bluuebunny/crossref_metadata_2025 huggingface dataset:
The NASA Multi-Angle Imager for Aerosols (MAIA): Providing Actionable Air Quality Data in Europe and Around the Globe
Authors: Nastan Abigail
Published: March 2022

The Multi-Angle Imager for Aerosols (MAIA) project is a NASA project focused on improving our understanding of the associations between speciated particulate matter (PM) air pollution and human health. The MAIA satellite instrument is currently being built at the NASA Jet Propulsion Laboratory (JPL), and NASA and JPL will identify a host satellite, with launch currently expected circa 2024 for a three-year baseline mission. The instrument will collect data on aerosol optical properties over a set of globally distributed target areas, which will be used in a geostatistical regression model, in combination with surface monitor data and chemical transport modeling, to derive surface-level PM concentrations. Epidemiologists on the MAIA Science Team will conduct studies in the eleven planned Primary Target Areas (PTAs) using the MAIA products to associate PM with various health outcomes. Observations are also planned in Secondary Target Areas (STAs) to provide data of interest to the community.

MAIA has a strong presence in Europe with two PTAs (Barcelona and Rome) and one STA, Belgrade, planned in the region. In the PTAs, the MAIA project will be providing data products including per-observation aerosol property data and per-observation and daily surface-level PM data (including total PM10 and PM2.5, and sulfate, nitrate, organic carbon, elemental carbon, and dust PM2.5). The project’s capacity to process the full suite of data products in any given STA is dependent on the associated observational objectives and availability of resources. MAIA data will be available free of charge from the NASA Atmospheric Science Data Center. This presentation will cover details of the MAIA target areas in Europe, prospective health studies, potential synergies with Sentinel-4 data, and how potential users can receive resources including MAIA simulated data.
Molecular recognition between membrane epitopes and nearly free surface silanols on silica: a new paradigm for particle toxicity mechanism
Authors: Turci Francesco , Pavan Cristina , Bellomo Chiara , Cananà Stefania , Rebba Erica , Sydor Matthew , Leinardi Riccardo , Kendall Rebekah , Mino Lorenzo , Holian Andrij , Lison Dominique
Published: March 2022

Respirable crystalline silica (RCS) is the leading cause of occupational respiratory disease worldwide. RCS is associated with silicosis, cancer, and autoimmune diseases [1]. Silica (SiO2) is a simple, yet structurally very complex oxide and tens of variable crystalline and amorphous forms exist with different structures and surfaces. Structural heterogeneity is reflected in variable toxic effects, and this in turn generates one of the most intriguing enigmas in particle toxicology, i.e., deciphering the exact molecular nature of the interaction between silica and biological matter.

A large set of synthetic and natural, crystalline and amorphous, micrometric and nanometric silica particles were prepared, modified, and characterized. The interaction of these surface-modified silicas with membrane systems of decreasing molecular complexity, e.g., red blood cells, liposomes, and phospholipid supramolecular structures (PLS), was investigated and compared with the results of in vitro and in vivo particle toxicity assessment.

A specific silanol (≡Si-OH) sub-group at silica surface, the “nearly free silanols” (NFS), was evidenced as the cause for the membranolytic and inflammatory effect of silica [2]. Silica powders with NFS-rich surfaces caused RBC membrane lysis, and selectively perturbed liposomes and adsorbed PLS. Specific amino groups exposed at the membrane surface are proposed as recognition epitopes for the selective interaction with NFS, which are in turn proposed as the molecular pattern that defines the interaction of silica with biomembranes [3]. Our findings open a new perspective for tailoring less toxic silica particles and for designing improved technological applications of silica. NFS and hydroxylated surface moieties may be also relevant for the toxicity of other respirable mineral dusts, suggesting a new paradigm for particle toxicity mechanism.

References
[1] Leung et al., Lancet 2012, 379, 2008; [2] Pavan et al., Proc. Natl. Acad. Sci USA 2020, 117, 27836; [3] Pavan et al., sumbitted to ACS Central Science
The societal impacts of volcanically induced climate forcing on Carthaginian (pre-Roman) northwestern Africa (396-146 BCE)
Authors: Hill Andrew , Ludlow Francis , McGovern Rhonda , Kostick Conor , Medenieks Selga
Published: March 2022

Before its destruction by the Roman army in 146 BCE, Carthage was one of the largest cities on earth. Established on a site some 15 km from modern day Tunis in ca. 814, the ancient town developed into the first truly urban centre of northwestern Africa; eventually housing a population of over half a million within its environs. As the hegemon of a vast territorial and maritime domain stretching by the fourth century from Morocco in the west to Libya in the east, Carthage was also the first state in the Maghreb to face the challenges incumbent in administrating provinces of such pronounced environmental diversity as their rain-fed hinterland in northern Tunisia and the arid coastal region of Tripolitania in modern Libya. Today, the majority of agriculture in Tunisia remains centred on the north of the country which benefits from the fickle graces of a Mediterranean climate, and where food production is deeply connected with the spatial distribution of winter rains critical to the farming season. Further south, and inland, drought risk increases concomitant with higher temperatures and less rainfall.

