bluuebunny/crossref_metadata_2025 huggingface dataset:
Listening for the Landing: Seismic Detections of Perseverance's Arrival at Mars With InSight
Authors: Fernando Benjamin , Wójcicka Natalia , Froment Marouchka , Maguire Ross , Stähler Simon C. , Rolland Lucie , Collins Gareth S. , Karatekin Ozgur , Larmat Carene , Sansom Eleanor K. , Teanby Nicholas A. , Spiga Aymeric , Karakostas Foivos , Leng Kuangdai , Nissen‐Meyer Tarje , Kawamura Taichi , Giardini Domenico , Lognonné Philippe , Banerdt Bruce , Daubar Ingrid J.
Published: March 2021

The entry, descent, and landing (EDL) sequence of NASA's Mars 2020 Perseverance Rover will act as a seismic source of known temporal and spatial localization. We evaluate whether the signals produced by this event will be detectable by the InSight lander (3,452 km away), comparing expected signal amplitudes to noise levels at the instrument. Modeling is undertaken to predict the propagation of the acoustic signal (purely in the atmosphere), the seismoacoustic signal (atmosphere‐to‐ground coupled), and the elastodynamic seismic signal (in the ground only). Our results suggest that the acoustic and seismoacoustic signals, produced by the atmospheric shock wave from the EDL, are unlikely to be detectable due to the pattern of winds in the martian atmosphere and the weak air‐to‐ground coupling, respectively. However, the elastodynamic seismic signal produced by the impact of the spacecraft's cruise balance masses on the surface may be detected by InSight. The upper and lower bounds on predicted ground velocity at InSight are 2.0 × 10−14 and 1.3 × 10−10 m s−1. The upper value is above the noise floor at the time of landing 40% of the time on average. The large range of possible values reflects uncertainties in the current understanding of impact‐generated seismic waves and their subsequent propagation and attenuation through Mars. Uncertainty in the detectability also stems from the indeterminate instrument noise level at the time of this future event. A positive detection would be of enormous value in constraining the seismic properties of Mars, and in improving our understanding of impact‐generated seismic waves.
Alkalinity Production Coupled to Pyrite Formation Represents an Unaccounted Blue Carbon Sink
Authors: Reithmaier Gloria M. S. , Johnston Scott G. , Junginger Tobias , Goddard Madeline M. , Sanders Christian J. , Hutley Lindsay B. , Ho David T. , Maher Damien T.
Published: March 2021

Blue carbon ecosystems, including mangroves, saltmarshes, and seagrasses, mitigate climate change by storing atmospheric carbon. Previous blue carbon research has focused on organic carbon stocks. However, recent studies suggest that lateral inorganic carbon export might be equally important. Lateral export is a long‐term carbon sink if carbon is exported as alkalinity (TAlk) produced via sulfate reduction coupled to pyrite formation. This study evaluates drivers of pyrite formation in blue carbon ecosystems, compares pyrite production to TAlk outwelling rates, and estimates global pyrite stocks in mangroves. We quantified pyrite stocks in mangroves, saltmarshes, and seagrasses along a latitudinal gradient on the Australian East Coast, including a mangrove dieback area, and in the Everglades (Florida, USA). Our results indicate that pyrite stocks were driven by a combination of biomass, tidal amplitude, sediment organic carbon, sediment accumulation rates, rainfall, latitude, temperature, and iron availability. Pyrite stocks were three‐times higher in mangroves (103 ± 61 Mg/ha) than in saltmarshes (30 ± 30 Mg/ha) and seagrasses (32 ± 1 Mg/ha). Mangrove pyrite stocks were linearly correlated to TAlk export at sites where sulfate reduction was the dominant TAlk producing process. However, pyrite generation could not explain all TAlk outwelling. We present the first global model estimating pyrite stocks in mangroves, giving a first‐order estimate of 197 Mg/ha (RMSE = 24 Mg/ha). In mangroves, estimated global TAlk production coupled to pyrite formation (∼3 mol/m2/y) is equal to ∼24% of their global carbon burial rate, highlighting the importance of including TAlk export in future blue carbon budgets.
The Role of Sulfuric Acid in Continental Weathering: Insights From Dissolved Major Ions and Inorganic Carbon Isotopes of the Teesta River, Lower Brahmaputra System
Authors: Das Satyabrata , Tripathy Gyana Ranjan , Rai Santosh K. , Danish Mohd , Thakur Divya , Dutt Som , Sarangi Shushanta
Published: March 2021

Chemical weathering in the Himalayan river basins plays a key role in the global carbon cycle that controls the climate. In this contribution, the spatial distribution of dissolved major ions and (inorganic) carbon isotopic compositions of the Teesta River, a major tributary of the Brahmaputra River, has been investigated to constrain solute sources, weathering patterns, and acids involved in these processes. Mixing diagrams and piper plots of major ions indicate a dominant solutes supply by weathering of silicates and carbonates. The average sulfate concentration of the Teesta samples (92 ± 47 µM) is significantly higher than that reported earlier for atmospheric deposition (∼5 µM) in this basin. The carbon isotopic compositions of the dissolved inorganic fractions (δ13CDIC) of the samples vary between −11.87‰ and −3.82‰ (mean: −7‰ ± 2‰). Comparison of δ13CDIC – SO4/(SO4 + HCO3) – HCO3/(Ca + Mg) trends with their corresponding values expected for H2SO4 and H2CO3 acid‐mediated weathering indicates that both these acids contribute to chemical weathering in the Teesta river catchment. Inversion modeling of major ions and δ13CDIC data have been used to quantify the impact of carbonic (H2CO3) and sulfuric acids (H2SO4) on the Teesta water chemistry. On average, the fractions of cations derived from H2CO3‐mediated weathering of carbonates (0.27 ± 0.14) and silicates (0.20 ± 0.09) are comparable with H2SO4‐mediated carbonate (0.38 ± 0.18) and silicate (0.15 ± 0.11) weathering in this basin. These results show that the amount of CO2 uptake (via H2CO3‐mediated silicate weathering) and release (via H2SO4‐mediated carbonate weathering) are in balance for the Teesta River.
The Effect of the Martian 2018 Global Dust Storm on HDO as Predicted by a Mars Global Climate Model
Authors: Rossi Loïc , Vals Margaux , Montmessin Franck , Forget François , Millour Ehouarn , Fedorova Anna , Trokhimovskiy Alexander , Korablev Oleg
Published: March 2021

