bluuebunny/crossref_metadata_2025 huggingface dataset:
Strong inclination pacing of climate in Late Triassic low latitudes revealed by the Earth-Saturn tilt cycle
Authors: Margulis-Ohnuma Miranda , Whiteside Jessica , Olsen Paul
Published: March 2021

Gravitational interactions among masses in the solar system are recorded in Earth’s paleoclimate history because variations in the geometry of Earth’s orbit and axial orientation modulate solar insolation. However, astronomical models prior to ca. 60 Ma are unreliable due to the unpredictable nature of orbital chaos in the solar system, and therefore such models must be constrained using geological data. Here, we use natural gamma radioactivity and other environmental proxies from paleo-tropical Late Triassic lake deposits of the Newark Rift Basin of eastern North America, previously shown to be paced by variations in axial precession and orbital eccentricity and stratigraphically constrained by U-Pb dating, to explore hitherto undescribed strong variations in orbital inclination in the 201–206 Ma interval (lacustrine, upper Passaic Formation), where lake level variations are particularly muted. We identify the Earth-Saturn 173 kyr orbital inclination cycle and use it to tune the sequence because it exhibits high theoretical stability and metronomic behavior due to the very large mass of Saturn. We tune separately to long-eccentricity as well, with similar effect. Slight, complimentary offsets in the other inclination and eccentricity periods revealed by the Earth-Saturn (s3-s6) and Venus-Jupiter (g2-g5) tunings are apparent that may be due to chaotic variations of the secular fundamental frequencies in the nodal and perihelion orbital precessions of Earth and Venus, respectively. The surprising strength of the inclination cycles in this specific sequence suggest an additional modulating effect of the Earth System on expression of the components of orbital pacing of climate, as well a mechanism to more fully constrain the secular fundamental frequencies of the solar system beyond the ca. 60 Myr limit of predictability that chaos imposes on astronomical solutions.
A Geologic Symphony: A Model for Scientific Engagement through the Arts
Authors: Nytch Jeffrey
Published: March 2021

As part of its 125th Anniversary in 2013, the Geological Society of America commissioned Symphony No. 1: Formations from composer Jeffrey Nytch and premiered the work, performed by the Boulder Philharmonic, and the GSA’s annual meeting in Denver. The project attracted national and international attention for its mix of music and geology: unlike most musical works inspired by landscapes, Formations was inspired by geological processes themselves—specifically, those that shaped the Rocky Mountains. Nytch, who holds undergraduate degrees in both geology and music, will discuss how the project educated laypersons in the basics of Rocky Mountain geology while simultaneously building an audience for the orchestra. The Formations project is a type example of how the arts can be used to increase understanding within communities of the science happening all around them, provide the scientific community with a new lens through which to see their work, and establish a new channel for arts organizations to engage their community and build their audience. This complementary dynamic results in increased knowledge, understanding, and community amongst and between groups of people who might not otherwise experience each other’s worlds, and suggests that the arts can play a significant role in increasing scientific literacy and understanding.
Modelling of Microwave Multi-Frequency Emission and Backscatter by a Community Land Active Passive Microwave Radiative Transfer Modelling Platform (CLAP)
Authors: Zhao Hong , Zeng Yijian , Su Bob , Hofste Jan
Published: March 2021

Emission and backscattering at different frequencies have varied responses to soil physical processes (e.g., moisture redistribution, freeze-thaw) and vegetation growing/senescencing. Combing the use of active and passive microwave multi-frequency signals may provide complementary information, which can be used to better retrieve soil moisture, and vegetation biomass and water content for ecological applications. To this purpose, a Community Land Active Passive Microwave Radiative Transfer Modelling Platform (CLAP) was adopted in this study to simulate both emission (TB) and backscatter (σ0), in which the CLAP is backboned by the TorVergata model for modelling vegetation scattering, and an air-to-soil transition model (ATS) (accounting for surface dielectric roughness) integrated with the Advanced Integral Equation Model (AIEM) for modelling soil surface scattering. The accuracy of CLAP was assessed by both ground-based and spaceborne measurements, and the former was from the deployed microwave radiometer/scatterometer observatory at Maqu site on an alpine meadow over the Tibetan plateau. Specifically, for the passive case, simulated TB (emissivity multiplied by effective temperature) were compared to the ground-based ELBARA-III L-band observations, as well as C-band Advanced Microwave Scanning Radiometer 2 (AMSR2) and L-band Soil Moisture Active Passive (SMAP) observations. For the active case, simulated σ0 were compared to the ground-based scatterometer C- and L-bands observations, and C-band Sentinel and L-band Phased Array type L-band Synthetic Aperture Radar 2 (PALSAR-2) observations. This study is expected to contribute to improving the soil moisture retrieval accuracy for dedicated microwave sensor configurations.
Gravimetric Analysis of Solid Waste from Sanitary Sewage Operating Units of the Insular System, Florianópolis, State of Santa Catarina, Brazil.
Authors: Bortolotto Nadine Lory , Poleto Cristiano
Published: March 2021