In 396, the Carthaginians faced a major rebellion of the subaltern working population of the countryside – one of a series of six rebellions recorded in classical sources for the 250 years until the fall of the city. Acknowledging the role of climate in influencing rapid social and political change in the modern region – with the outbreak of the Arab Spring occurring in the water-stressed region of Sidi Bouzid in Tunisia in 2011, for example – this paper examines whether the timing of internal war in the Carthaginian state was influenced by volcanically induced climatic perturbations via impacts on the agro-economy. Made possible by the publication of a revised chronology of explosive volcanic eruptions over the past 2,500 years (Sigl et al. (2015)), preliminary statistical testing reveals a non-random correlation with the timing of internal war. Recognising the complexity of the linkages between climate and conflict in agriculturally based economies, it can be hypothesized that the non-uniform impact of climatic shocks across geographically and demographically diverse spaces, as well as social strata within regions, was a key driver of unrest by increasing competition for land and resources between more well off resilient communities and those surviving on subsistence (Vesco et al. (2021)).
Atmospheric blocking patterns around the Antarctic Peninsula and their influences on temperature and moisture transport
Authors: Bozkurt Deniz , Marín Julio C. , Barrett ‪Bradford S.
Published: March 2022

This study analyzes the seasonal evolution and trends of atmospheric blocking and their influences on temperature and moisture transport around the Antarctic Peninsula for the period 1979-2020. A geopotential height-based method based on the ECMWF’s ERA5 and its predecessor ERA-Interim was applied over two domains, one located to the west (150-90W, 50-70S) and the other over and to the east (90-30W, 50-70S) of the Antarctic Peninsula. Spatial patterns of geopotential heights on days with blocking feature well-defined ridge axes over and west of much of South America, and days with the most extreme blocking (above the 99th percentile) show upper-tropospheric ridge and cut-off low features that have been associated with extreme weather patterns. Blocking days are found to be more frequent in the first half of the period (1979-1998) than the second (1999-2018) in all seasons in the west domain, whereas they seem to be more common over the eastern (Peninsula) domain in 1999-2018 for austral winter, spring, and autumn, although all these differences are not statistically significant. Meteorological observations in the Antarctic Peninsula indicate colder conditions than the observed climatology in the Antarctic Peninsula during blocking days over the western domain. On the contrary, mean blocking days over and to the east of the Peninsula yield warmer conditions than the climatology. Similar to the observed pattern, ERA5 also shows colder and warmer conditions during blocking days over the western and eastern domains, respectively. A further analysis with ERA5 indicates that blocking days over the Drake Passage and to the east of the Peninsula are associated with positive moisture transport anomalies towards the Peninsula coinciding with atmospheric river events, which trigger warm and humid conditions over the Peninsula, particularly in austral autumn. These results suggest that blocking patterns around the Antarctic Peninsula can have notable impacts on moisture transport and extreme temperature events affecting the cryospheric processes, particularly over the leeward side of the Peninsula and Larsen C Ice Shelf.
Automatic Picking of Teleseismic P- and S-Phases using an Autoregressive Prediction Approach 
Authors: Stampa Johannes , Eckel Felix , Kallinich Nina , Meier Thomas
Published: March 2022

In the recent decade, the amount of available seismological broadband data has increased steeply. Picking later arriving phases such as S-phases is difficult, and there are few manual picks available for these phases. Data sets of manual picks can also be problematic, since phase arrival picks are sensitive to the parameters of the filtering, which are often unknown, and the individual picking behavior of the analysts. However, accurate arrival times, especially for these phases, could be used to improve the accuracy of velocity models obtained from seismic tomography. This necessitates the adoption of automatic techniques for determining teleseismic phase arrival times consistently over a large data set.

In this work, a robust automatic picking algorithm based on autoregressive, multi-component, multiple-sample forward prediction is examined with regards to its accuracy. The phase is identified using the Akaike criterion and the onset time is found by evaluating discontinuities in the instantenous period of the signal. This signal analytic approach is tested using synthetic waveforms as well as real data in conjunction with manual picks obtained from the reviewed ISC-catalog.

Picking errors are estimated by comparing the automatic picks with manual picks, automatic picks at the neighboring stations as well as statistical meth- ods. The quality evaluations suggest potential of using these automatically determined phase arrival times for a travel time tomography.
Stretch and fold: Multistage analogue experiments of rifting, inversion, and orogenesis
Authors: Samsu Anindita , Betts Peter , Amirpoorsaeed Fatemeh , Cruden Alexander , Gorczyk Weronika
Published: March 2022

Analogue models are powerful tools for investigating extensional and convergent tectonic processes in 4D and at multiple scales. However, rarely do we introduce two successive phases of tectonism in a single analogue experiment to study the interaction between structures from two kinematically distinct tectonic events. Here we showcase a series of analogue experiments in which lithospheric-scale models are extended and subsequently shortened, simulating rifting followed by inversion and mountain building.

