bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Global Budget of Atmospheric Methanol: New Constraints on Secondary, Oceanic, and Terrestrial Sources
Authors: Bates Kelvin H. , Jacob Daniel J. , Wang Siyuan , Hornbrook Rebecca S. , Apel Eric C. , Kim Michelle J. , Millet Dylan B. , Wells Kelley C. , Chen Xin , Brewer Jared F. , Ray Eric A. , Commane Róisín , Diskin Glenn S. , Wofsy Steven C. 
Published: February 2021

AbstractMethanol is the second‐most abundant organic gas in the remote atmosphere after methane, but its sources are poorly understood. Here, we report a global budget of methanol constrained by observations from the ATom aircraft campaign as implemented in the GEOS‐Chem global atmospheric chemistry model. ATom observations under background marine conditions can be fit in the model with a surface ocean methanol concentration of 61 nM and a methanol yield of 13% from the newly implemented CH3O2 + OH reaction. While terrestrial biogenic emissions dominate the global atmospheric methanol budget, secondary production from CH3O2 + OH and CH3O2 + CH3O2 accounts for 29% of the total methanol source, and makes up the majority of methanol in the background marine atmosphere sampled by ATom. Net emission from the ocean is comparatively minor, particularly because of rapid deposition from the marine boundary layer. Aged anthropogenic and pyrogenic plumes sampled in ATom featured large methanol enhancements to constrain the corresponding sources. Methanol enhancements in pyrogenic plumes did not decay with age, implying in‐plume secondary production. The atmospheric lifetime of methanol is only 5.3 days, reflecting losses of comparable magnitude from photooxidation and deposition. GEOS‐Chem model results indicate that methanol photochemistry contributes 5%, 4%, and 1.5% of the tropospheric burdens of formaldehyde, CO, and ozone, respectively, with particularly pronounced effects in the tropical upper troposphere. The CH3O2 + OH reaction has substantial impacts on radical budgets throughout the troposphere and should be included in global atmospheric chemistry models.
Reply to Comment by Velasco on “High‐Resolution, Multilayer Modeling of Singapore’s Urban Climate Incorporating Local Climate Zones”
Authors: Mughal M. O. , Li Xian‐Xiang , Yin Tiangang , Martilli Alberto , Brousse Oscar , Dissegna Maria Angela , Norford Leslie K. 
Published: February 2021

AbstractIn response to the comment on our paper “High‐resolution, multilayer modeling of Singapore's urban climate incorporating local climate zones,” we provide detailed response to each of the incorrect accusations with scientifically based evidence. We have evaluated our model using all the available observational data, and the results showed good agreement. Our modeling study includes assumptions, as all modeling work does, and we have discussed their rationales and possible implications.
Restoration Thinning in a Drought‐Prone Idaho Forest Creates a Persistent Carbon Deficit
Authors: Stenzel J. E. , Berardi D. M. , Walsh E. S. , Hudiburg T. W. 
Published: February 2021

AbstractWestern US forests represent a carbon sink that contributes to meeting regional and global greenhouse gas targets. Forest thinning is being implemented as a strategy for reducing forest vulnerability to disturbance, including mortality from fire, insects, and drought, as well as protecting human communities. However, the terrestrial carbon balance impacts of thinning remain uncertain across regions, spatiotemporal scales, and treatment types. Continuous and in situ long‐term measurements of partial harvest impacts to stand‐scale carbon and water cycle dynamics are nonetheless rare. Here, we examine post‐thinning carbon and water flux impacts in a young ponderosa pine forest in Northern Idaho. We examine in situ stock and flux impacts during the 3 years after treatment as well as simulate the forest sector carbon balance through 2050, including on and off‐site net emissions. During the observation period, increases in tree‐scale net primary production (NPP) and water use persistence through summer drought did not overcome the impacts of density reduction, leading to 45% annual reductions of NPP. Growth duration remained constrained by summer drought in control and thinned stands. Ecosystem model and life cycle assessment estimates demonstrated a net forest sector carbon deficit relative to control stands of 27.0 Mg C ha−1 in 2050 due to emissions from dead biomass pools despite increases to net ecosystem production. Our results demonstrate dynamics resulting in carbon losses from forest thinning, providing a baseline with which to inform landscape‐scale modeling and assess tradeoffs between harvest losses and potential gains from management practices.
Carbon Isotopic and Lithologic Constraints on the Sources and Cycling of Inorganic Carbon in Four Large Rivers in China: Yangtze, Yellow, Pearl, and Heilongjiang
Authors: Shan Sen , Luo Chunle , Qi Yuanzhi , Cai Wei‐Jun , Sun Shuwen , Fan Di , Wang Xuchen 
Published: February 2021