This work aims to identify means of analysing the gravimetric composition of solid waste retained in the fences of some operational units of the Insular sewage system in the municipality of Florianópolis, State of Santa Catarina, Brazil. Two sewage pumping stations (Beira-Mar Norte and Hospital Universitário-Trindade) units were chosen and the railing at the entrance to the sewage treatment station of the system (Insular). The following classes of solid waste were adopted: plastics, metals, styrofoam, civil construction material, dead animals, sanitary napkins, diapers, rags and cloths, organic matter, other or tailings. It is being identified the solid waste observed in greater quantities and in percentages in the sanitary sewage system, which may cause damage to the operational units. The intending action is to be able to propose to local government and the system operator, different ways to educate the population and try to prevent or reduce the appearance of these residues in the sewage systems.
Midwinter snow ablation patterns, drivers, and hydrologic consequences in the Western U.S.
Authors: Haleakala Kayden , Gebremichael Mekonnen , Lettenmaier Dennis P.
Published: March 2021

Climate warming is expected to reduce radiation-driven snowmelt rates from deep mountain snowpacks, and increase the duration of low-intensity melt periods, especially from shallow snowpacks. It should also increase the humidity-dependence of melt rates, especially in winter. Taken together, these effects will raise the importance of snow ablation in midwinter, the magnitude of which has implications for shifting surface runoff regimes, groundwater recharge, and flood risk. We address two related questions: first, what is the relative effect of radiation, turbulent energy exchange, and precipitation as they relate to midwinter snow ablation, and how important are they to seasonal and annual streamflow generation; and second, how do midwinter ablation episodes and their drivers vary regionally and topographically, and how have those characteristics changed over time (if at all)? We answer these questions using a network of over 500 SnoTel snow pillows across the Western United States that have recorded daily snow water equivalent (SWE) since 1985 or earlier. With ancillary climate data, we identify distributions of midwinter snow ablation episodes along with their trends and sensitivity to meteorological drivers. We then focus on 32 small catchments with nearby daily streamflow and SWE measurements to assess regional differences in the importance of midwinter ablation to winter and annual flows.
How Extreme Apparitions of the Volcanic and Anthropogenic South East Asian Aerosol Plume Trigger and Sustain El Niño events using data from the Last Millennium Ensemble, Large Ensemble, MERRA-2 Reanalysis, four Satellites and the Global Volcanism P
Authors: Potts Keith
Published: March 2021

Volcanic aerosols over south east Asia have always been the trigger and sustaining cause of ENSO events. In recent decades this natural plume has been augmented by the anthropogenic plume which has intensified ENSO events especially in SON. Data from the Last Millennium Ensemble (13,872 months), and Large Ensemble (3,012 months) demonstrate this connection with three ENSO indices and aerosol data derived from the same datasets correlating at 1.00 (LME), 0.97 and 0.99 magnitude (segmented and averaged). ENSO events are the dominant mode of variability in the global climate responsible for Australian, Indian and Indonesian droughts, American floods and increased global temperatures. Understanding the mechanism which enables aerosols over SE Asia and only over SE Asia to create ENSO events is crucial to understanding the global climate. I show that the South East Asian aerosol Plume causes ENSO events by: reflecting/absorbing solar radiation which warms the upper troposphere; and reducing surface radiation which cools the surface under the plume. This inversion reduces convection in the region thereby suppressing the Walker Circulation and the Trade Winds which causes the SST to rise in the central Pacific Ocean and creates convection there. This further weakens/reverses the Walker Circulation driving the climate into an ENSO state which is maintained until the aerosols dissipate and the climate system relaxes into a non-ENSO state. Measured aerosol data from four NASA satellites, estimates of volcanic tephra from the Global Volcanism Program (GVP) for over 100 years and the NASA MERRA-2 reanalysis dataset all confirm this analysis.
The Southern Annular Mode in CMIP6 simulations
Authors: Morgenstern Olaf
Published: March 2021

Stratospheric ozone depletion, along with increases in long-lived greenhouse gases, is well known to cause a strengthening of the Southern Annular Mode (SAM), the leading mode of variability in the Southern Hemisphere.  I here analyze simulations contributed to CMIP6 for signatures of these two leading drivers of climate change. For the period 1957-2014, seasonally large disagreements are found between four observational references; CMIP6-derived trends are in agreement with two out of four commonly used references. Using a regression analysis applied to model simulations with and without interactive ozone chemistry, a strengthening of the SAM in summer is attributed nearly completely to ozone depletion because a further strengthening influence due to long-lived greenhouse gases is almost fully counterbalanced by a weakening influence due to stratospheric ozone increases associated with these greenhouse gas increases. Ignoring such ozone feedbacks (an approach commonly used with no-chemistry climate models) would yield comparable contributions from these two influences, an incorrect result. In winter, trends are smaller but an influence of greenhouse gas-mediated ozone feedbacks is also identified. The regression analysis furthermore yields significant differences in the attribution of SAM changes to the two influences between models with and without interactive ozone chemistry, with ozone depletion and GHG increases playing seasonally a stronger and weaker, respectively, role in the chemistry models versus the no-chemistry ones. The results suggest that adequately representing stratospheric ozone feedbacks in climate models is critical for a correct attribution of trends in the SAM.
A multi-sensor monitoring system of surface water level changes in wetlands
Authors: Wdowinski Shimon , Liao Heming , Zhang Boya (Paul)
Published: March 2021