The deuterium to hydrogen (D/H) ratio is commonly used to investigate the history of water on Mars, yet the mechanisms controlling present‐day HDO behavior are poorly understood. Significant variations of the D/H ratio were first predicted on the basis of a 3D global climate model, which were later confirmed by ground‐based observations. This behavior, consisting of lower HDO/H2O ratios in the colder regions of Mars, is related to the isotopic fractionation occurring at condensation. We leverage this previous effort and present an updated implementation, using the modern version of the model, that remains in agreement with the older version. We explore the impact of the global dust storm (GDS) that occurred during Martian year 34 (MY34) on HDO. Our simulations indicate that HDO is on average 40% more abundant at 100 km during the MY34 GDS year than during a regular year, with likely large consequences for the escape flux of water that year.
Deadly Heat Stress to Become Commonplace Across South Asia Already at 1.5°C of Global Warming
Authors: Saeed Fahad , Schleussner Carl‐Friedrich , Ashfaq Moetasim
Published: March 2021

South Asia (SA) is one of those hotspots where earliest exposure to deadly wet‐bulb temperatures (Tw >35°C) is projected in warmer future climates. Here we find that even today parts of SA experience the upper limits of labor productivity (Tw >32°C) or human survivability (Tw >35°C), indicating that previous estimates for future exposure to Tw‐based extremes may be conservative. Our results show that at 2°C global warming above pre‐industrial levels, the per person exposure approximately increases by 2.2 (2.7) folds for unsafe labor (lethal) threshold compared to the 2006–2015 reference period. Limiting warming to 1.5°C would avoid about half that impact. The population growth under the middle‐of‐the‐road socioeconomic pathway could further increase these exposures by a factor of ∼2 by the mid‐century. These results indicate an imminent need for adaptation measures, while highlighting the importance of stringent Paris‐compatible mitigation actions for limiting future emergence of such conditions in SA.
An Atmospheric Signal Lowering the Spring Predictability Barrier in Statistical ENSO Forecasts
Authors: Mukhin Dmitry , Gavrilov Andrey , Seleznev Aleksei , Buyanova Maria
Published: March 2021

The loss of autocorrelations of tropical sea surface temperatures (SST) during late spring, also called the spring predictability barrier (SPB), is a factor that strongly limits the predictability of El Nino Southern Oscillation (ENSO), and especially the statistical SST‐based ENSO forecasts starting from the winter‐spring season. Recent studies show that Pacific atmospheric circulation anomalies in winter‐spring may have a long‐term impact on the summer tropical climate via the SST footprint. Here, we infer an index based on sea level pressure (SLP) data from February to March in a single area surrounding Hawaii, and show that this area is the most informative part of the large SLP pattern initiating the SST footprinting mechanism. We then construct a statistically optimal linear model of the Nino 3.4 index taking this atmospheric index as a forcing. We find that this forcing efficiently lowers the SPB and provides significant improvements of interseasonal Niño 3.4 forecasts.
Poroelasticity Contributes to Hydraulic‐Stimulation Induced Pressure Changes
Authors: Dutler N. O. , Valley B. , Amann F. , Jalali M. , Villiger L. , Krietsch H. , Gischig V. , Doetsch J. , Giardini D.
Published: March 2021

High‐pressure fluid injections cause transient pore pressure changes over large distances, which may induce seismicity. The zone of influence for such an injection was studied at high spatial resolutions in six decameter‐scaled fluid injection experiments in crystalline rock. Pore pressure time series revealed two distinct responses based on the lag time and magnitude of pressure change, namely, a near‐ and far‐field response. The near‐field response is due to pressure diffusion. In the far‐field, the fast response time and decay of pressure changes are produced by effective stress changes in the anisotropic stress field. Our experiments confirm that fracture fluid pressure perturbations around the injection point are not limited to the near field and can extend beyond the pressurized zone.
Spatiotemporal Heterogeneity of Aerosol and Cloud Properties Over the Southeast Atlantic: An Observational Analysis
Authors: Chang Ian , Gao Lan , Burton Sharon P. , Chen Hong , Diamond Michael S. , Ferrare Richard A. , Flynn Connor J. , Kacenelenbogen Meloë , LeBlanc Samuel E. , Meyer Kerry G. , Pistone Kristina , Schmidt Sebastian , Segal‐Rozenhaimer Michal , Shinozuka Yohei , Wood Robert , Zuidema Paquita , Redemann Jens , Christopher Sundar A.
Published: March 2021