AbstractTransport of terrigenous carbon by rivers has been affected extensively by climate change and anthropogenic activities in China over the last few decades. Here, we present results on carbon isotopes (13C, 14C) of dissolved and particulate inorganic carbon (DIC and PIC) and combined with major lithologic ions measured in the four largest rivers in China, namely, the Yangtze, Yellow, Pearl, and Heilongjiang rivers, to reveal the sources and transport of terrigenous inorganic carbon in the rivers. The DIC concentrations showed large variations in the four rivers and ranged from 253 to 3,122 μM. The Yangtze, Yellow and Pearl rivers transported high DIC contents that had low Δ14C values of millennium‐aged DIC and very old PIC; however, the Heilongjiang River presented a lower DIC concentration with much younger 14C ages than the global average (1,100 μM). The strong correlations between the DIC isotope values and major lithological ions (Ca2+ and Mg2+) suggest that chemical weathering played important but variable roles in controlling the production and fate of DIC in the rivers. Using dual isotopes and the MixSIAR model, we calculated that the chemical weathering of carbonate rocks contributed 95 ± 5% of the riverine DIC to the headwater of the Yangtze River while silicate rock weathering and riverine organic matter respiration contributed 62 ± 25% and 5 ± 5% of the DIC in the middle and lower reaches of the river, respectively. In contrast, chemical weathering of silicate rocks contributed the dominant fraction of DIC in the Yellow (55 ± 17%), Pearl (61 ± 20%) and Heilongjiang (83 ± 29%) rivers.
Evolution of Near‐Surface Wind Strength in Northeastern Arid Central Asia During the Holocene
Authors: Gao Fuyuan , Zheng Xiangmin , Jia Jia , Li Kaiming , Xia Dunsheng , Yang Junhuai , Lu Hao , Shi Fuxi , Chen Zixuan , Wang Shuyuan 
Published: February 2021

AbstractWind dynamics in dust source areas are influenced by climate change on both regional and global scales. Northeastern arid central Asia is one of the most important sources of Asian dust. We conducted grain size analyses of the extracted quartz component of bulk samples from four Holocene aeolian sedimentary sequences in northeastern arid central Asia, in order to reconstruct variations in strength of near‐surface wind, and discussed the possible mechanism. X‐ray diffraction and geochemical analyses were also conducted. The results suggest that in the study area the mean grain size of the quartz component of aeolian sediments is a more reliable proxy for the strength of near‐surface wind and Siberian high‐pressure system. Stronger near‐surface wind and Siberian high‐pressure system occurred during the early to middle Holocene and subsequently their gradually weakened. Lower winter insolation, lower atmospheric CO2 content, and remnant high‐latitude continental ice‐sheets resulted in relatively low winter temperatures in middle and high latitudes of the Northern Hemisphere during the early to middle Holocene. The lower winter temperatures indicate a stronger Siberian high‐pressure system, which may have been the cause of the stronger near‐surface winds. Due to increasing winter solar insolation and atmospheric CO2 content, and the shrinking high‐latitude continental ice‐sheets, the Siberian high‐pressure system weakened in response to rising winter temperatures during the middle to late Holocene, likely resulting in decreased near‐surface wind strength.
Tropical Sea Surface Temperatures Following the Middle Miocene Climate Transition From Laser‐Ablation ICP‐MS Analysis of Glassy Foraminifera
Authors: Nairn Michael G. , Lear Caroline H. , Sosdian Sindia M. , Bailey Trevor R. , Beavington‐Penney Simon 
Published: February 2021