Wetlands store roughly 10% of global surface water in the terrestrial portion of the water cycle, cover roughly 9% of the Earth’s surface, and provide critical habitat for a wide variety of plant and animal species. Over the past century, many wetland areas have been lost, degraded, or stressed mainly due to anthropogenic activities, as water diversion, agricultural development, and urbanization, but also in response to natural processes, as sea level rise and climate change. Global and regional monitoring of wetland health and response to their natural and anthropogenic stressors are important and are best conducted using space-based remote sensing techniques, due to wetlands’ vast extent and often inaccessibility.

Several space-based remote sensing technologies provide high spatial resolution observations of wetland water level and its changes over time. These techniques include Synthetic Aperture Radar (SAR), optical imagery, radar and laser altimetry, and Surface Water Ocean Topography (SWOT). SAR observations include two independent observables, amplitude and phase; each observable is sensitive to different hydrological parameters. Radar and laser altimetry missions provide cm-level accuracy water level measurements along the satellite track. The SWOT mission, which is scheduled for a February 2022 launch, will use radar interferometer for repeated measurements of cm-level water level measurements over a 50-100 km wide swaths. As part of a NASA supported project, we develop a space-based multi-sensor monitoring system of surface water level changes in wetlands. The multi-sensor system will generate detailed multi-temporal maps of wetland inundation extent, water levels, and water level changes. The development of the multi-sensor monitoring system will be conducted over the south Florida Everglades, which can be considered as a natural laboratory due to its variable land cover and the availability of ground-based hydrological observations. Preliminary results based on Interferometric Synthetic Aperture Radar (InSAR) observations yielded detailed maps of water level changes of the entire Everglades wetlands with 100 m spatial resolution and 3-4 cm accuracy level. After development, the system will be tested in two other wetland areas located in Louisiana, and Peace–Athabasca Delta (Alberta, Canada).
Polar cap patches, GPS TEC variations, and atmospheric gravity waves
Authors: Prikryl Paul , Gillies Robert G. , Themens David R. , Kunduri Bharat S. R. , Varney Roger , Weygand James M.
Published: March 2021

The southward pointing field of view of the Canadian component of the Resolute Bay Incoherent Scatter Radar (RISR-C) is well suited for observing the ionospheric signatures of flux transfer events and subsequent polar patch formation in the cusp.  The fast azimuthally oriented flows and associated density depletions often show an enhanced ion temperature from Joule heating caused by the sudden change in plasma flow direction. The newly formed polar patches are then observed as they propagate through the field-of-views of both RISR-C and RISR-N. In the ionosphere, the electron density gradients imposed in the cusp, and small-scale irregularities resulting from gradient-drift instability, particularly in the trailing edges of patches, cause GPS TEC and phase variations, and sometimes amplitude scintillation. The neutral atmosphere is affected by ionospheric currents resulting in Joule heating. The pulses of ionospheric currents in the cusp launch atmospheric gravity waves (AGWs) causing traveling ionospheric disturbances, as they propagate equatorward and upward. On the other hand, the downward propagating AGW packets can impact the lower atmosphere, including the troposphere. Despite significantly reduced wave amplitudes, but subject to amplification upon over-reflection in the upper troposphere, these AGWs can trigger/release existing moist instabilities, initiating convection and latent heat release, the energy leading to intensification of storms.
Effects of lithology on bedrock channel occurrence: an examination from the Seogang River in South Korea
Authors: Chen Hui , Byun Jongmin
Published: March 2021