The southeast Atlantic has expansive aerosol plumes overlying clouds for a third of each year. Aerosol optical depths (AODs) were measured from the airborne Sun photometer and lidar during the 2016 NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) field campaign. We compare these measurements with one another and with collocated Moderate Resolution Imaging Spectroradiometer (MODIS) observations at native spatial resolutions using <15‐min and 3‐h temporal collocation criteria. We find better statistical relationships for the <15‐min temporal resolution, indicating that AODs in the southeast Atlantic commonly vary below three‐hourly temporal scales over MODIS spatial resolutions. We also use the airborne Solar Spectral Flux Radiometer (SSFR) to conduct the first comprehensive evaluation of attenuation‐corrected below‐aerosol cloud optical depths (CODs) from MODIS and the Spinning Enhanced Visible and Infrared Imager (SEVIRI). MODIS COD retrievals improve their agreement with the SSFR when accounting for overlying aerosol attenuation whereas SEVIRI CODs are mostly underestimated.
More Significant Impacts From New Particle Formation on Haze Formation During COVID‐19 Lockdown
Authors: Tang Lizi , Shang Dongjie , Fang Xin , Wu Zhijun , Qiu Yanting , Chen Shiyi , Li Xin , Zeng Limin , Guo Song , Hu Min
Published: March 2021

During the COVID‐19 lockdown in 2020, large‐scale industrial and transportation emissions were reduced, but high PM2.5 concentration still occurred. This study investigated the variation of particle number size distribution during the lockdown, and analyzed the characteristics of new particle formation (NPF) events and its potential impact on haze formation. Through measurement conducted in urban Beijing during the first 3 months of 2020, and comparison with year‐over‐year data, the decrease of primary Aitken‐mode particles was observed. However, frequencies, formation rates and growth rates of NPF events remained stable between 2020 and 2019 in the same period. As a result, >25 nm particles produced by NPF events, would play a more important role in serving as the haze formation “seeds” compared to those produced by primary emissions. This finding emphasizes the significance on the understanding of NPF mechanisms when making pollution mitigation policy in the future.
How Robust Is the Apparent Break‐Down of Northern High‐Latitude Temperature Control on Spring Carbon Uptake?
Authors: Joyce Peter , Brienen Roel , Buermann Wolfgang , Wilson Chris , Chipperfield Martyn P. , Claret Mariona , Gloor Manuel
Published: March 2021

Vegetation growth in northern high‐latitudes during springtime is strongly temperature limited, and thus anomalously warm springs are expected to result in an increased drawdown of carbon dioxide (CO2). However, a recent analysis of the relationship between spring temperature anomalies and atmospheric CO2 anomalies at Point Barrow, Alaska, suggests that the link between spring carbon uptake by northern ecosystems and temperature anomalies has been weakening over recent decades due to a diminishing control of temperature on plant productivity. Upon further analysis, covering the 1982–2015 period, we found no significant change in the relationship between spring vegetation productivity derived from remote sensing data and air temperature. We showed that a reduction in spatial coherence of temperature anomalies, alongside a significant sensitivity to atmospheric transport, is likely responsible for the apparent weakening. Our results, therefore, suggest that spring temperature remains as an important control of northern high‐latitude CO2 uptake.
Extracting Near‐Field Seismograms From Ocean‐Bottom Pressure Gauge Inside the Focal Area: Application to the 2011 Mw 9.1 Tohoku‐Oki Earthquake
Authors: Kubota Tatsuya , Saito Tatsuhiko , Tsushima Hiroaki , Hino Ryota , Ohta Yusaku , Suzuki Syuichi , Inazu Daisuke
Published: March 2021

Recent studies have shown that ocean‐bottom pressure gauges (OBPs) can record seismic waves in addition to tsunamis and seafloor permanent displacements, even if they are installed inside the focal area where the signals are extremely large. We developed a method to extract dynamic ground motion waveforms from near‐field OBP data consisting of a complex mixture of various signals, based on an inversion analysis along with a theory of tsunami generation. We applied this method to the OBP data of the 2011 Tohoku‐Oki earthquake. We successfully extracted the low‐frequency vertical seismograms inside the focal area (f < ∼0.05 Hz), although those of the Mw ∼9 megathrust earthquake had never previously been reported. The seismograms suggested two dominant energy releases around the hypocenter. The seismic wave signals recorded by the near‐field OBP will be important not only to reveal earthquake ruptures and tsunami generation processes but also to conduct real‐time tsunami forecasts.
Simulated Thermocline Tilt Over the Tropical Indian Ocean and Its Influence on Future Sea Surface Temperature Variability
Authors: Wang Guojian , Cai Wenju , Santoso Agus
Published: March 2021

Most coupled climate models simulate an overly shallow thermocline over the southeastern equatorial Indian Ocean (SEIO). Through the Bjerknes feedback loop, the associated unrealistic thermocline tilt leads to warmer sea surface temperature (SST) over the western equatorial Indian Ocean than the SEIO, which is conducive to equatorial easterly winds. Similar to phase 5 of the Coupled Model Intercomparison Project (CMIP), phase 6 of the CMIP continues to simulate such overly tilted thermocline. On the one hand, this leads to overly strong SST variability, and on the other hand, it provides an inherent limit for the thermocline to incline further under greenhouse warming. Consequently, models with a more realistic tilt in the present‐day climate project a greater shoaling of the thermocline under global warming, which facilities upwelling of cool subsurface water, leading to stronger increase in SST variability over the SEIO, compared to models with an overly large thermocline tilt.
The Synoptic to Decadal Variability in the Winter Surface Wind Speed Over China by the Weather Regime View
Authors: Zhang Zhengtai , Wang Kaicun
Published: March 2021

