bluuebunny/crossref_metadata_2025 huggingface dataset:
Inferring atmospheric dynamics from tracer observations in 4D-Var: flow-dependent aspects
Authors: Zaplotnik Žiga , Žagar Nedjeljka
Published: March 2020

In the operational NWP, the assimilation of ozone causes large wind and temperature analysis increments in the stratosphere to accommodate for the differences between background and observations. In such cases, unless the ozone feedback on dynamics is switched off, the strong-constraint 4D-Var internal dynamics without comprehensive bias correction makes spurious flow adjustments, especially in the regions with larger gradients in the tracer background field, and when there are insufficient constraints such as large background flow uncertainties and a lack of observations of dynamic variables. The wind-tracer feedback is also turned off for the aerosols and the trace gases. Thus, their useful information on the wind advection is not accounted for anywhere in the domain at any time instance. In this way, the tracer analysis quality is also deteriorated. Somewhat smarter, selective use of tracer information would be beneficial to alleviate unphysical analysis increments in certain regions and at the same time to retain the benefits of wind extraction in other areas.

Thus, we formulate the method for flow-dependent 4D-Var wind extraction, which switches the wind-tracer feedback on or off in the tracers’ tangent-linear model and wind adjoint model. The objective criterion for the selection is deduced from the ensemble of simulations and is based on the ratio of the tracer physical forcings’ uncertainty and the mean tracer advection rate. The numerical tests with an intermediate-complexity incremental 4D-Var system MADDAM show promising results for both wind and tracer analyses. We also demonstrate that the aerosols have theoretically an even larger potential as the carriers of the advection information than humidity due to larger relative spatial gradients, which are crucial for successful wind extraction. The flow-dependent wind extraction method is compared with the weak-constraint 4D-Var, where the tracer model error obtained from the ensemble implicitly controls the amount of wind-tracer coupling.
In situ ammonia measurements in wildfire and agricultural fire plumes in the US
Authors: Tomsche Laura , Mikoviny Tomas , Nowak John B. , Piel Felix , Wisthaler Armin
Published: March 2020

Emissions of trace gases and particles from fires have a major impact on climate, visibility, air quality, and public health. Biomass burning emissions include reactive nitrogen gases, in particular, ammonia (NH3). NH3 is a short-lived gas that acts as precursor for secondary aerosols formed in the downwind plume. This process is still poorly constrained.

In summer 2019, NASA and NOAA carried out the joint airborne FIREX-AQ (Fire Influence on Regional to global Environments and Air Quality) mission over the continental US to sample plumes from wildfires and agricultural fires. On board the NASA DC-8, we used a modified PTR-ToF-MS instrument for measuring NH3 in situ and at high time resolution. Over the course of the mission, we collected a large set of NH3 data in plumes associated with different fire types and burning conditions. Herein, we will present exemplary data and show results of our initial analyses.
Soils in the urban critical zone - Analyse of anthropogenic pressures and current proposals to preserve soil functions and ecosystem services
Authors: Bechet Beatrice , Beaudet Laure , Branchu Philippe , Cannavo Patrice , Delolme Cécile , Jean-Soro Liliane , Lebeau Thierry , Le Guern Cécile , Marseille Fabienne , Schwartz Christophe
Published: March 2020

By 2017, the book "Soils within cities" (Levin et al., 2017) is moving away from the pedologist's description of urban soils to a broader understanding of urban soils, including the functions and the services they provide. This approach, which complements the naturalistic description of the soil, corresponds to the approach derived from the millennium ecosystems assessment (Morel et al., 2015; Walter et al., 2015). It is considered to be relatively anthropocentric and thus favours the integration of the soil in the urban socio-ecosystem.

Considering the soil by both its pedogenesis and functioning in ecosystems induces taking into account the dynamics of this system, but raises, with regard to the literature on urban soils, the existing lack to qualify and quantify the processes of genesis and evolution, especially in relation to ongoing climate change (Baveye et al., 2016). On the other hand, the description of soil ecosystem services (regulation, provisioning, cultural services) immediately reveals the interdependence of soil biophysicochemical processes with those occurring in the hydrosphere, the atmosphere and the biosphere (Adhikari and Hartemink, 2016). In this respect, the soil plays an interface role, but is deeply disturbed in urban areas.

The objective of the communication will be to review the status of urban soil in the "urban critical zone" concept. Through methodologies and results from projects implemented in French major cities that have enabled the development of databases, we will review the classification of these atypical soils and the changes in their properties and functions. Through the definition of the services they provide, we will propose a more integrated vision of this compartment of the urban ecosystem, by specifying the forcing caused by its interface position, but also the opportunities of improvement foreseen by the development of solutions for revegetation and de-sealing. We will see how the timeframe of soil evolution in urban zones can influence the data collection of soil parameters and mapping.
Fault linkage and its controls on fault growth and basin evolution: Insights from analogue experiments
Authors: Avila Paez Michael Andrés , Quintana Gomez Rafael , Kammer Urs Andreas , Saavedra Daza Fabian
Published: March 2020

The evolution of fault-bounded basins and the concomitant migration of hydrocarbons and fluids are strongly influenced by fault activity and, in the case of an extensional tectonic setting, by the interaction of fault planes in relay zones. Fault linkage is a process that develops at relays between sufficiently closely spaced fault planes during their propagation. Fault interaction depends on several factors, such as the degree of under- or overlapping fault arrays, the similar or opposed polarity of fault planes and a separation that should not exceed a critical distance.