In our experiments, we simulate rifting by extending a multi-layer, brittle-ductile model lithosphere; this initial model is analogous to a hot, thickened lithosphere immediately after orogenesis. We demonstrate that the absence or presence of a narrow, pre-existing weakness in the lithospheric mantle results in end-member models of either wide or narrow rifting, respectively. Extension is immediately followed by shortening of the model, where we observe that contractional structures are localised along pre-existing rift basins. Analyses of particle imaging velocimetry (PIV) data reveal that shortening is accommodated by several mechanisms, including reverse reactivation of normal faults and buckling and/or inversion within pre-existing basins. We also show that these findings are consistent with field and geophysical observations from northern Australia as well as previous numerical experiments.
Space-Time Monitoring of Groundwater via Seismic Interferometry 
Authors: Mao Shujuan , Lecointre Albanne , van der Hilst Robert D. , Campillo Michel
Published: March 2022

Historic levels of droughts are plaguing the globe, raising a vital call for sustainable freshwater management. Urgently needed is a refined understanding about the structures and dynamics of underground aquifers. Here we present a novel approach for in-situ monitoring of groundwater fluctuations by making use of existing seismograph arrays in California. By advancing the seismic interferometry techniques, we manage to measure not only the temporal evolution but also the spatial distribution of Relative Changes in Seismic Velocity (Δv/v) in the Coastal Los Angeles Basins during 2000-2020. We find Δv/v to recover the hydraulic head, illustrating the potential of leveraging seismometers to propel the temporal and spatial density of well measurements. Images of Δv/v seasonality agree with surface deformation inferred from InSAR, but also further enable the characterization of aquifers and their hydrology at different depths. Long-term Δv/v suggest that distinct trends (decline or recovery) of groundwater storage occurred in adjacent basins, due to anthropogenic pumping practices compounding the effect of climate change. This pilot application bridges the gap between seismology and hydrology, and shows the promise of using seismometers to monitor, image and evaluate underground hydrologic processes. We anticipate Δv/v to be a unique type of 4D geodata that will bring new insights to studying various time-varying processes in Earth’s shallow subsurface.
The global reach of gravity waves at the stratospheric speed limit from the 2022 Hunga Tonga volcanic eruption
Authors: Hindley Neil , Hoffmann Lars , Alexander M. Joan , Mitchell Cathryn , Osprey Scott , Randall Cora , Wright Corwin , Yue Jia
Published: March 2022

At around 04:14 UTC on the 15th January 2022, a major volcanic eruption began beneath the Tongan islands of Hunga Tonga and Hunga Ha’apai (175.4W, 20.5S). Located under only a shallow depth of water, the volcano rapidly launched a plume of super-heated ash and vapourised water upwards into the atmosphere. Over the next few hours, satellite observations reveal unprecedented large-scale concentric waves in the mid-stratosphere (near 40km altitude) radiating away from the eruption across the entire Pacific Ocean. In this presentation, we show brightness temperature perturbations in the 4.3 micron bands of the AIRS/Aqua, CrIS/Suomi-NPP and CrIS/JPSS-1 instruments that reveal three groups of atmospheric waves of special interest. First, an initial concentric wave is found travelling near the stratospheric speed of sound, likely to be an acoustic compression wave. There then follows a gap, which corresponds to phase speeds not permitted by theory, then a second group of waves likely to be gravity waves. These gravity waves are shown to be travelling near the maximum phase speed permitted, and there is a suggestion that some may travel the whole way around the globe in the tropics. Third, we observe small-scale gravity waves that pervade many thousands of kilometres across almost the entire Pacific Ocean, suggesting an extremely consistent heating source. All three of these wave observations are unprecedented in more than 20 years of stratospheric satellite observations, and this eruption may potentially have produced the first observations of an acoustic wave in the mid-stratosphere that can be measured from space. Now that we have space-borne instruments to observe it, this volcanic eruption provides a unique test of theoretical predictions of atmospheric wave phase speeds on some of the largest scales possible.
Capturing the Effects of Surface Heterogeneity Induced Secondary Circulations on the Lower Sub-grid Atmosphere in Earth System Models
Authors: Waterman Tyler , Bragg Andrew , Simon Jason , Chaney Nathaniel
Published: March 2022

Earth System Models (ESMs) traditionally operate at large horizontal resolutions, on the order of 100km, which can obscure the effects of smaller scale heterogeneity. The literature, as well as work in the Coupling of Land and Atmospheric Subgrid Parameterizations (CLASP) project, indicates that surface heterogeneity, particularly in surface fluxes, has important implications for not only surface processes but atmospheric processes as well. Previous work using large-eddy simulation (LES) shows that spatial variability in surface heating can produce significant secondary circulations that are closely related to the type and scale of heterogeneity and are not currently captured by single column sub-grid atmospheric parameterizations used in ESMs.. This presentation aims to address this persistent weakness by using a multi-column approach, where two single column models, one over a high sensible heat flux portion of a climate gridcell domain and another over a low sensible heat flux portion, are coupled through a modeled secondary circulation. 