Bedrock river is rock-bound, its bed and banks are composed mainly of in-place bedrock. Bedrock channel reaches, commonly short and intermittent, often occur where transport capacity exceeds bedload sediment flux. Despite the abundant research on the typical patterns of alluvial channel reaches, the distribution of bedrock channels has not been well studied. Rock type may affect the occurrence of bedrock channels because the strength, joint density, and erosion process of bedrock vary depending on the rock type. Previous studies have viewed the bedrock channel occurrence in the aspect of the excessive sediment transport capacity, but the influence of lithology has not been considered in the literature. To understand the influence of lithology on bedrock channel occurrence in a drainage basin-scale, we investigated the distribution of bedrock channels in relation to varying lithology and unit stream power along the Seogang River in South Korea. We used satellite images with high resolution for the identification of bedrock channel reaches and then verified them through field surveys. Geological maps and 1 arc-second SRTM DEMs were used to analyze lithological effects and calculate unit stream power.  As a result of the analysis, we identified 94 bedrock channels in the studied river, varying depending on lithologies. The frequency of bedrock channels in granitic gneiss areas (0.73/km) is much higher than those in the other rock type areas (granite areas, 0.57/km; limestone areas, 0.16/km). In the more frequent granitic gneiss areas, the bedrock channels are steepened (average channel slope: 0.0074 m/m) and narrow (average channel width: 65 m) and mainly reside within steepened and narrow (average valley width: 123 m) rock-bound valleys so that their occurrence is mainly associated with high unit stream power. In contrast, the bedrock channels over the other lithologies are wider (89 m) and lower-gradient (0.0056 m/m) and occur along flat and broad valleys (391 m). Consequently, the bedrock channels in the studied river were divided into two types: confined and unconfined bedrock channels. The confined bedrock channels are within the steepened and narrow valleys composed of resistant granitic gneiss and show the evidence for recent bedrock incision processes. However, the unconfined bedrock channels are mainly within the broad and flat valleys of weak saprolites and limestone with high joint density have lower unit stream power and don't show any marker for bedrock incision. In conclusion, high-relief landscape mainly composed of more resistant rocks generates steep and narrow valleys, which leads to the formation of continuous and actively incising bedrock channels. However, low-relief landscape underlain by non-resistant rocks shows wider and lower-gradient channels, with intermittent bedrock channels due to locally more resistant rock bodies.
Stocks drift and vortex instability of the potential surface wave
Authors: Benilov Alexander
Published: March 2021

It is shown that in the case of potential surface wave an exact solution of the equations of the nonlinear Lagragian’s dynamics of the fluid particle has the drift velocity as an eigenvalue. The fluid particle trajectory is a circular rotation around a center point moving with a constant drift velocity. The rotation frequency differs from the wave frequency by the Doppler’s shift caused by the drift velocity. The constant drift velocity, for the surface wave of small amplitude, coincides with the classical expression for the Stokes drift velocity.

It is also shown that in the cases with absence of the Stokes drift and with presence of the Stokes drift the vortex instability of a potential surface wave has the same futures. But the vortex temporal variability in the case of the Stokes drift is affected by the Doppler’s shift caused by the Stokes drift velocity. Hence it allows a conclusion that the vortex instability of a potential surface wave initiates turbulent mixing and Lengmure circulation in the ocean upper layer.      

 
Assessment of Aeolus DWL data and impact of assimilation in the JMA’s global data assimilation system
Authors: Okabe Izumi , Okamoto Kozo
Published: March 2021

The horizontal line of sight (HLOS) wind data from Aeolus Doppler Wind Lidar (DWL) is available from the European Space Agency (ESA) Earth Online Portal. The data quality after the mirror bias correction was investigated using data from July to September 2020. According to the first guess departure (observation minus background) statistics in Japan Meteorological Agency’s (JMA’s) global data assimilation (DA) system, the biases were very small for both  Rayleigh and Mie HLOS wind data after quality controlled. Significant positive impacts of Aeolus HLOS wind data assimilation in the global DA system on the analysis accuracy and forecasting scores were found in experiments with Rayleigh wind data under clear-sky condition and Mie wind data under cloudy condition. Improvement of tropical cyclone track forecasting was also found for the typhoons in the Northwest Pacific Ocean and for the hurricanes in the Atlantic Ocean. The details of results of data assessment and assimilation experiments will be shown in the presentation.
Astronomical time scale for the  Doushantuo Formation ofEdiacaran in South China: Implications for the duration of the negative δ13C excursion
Authors: Sui Yu , Wang Zhixiang , Huang Chunju
Published: March 2021

Reconstructing the high-resolution astrochronology framework for the Ediacaran is critical to fully understand the evolution of the sedimentary environment and the carbon cycle in South China. The Ediacaran was perhaps one of the most important intervals in the Earth's sedimentary environment and biological evolution history, which witnessed the carbon isotope perturbation frequently, the emergence and evolution of metazoans, and the extreme climate change. There are many controversies for the characteristics and origin of these geological, biological and extreme climate events due to the lack of continuous and high-resolution astronomical time scale in the Ediacaran. We here propose to study the systematic cyclostratigraphic analysis of the Doushantuo Formation based on the Jiulongwan section in South China, and then use the long-eccentricity (405-kyr) for astronomical tuning to establish continuous and high-resolution astrochronologic framework, which would provide chronological constraints on carbon isotope negative  excursions, biological evolution and the extreme climate change for the Ediacaran. In order to reveal the inner correlation of the onset age, sequence of these major geological events as well as biological evolution in the Doushantuo Formation on the Ediacaran. Moreover, we also try to discuss the astronomical orbits-forcing factor that may lead to the occurrence and evolution of these major geological events, which would provide scientific evidence for studying the global climate change in the future.
Cloud forcing of glacier surface energy balance in diverse mountain environments
Authors: Conway Jonathan
Published: March 2021