Motivated by observations at a km-scale fault relay of a major normal fault in the Magdalena Valley, Northern Andes of Colombia, we designed an analogous sandbox model, in which we simulated the linkage of rift zones separated at distances equivalent to two to four times the dimension of the height of a uniform sand layer. Fault nucleation took place at pre-designed seeds or at the velocity discontinuity of a moving sheet along the base of the sandbox and gave rise to two offset graben structures. Early fault linkage took place by means of two sub-vertical faults, which formed a shortcut between an inner and an adjacent outer border fault of the offset graben structures, enclosing a small horst in between.

The kinematic meaning of these short-cut faults became evident by the subsequent growth pattern of the faults opposite to the linked strands. On approaching the relay zone, these faults turned into an attitude almost perpendicular to their imposed trend. According to the displacement senses set up parallel to the axes of the offset graben structures, the displacement transfer on the two short-cut faults accommodated a strike-slip component. Particle analysis by means of the MATLAB’s PIVlab © tool and photogrammetric processes corroborated these findings. Displacement transfer on the short-cut faults set in at the very onset of the formation of the two graben structures. During successive deformation stages two distinct velocity fields parallel to the graben axes became established, each one pointing away from the structural high of the relay zone.

Although our boundary conditions are restricted to a uniform layer and orthogonal extension, this experimental scenario may form a starting point for testing new questions about the propagation of bounding faults at the termination of graben structures, such as those found at the East Africa Rift. Here, rifting evolved within a lithospheric high, impeding the accumulation of fine-grained or “soft” sedimentary sequences in precursor basins.
Insights into potential submarine landslide tsunamis in the South China Sea: A comparative study of the Baiyun Slide and the Brunei Slide
Authors: Li Linlin , Qiu Qiang , Shi Fengyan , Ma Gangfeng
Published: March 2020

We investigate the sliding dynamics of two giant submarine landslides and their tsunamigenic capacity in the South China Sea (SCS) region: the Baiyun slide in the Pearl River Mouth Basin and the Brunei Slide in Northwest offshore Brunei. The two slides have comparable sizes with the estimated volumes of 1035 km3 for Baiyun Slide versus 1200 km3 for Brunei Slide and areas of 5500 km2 versus 5300 km2. Based on the available geophysical observations, we construct hypothetical scenarios for both slides. By treating the slides as translational mudflow, we are able to reproduce the observed run-out distribution of the Baiyun Slide. The sliding speeds of the failed material could reach 25~35 m/s in both slide events. Both slides could generate devastating tsunamis in the SCS although the tsunamigenic capacity of the Brunei Slide is significantly larger than the Baiyun Slide. Through a series of numerical experiments, we demonstrate that the steepness of the slope and initial water depth of the slides play the key role of determining their tsunamigenic capacity. The tsunami generated by the Baiyun Slide mainly affects the northern part of the SCS. Coastlines including the southern China, central Vietnam, western Philippines suffer the highest tsunami waves.  The tsunami waves generated by the Brunei Slide causes significant impact in northern coasts of Borneo Island, coasts of central and southern Vietnam and Palawan.
Be-10 measurements and modeling results from the South Pole ice core – here comes the sun!
Authors: Schaefer Joerg M. , Steig Eric J. , Ding Qinghua
Published: March 2020

The production of 10Be in the atmosphere in the high latitudes is modulated by solar variability. Time-series records of 10Be from ice cores therefore provide important information on variations in solar activity through time, which is fundamental to understanding climate variability. However, deposition of 10Be to the ice surface is also influenced by variability in atmospheric circulation and deposition processes, and thus, many 10Be ice core records remain difficult to interpret.

South Pole is arguably the best available location for minimizing the influence of variable atmospheric circulation on 10Be deposition. The single existing 10Be record from South Pole covers the last millennium and ends in CE 1982.

We present a new South Pole 10Be record from the late Holocene, together with examplary measurements from the last glacial period, complemented by climate modeling experiments of atmospheric 10Be production, transport and deposition physics. Our continuous one-meter resolution record covers so far the last three millennia. The data from the last millennium agree well with the existing 10Be record by Raisbeck et al. (1990). The 10Be data from the South Pole ice core matches the historic sunspot records strikingly, providing a robust calibration between sunspot number and 10Be deposition. The coincident timing of major shifts in sunspot number and 10Be provides an independent confirmation of the South Pole ice core timescale.