 

To accomplish this task, we run the Cloud Layers Unified By Binomials (CLUBB) standalone single column model over a 100 km box centered at the Southern Great Plains site in Oklahoma for a variety of surface and atmospheric conditions both as a single column model, and with two coupled columns. Results are also compared to LESs that use a homogeneous surface flux field and LESs that use realistic, high resolution surface flux fields. Initial results focus on liquid water path (LWP) response to added heterogeneity for 43 day long simulations. We observed qualitatively similar responses in LWP as a result of accounting for heterogeneity induced secondary circulations in both LES and multi-column CLUBB as well as indications of clear trends in response based on the atmospheric conditions. This work indicates that a multi-column setup has significant promise for modeling the impacts of heterogeneity induced secondary circulations for application in ESMs at a fraction of the computational expense of LES. Continuing work expands this analysis to cover a wider variety of surface and atmospheric conditions, determine when multi column CLUBB has significant sensitivities to heterogeneity induced secondary circulations, and explore avenues for further simplification of the model setup.
Identifying sensitivities and uncertainties in the attribution of global fire weather extremes using CMIP6 ensembles
Authors: Liu Zhongwei , Eden Jonathan , Dieppois Bastien , Drobyshev Igor , Blackett Matthew
Published: March 2022

In response to the occurrence of a number of large wildfire events across the world in recent years, the question of the extent to which climate change may be altering the meteorological conditions conducive to wildfires has become a hot topic of debate. Despite the development of attribution methodologies for extreme events in the last decade, attribution studies dedicated explicitly to wildfire, or otherwise extreme ‘fire weather’, are still relatively few. In turn, there is a lack of consensus on how to define fire risk in a meteorological context, posing a challenge for research in this subfield. Recent work has offered clarification on uncertainties associated with the choice of meteorological indicator to represent fire weather in the context of extreme event attribution but there are additional sensitivities that are still not fully understood.

Here, using established statistical methodologies applied to six large (>10-member) CMIP6 model ensembles, we conduct probabilistic attribution of fire weather extremes across the world’s fire-prone regions. We assess trends in extremes in the Canadian Fire Weather Index (FWI) using extreme value distributions, fitted with both annual maxima and peaks over a pre-defined threshold, and scaled to global mean surface temperature. An initial evaluation of model performance shows that, while all models are able to reasonably reproduce observed global patterns in extreme distribution parameters, there are some notable differences at the regional scale. Subsequently, we use probability ratio maps to quantify the influence of rising global temperatures on the changing frequency of FWI extremes. Our results highlight the sensitivity of probabilistic fire weather attribution methodologies to the choice of climate model ensemble. In conclusion, we therefore make a set of recommendations for future attribution of extreme fire weather episodes: (i) the use (and comparison) of multiple model ensembles; (ii) robust evaluation of model capacity to represent fire weather extremes.
Quantifying and partitioning evapotranspiration using Bayesian inversion of an isotope-enabled soil water balance model
Authors: Bowen Gabriel , Austin Paige , Allen Scott , Anderegg William , Good Stephen , Noone David , Still Christopher
Published: March 2022

Isotope ratios of soil water and atmospheric water vapor have been used to estimate soil evaporation fluxes and to partition evapotranspiration at local (plot, stand) scales, but the application of these methods has been limited by 1) challenges associated with data acquisition, and 2) the complexity of and lack of consensus about appropriate data interpretation methods. New initiatives that have expanded access to data, such as the U.S. National Ecological Observatory Network (NEON), are beginning to address the first of these limitations. In order to make progress toward the second, we link a model of soil water and water isotope balance, based on the widely used Noah land surface model, to a range of core NEON measurements and ancillary field-collected data using a Bayesian hierarchical framework. This model framework allows self-consistent treatment of the water and isotope cycles, including representation of uncertainties and differing assumptions, and simultaneous optimization of all model parameters conditioned on all data using Markov-Chain Monte Carlo sampling. We test the framework by applying it to estimate evapotranspiration partitioning at a dryland NEON site in central Utah and show that the posterior estimates give reasonable and useful constraints on flux rates and provide constraints on model parameters that could inform our understanding of soil properties and isotopic systematics in the system. This flexible framework for interpretation of water isotope data in evapotranspiration studies is amenable to application across ecosystems and at sites with different levels of data availability in support of cross-site syntheses and validation/testing of earth system models.
Ground motion simulations relating topographic amplification and landslide initiation during the Mw7.6 2005 Kashmir Earthquake.
Authors: Dunham Audrey , Kiser Eric , Kargel Jeffrey , Haritashya Umesh , Watson Scott , Shugar Dan
Published: March 2022