AbstractThe mid‐to‐late Miocene is proposed as a key interval in the transition of the Earth's climate state toward that of the modern‐day. However, it remains a poorly understood interval in the evolution of Cenozoic climate, and the sparse proxy‐based climate reconstructions are associated with large uncertainties. In particular, tropical sea surface temperature (SST) estimates largely rely on the unsaturated alkenone Uk37 proxy, which fails to record temperatures higher than 29˚C, the TEX86 proxy which has challenges around its calibration, and Mg/Ca ratios of poorly preserved foraminifera. We reconstruct robust, absolute, SSTs between 13.5 Ma and 9.5 Ma from the South West Indian Ocean (paleolatitude ∼5.5˚S) using laser‐ablation inductively coupled‐plasma mass spectrometer microanalysis of glassy planktic foraminiferal Mg/Ca. Employing this microanalytical technique, and stringent screening criteria, permits the reconstruction of paleotemperatures using foraminifera which although glassy, are contaminated by authigenic coatings. Our absolute estimates of 24–31°C suggest that SST in the tropical Indian Ocean was relatively constant between 13.5 and 9.5 Ma, similar to those reconstructed from the tropics using the Uk37 alkenone proxy. This finding suggests an interval of enhanced polar amplification between 10 and 7.5 Ma, immediately prior to the global late Miocene Cooling.
Reconstruction of the Radiation Belts for Solar Cycles 17–24 (1933–2017)
Authors: Saikin A. A. , Shprits Y. Y. , Drozdov A. Y. , Landis D. A. , Zhelavskaya I. S. , Cervantes S. 
Published: February 2021

AbstractWe present a reconstruction of the dynamics of the radiation belts from solar cycles 17 to 24 which allows us to study how radiation belt activity has varied between the different solar cycles. The radiation belt simulations are produced using the Versatile Electron Radiation Belt (VERB)‐3D code. The VERB‐3D code simulations incorporate radial, energy, and pitch angle diffusion to reproduce the radiation belts. Our simulations use the historical measurements of Kp (available since solar cycle 17, i.e., 1933) to model the evolution radiation belt dynamics between L* = 1–6.6. A nonlinear auto regressive network with exogenous inputs (NARX) neural network was trained off GOES 15 measurements (January 2011–March 2014) and used to supply the upper boundary condition (L* = 6.6) over the course of solar cycles 17–24 (i.e., 1933–2017). Comparison of the model with long term observations of the Van Allen Probes and CRRES demonstrates that our model, driven by the NARX boundary, can reconstruct the general evolution of the radiation belt fluxes. Solar cycle 24 (January 2008–2017) has been the least active of the considered solar cycles which resulted in unusually low electron fluxes. Our results show that solar cycle 24 should not be used as a representative solar cycle for developing long term environment models. The developed reconstruction of fluxes can be used to develop or improve empirical models of the radiation belts.
Development of Space Weather Reasonable Worst‐Case Scenarios for the UK National Risk Assessment
Authors: Hapgood Mike , Angling Matthew J. , Attrill Gemma , Bisi Mario , Cannon Paul S. , Dyer Clive , Eastwood Jonathan P. , Elvidge Sean , Gibbs Mark , Harrison Richard A. , Hord Colin , Horne Richard B. , Jackson David R. , Jones Bryn , Machin Simon , Mitchell Cathryn N. , Preston John , Rees John , Rogers Neil C. , Routledge Graham , Ryden Keith , Tanner Rick , Thomson Alan W. P. , Wild James A. , Willis Mike 
Published: February 2021

AbstractSevere space weather was identified as a risk to the UK in 2010 as part of a wider review of natural hazards triggered by the societal disruption caused by the eruption of the Eyjafjallajökull volcano in April of that year. To support further risk assessment by government officials, and at their request, we developed a set of reasonable worst‐case scenarios and first published them as a technical report in 2012 (current version published in 2020). Each scenario focused on a space weather environment that could disrupt a particular national infrastructure such as electric power or satellites, thus, enabling officials to explore the resilience of that infrastructure against severe space weather through discussions with relevant experts from other parts of government and with the operators of that infrastructure. This approach also encouraged us to focus on the environmental features that are key to generating adverse impacts. In this paper, we outline the scientific evidence that we have used to develop these scenarios, and the refinements made to them as new evidence emerged. We show how these scenarios are also considered as an ensemble so that government officials can prepare for a severe space weather event, during which many or all of the different scenarios will materialize. Finally, we note that this ensemble also needs to include insights into how public behavior will play out during a severe space weather event and hence the importance of providing robust, evidence‐based information on space weather and its adverse impacts.
The Role of Pre‐existing Crustal Weaknesses in the Uplift of the Eastern Tibetan Plateau: 2D Thermo‐Mechanical Modeling
Authors: Xie Renxian , Chen Lin , Xiong Xiong , Wang Kai , Yan Zhiyong 
Published: February 2021