Independently, our model simulations of both internannual variablity and glacial vs. interglacial 10Be production, transport and deposition indicate that 10Be in South Pole snow is robust even to significant climate changes, suggesting that the measured 10Be primarily reflect changes of solar activity over that period. In turn, our model-data comparison allows to evaluate potential shifts in solar activity through the late Holocene, and during the glacial-interglacial transition.
Using machine learning to identify magnetic reconnection in two-dimensional simulations
Authors: Hu Andong , Teunissen Jannis , Sisti Manuela , Califano Francesco , Dargent Jérémy , Pedrazzi Giorgio , Ponti Francesca Delli
Published: March 2020

The understanding of fundamental processes at play in a collisionless plasmas such as the solar wind, is a frontier problem in space physics. We investigate here the occurrence of magnetic reconnection in a plasma with parameters corresponding to solar wind plasma and its interplay with a fully-developed turbulent state. Ongoing magnetic reconnection can, at the moment, be accurately identified only by humans. Therefore, as a first step, the goal of this study is to present a new method to automatically recognise reconnection events in the output of two-dimensional HVM (Hybrid Vlasov Maxwell) simulations where ions evolve by solving the Vlasov equation and the electrons are treated as a fluid with mass. A large dataset with labelled reconnection events was prepared, including parameters such as the magnetic field, the electron velocity field and the current density. We consider two types of machine learning models: classical approaches using on physics-based features, and convolutional neural networks (CNNs). We will investigate which approach performs better, and which input variables are most relevant. In addition, we will try to categorize magnetic reconnection regions (current sheets). This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 776262 (AIDA, www.aida-space.eu).
Seasonal land cover and annual land use mapping for fire modeling
Authors: Gong Peng , Liu Han , Bai Yuqi
Published: March 2020

Fire modeling needs timely fuel information.  Land cover and land use data are often used for fuel type mapping.  Existing large scale mapping efforts do not provide frequent land cover information, due partly to the lack of frequent raw data, and partly to the huge computational cost.  In this presentation, we will report our latest land cover and land use mapping efforts toward mapping global land cover at seasonal steps while mapping land use at annual intervals.  We report a data-cube approach applied to over 20-year Landsat and Terra and Aqua data (2000-2019) that made it convenient to experiment with various land cover and land use mapping procedures.  

With a data cube, time series analysis can be easily done that allows not only fuel type mapping but also fire event detection.  We report the use of multiple season land cover samples collected in a specific year at the global scale to map seasonal land cover.  We also report the use of historical land use for annual land use mapping. In addition, we report burnt area detection results from the using selected data from historical burnt area maps in training machine learning algorithms based on the data cube.  Land cover and land use data are cross-walked to fuel type data. This approach provide more accurate fuel type data for fire emission estimation and fire behavior modeling.

 
Deep structure of the Central-Chile continental wedge and its implications for large megathrust earthquakes
Authors: Maksymowicz Andrei , Montecinos Daniela , Díaz Daniel
Published: March 2020

subduction zone ruptured by the high slip patch of the 1960 Mw9.5 Valdivia earthquake. The density structure of the upper plate was generated by using a 2-D forward modeling schema (GGrad) offshore, and 3D inversion onshore (GRAV3D) with a database composed by a recompilation of previous marine and onshore gravity measurements, complemented by 113 new gravimetric station acquired by our group. The modelling was constrained by independent seismological data, active seismic information and electromagnetic soundings registered during the project. The joint analyze of the obtained density model with magnetic data and seismic models, provide new insight about the structure of the upper plate forearc, where an East-West segmentation of physical parameters (perpendicular to the margin) is associated with first order changes in the surface geology, deep structural style and seismotectonics characteristics of the margin. The systematical comparison of the results observed in this segment with surrounding regions of the Chilean margin, suggests a causal link between complex sequence of large earthquakes ruptures and changes of rheology/lithology along the interplate boundary, determined in turn, by the long term tectonic and geodynamic evolution of the subduction zone.

   

 

 

 
A Novel Modeling Framework to Represent Turbulent Mixing in the Benthic Biolayer of Streams
Authors: Gomez-Velez Jesus D. , Grant Stanley B. , Ghisalberti Marco , Guymer Ian , Boano Fulvio , Roche Kevin , Harvey Judson W
Published: March 2020

Many of the most important ecosystem services performed by streams occur in the benthic biolayer, the biologically active upper layer of the streambed. Here we develop and test a rigorous modeling framework for the unsteady one-dimensional transport and mixing of a solute in the benthic biolayer of a turbulent stream. Our framework allows for depth-varying diffusivity profiles, accounts for the change in porosity across the sediment-water interface and captures the two-way feedback between evolving solute concentrations in both the overlying water column and interstitial fluids of the sediment bed. We apply this new modeling framework to an extensive set of previously published laboratory data, with the goal of evaluating four diffusivity profiles (constant, exponentially declining, and two hybrid models that account for molecular diffusion and enhanced turbulent mixing in the surficial portion of the bed). The exponentially declining and enhanced mixing profiles are superior and their reference diffusivities scale with a dimensionless measure of stream turbulence and streambed permeability called the Permeability Reynolds Number, ReK. The dependence on ReK changes abruptly at ReK = 1, reflecting different modes of mixing below (dispersion) and above (turbulent diffusion) this threshold value. Because our modeling framework can be applied to open systems, it should inform the prediction and management of pollutant migration through a diverse array of aquatic ecosystems.
Early human occupation in mainland East Asia: Implication for climate change and human evolution
Authors: Zhu Rixiang
Published: March 2020