Glaciers are iconic features of mountain landscapes with significant cultural, environmental, scientific, and economic value. While we know that glaciers are sensitive to changes in their local climate, the extent to which cloud cover will amplify or reduce the melting of a glacier in response to future atmospheric warming is uncertain. Clouds alter the solar and infrared radiation available for glacier melt and can enhance or dampen the influence of surface meteorology, albedo feedbacks and subsurface processes (e.g. refreezing) on melt. How these processes interact in different mountain glacier environments and climate regimes has not been well established. To address this knowledge gap, published surface energy and mass balance datasets from 15 mountain glacier sites around the world have been collated and analysed in a common framework. The framework seeks to reveal how melt rate is altered by cloud cover in each environment and which processes are more important for determining how cloud cover modifies melt. For example, does a decrease in incoming solar radiation dominate the effect of clouds on melt, or does covariance between clouds and other meteorological forcing moderate this effect in different environments? By unravelling the interacting effects of clouds and other atmospheric processes on glacier melt in diverse mountain locations, we hope to add fundamental understanding of the processes determining mountain glacier response to climate change.
Subgrid-scale parametrization of unresolved scales in forced Burgers equation using Generative Adversarial Networks (GAN)
Authors: Timofeyev Ilya , Alcala Jeric
Published: March 2021

Stochastic subgrid-scale parametrizations aim to incorporate effects of unresolved processes in an effective model by sampling from a distribution usually described in terms of resolved modes. This is an active research area in climate, weather and ocean science where processes evolved in a wide range of spatial and temporal scales. In this study, we evaluate the performance of conditional generative adversarial network (GAN) in parametrizing subgrid-scale effects in a finite-difference discretization of stochastically forced Burgers equation. We define resolved modes as local spatial averages and deviations from these averages are the unresolved degrees of freedom. We train Wesserstein GAN (WGAN) conditioned on the resolved variables to learn the distribution of subgrid flux tendencies for resolved modes and, thus, represent the effect of unresolved scales. Resulting WGAN is then used in an effective model to reproduce the statistical features of resolved modes. We demonstrate that various stationary statistical quantities such as spectrum, moments, autocorrelation, etc. are well approximated by this effective model.
The Origin and Melt Evolution of Massif-type Anorthosite Parental Magmas: Thermodynamically Controlled Major Element Constraints
Authors: Fred Riikka , Heinonen Aku , Heinonen Jussi S.
Published: March 2021

The parental magmas of massif-type anorthosites are suggested to originate from either the mantle or lower crust. If the source is the mantle, the magmas are presumed to have undergone crustal assimilation prior to plagioclase crystallization, which has produced melt compositions similar to anorthosite parental magmas (high-Al gabbros/basalts). If the source is the lower crust, the produced anorthosite parental melts are presumed to be monzodioritic (jotunitic) in composition. However, many studies have suggested that the monzodioritic rocks related to massif-type anorthosites rather represent residual melt compositions left after anorthosite fractionation. In this study, we have used the most recent thermodynamic modeling tools, Magma Chamber Simulator (MCS) and Rhyolite-MELTS to conduct partial melting, assimilation-fractional crystallization (AFC), and fractional crystallization (FC) models to address the unresolved questions about the source and compositional evolution of the anorthosite parental magmas.

AFC models were conducted at high lower crustal pressures (1000 MPa) by using MCS. In the models, we used four different sublithospheric mantle partial melt compositions and 11 different assimilants with representative average lower crustal compositions compiled from literature. In addition, equilibrium partial melting of the same lower crustal compositions was modeled separately by using rhyolite-MELTS. The melt major element compositions produced by both modeling tools were compared to suggested natural anorthosite parental magma compositions. Finally, to further study the evolution of these melts after their generation, FC models were run at different crustal pressures (1000-100 MPa) by using MCS. These differentiated melt compositions were compared to a global array of monzodioritic rocks presumed to represent residual melts left after anorthosite fractionation.