The observed surface wind speed (SWS) has declined over the past 4 decades over China, which have has been examined from a climatological perspective. However, the SWS is highly variable and is dependent on the weather regime (WR). This study investigates the variability of winter SWS under six typical WRs and assesses the variability at the synoptic to decadal time scales. Our results reveal that the WRs impose important impacts on the spatial pattern and inter‐annual variability of SWS over China. The Siberian high pressure exerts an important influence on the WR occurrence over Eastern Asia and affects the SWS variations, with more prominent impacts at the decadal time scale. The Aleutian low pressure exhibits weak inter‐annual correlations with the SWS under all WRs but reveals closer decadal connections under certain WRs. However, WRs cannot sufficiently explain the decreasing trend of SWS from 1980 to 2017.
Whistler‐Mode Waves Trapped by Density Irregularities in the Earth's Magnetosphere
Authors: Ke Yangguang , Chen Lunjin , Gao Xinliang , Lu Quanming , Wang Xueyi , Chen Rui , Chen Huayue , Wang Shui
Published: March 2021

Whistler‐mode waves are electromagnetic waves pervasively observed in the Earth's and other planetary magnetospheres. They are considered to be mainly responsible for producing the hazardous radiation and diffuse aurora, which heavily relies on their properties. Density irregularities, frequently observed in the Earth's magnetospheres, are found to change largely the properties of whistler‐mode waves. Here we report, using Van Allen Probes measurements, whistler‐mode waves strongly modulated by two different density enhancements. With particle‐in‐cell simulations, we propose wave trapping caused by field‐aligned density irregularities (ducts) may account for this phenomenon. Simulation results show that whistler‐mode waves can be trapped inside the enhanced density ducts. These trapped waves remain quasi‐parallel and usually get much larger amplitudes than those unducted whistler waves during propagation away from the magnetic equator, and tend to focus at a spatially narrow channel, consistent with observations. Our results imply density irregularities may be significant to modulate radiation‐belt electrons.
A New Method to Calculate the Fluxgate Magnetometer Offset in the Interplanetary Magnetic Field: 1. Using Alfvén Waves
Authors: Wang Guoqiang , Pan Zonghao
Published: March 2021

Magnetic field measurements are essential to explore space. However, the measurement of the fluxgate magnetometer (FGM) is not zero in the null magnetic field. Three methods have been provided to calculate the zero offset of the FGM on‐board spacecraft in the solar wind based on the assumption that the fluctuations are Alfvén waves. Here, we develop a new method to calculate the zero offset O based on the characteristic of Alfvén waves. We first build an offset cube based on the possible range of O since the strength of the interplanetary magnetic field is limited. The variance of the modified BT (marked as δ) at a point in the offset cube can be obtained. We find that the point with the minimum δ in each plane along a certain axis forms a straight line, which is referred to as the optimal offset line. Interestingly, this line crosses the point with a value equal to O, and its direction is associated with the ambient magnetic field of Alfvén waves. We also find that different optimal offset lines have an intersection with a value of O, suggesting that these characteristics of the optimal offset line can be used to determine the zero offset of the FGM. The test results show that our method can get a zero offset with a high accuracy. We suggest that the new method is a useful technique to find the zero offset of the magnetometer for solar wind monitors.
Paleointensity Results From Pliocene Lavas of the Lesser Caucasus Obtained Using the Multispecimen Parallel Differential pTRM Method: A Comparison With Thellier‐Thellier and IZZI Data
Authors: Sánchez‐Moreno Elisa M. , Calvo‐Rathert Manuel , Goguitchaichvili Avto , Vashakidze George T. , Camps Pierre , Morales‐Contreras Juan , Vegas‐Tubía Néstor , Lebedev Vladimir A.
Published: March 2021

We report paleointensity results obtained with the multispecimen method (MSP) over the Pliocene sequence of Apnia (Georgia) which records a polarity reversal. Paleointensity determinations with the multispecimen technique were performed on 12 flows with the original (MSP‐DB) and the domain‐state corrected (MSP‐DSC) protocol. Eight MSP‐DSC determinations passed the proposed quality criteria. To obtain highly reliable data through the agreement between intensity values from different methods, MSP results were combined with paleointensities from a previous study with Thellier‐type methods and especially strict selection criteria (RCRIT) on same flows (Sánchez‐Moreno et al., 2020). Application of this multimethod procedure resulted in three new paleointensities including both MSP and Thellier‐type results and an additional one obtained with two different Thellier‐type methods, yielding one paleointensity of 36.9 µT in the normal‐polarity, and three paleointensities between 19.2 and 24.1 µT in the reverse‐polarity section. Additionally, Thellier‐type data have been reinterpreted in this study with more flexible criteria (TTP) and the results combined with the MSP data. As a result, four flows yield paleointensities including MSP and Thellier‐type determinations and seven include paleointensities obtained with two different Thellier‐type methods. Results range from 37.2 and 44.3 μT in the normal‐polarity and from 12.5 to 24.6 μT in the reverse‐polarity section. Comparison of results from the four flows yielding multimethod determinations applying RCRIT criteria with those from the same flows under TTP criteria yields no significant difference in paleointensity values and their experimental uncertainty. Thus, application of a multimethod approach supports the possibility of using TTP criteria.
Sources of Subseasonal‐To‐Seasonal Predictability of Atmospheric Rivers and Precipitation in the Western United States
Authors: Huang Huanping , Patricola Christina M. , Bercos‐Hickey Emily , Zhou Yang , Rhoades Alan , Risser Mark D. , Collins William D.
Published: March 2021