East Asia is a key area for early human migration and evolution in the Old World. During the early Pleistocene, humans began to spread out of Africa. Detailed magnetostratigraphic dating coupled with high-precision isotopic chronology of early humans in mainland East Asia, western and southeastern Asia has provided insights into our understanding of early human adaptability to a variety of environments in the eastern Old World. Before the Middle Pleistocene, early humans occupied over a broad latitudinal range, from temperate northern China (e.g., the Nihewan Basin and the Loess Plateau) to subtropical southern China (e.g., the Yuanmou Basin). Thus oldest recorded human dispersal to East Asia apparently culminated in the ability to adapt diverse environments. Around the Middle Pleistocene Climate Transition, when the climate of Earth underwent profound changes in the length and intensity of its glacial-interglacial cycles with the dominant periodicity of high-latitude climate oscillations changing from 41 kyr to 100 kyr, there is a prominent early human flourishing in the high northern latitudes of East Asia and geographic expansion from low, through middle, to high northern latitudes of the area. The improved ability to adjust to diverse environments for early humans could have benefited from the increasing variability of global, regional and local paleoclimates and paleoenvironments and from the innovation of diet, e.g., the use of animal tissues.
Envisaging post-earthquake snowmelt-induced shallow landslides under climate change
Authors: Siva Subramanian Srikrishnan , Fan Xuanmei , Yunus Ali. P. , van Asch Theo , Xu Qiang , Huang Runqui
Published: March 2020

Seasonal snow cover occupies around 33 % of the earth’s surface and draws the underlying landscape to serious natural hazards under climate change. The frequency of shallow landslides in seasonal cold regions is increasing, i.e., in the French Alps, Umbria in Italy, and Hokkaido in Japan. Further, tectonically active seasonally cold areas are more susceptible to spring landslides if an earthquake occurs during pre-winter. Hazard assessment and risk mitigation of snowmelt-induced landslides in such a scenario requires physically-based prediction models. However, studies focusing on the impacts of future snowmelt on shallow landslides are scarce. To comprehend these, the complex interactions between the atmosphere, hydrological, and geomechanical systems within a catchment under future climate need detailed studies. Present methods for snowmelt induced soil slope instability analysis are single-slope based and applied for individual cases. The challenge remain is to simulate the interactions between the atmosphere, hydrological, and geomechanical systems by coupling micro and macro-scale processes within a catchment for regional-scale future forecasts. In this perspective, we developed a novel spatially distributed, a physically-based numerical approach to compute slope stability within a basin, explicitly considering the atmosphere-ground, hydrology, and mechanical interactions on a day to day time step. Using this model, we envisaged future snowmelt-induced landslides under increased and decreased melt rates and post-earthquake settings. We obtained the probability density curves of these future landslides and found that under slower snowmelt rates, the occurrence probability of individual landslides remains the same, whereas, under rapid and increased snowmelt rates, the size-distribution of the landslides increase one magnitude and doubles if rapid snowmelt follows an earthquake.
Trigger atmospheric conditions for RIL in the Southern Andes.
Authors: Manque Roa Nataly , Fustos-Toribio Ivo , Somos-Valenzuela Marcelo
Published: March 2020

Rainfall-Induced Landslides (RIL) are one of the most important natural hazards due to their damage to populated areas, critical infrastructure, and roads. Therefore, their deep understanding is critical for decision-makers. The Southern Andes (~ 41.1ºS, 72.5ºW) has undergone recurring RIL processes in recent years, which have affected interurban connectivity with strong social impacts. The objective of this study is to understand the atmospheric conditions that could trigger RIL at the Southern Andes. We propose a correction of high-resolution atmospheric simulations based on the Weather and Research Forecast (WRF) model. Our results were corrected by meteorological in-situ stations using geostatistical techniques. We identify precursor signals at different pressure heights that could be used to the future in an early warning system. Our proposed methodology will support the generation of public policies in the context of climate change scenarios in catchments with low-dense instrumentation and low uncertainty. Hence, our database will provide new hydrometeorological perspectives in RIL studies. To the future, these results will allow the development of an early warning system applicable in the central-southern zone of Chile.
Improving the uncertainty of ocean surface wind and wave parameters estimated by a single HF radar system
Authors: Dao Duy-Toan , Chien Hwa , Flament Pierre
Published: March 2020

A 16 Rx element linear array HF radar system (LERA III), working at 27.75 MHz and 300kHz in bandwidth, was installed at the north of Taichung harbor at the western coast of Taiwan in November 2018. This LERA system is low-cost, compact in size, easy to set-up, and maintain. The purpose of present studies is to implement algorithms for retrieving wave and wind fields and assess the system performance in terms of operational mode. For inter-comparison, the long-term in-situ wave data measured by an AWAC was adopted. Wind data were measured from a coastal wind gauge. The inter-comparisons between radar data and in-situ data were carried out on seasonal basis, including severe sea states during winter monsoon and passage of typhoon as well as calm seas during spring.