The preliminary modeling results point towards the mantle being a more suitable candidate for the source of the anorthosite parental magmas and that the parental magma compositions are better represented by high-Al gabbros than monzodioritic rocks: assimilation of mafic lower crustal material by mantle-derived magmas produces melts that are the most fitting analogues. Somewhat similar melts can also be produced by directly melting the lower crust, but this requires the crust to melt completely, which we consider improbable. The models further suggest fractional crystallization of high-Al gabbroic parental magmas produce residual melt evolution trends similar to the array of anorthosite-related monzodioritic rocks.
Impact of Saline Ground water Pumping on density dependent Seawater circulation in Coastal aquifers
Authors: Narayanan Dhanya , t i Eldho
Published: March 2021

Demand for more sustainable aquifer management solution has exacerbated in view of the seawater intrusion occurring in coastal aquifers, particularly in arid areas, where surface water is not aplenty. Feasibility studies showed saline ground water pumping from within saltwater wedge, aiding in mitigation of seawater intrusion and thus re-freshening the aquifer. Such pumping from nearshore aquifer mostly draws water from the sea. The impact is pronounced for higher pumping rates, where the interface would be lowered and toe position get shifted towards seaward side. This implies that, the change in fluid motion may reduce the outflow through seepage face, which in turn affect the circulation of seawater within the wedge. In the present study, a standard test aquifer was simulated with finite difference model, SEAWAT, to know the effect of change in hydraulic gradient due to pumping, on seawater circulation. Saltwater circulation rates were calculated as the ratio between the total inflow across the seaside boundary to terrestrial freshwater flow.  The result demonstrated the shape of interface to resume a depressed conical form establishing a dispersed interface near the surrounding of saline groundwater well. This localized dispersion observed deduce the presence of weak density gradients between two fluids, hence reducing convective overturn. Performance analysis were carried out to infer the interaction between density dependent seawater circulation and change in hydraulic gradient for different pumping rates. This interaction needs to be known in advance before designing saline water pumping rates, as, significant transport of nutrients and contaminants occur within the saltwater wedge.
Improved detection of flash droughts using hyper-resolution hydrological modeling
Authors: Vergopolan Noemi , Herrera-Estrada Julio E. , Sheffield Justin , Estes Lyndon , Wood Eric F.
Published: March 2021

Drought is the most threatening natural hazard for agriculture. Between 1983 and 2003, drought led to a cumulative agriculture production loss of 166 billion U.S. dollars globally, thus monitoring and forecasting capabilities are essential for adaptation and preparedness. Soil moisture simulations play an indispensable role in reconstructing historic drought conditions and predicting future scenarios. However, there is a spatial scale gap between the resolution of soil moisture-based drought indices (10–25 km) and typical farm field sizes (1–2 ha). This spatial-scale gap hampers drought indices’ applicability for capturing and monitoring flash and local-scale agricultural droughts, particularly over heterogeneous landscapes and smallholder farming. 

This work presents a novel approach that uses hyper-resolution modeling and machine learning to identify droughts, characterize their topologies, and evaluate detection rates. We present a case-study for Zambia, where we simulated the root zone soil moisture at a daily 30-m resolution between 1981–2018 using the HydroBlocks land surface model. Using these simulations, we computed a weekly percentile-based drought index, defining it as in drought when the index dropped below the 20th percentile. Given the space and time location of the drought conditions, we applied a Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN) algorithm to determine space- and time-connected clusters/events. We analyzed the topology of 7712 drought events, with a minimum 10-km2 coverage and two weeks duration. Our results showed that 88% were flash droughts (lasting less than one month), 82% were local events (less than 1,000 km2), and 62% were local flash droughts happening during the growing season (October–May). We performed a synthetic spatial scaling analysis to compute the change in detection rate across spatial resolutions. When considering drought conditions over at least 1,000-km2, our results showed that 10–50 km spatial resolution data missed 19 to 44 % of drought conditions captured with 30-m resolution data. This work demonstrates how current capabilities are likely underestimating droughts, and it highlights the urgent need to monitor and forecast droughts at a high spatial resolution. Such refined data can critically benefit local-scale drought mitigation and food security policy design.
Application of Dissolved Organic Carbon Runoff Model Considering Soil Infiltration and River Runoff Processes in Multiple Forested Watersheds
Authors: Ebata Kazunori , Ichikawa Yutaka , Ishidaira Hiroshi , Matsumoto Yoshitaka , Nishida Kei
Published: March 2021

Estimation of dissolved organic carbon (DOC) runoff load in forested watershed is important for the assessment of the global carbon cycle as well as for the control of regional water environments. A few process-based models have been proposed to estimate the DOC load to water environments, which assume DOC source in topsoil and transport processes to the river, however, these models exhibited difficulties with the availability of input data and applicability to short time-scale rainfall-runoff processes in the Asian monsoon area. This study presents a new process-based model that consists of two separate systems for determining DOC load enforced by DOC Source Area (DSA) concept. For the runoff system, a semi-distributed hydrological modelling unit (‘modified-TOPMODEL’) was installed, by which surface and subsurface water flows, representing for DSA, were sequentially simulated. For the soil system, a wet-dry cycle was successfully simulated by an advection-diffusion and dissolution formulation as well as seasonal temperature effect. The model is first evaluated upstream (98ha) and downstream (1798ha) in the Mizugaki Watershed, Yamanashi, Japan and then applied for a Miuchi (203ha) watershed, Aichi, Japan during 2014 to 2018. The results of cumulative DOC load at baseflow and stormflow periods that the model performed well between the simulations and observations for both study sites. Considering the stormflow periods, from 25.2% to 32.0%, and 31.1% of high flows contributed to 50% of the total DOC load at Mizugaki and Miuchi watershed, respectively. Overall, the proposed model successfully simulated DOC load under different geochemical and hydrological condition by capturing the DSA variability.
Experimental study on brine-CO2-rock interaction in carbonate formations of Tazhong-Uplift, Tarim Basin China
Authors: Aihemaiti Kaisaerjiang , Cheng Jianmei , Wang Shiyi , Zhao Ruirui , Ma Xiaoli
Published: March 2021