The 2005 Mw 7.6 Kashmir earthquake is the most devastating earthquake to occur along the Himalayan arc, resulting in 87,000 fatalities, 69,000 injuries, and 2.8 million people left homeless. The rupture occurred on a 30° NE dipping thrust fault and generated a ~70 km long surface rupture that concentrated much of the damage. Along with the primary hazard caused by the seismic shaking, many secondary hazards, including nearly 3,000 coseismic landslides, were initiated due to the shaking from this event. In the absence of seismic data recorded near the source of this earthquake, we attempt to understand the relationships between ground shaking and coseismic landslides by using numerical techniques to model the ground motions and topographic amplification from the Kashmir earthquake. We use the spectral element method implemented in SPECFEM3D to model kinematic rupture scenarios for the Kashmir earthquake in both high resolution and flat topography, obtaining a topographic amplification factor by comparing these simulations. We generate a range of seismic source models using the rupture generator FakeQuakes, starting with a mean slip model from the earthquake and adding stochastic variations to both static and kinematic rupture properties to produce variable rupture scenarios. The advantages of this technique, compared to calculating ground motions from one finite fault model, is that by adding stochastic variations, the source model has higher, more realistic, frequencies, and that it enables the investigation of how varying rupture properties affect topographic amplification. We calculate both peak ground velocity (PGV) and topographic amplification for each scenario and compare the average and standard deviations to locations of landslide initiation. Preliminary results from five earthquake sources shows that with changing source parameters, PGV and topographic amplification patterns remain relatively constant and that positive amplifications are concentrated at the peaks of ridges and negative amplifications are concentrated in valleys. There are no obvious relationships between the patterns of amplification and landsliding, possibly due to limitations in landslide mapping. Other causes of landslides--such as variations in lithology, distance to anthropogenic features (roads, construction), distance to faults, and distance to ridges, and rivers--will be investigated further to understand the relationships between topographic amplification and other triggers. Future work includes combining these results with similar studies for earthquakes with different source properties and in different topographic settings to further understand the controlling factors of topographic amplification as a trigger for coseismic landslides.
Predicting climate change impacts to peatland soil moisture in Southeast Asia
Authors: Dadap Nathan , Cobb Alexander , Hoyt Alison , Harvey Charles , Feldman Andrew , Im Eun-Soon , Konings Alexandra
Published: March 2022

Soil moisture is a key hydrologic variable that determines peat flammability and predicts burned area. In recent decades, there has been a rise in deadly peat fires across Southeast Asia, indicating the presence of dry conditions. This has largely been attributed to the extensive deforestation, drainage, and conversion to agricultural use that has occurred in the region. Climate also plays a role in mediating soil moisture, and the most severe fire years have previously only occurred when there are droughts during strong El Niño years. Thus, climate change threatens drier peat soil moisture conditions which would increase peat fire risk. Here, we assess these potential impacts by modeling soil moisture responses to predicted climate change. To overcome the lack of regional-scale data for hydrologic variables and peat properties necessary to parametrize a physical model, we used for a statistical modeling approach. Specifically, we used an artificial neural network to relate remotely sensed observations of soil moisture (SMAP) to climate reanalysis forcings (ERA5) and other datasets that characterize peatland degradation such as tree cover and canal density. After training the neural network on data from 2015-2020, we then compared moisture regimes under recent and future climate from state-of-the-science regional climate model projections (CORDEX-CORE) under RCP 8.5. Our findings suggest that reduced precipitation and increased evaporative demand, as predicted by the regional climate models, may cause significantly drier soil moisture regimes in the future. Future mean dry season soil moisture is found to be similar to that during 2015 and 2019 El Niño years, suggesting higher baseline fire risk. We further explore geographic differences in soil moisture responses, as mediated by differences in climate sensitivity between land use types.
Reconstructed post gLGM glacier recession and climatic variability of the Changme Khangpu valley, Eastern Himalayas, INDIA
Authors: Debnath Manasi , Sharma Milap Chand , Syiemlieh Hiambok Jones , Chowdhury Arindam
Published: March 2022

The glaciated Changme Khangpu basin (CKB) covering an area of 767.8 km2, constitutes an important region in the Eastern Himalayas for palaeoclimate research to assess variability over recent geological times. Climatically, this part of the Himalayas is mainly controlled by the Indian Summer Monsoon (ISM). We provide a combination of multiproxy data, i.e., geomorphological, sedimentological, geochemical, Accelerator Mass Spectrometry 14C dating and Schmidt Hammer rebound value dating methods in reconstructing glacier and climatic changes related to the post global Last Glacial Maximum (gLGM) in the Changme Khangpu basin of the Sikkim Himalaya. The four set of well-preserved moraines depicted four advances of this glacier and palaeoclimate has been reconstructed after the Phase-II glacier advances i.e. post gLGM period. The post gLGM glacier recession in the Changme Khangpu (CK) valley witnessed a prolonged humid climate phase from <14.29 ± 0.22 ka to 7.08 ± 0.08 ka cal BP that inferred from the sedimentary log in this valley and incidentally correlate with the monsoonal reactivation (15 ka to 12 ka BP) in Southern Asia. This humid period was succeeded by dry climatic phases from 7.08 ka to 5.4 ka cal BP and from 5.18 to 4.65 ka cal BP, which well correlates with the dry phases in the Chopta valley, west of this area in Sikkim Himalaya. The glacier had receded from its Phase-III advance in between <4 and >1.3 ka BP. This period was followed by the active paraglacial fan formation and witnessed historical outburst events in this valley.