For the data processing, the Doppler-range spectrum for each azimuth direction was extracted by using the classical beam-forming technique and then provided as level 1 product for further analysis. Regarding the method for retrieving wave parameters, formulations directly derived from Barrick’s assumption was implemented. In those formulas, wave parameters are calculated based on the ratio of the 2nd order component multiplied by the coupling coefficient function to the 1st order component in the Doppler spectrum. It means that no empirical constants were included. Initially, Wyatt’s (1999, 2011) and Walsh & Howell’s (1993) methods were applied to determine the lower and higher bounds that separate the 1st and 2nd order component. For wind speed inversion, Dexter & Theodorides’s (1982) method was adopted. The Bragg wave direction was used as a proxy to the direction of the wind field.

It is found that when using Wyatt’s (1999, 2011) method, the wave height and period results often lead to bias estimations for severe sea-state, and with the presence of highly variable surface current. In order to improve the accuracy, adaptive methods for the identification of spectra component areas is crucial. In this study, an alternative method is proposed. This method is developed based on the concept proposed by Kirincich (2017), which includes the pretreatment of Doppler-rang spectrums, marker-controlled watershed segmentation, and an image processing technique. In this research, we will demonstrate the advantages of using the new method for wave and wind field retrieval. From comparative studies, the error indexes based on the sea truth data are discussed. It is found that the accuracy would be improved using the proposed method, especially for the cases of varying current fields, severe sea state, and noisy radio background.

Key words: high-frequency surface wave radar; phased array antennas; significant wave height, wave period, marker-controlled watershed segmentation (MCWS) techniques.
Impact of fault fracture development and distribution regularity on groundwater flow and solute transport in rock mass as exemplified at 3720 m of the first mining region of Pulang Copper Mine, SW China
Authors: Han Kexue , Zuo Rui , He Zhukun , Li Qiao
Published: March 2020

Statistical analysis of development and distribution of fault fissures at 3720 m in the first mining region of Pulang Copper Mine, SW China was performed. Strongly heterogeneous hydro-geological numerical models influenced by fault fissures were set up. Effects of developmental distribution cracks on solute transport in 65° and 307°directions were simulated. Rock mass with strong permeability water-conducting fissure was found favorable for solute transport, water-blocking fault was found to inhibit solute transport. The direction of fracture development was found consistent with direction of groundwater flow, which would be beneficial for solute transport along water-flow direction. When direction of fracture development intersects with that of groundwater flow and the strong lens affected by fracture changes direction of groundwater flow, direction of solute transport is changed.
Global trends of tree-ring carbon isotope discrimination under rising atmospheric CO2 and changing climate
Authors: Belmecheri Soumaya , szejner Paul , Frank David , Voelker Steve , Lavergne Alienor
Published: March 2020

Rising atmospheric CO2 concentrations are expected to stimulate plant carbon uptake (A) while also reducing transpiration via a decrease in stomatal conductance (gs), resulting in an increase in the intrinsic water use efficiency (iWUE, i.e. the ratio of A to gs). While there is overwhelming evidence of a secular iWUE increase in response to rising CO2 over the 20th-21st century, the magnitude of changes in iWUE reported so far in the literature strongly varies across climatic regions and biomes. Moreover, increasing iWUE has not systematically been translated into tree growth increment at many forested ecosystems, challenging the CO2 fertilization theory. There is thus a need to track down the key physiological and environmental mechanisms driving changes in iWUE.

Here we estimate the carbon isotopic discrimination (Δ13C) - defined as the difference between the stable carbon isotopic compositions (δ13C) measured in atmospheric CO2 and in tree rings – from 147 tree-ring δ13C chronologies to: 1) investigate the physiological responses of woody C3 plants to increasing atmospheric CO2 and, 2) disentangle climate vs CO2 effects on A and gs. We specifically study deviations of tree-ring Δ13C from the predicted Δ13C response to CO2 as reconstructed from a recent meta-analysis of paleo and elevated CO2 data. We identify the following: 1) negative deviations from the expected Δ13C for most records; 2) no apparent deviation from expected Δ13C or; 3) positive deviations, both in a small minority of records ; and 4) an apparent non-linear response with a switch from a more negative Δ13C deviations to a Δ13C-response consistent with predicted CO2-effects. The widespread negative Δ13C  deviations are consistent with gs having been reduced or A having not increased as much as expected for a given CO2-driven stimulation of A. The presented global tree-ring data analyses suggest that a warmer and often drier climate have had a stronger effect on Δ13C compared to that of rising CO2, and a substantial modulation of recent rises in iWUE by climate effects across the globe.
Statistical Study of Pitch Angle Diffusion during Substorm Injections
Authors: Ghaffari Reihaneh , Cully Christopher
Published: March 2020