Abstract: CO2 storage in saline aquifers is one of the most effective ways of geological carbon sequestration. In order to better understand brine-CO2-rock interaction in carbonate reservoirs, 4 series of autoclave experiments with the carbonate rock powder samples with injection of super critical CO2 have been performed. Two core samples were collected from the TC1well at the depth of 4030m (Lianglitage Formation) and 5100m (Qiulitage Formation), and another two samples from corresponding formation  and with varing mineral content were collected from the Yijianfang outcrop and Xiaoerbulake outcrop in Tazhong-Uplift, Tarim Basin, China. The experimental conditions simulate the environment of the reservoir around 4000m depth at the Tazhong Uplift with 25Mpa and 120 degree, where the brine water is CaCl2 type with TDS equal to 135g/l. The FESEM,EDS, XRD, ICP-OES analysis have been performed to examine the mineral chemical composition, morphology and water solution change. The results show that, in all cases after the injection of CO2, with CO2 dissolution, pH shows a decrease at the beginning days of the experiments and start to rise, becomes stable at the end of the experiment. Where as, with the dissolution of the minerals results in continuous increase in electrical conductivity. The SEM analysis demonstrates the dissolution of the calcite and dolomite resulted in a rough surface structure and the sharp edges of calcite and dolomite are dissolved. Also, it is able to observe the formations of new micropores and formation of secondary minerals such as ankerite. In the fluid analysis, Ca2+ is the dominant dissolved cation and originated from calcite and dolomite dissolution. The concentration of Ca2+will first increase sharply and then decreases, whereas concentration of Mg2+ will increase slowly, which means calcite dissolution take places faster than dolomite dissolution. Numerical modeling has been applied to validate the experimental observations with corrected reaction rate. These results can be used for numerical calculation of mineral trapping over long period. This study is helpful for implementation of carbon sequestration plan in Tarim Basin, China.
Development of Detachment Folds in the Mexican Ridges Foldbelt, Western Gulf of Mexico Basin
Authors: Yarbuh Ismael , Contreras Juan , González-Fernández Antonio , Spelz Ronald M. , Negrete-Aranda Raquel
Published: March 2021

Examples of natural folds growing in a homogenous mechanical stratigraphy of alternating competent and incompetent thin layers of fine- and coarse-grained sediments are examined, and the fold growth process is quantified. Our analysis reveals that the overall response to loading of siliciclastic sequences corresponds to that of flexural flow and parallel-to-bedding heterogeneous pure shear. Folds start out as low-amplitude sinusoidal disturbances that rapidly become finite-amplitude folds of heterogeneous strain. We also derive the following scaling relations: (i) degree of amplification scales with both the height above the detachment and strain, (ii) wavelength selectivity broadens with increasing strain, and (iii) deposition of syn-sedimentary geometries is function of strain. These relations are a natural consequence of idealized area-preserving laws of fold growth. From these results we devise a method to estimate fold strain by means of an amplitude versus depth diagram. We are also able to define a progression of fold shape change as a function of the fundamental parameter strain. Initially, structures grow by limb rotation and the selective amplification of a single dominant wavelength giving rise to sinusoidal folds. When strain reaches ~8%, softening/plastic yielding around hinges results in the development of sharp fold profiles. Limbs lock their dips at 35°–45°, suggesting that growth in this stage is permitted by hinge mobility along ramps and blind faults. Moreover, hinge migration causes fold development to accelerate spontaneously. These findings suggest that conclusions relating periods of accelerated erosion/uplift in contractional structures to tectonic processes should be treated with caution.
Mapping Groundwater Fluctuations in the Coastal Los Angeles Basin by Seismic Interferometry
Authors: Mao Shujuan , Campillo Michel , van der Hilst Robert , Lecointre Albanne
Published: March 2021

