest transition region. The secondary transformed carbonaceous aerosol components and biogenic secondary organic aerosol (BSOA) tracers have dominated over all other components (with a higher concentration in wet season) in terms of its impact on the aerosol radiative forcing (ARF). The averaged organic carbon (OC) and BSOA tracers increased from 13.3 ± 4.99 μg/m3, 29.5 ± 10.7 ng m−3 to 17.3 ± 4.47 μg/m3, 78.7 ± 43.7 ng m−3 in the dry and wet seasons, respectively. The corresponding root mean square errors of single scattering albedo and radiative forcing at the top of the atmosphere have increased by 8.4% and 16.9%. From the dry season to the wet season, the drastically aerosol composition and types variations caused the aerosol radiation effect reverse from cooling to heating. The increase in carbonaceous aerosols and BSOA transformed by forests in the wet season weakened the cooling effects. Driven by multiple factors, such as meteorological conditions, emission sources, and the mixed state of particulate matters, the transport patterns of air masses exhibit completely opposite effects to the ARF. Affected by the source location, wet deposition rate and components residence time, the uncertainty of ARF caused by long‐distance transport of aerosols is 68% higher than that of local aerosol situations under the condition of similar aerosol composition distributions. At similar transport distances, stronger aerosol secondary transformation increases the uncertainty of ARF by 20%.
Antarctic Atmospheric River Climatology and Precipitation Impacts
Authors: Wille Jonathan D. , Favier Vincent , Gorodetskaya Irina V. , Agosta Cécile , Kittel Christoph , Beeman Jai Chowdhry , Jourdain Nicolas C. , Lenaerts Jan T. M. , Codron Francis 
Published: March 2021

AbstractThe Antarctic ice sheet (AIS) is sensitive to short‐term extreme meteorological events that can leave long‐term impacts on the continent's surface mass balance (SMB). We investigate the impacts of atmospheric rivers (ARs) on the AIS precipitation budget using an AR detection algorithm and a regional climate model (Modèle Atmosphérique Régional) from 1980 to 2018. While ARs and their associated extreme vapor transport are relatively rare events over Antarctic coastal regions (∼3 days per year), they have a significant impact on the precipitation climatology. ARs are responsible for at least 10% of total accumulated snowfall across East Antarctica (localized areas reaching 20%) and a majority of extreme precipitation events. Trends in AR annual frequency since 1980 are observed across parts of AIS, most notably an increasing trend in Dronning Maud Land; however, interannual variability in AR frequency is much larger. This AR behavior appears to drive a significant portion of annual snowfall trends across East Antarctica, while controlling the interannual variability of precipitation across most of the AIS. AR landfalls are most likely when the circumpolar jet is highly amplified during blocking conditions in the Southern Ocean. There is a fingerprint of the Southern Annular Mode (SAM) on AR variability in West Antarctica with SAM+ (SAM−) favoring increased AR frequency in the Antarctic Peninsula (Amundsen‐Ross Sea coastline). Given the relatively large influence ARs have on precipitation across the continent, it is advantageous for future studies of moisture transport to Antarctica to consider an AR framework especially when considering future SMB changes.
Calculating Chlorine Concentration Bounds in Water Distribution Networks: A Backtracking Uncertainty Bounding Approach
Authors: Vrachimis Stelios G. , Eliades Demetrios G. , Polycarpou Marios M. 
Published: March 2021

AbstractThe estimation of chlorine concentration in water distribution networks is a challenging task due to hydraulic and water‐quality parameter uncertainties. In this work, we propose a methodology for calculating chlorine concentration bounds at node locations of water distribution networks which is suitable for sensor fault and contamination detection purposes. The proposed Backtracking Uncertainty Bounding Algorithm (BUBA) considers known bounds on hydraulic states and water‐quality model parameters to calculate the chlorine concentration bounds. The validity of the calculated bounds is demonstrated using a large number of Monte Carlo simulations on benchmark networks. Moreover, the proposed methodology can be used in conjunction with a real‐time parameter estimation algorithm, as it allows the use of time‐varying bulk reaction coefficients. A parameter estimation algorithm is designed and implemented to approximate the unknown bulk reaction coefficient of water at the sources of the WDN, which are typically water tanks filled with water originating from different sources. The BUBA then uses these time‐varying parameters to improve the chlorine concentration bounds, as demonstrated in a case study with real data from a water transport network.
Direct Measurements of Hydrodynamic Forces Induced by Tidal Bores
Authors: Riaz Muhammad Zain Bin , Yang Shu‐Qing , Sivakumar Muttucumaru , Enever Keith , Miguntanna Nadeeka Sajeewani , Khalil Usman 
Published: March 2021

AbstractTidal bores are sudden discontinuities in water depth, and can be classified as undular and breaking bores when tidal waves propagate upstream in a river mouth and on beaches. The impact of different types of bores on sediment transport is not clear; hence, specially designed experiments were conducted to clarify the mechanism of sediment initiation. Here, a laser Doppler anemometer, a force sensor, and ultrasonic displacement meters accompanied by video recordings were used to investigate simultaneously the incipient motion of sediment under tidal bores. No sediment motion was observed during the initial steady flows. It was observed that only a few particles changed their initial position during the undular bore; however, a group of particles were seen moving upstream during the breaking bore. The inception of sediment motion was closely related to the passage of the breaking roller, that is, the forces that caused the inception of particle motion were not only due to velocity but also to the sudden discontinuity in free water surface. According to the experimental results, the upward vertical force due to swelling in free water surface before the roller toe was the main force in destabilizing the particles. Later, a large upstream longitudinal force was found to be the dominant cause promoting upstream particle motion during the breaking roller passage. Furthermore, phases of both horizontal and vertical forces play an important role in tidal bore propagation. It is interesting to note that by using the measured force, the observed phenomenon can be well explained by the Shield threshold criterion.