Atmospheric rivers (ARs) account for a large portion of winter precipitation in the western US. To evaluate the sources of AR and precipitation predictability at subseasonal‐to‐seasonal timescales, we examine the relationships between two climate modes, the El Niño/Southern Oscillation (ENSO) and Madden‐Julian oscillation (MJO), and winter hydroclimate in the western US. Our analysis uses a large ensemble of the Weather Research and Forecast (WRF) model simulations from 1981 to 2017, facilitating the assessment of uncertainty in climate mode‐AR relationship due to climate variability and short length of observations. Over the North Pacific basin, we find ENSO‐related latitudinal shifts of ARs, but ENSO has little effect on basin‐wide averaged AR frequency. Over the western US, there is some uncertainty in the ENSO‐AR connection due to the impacts of ENSO indices and datasets. However, extreme El Niño events defined by the ENSO longitude index are consistently linked to increased landfalling AR activity. The MJO can lead to significantly enhanced or suppressed landfalling AR activity in the large‐ensembles, depending on the phase of MJO and time lag, while observations are too short in length to robustly show this signal. ENSO substantially modulates the MJO‐AR relationship, triggering variegated responses of landfalling ARs and AR precipitation in La Niña and El Niño years. Our findings highlight the need to evaluate concurrent effects of different climate modes on ARs and precipitation, and may shed light on a path toward more accurate subseasonal‐to‐seasonal prediction of ARs and precipitation over the western US.
Legacy Effects Following Fire on Surface Energy, Water and Carbon Fluxes in Mature Amazonian Forests
Authors: de Oliveira Gabriel , Brunsell Nathaniel A. , Chen Jing M. , Shimabukuro Yosio E. , Mataveli Guilherme A. V. , dos Santos Carlos A. C. , Stark Scott C. , de Lima Andre , Aragao Luiz E. O. C.
Published: March 2021

The ongoing deforestation process in Amazonia has led to intensified forest fires in the region, particularly in Brazil, after more than a decade of effective forest conservation policy. This study aims to investigate the recovery of two mature sub‐montane ombrophile Amazonian forests affected by fire in terms of energy, water and carbon fluxes utilizing remote sensing (MODIS) and climate reanalysis data (GLDAS). These two forest plots, mainly composed of Manilkara spp. (Maçaranduba), Protium spp. (Breu) (∼30 m), Bertholletia excelsa (Castanheira) and Dinizia excelsa Ducke (Angelim‐Pedra) (∼50 m), occupy areas of 100.5 and 122.1 km2 and were subject to fire on the same day, on September 12, 2010. The fire significantly increased land surface temperature (0.8°C) and air temperature (1.2°C) in the forests over a 3 years interval. However, the forests showed an ability to recover their original states in terms of coupling between the carbon and water cycles comparing the 3‐year periods before and after the fires. Results from a wavelet analysis showed an intensification in annual and seasonal fluctuations, and in some cases (e.g., daily net radiation and evapotrasnspiration) sub‐annual fluctuation. We interpreted these changes to be consistent with overall intensification of the coupling of energy balance components and drivers imposed by climate and solar cycle seasonality, as well as faster time scale changes, consistent with a shift toward greater forest openness and consequent reduction in the interception of incoming solar radiation by the canopy.
A Framework for Modeling Rock Glaciers and Permafrost at the Basin‐Scale in High Alpine Catchments
Authors: Pruessner L. , Huss M. , Phillips M. , Farinotti D.
Published: March 2021

Since rock glaciers are believed to be more resilient to climate change, water stores therein may become important water reservoirs in future, in particular in dry regions, which currently rely on glacial runoff. In order to estimate and evaluate the future runoff potential from permafrost and rock glaciers, distributed runoff models suitable for high Alpine catchments are needed. An extension to the distributed Glacier Evolution and Runoff Model (GERM) to include permafrost and rock glaciers in Alpine catchments is presented here, and compared to the established one dimensional (1D) physics‐based model SNOWPACK. The new permafrost component introduced to GERM treats permafrost as discreet depth layers in a 1D column for all grid cells, which have bulk thermal properties calculated from their constituents (ice, water, air, and solid component). The temperature evolution is computed using heat conduction and latent heat exchanges, modified by ventilation effects. Finally, we infer water runoff from permafrost degradation. Ground temperature variations calculated by both models are compared to borehole measurements at three Alpine sites and similar performances are found. Differences between the models are present in the amplitude of seasonal ground temperature variations, with SNOWPACK having a tendency to slightly overestimate them, while GERM underestimates them.
Prediction of Dynamic Plasmapause Location Using a Neural Network
Authors: Guo Deyu , Fu Song , Xiang Zheng , Ni Binbin , Guo Yingjie , Feng Minghang , Guo Jianguang , Hu Zejun , Gu Xudong , Zhu Jianan , Cao Xing , Wang Qi
Published: March 2021

As a common boundary layer that distinctly separates the regions of high‐density plasmasphere and low‐density plasmatrough, the plasmapause is essential to comprehend the dynamics and variability of the inner magnetosphere. Using the machine learning framework PyTorch and high‐quality Van Allen Probes data set, we develop a neural network model to predict the global dynamic variation of the plasmapause location, along with the identification of 6,537 plasmapause crossing events during the period from 2012 to 2017. To avoid the overfitting and optimize the model generalization, 5,493 events during the period from September 2012 to December 2015 are adopted for division into the training set and validation set in terms of the 10‐fold cross‐validation method, and the remaining 1,044 events are used as the test set. The model parameterized by only AE or Kp index can reproduce the plasmapause locations similar to those modeled using all five considered solar wind and geomagnetic parameters. Model evaluation on the test set indicates that our neural network model is capable of predicting the plasmapause location with the lowest RMSE. Our model can also produce a smooth magnetic local time variation of the plasmapause location with good accuracy, which can be incorporated into global radiation belt simulations and space weather forecasts under a variety of geomagnetic conditions.
Uncertainty Analysis and Identification of Key Parameters Controlling Bacteria Transport Within a Riverbank Filtration Scenario
Authors: Knabe Dustin , Guadagnini Alberto , Riva Monica , Engelhardt Irina
Published: March 2021