AbstractThe crust of the eastern Tibetan Plateau is cut through by several ancient fracture zones, which existed prior to the Cenozoic uplift of eastern Tibet. However, the role of these pre‐existing crustal weak zones (CWZs) in the Cenozoic evolution of eastern Tibet is still poorly understood. Here, we conduct a series of 2D thermo‐mechanical simulations to investigate the role of CWZs in the uplift of eastern Tibet. Our results show that CWZs embedded in the continental lithosphere facilitate crustal thickening via folding and thrusting deformation and uplift of a rugged surface at the early stage of convergence. As crustal thickening continues, the lowermost crust begins to partially melt due to strain and radioactive heating. With continued thickening and heating, melt volume gradually increases, leading to the lower crust melt preferentially accumulating where the CWZs are situated. At a later stage, the partially molten layer becomes thick enough and starts to flow in a channel with respect to its upper and lower solid layers. CWZs behave as windows to steer the ascension of the partial melts, leading to melt doming through the CWZs. The melt doming contributes to a second local surface uplift. Parameter tests demonstrate that increasing the number of CWZs can accelerate such geodynamical processes, and that the CWZ orientation controls the polarity of lithospheric underthrusting. We suggest that the Cenozoic episodic uplift of the eastern Tibetan Plateau, revealed by thermochronological studies, was likely caused by a combination of pure shear crustal thickening and melt doming along the pre‐existing CWZs.
Heat Dissipation Test With Fiber‐Optic Distributed Temperature Sensing to Estimate Groundwater Flux
Authors: del Val Laura , Carrera Jesús , Pool María , Martínez Lurdes , Casanovas Carlos , Bour Olivier , Folch Albert 
Published: February 2021

AbstractWe measure groundwater flux and thermal parameters around a borehole performing a heat dissipation test by heating the armor of a single fiber‐optic cable and interpreting the resulting heating curves with a new analytical method. The procedure is similar to thermal response tests, but benefitting from the high spatial and temporal resolution of distributed temperature sensing and lasting longer, so as to measure advective dissipation. Field installation relies on an innovative method in hydrogeology, which is based on the installation of the FO cable in the annular space of the well, close to the aquifer matrix. The proposed new analytical method, expands the traditional Moving Infinitesimal Line Source Model to account for the effects of the field set up and cable materials. In fact, we show that the resulting temperature build‐up goes through four periods easy to identify using the log derivative of temperature (dT/d (ln(t))): Initial response, skin (cable insulation), conduction dominated and advection dominated. We test the proposed method in an unconsolidated shallow aquifer with controlled pumping. Results are of the same order of magnitude of independent estimates of groundwater velocity.
Century‐Scale Reconstruction of Water Storage Changes of the Largest Lake in the Inner Mongolia Plateau Using a Machine Learning Approach
Authors: Fan Chenyu , Song Chunqiao , Liu Kai , Ke Linghong , Xue Bin , Chen Tan , Fu Congsheng , Cheng Jian 
Published: February 2021