Energetic Electron Precipitation (EEP) associated with substorm injections typically occurs when magnetospheric waves, particularly whistler-mode waves, resonantly interact with electrons to affect their equatorial pitch angle. This can be considered as a diffusion process that scatters particles into the loss cone. In this study, we investigate whistler-mode wave generation in conjunction with electron injections using in-situ wave measurements by the Themis mission. We calculate the pitch angle diffusion coefficient exerted by the observed wave activity using the quasi-linear diffusion approximation and estimate scattering efficiency in the substorm injection region to constrain where and how much scattering happens typically during these events.
The Arrested Ekman Layer Escapes! Ventilation of the BBL by Internal Swash.
Authors: Polzin Kurt , Wang Zhankun , Wang Binbin , Ruiz Angulo Angel
Published: March 2020

Moored data from the northern Deepwater Gulf of Mexico in the vicinity of DeepWater Horizon are presented.  Subinertial flows of O(0.1-0.2 m/s) are in the sense of Kelvin wave propagation and support a downwelling Ekman layer with reduced near boundary stratification.  The moored data document cross-slope and vertical buoyancy fluxes dominated by a frequency band that includes diurnal and inertial frequencies and extend to about an order of magnitude larger than inertial.  We refer to this frequency band as internal swash and the region of reduced stratification at the bottom boundary exhibiting these fluxes as the internal swash zone.  Vertical fluxes of cross-slope momentum associated with internal swash band frequencies are large, of similar order of magnitude as the drag associated with the viscous no-flow bottom boundary condition on the cross-slope subcentral current.  Typical mixing efficiencies of (Γ ~ 0.2) are found in association with elevated mixing O(100 times background) one-to-two hundred meters above the bottom. This enhanced turbulence appears in conjunction with near-inertial frequency motions that may be dynamically coupled to the mean flow.  

 
Water Chemistry in Estuaries Around Great Salt Lake, Utah, USA.
Authors: Matyjasik Marek
Published: March 2020

The Great Salt Lake (GSL) in northern Utah is a key natural resource for migratory waterfowl and the local economy. The quality and quantity of water reaching the Great Salt Lake are of concern, particularly as competing interests along source rivers, such as the Bear River, seek to divert and capture more water to meet their needs. This project presents preliminary field study and aims to improve the scientific understanding of the chemical mixing taking place where freshwater rivers discharge into the Great Salt Lake. Water samples were collected in 16 locations in mixing zones between the Bear River Bay, marshes of the mouth of the Ogden River, and shallow water zones in the Great Salt Lake. Water samples were acidified with nitric acid and filtered through 0.2 micrometer filter. Field in-situ parameters: temperature, pH, ORP, dissolved oxygen, and electric conductance were measured using Troll 9500 probe and concentrations of forty elements were analyzed in ICP-MS and ICP-OES. Field in-situ measurements indicated that pH is weekly alkaline with saline waters typically being more alkaline than fresh water. Saline waters are more reducing than fresh waters. Fresh water flows were extensive in very shallow environments. Extremely shallow environments were more affected by high salinity mud deposits. The results indicate higher concentrations of heavy metals transported from the Bear River Bay to the Great Salt Lake than from the Ogden River. The pattern of elemental concentrations is complex. Fresh water fluxes penetrate shallow saline waters over relatively long distances (hundreds of meters). The depth of lake waters was predominantly less than 0.5 meter. ICP-OES measurements showed that overall Bear River samples had somewhat higher concentrations of major ions than in in the Ogden River. ICP-MS measurements indicated similar patterns between trace elements in the Bear River and in the Ogden River. Both areas have relatively higher concentrations of Al, Fe, and Mn. Concentrations of Pb, As, Se, and Hg are also relatively high. Correlation between in-situ parameters indicates complex relationship between different elements. For example more acidic conditions do not necessarily result in higher concentration of metals. Higher concentrations of metals correlate better with more reducing conditions. Concentrations of metals did increase significantly at more acidic conditions, but they typically characterized less saline waters. We will attempt hydrochemical modeling in the next phase of this research which will be verified by laboratory experiments of mixing of waters in question. This will allow controlling the parameters since natural dynamic flow systems driven by wind in a very shallow water and freshwater fluxes flowing far into saline water bodies might compromise accuracy of thermodynamic modeling.
Data-adaptive harmonic analysis of high-dimensional oceanic turbulent flows
Authors: Kondrashov Dmitri
Published: March 2020

Oceanic turbulent flows consist of complex motions (fronts, eddies and waves) that co-exist on many different spatio-temporal scales and nonlinearly interacting with each other. In this study data-adaptive harmonic decomposition (DAHD) has been applied to high-dimensional datasets of complex turbulent flows simulated by ocean models of different complexity. DAHD allows a low-rank description of multiscale and chaotic dynamics by a small subset of data-adaptive patterns oscillating harmonically at given temporal frequency. The shape and scaling laws of temporal energy spectrum of the extracted patterns reveal global fingerprint of underlying dynamics, providing new opportunities to characterize and compare oceanic datasets and models. 