Managed aquifer recharge through bank filtration is an important method to produce sustainable drinking water. Yet, water quality related to transport of pathogens (bacteria and viruses) into groundwater systems from surface waters can be a matter of concern, especially in urbanized regions. Based on a 1‐year monitoring campaign, a reactive transport model was developed for bacteria transport at a riverbank filtration site located in Germany. The model allows simulating advective‐dispersive transport and relies on the colloid filtration theory to mimic attachment and detachment of bacteria to and from the sediment in addition to inactivation, straining and blocking of bacteria. Due to the complexity of the investigated processes, the reactive transport model is characterized by a high level of parametrization, encompassing parameters driving flow as well as solute and colloid transport. A global sensitivity analysis has been applied to identify the most relevant model parameters with respect to piezometric pressure heads, groundwater temperature, and concentrations of chloride, oxygen, coliforms, and Escherichia coli. The model has been calibrated within a stochastic framework, to provide model parameter estimates and to quantify their uncertainty. Our results suggest that bacteria transport models are highly sensitive to inactivation coefficients, straining coefficients, and bacteria size. Permeability of the colmation layer at the riverbank is a key factor for bacteria transport through its influence on residence times. Seasonal variability of boundary conditions, especially anoxic aquifer conditions in the summer and high groundwater flow velocities during flooding periods, resulted in a reduction of inactivation and increased bacteria concentrations at observation wells.
Deriving Melt Rates at a Complex Ice Shelf Base Using In Situ Radar: Application to Totten Ice Shelf
Authors: Vaňková Irena , Cook Sue , Winberry J. Paul , Nicholls Keith W. , Galton‐Fenzi Benjamin K.
Published: March 2021

A phase‐sensitive radar (ApRES) was deployed on Totten Ice Shelf to provide the first in situ basal melt estimate at this dynamic East Antarctic ice shelf. Observations of internal ice dynamics at tidal time scales showed that early arrivals from off‐nadir reflectors obscure the true depth of the ice shelf base. Using the observed tidal deformation, the true base was found to lie at 1,910–1,950‐m depth, at 350–400 m greater range than the first reflection from an ice‐ocean interface. The robustness of the basal melt rate estimate was increased by using multiple basal reflections over the radar footprint, yielding a melt rate of 22 ± 2.1 m a−1. The ApRES estimate is over 40% lower than the three existing satellite estimates covering Totten Ice Shelf. This difference in basal melt is dynamically significant and highlights the need for independent melt rate estimates using complementary instrumentation and techniques that rely on different sets of assumptions.
Treatment-free remission following frontline nilotinib in patients with chronic phase chronic myeloid leukemia: 5-year update of the ENESTfreedom trial
Authors: Radich Jerald P. , Hochhaus Andreas , Masszi Tamás , Hellmann Andrzej , Stentoft Jesper , Casares María Teresa Gómez , García-Gutiérrez J. Valentín , Conneally Eibhlin , le Coutre Philipp D. , Gattermann Norbert , Martino Bruno , Saussele Susanne , Giles Francis J. , Ross David M. , Aimone Paola , Li Sai , Titorenko Ksenia , Saglio Giuseppe
Published: March 2021

The ENESTfreedom trial assessed the feasibility of treatment-free remission (TFR) in patients with chronic myeloid leukemia in chronic phase (CML-CP) following frontline nilotinib treatment. Results for long-term outcomes after a 5-year follow-up are presented herein. Patients who had received ≥2 years of frontline nilotinib therapy and achieved MR4.5underwent a 1-year nilotinib treatment consolidation phase before attempting TFR. At the 5-year data cut-off, 81/190 patients entering the TFR phase (42.6%) were still in TFR, with 76 (40.0%) in MR4.5. Patients who lost major molecular response (MMR) entered a treatment re-initiation phase; 90/91 patients entering this phase (98.9%) regained MMR and 84/91 patients (92.3%) regained MR4.5. The Kaplan–Meier estimated treatment-free survival rate at 5 years was 48.2%. No disease progression or CML-related deaths were reported. Whereas the incidence of adverse events (AEs) declined from 96 weeks following the start of TFR, an increase in AE frequency was observed for patients in the treatment re-initiation phase. Low Sokal risk score,BCR-ABL1ISlevels at 48 weeks of TFR and stable MR4.5response for the first year of TFR were associated with higher TFR rates. Overall, these results support the efficacy and safety of attempting TFR following upfront nilotinib therapy of >3 years in patients with CML-CP.
Demonstration of an integrated nanophotonic chip-scale alkali vapor magnetometer using inverse design
Authors: Sebbag Yoel , Talker Eliran , Naiman Alex , Barash Yefim , Levy Uriel
Published: March 2021