AbstractLake Hulun is the fifth‐largest lake in China, playing a substantial role in maintaining the balance of the grassland ecosystem of the Mongolia Plateau, which is a crucial ecological barrier in North China. To better understand the changing characteristics of Lake Hulun and the driving mechanisms, it is necessary to investigate the water storage changes of Lake Hulun on extended timescales. The main objective of this study is to reconstruct the water storage time series of Lake Hulun over the past century. We employed a machine learning approach termed the extreme gradient boosting tree (XGBoost) to reconstruct the water storage changes over a one‐century timescale based on the generated bathymetry and satellite altimetry data and investigated the relationships with hydrological and climatic variables in long term. Results show that the water storage changes from 1961 to 2019 were featured by four fluctuation phases, with the highest water storage observed in 1991 (14.02 Gt) and the lowest point in 2012 (5.18 Gt). The century‐scale reconstruction result reveals that the water storage of Lake Hulun reached the highest point in the 1960s within the period of 1910–2019. The lowest stage occurred in the sub‐period of the 1930s–1940s, which was even lower than the alerted shrinkage stage in 2012. The predictive model results indicate the effective performance of the XGBoost model in reconstructing century‐scale water storage variations, with the mean absolute error of 0.68, normalized root mean square error of 0.11, Nash–Sutcliffe efficiency of 0.97, and correlation coefficient of 0.94. The annual fluctuations of water storage were mostly affected by precipitation, followed by vapor pressure, temperature, potential evapotranspiration, and wet day frequency. The dominating characteristics of different variables vary evidently with different sub‐periods. The atmospheric circulations of the Arctic Oscillation, El Nino Southern Oscillation, Pacific Decadal Oscillation, and North Atlantic Oscillation have tight associations with the water storage variations of Lake Hulun, which change with different study periods.
Spontaneous Imbibition in a Square Tube With Corner Films: Theoretical Model and Numerical Simulation
Authors: Zhao Jianlin , Qin Feifei , Fischer Robert , Kang Qinjun , Derome Dominique , Carmeliet Jan 
Published: February 2021

AbstractSpontaneous imbibition in an angular tube with corner films is a fundamental problem in many scientific and engineering processes. In this study, a modified interacting capillary bundle model is developed to describe the liquid imbibition dynamics in a square tube with corner films. The square tube is decomposed into several interacting subcapillaries and the local capillary pressure in each subcapillary is derived based on the specific shape of its meniscus. The conductance of each subcapillary is calculated using single‐phase lattice Boltzmann simulation. The modified interacting capillary bundle model and color‐gradient lattice Boltzmann method are used to simulate the liquid imbibition dynamics in the square tube with different fluid properties. The predictions by the modified interacting capillary bundle model match well with the lattice Boltzmann simulation results for different conditions, demonstrating the accuracy and robustness of the interacting capillary bundle model to describe the imbibition dynamics with corner films. In addition, the interacting capillary bundle model is helpful to investigate the mechanisms during spontaneous imbibition and the influences of fluid viscosity, surface tension, wetting phase contact angle and gravity on imbibition dynamics. Finally, a universal scaling law of imbibition dynamics for the main meniscus is developed and the scaling law for arc meniscus is also analyzed.
Identification of potential biomarkers associated with immune infiltration in the esophageal carcinoma tumor microenvironment
Authors: Wang Zhicheng , Chen Meilin , Qiu Yanbing , Yang Yuqin , Huang Yumei , Li Xiaoxu , Zhang Wenling 
Published: February 2021

Abstract
Tumor immune cell infiltration was significantly correlated with the progression and the effect of immunotherapy in cancers including esophageal carcinoma (ESCA). However, no biomarkers were identified which were associated with immune infiltration in ESCA. In the present study, a total of 128 common differentially expressed genes (DEGs) were identified between esophageal squamous cell carcinomas (ESCC) and esophageal adenocarcinomas (EAC). The results of gene ontology (GO) enrichment and Reactome pathway analysis displayed that the up-regulated DEGs were mainly involved in the regulation of extracellular matrix (ECM), while the down-regulated DEGs were mainly involved in the regulation of cornification and keratinocyte differentiation. The most significant module of up-regulated DEGs was selected by Molecular Complex Detection (MCODE). Top ten similar genes of COL1A2 were explored, then validation and the prognostic analysis of these genes displayed that COL1A2, COL1A1, COL3A1, ZNF469 and Periostin (POSTN) had the prognostic value which were up-regulated in ESCA. The expressions of COL1A2 and its four similar genes were mainly correlated with infiltrating levels of macrophages and dendritic cells (DCs) and showed strong correlations with diverse immune marker sets in ESCA. To summarize, COL1A2 and its four similar genes were identified as the potential biomarkers associated with immune infiltration in ESCA. These genes might be applied to immunotherapy for ESCA.