1. Ryzhov, E.A., D. Kondrashov, N. Agarwal, and P.S. Berloff, 2019: 
On data-driven augmentation of low-resolution ocean model dynamics, 
Ocean Modelling, 142, doi:10.1016/j.ocemod.2019.101464. 

2. Kondrashov, D., M. D. Chekroun and P. Berloff, 2018: 
Multiscale Stuart-Landau Emulators: Application to Wind-Driven Ocean Gyres,
Fluids, 3(1), 21, doi:10.3390/fluids3010021.
Reconstruction of solar radiation based on historical weather records in Japan - Climatic condition and market economy in the famine of 1830s -
Authors: Ichino Mika , Masuda Kooiti , Mikami Takehiko , Takatsuki Yasuo
Published: March 2020

Japan has plenty of diaries in the 17th to 19th centuries, which include records of daily weather conditions ("fine", "cloudy", "rainy", etc.) It is well known that they have been used for reconstructing climate variation and events, although it provided qualitative data, not instrumental observations.

We estimate global solar radiation from weather conditions. Global solar radiation is an important factor for the energy balance of the Earth, and is also fundamental to the hydrological cycle and agricultural productivity. Our method is effective for all seasons and which could produce reconstruction with higher temporal resolution than other proxy data, for example tree rings.

Weather descriptions are classified into 3 categories and weather categories convert to solar radiation. The parameters of conversion are calculated by using JMA observations from 1995 to 1999.

We reconstructed monthly mean global solar radiation from 1821 to 1850 based on the weather records described in 11 historical diary documents. We focused on the years of Tempo Famine from 1833 to 1839.

In 1836, monthly solar radiation in summer in the east-west zone of Japan including Kanto, Kinki, and northern Kyushu was smaller than the provisional normal (average of 1821-1850). It was 10% or more smaller than the normal in July and August. However, it was not particularly small in Tohoku to the north of the zone and in southern Kyushu to the south of the zone. The characteristic of reconstruction in 1836 is that lower solar radiation prolonged from May to September in the central area of Japan. This suggests that climatic condition similar to Baiu was prolonged, and that it was cold in Tohoku. On the other hand, in 1833 and 1838, when famines also occurred, the reconstructed solar radiation was low in Tohoku.

We also checked the effect on market economy by observing the daily price of rice, the main crop at that time. For 1836, we can observe the sharp rise of the price in July. It suggests that the market had reacted to the bad climate condition before the harvest season. After this sharp rise, four times higher than usual, rice price reached a plateau then fell in September 1837.

While the rice price in 1833 and 1838 also rose up in summer, they were only two or three times higher than usual and, more importantly, they quickly bounced back.

Cross check between the reconstructed solar radiation and the rice price data support thus enables us to conclude that there existed a big difference even among the years recorded as “famine years” on the historical documents.
Lithological control of drainage basins development post LGM and oscillating climate condition
Authors: Chyi Shyh-Jeng , Chen Jia-Hong , Yen Jiun-Yee , Ho Lih-Der , Jen Chia-Hung , Lüthgens Christopher , Wu Ting-Yu , Chang Ting-Yi , Yen I-Chin , Lu Cheng-Hao
Published: March 2020

Compare to rivers originated from western Taiwan flowing westward, rivers   originated from the southeastern side of the Central Range and the eastern side of the Coastal Range flow eastward directly into the Pacific Ocean and form very narrow alluvial plains or coastal plains immediately next to the mountain front. Based on the field evidences and mapping from field and high-res DTM, we classified these river basins into two types.

 

The geomorphic features of the first type are remarkably wide valley plain with flights of fill terrace and relatively narrow active channel in the downstream area. The radiocarbon dates of terrace sediments indicate that large-scale aggradation took place before 7ka, and formed fill terraces with the largest relative height of around 50 meters relative to the modern channel bed in the mid to late Holocene. We proposed the landscape evolutionary history for the first type of river basins is that significant river aggradation caused by rapid sea-level rise in estuary during the late Pleistocene to the early Holocene, followed by continuous and slow uplift or the relative sea-level falling that induced a long term basin-wide river incision.