Recently, there has been growing interest in the miniaturization and integration of atomic-based quantum technologies. In addition to the obvious advantages brought by such integration in facilitating mass production, reducing the footprint, and reducing the cost, the flexibility offered by on-chip integration enables the development of new concepts and capabilities. In particular, recent advanced techniques based on computer-assisted optimization algorithms enable the development of newly engineered photonic structures with unconventional functionalities. Taking this concept further, we hereby demonstrate the design, fabrication, and experimental characterization of an integrated nanophotonic-atomic chip magnetometer based on alkali vapor with a micrometer-scale spatial resolution and a magnetic sensitivity of 700 pT/√Hz. The presented platform paves the way for future applications using integrated photonic–atomic chips, including high-spatial-resolution magnetometry, near-field vectorial imaging, magnetically induced switching, and optical isolation.
Metabolomic analyses of COVID-19 patients unravel stage-dependent and prognostic biomarkers
Authors: Danlos François-Xavier , Grajeda-Iglesias Claudia , Durand Sylvère , Sauvat Allan , Roumier Mathilde , Cantin Delphine , Colomba Emeline , Rohmer Julien , Pommeret Fanny , Baciarello Giulia , Willekens Christophe , Vasse Marc , Griscelli Frank , Fahrner Jean-Eudes , Goubet Anne-Gaëlle , Dubuisson Agathe , Derosa Lisa , Nirmalathasan Nitharsshini , Bredel Delphine , Mouraud Séverine , Pradon Caroline , Stoclin Annabelle , Rozenberg Flore , Duchemin Jérôme , Jourdi Georges , Ellouze Syrine , Levavasseur Françoise , Albigès Laurence , Soria Jean-Charles , Barlesi Fabrice , Solary Eric , André Fabrice , Pène Frédéric , Ackerman Félix , Mouthon Luc , Zitvogel Laurence , Marabelle Aurélien , Michot Jean-Marie , Fontenay Michaela , Kroemer Guido
Published: March 2021

The circulating metabolome provides a snapshot of the physiological state of the organism responding to pathogenic challenges. Here we report alterations in the plasma metabolome reflecting the clinical presentation of COVID-19 patients with mild (ambulatory) diseases, moderate disease (radiologically confirmed pneumonitis, hospitalization and oxygen therapy), and critical disease (in intensive care). This analysis revealed major disease- and stage-associated shifts in the metabolome, meaning that at least 77 metabolites including amino acids, lipids, polyamines and sugars, as well as their derivatives, were altered in critical COVID-19 patient’s plasma as compared to mild COVID-19 patients. Among a uniformly moderate cohort of patients who received tocilizumab, only 10 metabolites were different among individuals with a favorable evolution as compared to those who required transfer into the intensive care unit. The elevation of one single metabolite, anthranilic acid, had a poor prognostic value, correlating with the maintenance of high interleukin-10 and -18 levels. Given that products of the kynurenine pathway including anthranilic acid have immunosuppressive properties, we speculate on the therapeutic utility to inhibit the rate-limiting enzymes of this pathway including indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase.
Bat and pangolin coronavirus spike glycoprotein structures provide insights into SARS-CoV-2 evolution
Authors: Zhang Shuyuan , Qiao Shuyuan , Yu Jinfang , Zeng Jianwei , Shan Sisi , Tian Long , Lan Jun , Zhang Linqi , Wang Xinquan
Published: March 2021

In recognizing the host cellular receptor and mediating fusion of virus and cell membranes, the spike (S) glycoprotein of coronaviruses is the most critical viral protein for cross-species transmission and infection. Here we determined the cryo-EM structures of the spikes from bat (RaTG13) and pangolin (PCoV_GX) coronaviruses, which are closely related to SARS-CoV-2. All three receptor-binding domains (RBDs) of these two spike trimers are in the “down” conformation, indicating they are more prone to adopt the receptor-binding inactive state. However, we found that the PCoV_GX, but not the RaTG13, spike is comparable to the SARS-CoV-2 spike in binding the human ACE2 receptor and supporting pseudovirus cell entry. We further identified critical residues in the RBD underlying different activities of the RaTG13 and PCoV_GX/SARS-CoV-2 spikes. These results collectively indicate that tight RBD–ACE2 binding and efficient RBD conformational sampling are required for the evolution of SARS-CoV-2 to gain highly efficient infection.
Flexible and high-performance electrochromic devices enabled by self-assembled 2D TiO2/MXene heterostructures
Authors: Li Ran , Ma Xiaoyuan , Li Jianmin , Cao Jun , Gao Hongze , Li Tianshu , Zhang Xiaoyu , Wang Lichao , Zhang Qinghong , Wang Gang , Hou Chengyi , Li Yaogang , Palacios Tomás , Lin Yuxuan , Wang Hongzhi , Ling Xi
Published: March 2021

Transition metal oxides (TMOs) are promising electrochromic (EC) materials for applications such as smart windows and displays, yet the challenge still exists to achieve good flexibility, high coloration efficiency and fast response simultaneously. MXenes (e.g. Ti3C2Tx) and their derived TMOs (e.g. 2D TiO2) are good candidates for high-performance and flexible EC devices because of their 2D nature and the possibility of assembling them into loosely networked structures. Here we demonstrate flexible, fast, and high-coloration-efficiency EC devices based on self-assembled 2D TiO2/Ti3C2Tx heterostructures, with the Ti3C2Tx layer as the transparent electrode, and the 2D TiO2 layer as the EC layer. Benefiting from the well-balanced porosity and connectivity of these assembled nanometer-thick heterostructures, they present fast and efficient ion and electron transport, as well as superior mechanical and electrochemical stability. We further demonstrate large-area flexible devices which could potentially be integrated onto curved and flexible surfaces for future ubiquitous electronics.
An extended APOBEC3A mutation signature in cancer
Authors: Langenbucher Adam , Bowen Danae , Sakhtemani Ramin , Bournique Elodie , Wise Jillian F. , Zou Lee , Bhagwat Ashok S. , Buisson Rémi , Lawrence Michael S.
Published: March 2021