 

Keywords: Changme Khangpu glacier (Sikkim); Eastern Himalayas; Last Glacial Maximum; Palaeoclimate; Glacier geomorphology; 14C AMS dating; Chemical index of alteration.
What triggered the Little Ice Age? 
Authors: Lapointe Francois , Bradley Raymond
Published: March 2022

The Little Ice Age (LIA) was one of the coldest periods of the postglacial period in the Northern Hemisphere. Although there is increasing evidence that this time interval was associated with weakening of the subpolar gyre (SPG), the sequence of events that led to its weakened state has yet to be explained. Here, we use a recently reconstructed record of Atlantic Multidecadal Variability (AMV) to provide insights into the sequence of events that led to the LIA. We show that the LIA was preceded by an intrusion of warm Atlantic water into the Nordic Seas in the late 1300s. The intrusion was a consequence of persistent atmospheric blocking over the North Atlantic, linked to unusually high solar forcing in times of lower volcanic activity. The warmer water led to the breakup of sea ice and calving of tidewater glaciers. Weakening of the blocking anomaly in the late 1300s allowed the large volume of ice that had accumulated to be exported into the North Atlantic, contributing to the weakening of the Atlantic Meridional Overturning Circulation (AMOC).

The modern spatial fingerprints involving fast AMOC changes are captured by many highly resolved records from around the Atlantic during the transition from the late 1300s to the early 1400s. Paleoclimatic evidence from the Tropics suggest a more northerly Intertropical Convergence Zone (ITCZ) in the late 1300s followed by a rapid southward shift of the ITCZ in the early 1400s, which is consistent with model simulations of the climatic response in the Tropics to a slowdown in AMOC. While this Atlantic intrusion into the Nordic Seas triggered the main phase of the LIA, the cooling condition was maintained by higher volcanic activity in the ensuing decades that was coincident with lower solar irradiance.

 

 
Understanding the effects of Modern Lossless and Lossy Compressors on the Community Earth Science Model
Authors: Underwood Robert , Di Sheng , Cappello Franck
Published: March 2022

Large scale climate simulations such as the Community Earth Science Model (CESM) produce enormous volumes of data per run. Transferring and storing this volume of data can be challenging leading researchers to consider data compression in order to mitigate the performance, monetary and environmental costs. In this work, we survey 8 methods ranging from higher-order SVD, multigrid, transform, and prediction based lossy compressors as well as specialized floating point lossless and lossy compressors and general lossless compressors to determine which methods are most effective at reducing the storage footprint.  We consider four components (atmosphere, ice, land, and ocean) within CESM taking into account the stringent quality thresholds required to preserve the integrity of climate research data. Our work goes beyond existing studies of compressor performance by considering these newer compression techniques, and by accounting for the candidate quality thresholds identified in prior work by Hammerling et al.  This provides a more realistic picture of the performance of lossy compression methods relative to lossless compression methods subject to each of these constraints with up to a 5.2x improvement over the leading lossless compressor and 21x over no compression. Our work features an automated method to automatically identify a configuration that satisfies the quality requirements for the lossy compressors that is agnostic to compressor implementations. 
Evidence for Magnetic Reconnection at Ganymede’s Upstream Magnetopause during the PJ34 Juno Flyby
Authors: Ebert Robert W. , Allegrini Frederic , Angold NIgel , Bagenal Fran , Bolton Scott J. , Connerney Jack , DiBraccio Gina , Fattig Eric , Fuselier Stephen A. , Levin Steve , McComas David J. , Montgomery Jake , Romanelli Norberto , Szalay Jamey R. , Valek Phil , Wilson Robert J.
Published: March 2022

Juno made a close flyby of Ganymede and flew through its magnetosphere on June 7, 2021. This flyby included a crossing of Ganymede’s upstream magnetopause on the outbound segment of the spacecraft transit. We present plasma and magnetic field observations near that magnetopause crossing from Juno’s Jovian Auroral Distributions Experiment (JADE; McComas et al. 2017) and magnetometer (MAG; Connerney et al. 2017), respectively. JADE observed enhanced electron fluxes, including heated, streaming electrons, some with bi-directional pitch angle distributions, as Juno crossed the magnetopause current layer (MCL) as identified by the magnetic field observations. The acceleration of cold ions, both protons and heavy ions originating from Ganymede, was observed on approach to the magnetopause along with a likely mixing of ions from Ganymede and Jupiter’s plasma sheet within the MCL. These observations are used to examine the physics of plasma interactions at this boundary, including evidence that magnetic reconnection, considered a key driver of magnetospheric dynamics at Ganymede, was occurring along the magnetopause at that time.
Ice fabrics and textures in coastal East Antarctica reveal seasonal variations
Authors: Tsibulskaya Veronica , Tison Jean-Louis
Published: March 2022