 

The geomorphic features of the second type of the river basins are those that the knickpoint developed in the igneous rock gorge near the river mouth and often formed incised meander and unpaired rock terraces in its upstream area. The radiocarbon dates of terrace sediments indicate the average bedrock incision rate of upstream area is  noticeably lower than the rate near  the coast/river mouth area. For the second type river basins, we proposed that the climate turns warm and wet since the end of the last glacial period and the retreat of knickpoint in the igneous rock gorge exert the primary influence on terrace formation in the upper reaches, and the relative sea level falling is the main control on the terrace formation in the coastal area. In addition to those, the terraces of the main tributaries of the second type river basins which reveal the different cut-and-fill histories might be the results of complex response of sub-drainage systems to the multiple controls.
Evolution from lithospheric to sub-lithospheric potassic liquids with sulfide droplets in Wudalianchi, NE China
Authors: Chuvashova Irina , Yasnygina Tatyana , Saranina Elena , Sun Yi-min , Rasskazov Sergei
Published: March 2020

On the diagram of uranogenic leads, we define 1.88 Byr locus of lithospheric sources for low-Mg rocks from Wudalianchi and a non-lithospheric recently homogenized material (referred to the Molabu source) for moderate-Mg rocks. Lithosphere-derived liquids were characteristic of the initial Laoshantou and Old Gelaqiushan lava flows erupted along a north-south volcanic line 2.5–2.0 Myr ago. Due to eastward expansion of the Wudalianchi melting anomaly, its NNE limit was designated by lithosphere-derived liquids erupted in North Gelaqiushan and Weishan volcanoes between 0.6 and 0.4 Myr ago. In the evolution of the melting anomaly, other volcanoes showed compositions derived due to mixing lithospheric and non-lithospheric components. The only exception was moderate-Mg rocks from East Longmenshan volcano that yielded peculiar compositions modified after liquids from the Molabu source. Decreasing Pb, S, and Ni abundances, Ni/Co, Ni/MgO ratios as well as increasing 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, Ce/Pb, Th/Pb, and U/Pb ratios are indicative for liquids likely affected by segregating small amounts of sulfide droplets. We infer that the Wudalianchi melting anomaly was firstly generated in the lithosphere and was evolved to melting of the sub-lithospheric medium.

This work is supported by the RSF grant 18-77-10027.
The synthetic spectra of potential earthquakes for Taipei basin
Authors: Huang Ming-Wey , Chang Chi-Ling , Liu Sheu-Yien
Published: March 2020

Modeling the amplitude spectra based on the source term, the path one and site ones for 54 sites located in and around the Taipei basin is the aim of this study. The site term includes the amplification function varied with frequency and the site-specific parameter (k0). The amplification functions for Class-C, -D, and -E site are from Huang et al. (2007) for the central Taiwan. Meanwhile, the amplification function for Class-B site can be referred to Boore and Joyner (1997). The root-mean-squared spectral amplitudes of two horizontal shear waves after three-point smoothing from the observed seismograms are compared to the synthetic amplitude spectra. The goodness of fit coefficient (GFC) and the residual errors (ERR) are calculated for concluding the fitness of the modeling amplitude spectra. Results show both the GFC and ERR of stations are varied with the earthquake magnitude and hypo-central distance. The averaged GFC are larger than 0.8 for 42 stations. Meanwhile, there are 12 station with averaged GFC smaller than 0.8. Besides, the ERRs of 28 stations are less than 0.5. Meanwhile, there are 18 stations with ERRs in the range of 0.5-0.6. The obtained results may be used for modeling the amplitude spectra for the Taipei area. The more accurate amplitude spectra can be improved by updating the parameters utilized in the source-, the path- and the site terms.
Hydrological Response Mechanism of Aquifer Dynamic Storage during the Dry and Wet Seasons
Authors: Huang Chia-Chi , Yeh Hsin-Fu
Published: March 2020

Streamflow recession usually exists between rainfall events, and the recession can be expressed as the power relationship between the streamflow and the recession rate. Under the assumption that groundwater drainage from the aquifer to the river channel, this method can inversely evaluate the basin-scale groundwater storage using observed streamflow. It has often been used to explore regional groundwater storage conditions and storage-discharge relationships, and even to estimate hydrogeological parameters. However, the groundwater storage generating the streamflow is only a component of the dynamic storage that includes streamflow and evapotranspiration dynamic, or other forms of mobile groundwater. In order to understand the mechanism of the aquifer dynamic storage responses under environmental changes (included climate change, human activities, etc.), this study used the analytic streamflow distribution model to optimize the estimation of recession parameters during the dry and wet seasons, and explored the parameters change over time and the relationship with seasonal evapotranspiration and basin wetness conditions. Combining the water balance methods, we also quantified the dynamic storage relevant to groundwater drainage and vegetation available water (i.e. storage insensitive to streamflow), respectively, to explore the hydrological response mechanism of aquifer dynamic storage in two seasons. The results showed that the difference in recession parameters in the dry and wet seasons is related to the basin wetness condition, and the evapotranspiration effect is relatively limited. In addition, the parameters change over time also indicated that the environmental change has gradually changed the streamflow recession mechanism. By comparing the response of dynamic storage components to rainfall events and evapotranspiration, this study also demonstrated that the variability in different forms of dynamic storages during each season, which is helpful for understanding the store and loss process of groundwater storage at the basin scale and improving the possibility for predicting the different environmental impacts on groundwater storage.