Changes in crustal seismic velocity (dv/v) can be monitored continuously in time by interferometry of seismic ambient noise. This approach has been successfully employed to study temporal perturbations in stress fields, rock fractures, and fluids. Here we go one step further with this monitoring technique, by not only detecting the temporal changes but also imaging the inhomogeneous spatial distributions of dv/v. We implement the spatial imaging by leveraging travel-time shifts at successive lag times and solving inverse problems based on coda-wave sensitivity kernels. We then use these space-time observations of dv/v to investigate the groundwater fluctuations in the Coastal Los Angeles (LA) Basin during 2000-2020. Imaging of dv/v demonstrates the spatial patterns of groundwater variations: Seasonal changes are most pronounced within confined zones in Santa Ana Basin and LA Central Basin, whereas the long-term changes extend to a broader area including the unconfined forebay. We further compare dv/v observations with InSAR measurements and find strongly consistent spatial patterns. Compared with surface deformation measurements, dv/v additionally help to characterize the depths of several aquifers in the study area. This real-data application substantiates the validity of our dv/v imaging protocol, and shows the promise of using spatio-temporal dv/v observations to monitor surficial hydrological processes.
Spatiotemporal wind energy potential estimation and analysis in Japan
Authors: Matsuoka Taichi , Amano Tetsushi , Delage Remi , Nakata Toshihiko
Published: March 2021

For an efficient integration of wind and solar resources toward sustainable energy systems, it is crucial to consider their fluctuations in space and time. Current spatial wind potential estimations in Japan are limited to the annual average of wind speed. In this study, we evaluate the spatial and temporal evolution of both onshore and offshore wind energy potential in Japan based on 5 km mesh and 1-hour sampling weather forecast data. We then demonstrate the benefits of cross-border sharing on the power output stability and identify important sites having high average potential and low average correlation with other sites for the temporal smoothing of power output.
Volcanoes geological mapping and structural geology with UAS High Resolution Digital Terrain Model : the Kuei-Shan Tao case example (Eastern Taiwan).
Authors: Deffontaines Benoit , Chang Kuo-Jen , Magalhaes Samuel , Fortunato Gérardo
Published: March 2021

Volcanic areas in the World are often difficult to map especially in a structural point of view as (1) fault planes are generally covered and filled by more recent lava flows and (2) volcanic rocks have very few tectonic striations. Kuei-Shan Tao (11km from Ilan Plain – NE Taiwan) is a volcanic island, located at the soutwestern tip of the South Okinawa trough (SWOT). Two incompatible geological maps had been already published both lacking faults and structural features (Hsu, 1963 and Chiu et al., 2010). We propose herein not only to up-date the Kuei-Shan Tao geological map with our high resolution dataset, but also to create the Kuei-Shan Tao structural scheme in order to better understand its geological and tectonic history.

Consequently, we first acquired aerial photographs from our UAS survey and get our new UAS high resolution DTM (HR UAS-DTM hereafter) with a ground resolution <10cm processed through classical photogrammetric methods. Taking into account common sense geomorphic and structural interpretation and reasoning deduced form our HR UAS-DTM, and the outcropping lithologies situated all along the shoreline, we have up-dated the Kuei-Shan Tao geological mapping and its major structures. To conclude, the lithologies (andesitic lava flows and pyroclastic falls) and the new structural scheme lead us to propose a scenario for both the construction as well as the dismantling of Kuei-Shan Tao which are keys for both geology and geodynamics of the SWOT.
Stand dynamics and species composition control long-term post-fire trends in evapotranspiration and streamflow from South-eastern Australia’s Temperate Eucalyptus forests
Authors: Inbar Assaf , Benyon Richard , Lane Patrick , Lakmali Shyanika , Haydon Shane , Sheridan Gary
Published: March 2021

Most of the water that ends up in Melbourne’s water supply catchments originates from wet Eucalyptus forests that are dominated by Eucalyptus regnans, the tallest known angiosperm on earth. Studies had shown that catchments that are dominated by these forests can experience a significant long-term (>100 years) reduction in streamflow after a stand-replacing fire, which was attributed to higher water-use of the dense overstory regrowth. However, despite several lines of evidence, the direction, extent and duration of post-fire hydrological behaviour vary significantly between catchments and between fire events. Here we propose that this variability is caused by initial stocking density and species composition after the fire, and the climatic conditions that prevail during forest regeneration that affect tree growth and mortality rates. In order to test the hypothesis, we formulated an ecohydrological model that simulates hydrology, growth and forest dynamics of E. regnans and Acacia dealbata, which are known to compete for resources during the initial stages of vegetation recovery. The new model shows high skill in predicting long-term streamflow when compared to observations using multiple sources of data. Simulation analysis shows that the direction, extent and duration of post-fire hydrological behaviour are sensitive to initial stocking density and to the relative abundance of species that regenerate after the fire, which influence the rate of self-thinning during stand development. Furthermore, simulation results show that the observed long-term reduction in streamflow is less likely to occur when the forest would have been less dense before the fire, which theoretically could only occur when a high proportion of the short-lived A. Dealbata regenerated after the previous fire. This highlights the importance of including mechanisms that control the effect of species composition on forest dynamics when modelling the effect of possible future climatic scenarios on water yield.