APOBEC mutagenesis, a major driver of cancer evolution, is known for targeting TpC sites in DNA. Recently, we showed that APOBEC3A (A3A) targets DNA hairpin loops. Here, we show that DNA secondary structure is in fact an orthogonal influence on A3A substrate optimality and, surprisingly, can override the TpC sequence preference. VpC (non-TpC) sites in optimal hairpins can outperform TpC sites as mutational hotspots. This expanded understanding of APOBEC mutagenesis illuminates the genomic Twin Paradox, a puzzling pattern of closely spaced mutation hotspots in cancer genomes, in which one is a canonical TpC site but the other is a VpC site, and double mutants are seen only in trans, suggesting a two-hit driver event. Our results clarify this paradox, revealing that both hotspots in these twins are optimal A3A substrates. Our findings reshape the notion of a mutation signature, highlighting the additive roles played by DNA sequence and DNA structure.
Harmonized and high-quality datasets of aerosol optical depth at a US continental site, 1997–2018
Authors: Kassianov Evgueni , Cromwell Erol , Monroe Justin , Riihimaki Laura D. , Flynn Connor , Barnard Jaime , Michalsky Joseph J. , Hodges Gary , Shi Yan , Comstock Jennifer M.
Published: March 2021

Aerosol optical depth (AOD) characterizes the aerosol burden in the atmosphere, while its wavelength dependence is a sign of particle size. Long-term records of wavelength-resolved AOD with high quality and suitable continuity are required for climate change assessment. Typically, climate-related studies use AOD products provided by several, and perhaps different, ground-based instruments. The measurements from these instruments often have different accuracy and temporal resolution. To preserve the advantages of these products (high quality) and to reduce their disadvantages (patchy records), we generate a merged dataset obtained from four instruments deployed at a US continental site in which a nearly-continuous AOD record is found at two wavelengths (500 and 870 nm) with high quality and high temporal resolution (1-min) for a 21-yr period (1997–2018). The combined dataset addresses: (1) varying data quality and resolution mismatch of the individual AOD records, and (2) the uncertainty of the merged AOD and its relevance for user-specified needs. The generated dataset will be beneficial for a wide range of applications including aerosol-radiation interactions.
Forager and farmer evolutionary adaptations to malaria evidenced by 7000 years of thalassemia in Southeast Asia
Authors: Vlok Melandri , Buckley Hallie R. , Miszkiewicz Justyna J. , Walker Meg M. , Domett Kate , Willis Anna , Trinh Hiep H. , Minh Tran T. , Nguyen Mai Huong T. , Nguyen Lan Cuong , Matsumura Hirofumi , Wang Tianyi , Nghia Huu T. , Oxenham Marc F.
Published: March 2021

Thalassemias are inherited blood disorders that are found in high prevalences in the Mediterranean, Southeast Asia and the Pacific. These diseases provide varying levels of resistance to malaria and are proposed to have emerged as an adaptive response to malaria in these regions. The transition to agriculture in the Holocene has been suggested to have influenced the selection for thalassemia in the Mediterranean as land clearance for farming encouraged interaction between Anopheles mosquitos, the vectors for malaria, and human groups. Here we document macroscopic and microscopic skeletal evidence for the presence of thalassemia in both hunter-gatherer (Con Co Ngua) and early agricultural (Man Bac) populations in northern Vietnam. Firstly, our findings demonstrate that thalassemia emerged prior to the transition to agriculture in Mainland Southeast Asia, from at least the early seventh millennium BP, contradicting a long-held assumption that agriculture was the main driver for an increase in malaria in Southeast Asia. Secondly, we describe evidence for significant malarial burden in the region during early agriculture. We argue that the introduction of farming into the region was not the initial driver of the selection for thalassemia, as it may have been in other regions of the world.
Anti-EGFR antibody 528 binds to domain III of EGFR at a site shifted from the cetuximab epitope
Authors: Makabe Koki , Yokoyama Takeshi , Uehara Shiro , Uchikubo-Kamo Tomomi , Shirouzu Mikako , Kimura Kouki , Tsumoto Kouhei , Asano Ryutaro , Tanaka Yoshikazu , Kumagai Izumi
Published: March 2021

Antibodies have been widely used for cancer therapy owing to their ability to distinguish cancer cells by recognizing cancer-specific antigens. Epidermal growth factor receptor (EGFR) is a promising target for the cancer therapeutics, against which several antibody clones have been developed and brought into therapeutic use. Another antibody clone, 528, is an antagonistic anti-EGFR antibody, which has been the focus of our antibody engineering studies to develop cancer drugs. In this study, we explored the interaction of 528 with the extracellular region of EGFR (sEGFR) via binding analyses and structural studies. Dot blotting experiments with heat treated sEGFR and surface plasmon resonance binding experiments revealed that 528 recognizes the tertiary structure of sEGFR and exhibits competitive binding to sEGFR with EGF and cetuximab. Single particle analysis of the sEGFR–528 Fab complex via electron microscopy clearly showed the binding of 528 to domain III of sEGFR, the domain to which EGF and cetuximab bind, explaining its antagonistic activity. Comparison between the two-dimensional class average and the cetuximab/sEGFR crystal structure revealed that 528 binds to a site that is shifted from, rather than identical to, the cetuximab epitope, and may exclude known drug-resistant EGFR mutations.