The fabric and texture evolution with depth was investigated on several firn/ice cores from ice rises on Princess Ragnhild Coast, East Antarctica. Results at 5 m sampling resolution show important variations in the crystal orientation fabrics as well as in the grain size, on centimetric to decimetric scale. Further analysis on continuous sections spanning several meters of firn core brings to light periodic variations in the fabric clustering. The fabric’s decimetre-scale periodicity displays a clear correlation with the seasonal variability of δ18O and ECM conductivity in the ice. It also reveals a previously unobserved fabric shape. This constitutes an opportunity for a close-up look of the climatic signal burial through the transition from firn to ice.
Measuring Sediment Transport Capacity of Concentrated Water Flow with a New Erosion Feeding Method
Authors: Qu Liqin , Lei Tingwu , Zhou Chenyan , Liu Zhiqiang
Published: March 2022

Sediment transport capacity is not only an important parameter for rill erosion modeling but also a critical parameter for estimating other rill erosion model parameters. Sediment capacity is difficult to be measured, especially at gentle slopes with limited rill length. In this study, a special flume with variable slope gradients in different sections was implemented to feed and to transport sediments. Silt loam soil materials, collected from Beijing, were used in the laboratory experiments to measure sediment transport capacity to verify the method,. The experiments were designed under slope gradients of 5, 10, 15, 20 and 25° and flow rate of 2, 4, 8 and 16 L/min. Measured sediment transport capacity values were compared with reference measurements from other rill erosion experiments with similar soil materials. At high slope gradients of 15, 20 and 25°, the newly-suggested method produced almost the same transport capacity values as measured through rill erosion process data. Under the low slope gradients of 5 and 10°, limited length of eroding rill used in the previous experiments was not capable of producing sufficient sediments to make the flow reach sediment transport capacity. Data analysis indicates that rill erosion with a 8 m long flume produced maximum sediment concentrations about 36% lower than the values measured with the new method under low slope gradients of 5 and 10°. The sediment transport capacities at lower slopes measured with the new method followed the same trend as those at higher slopes. The experimental results indicated that the new method is capable of supplying sufficient sediments to ensure the flow approach transport capacity measurement. The method proposed in this study can provide a feasible approach for estimating sediment transport capacity as an  important model parameter for soil erosion prediction.
Sorption of Per- and Polyfluoroalkyl Substances (PFAS) by Porous Media in Saturated Zone: A Review Study
Authors: Obeid Ali A.A. , Zoboli Ottavia , Gundacker Claudia , Derx Julia , Blaschke Alfred Paul , Zessner Matthias
Published: March 2022

PFAS are of emerging concern due to their high environmental persistence, human health effects, and bioaccumulation attributed to their chemical properties. These chemical properties make them preferable for many industrial and domestic purposes. In turn, PFAS are emitted from a vast amount of sources and eventually reach the surface water and groundwater environments. The most critical pathways for groundwater are infiltration via the unsaturated zone and riverbank filtration. Natural filtration of PFAS reduces the risk of PFAS contamination, and sorption is considered the most crucial removal mechanism of PFAS from saturated porous media. This study aims to better understand the sorption processes and factors affecting the affinity of soil to sorb different types of PFAS. A thorough understanding of these processes is needed to model PFAS fate and transport in groundwater and estimate human health's impact. To meet this aim, we conducted a literature survey involving PFAS sorption behavior to soil and external sorbents in batch and column experimental studies and monitoring studies in the field.

PFAS tail group are hydrophobic organic chemicals. Hydrophobic interactions are thus one of the main sorption mechanisms in groundwater, especially when the soil has a higher organic carbon content. Several studies have found that the retention of PFAS is increased with the increase in PFAS hydrophobicity and the amount of organic matter in the soil. Another important forces affecting the interaction of PFAS with soil are the electrostatic forces. Many PFAS are present in the environment in their anion form and bond to positively charged soil surfaces. Soils with a negative charge surface can repel PFAS and reduce retention. Other minor processes such as the hydrogen bond and PFAS functional group forming complexes can increase the sorption to soil. Soil properties and solution chemistry significantly affect these forces and bonds and can either reduce or increase the affinity of PFAS sorption to soil. The presence of co-contaminants and nonaqueous phase liquids in groundwater further affects these processes.

Difficulties in degrading PFAS compounds led to alternative ways of remediation, such as stabilizing PFAS in soil by employing sorption processes. With the gained knowledge, external sorption enhancers can be used to increase the PFAS sorption besides altering the solution chemistry to maximize the retention and stabilization of PFAS in soil.

The dynamics of the sorption process are affected by preferential flow and intra-sorbent diffusion, leading to rate-limited sorption effects. These dynamics are essential for the model selection and estimating the time needed for the clean-up during remediation.
Effects of stemflow on radiocesium infiltration into the forest soil
Authors: Kato Hiroaki , Iida Hikaru , Shinozuka Tomoki , Niwano Yuma , Onda Yuichi
Published: March 2022

Radiocesium deposited in the forest canopy is transferred to the forest floor by rainwater and　litterfall. Among them, stemflow likely increases the radiocesium inventory by concentrating rainwater around the trunk. However, the effects of stemflow on the influx of radiocesium into forest soil have not been evaluated quantitatively. In this study, the fluxes of rainwater via stemflow, throughfall, and soil infiltration water were observed. The concentration of dissolved 137Cs was measured in a cedar forest in Fukushima Prefecture, Japan. Soil infiltration water was collected at 5 cm and 20 cm depths at the distant point from the tree trunk (Bt), and the base of the tree trunk (Rd), where the influence of stemflow was strong. The observations were conducted during the period from September 2019 to November 2021. During the observation period, an experiment was conducted to intercept the inflow of rainwater via the throughfall or stemflow, and the change in soil infiltration water was observed. The observation results showed that the infiltration flux of radiocesium into the forest soil was significantly higher at the Rd site and about three times larger than at the Bt site. Particularly at the 20 cm depth at the Rd site, the soil infiltration water flux increased with the stemflow. The stemflow exclusion resulted in the dcrease of radiocesium flux by about 70% at all depths at the Rd site. These results suggest that the stemflow increases the input of radiocesium to the base of the tree trunk and facilitates its transfer to the deeper soil layers.
Investigating factors impacting phosphorus dynamics and phosphate sorption capacity of manure amended soils of Ontario
Authors: Xiang Enqi , DiLoreto Zachary , Mugalingam Shan , Dittrich Maria
Published: March 2022

Phosphorus (P) in agricultural soil is an essential nutrient for plant growth. Manure application as an organic phosphorus fertilizer improves P supply to plants. Labile P from manure can be easily transported from agricultural fields through surface runoff. Excessive P fertilizer in amended soils change into more stable forms. These processes cause eutrophication of lakes. Understanding P dynamics and P compositions in manure and soils is important. This study analyzed how do the total P and bioavailable P fraction in manure-amended agricultural soils change over seasons, as well as what factors may contribute to these changes. Additionally, we tested P sorption capacity in two soils. This study was conducted with agricultural soils from Bay of Quinte area, Ontario, Canada.

 

Our results showed that the total phosphorus (TP) amount tend to decline with aging of applied manure. Soils amended by manure in 2019 summer have around 1.17 mg TP g-1 in average, while soils with manure application more than 6 years ago have approximately 0.97 mg TP g-1 in average. Compared to manure with 4.19 mg TP g-1, the TP in soils was much less indicating low P fertilization efficiency. Comparing the concentration of TP and bioavailable P among seasons, both parameters showed an increasing trend with decreasing temperature. Reduced uptake of P by plants, the limitation of mineralization, and less rain events in winter contribute to the high values of P in winter. P sorption were examined by soil incubation experiments on two soil samples with potassium dihydrogen phosphate (KH2PO4) as inorganic fertilizer. Results indicated a negative correlation between adsorbed P and added P. Even with additional geothite as an extra iron oxide-hydroxide source, the same relation was observed. It signifies that these soils have low P-sorption capacity. The abundant amount of OM and Ca from manure and soils negatively correlated to P adsorption onto iron oxide-hydroxides. The degree of phosphorus saturation (DPS) of these two soils (95.78 and 82.46%) exceeded the threshold of P saturation level in agricultural soils (80%) and explained the release of P from solid phase.
Temporal variation estimates of apparent resistivities associated with occurrence of seismic activity around Bogotá - Colombia using MT records from the RSUNAL seismic network
Authors: Gómez Camacho Juan Sebastián , Gómez Rodriguez Juan José , Vargas Jiménez Carlos Alberto
Published: March 2022

This work allowed us to estimate the space-time variations of the apparent resistivity (AR) at the USME station of the Red Sismológica de la Universidad Nacional de Colombia (RSUNAL), located in the center of Colombia at the Eastern Cordillera, and correlate these changes with seismic activity within a radius of 500 km to the station.

This project used recorded time series of the natural earth’s electric and magnetic field, processed its data with a computational algorithm of our own (which follows the magnetotelluric (MT) method’s fundamentals), and yielded positive results for the 6.1 Mw earthquake of December 24th, 2019 in Mesetas (Meta - Colombia) with some anomalies registered 8 hours before the mainshock. Although there is just one abnormal behavior for 1 of 5 study cases, it is seen in a good way a possible relation between the magnitude of the event and the AR anomaly as an input to the study of seismic precursors.