bluuebunny/crossref_metadata_2025 huggingface dataset:
Internal Wave Generation in Tropical Upwelling Regions: the Angolan and Peruvian Shelves
Authors: Lamb Kevin , Brandt Peter , Dengler Marcus
Published: March 2020

The Angolan and Peruvian shelves are located in upwelling regions along the eastern boundaries of the tropical Atlantic and Pacific Oceans. They are sites of important fisheries supported by high productivity which is driven by fluxes of nutrients from deep to near surface water along the coast. Mixing associated with internal waves is believed to play a role in this process. Recent field observations have shown the presence of an active internal wave field that includes internal solitary waves. In this talk results of high-resolution two-dimensional simulations of internal wave generation by tide-topography interactions on the Angolan and Peruvian shelves are presented. The simulations show the generation of internal wave beams at near-critical slopes and the generation of high-frequency internal solitary waves. The high-frequency IW spectrum is enhanced when small scale bathymetric ripples are included. Wave generation during winter and summer stratifications will be compared.
North American Warm-west/Cold-East air temperature pattern and its linkage to different El Nino types
Authors: Ge Yao , Luo Dehai
Published: March 2020

 

In recent years, the surface air temperature (SAT) anomalies in winter over North America show a “warm-West/cool-East” (WWCE) dipole pattern. The underlying mechanism of the North American WWCE dipole pattern has been an important research topic. This study examines the physical cause of the WWCE dipole generation.

It is found that the positive phase (PNA+) of the Pacific North American (PNA) pattern can lead to the generation of the WWCE SAT dipole. However, the impact of the PNA+ on the WWCE SAT dipole over North America depends on the type of the El Nino SST anomaly. When an Eastern-Pacific (EP) type El Nino occurs, the anticyclonic anomaly center of the PNA+ over the North American continent is displaced eastward near 100°W due to intensified midlatitude westerly winds over North Pacific so that its anticyclonic anomaly dominates the whole North America. In this case, the cyclonic anomaly of the PNA+ almost disappears over the North America. Thus, the WWCE SAT dipole over the North America is weakened. In contrast, when a central-Pacific (CP) type El Nino appears, the anticyclonic anomaly center of the associated PNA+ is located over the North America west coast due to reduced midlatitude westerly winds over North Pacific. As a result, the cyclonic anomaly of the PNA+ can appear over the east United States to result in an intensified WWCE SAT dipole over the North America
Low-Earth-Orbit observations for space weather and space climate
Authors: Zakharenkova Irina , Cherniak Iurii , Sokolovskiy Sergey , Schreiner William , Wu Qian , Braun John
Published: March 2020

Many of the modern Low-Earth-Orbiting satellites are now equipped with dual-frequency GPS receivers for Radio Occultation (RO) and Precise Orbit Determination (POD). The space-borne GPS measurements can be successfully utilized for ionospheric climatology and space weather monitoring. The combination of GPS measurements, which include RO observations and POD measurements from the upward-looking GPS antenna, provides information about electron density distribution (profile) below the satellite orbit and an integrated Total Electron Content (TEC) above the satellite representing an important data source for electron density climatology above the F2 layer peak on a global scale. We demonstrate the advantages of using space-borne LEO GPS measurements, both RO and upward-looking, for Space Weather activity monitoring including specification of ionospheric plasma density structures at different altitudinal domains of the ionosphere in quiet and disturbed conditions. After the great success of the COSMIC-1 (Constellation Observing System for Meteorology, Ionosphere, and Climate) mission operating since 2006, the six COSMIC-2 satellites were launched into a 24 deg inclination orbit in June 2019. The COSMIC-2 scientific payloads with the advanced Tri-GNSS Radio-Occultation Receiver System provide multiple observation types including multi-GNSS TEC (limb and overhead), RO electron density profiles, amplitude/phase scintillation indices, in-situ ion densities and velocities. The COSMIC-2 advanced instruments allow detection of ionospheric plasma density structures of various scales, and the monitoring of high-rate amplitude and phase scintillations both above and below a satellite orbit. The COSMIC-2 multi-instrumental observations will contribute to a better understanding of the equatorial ionosphere morphology and future forecasting of ionospheric irregularities and radio wave scintillations that harmfully affect satellite-to-Earth communication and navigation systems. We present results of post-event analyses for severe space weather events demonstrating a great potential and contribution of the COSMIC-1/2 missions in combination with the ground-based GNSS receivers and other LEO missions like C/NOFS, DMSP, MetOp, TerraSAR-X, and Swarm for monitoring the space weather effects in the Earth’s ionosphere.
Focused groundwater recharge in a dryland environment: hydrometric and isotopic evidence from central Tanzania
Authors: Seddon David , Kashaigili Japhet J. , Taylor Richard G. , Cuthbert Mark O. , Mihale Lucas , Mwihumbo Catherine , MacDonald Alan M.
Published: March 2020

Groundwater, and its replenishment via recharge, is critical to livelihoods and poverty alleviation in drylands of sub-Saharan Africa and beyond, yet the processes by which groundwater is replenished remain inadequately observed and resolved. Here, we present three lines of evidence, from an extensively-monitored wellfield in central semi-arid Tanzania, indicating focused groundwater recharge occurring via leakage from episodic, ephemeral stream discharges. First, the duration of ephemeral streamflow observed from daily records from 2007 to 2016 correlates strongly (R2 = 0.85) with the magnitude of groundwater recharge events observed and estimated from piezometric observations. Second, high-resolution (hourly) monitoring of groundwater levels and stream stage, established in advance of the 2015-16 El Niño, shows the formation and decay of groundwater mounds beneath episodically inundated adjacent streambeds. Third, stable-isotope ratios of O and H of groundwater and precipitation as well as perennial and ephemeral surface waters trace the origin of groundwater to ephemeral stream discharges. The identification and characterisation of focused groundwater recharge have important implications not only, locally, for protecting and potentially augmenting replenishment of a wellfield supplying the capital of Tanzania through Managed Aquifer Recharge but also, more widely, in understanding and modelling groundwater recharge in dryland environments.
Seasonal variability of the M2 tide in the Bohai Bay: development and application of modified enhanced harmonic analysis
Authors: Wang Daosheng , Pan Haidong , Mu Lin
Published: March 2020

The seasonal variability of the M2 tide exerts a major influence on the coastal ocean environment. In this study, a novel method, namely modified enhanced harmonic analysis (MEHA), is developed to synchronously extract the temporally varying amplitudes and phase lags of significant tides and the constant values of the other constituents. The seasonal variability of the M2 tide in the Bohai Bay, China, is investigated by analyzing one-year sea level observations at two stations with MEHA.

In ideal twin experiments, the artificial sea level observations were analyzed. Both the estimated temporally varying amplitude and phase lag of the M2 tide and constant values of the S2, K1 and O1 tides using MEHA were much closer to the prescribed values than those obtained using the other methods, indicating the capability and efficacy of MEHA. When the real sea level observations were analyzed using MEHA, the estimated M2 tidal amplitude has significant seasonal variability, with large values in summer and small values in winter, which is robust and not affected by experimental settings. The results of numerical experiments indicate that the seasonality of vertical eddy viscosity induces seasonal variations of the M2 tide in the Bohai Bay.
Inverse Energy Cascade of Fast Magnetosonic Turbulence in the Heliosheath
Authors: Zieger Bertalan
Published: March 2020

The solar wind in the heliosheath beyond the termination shock (TS) is a non-equilibrium collisionless plasma consisting of thermal solar wind ions, suprathermal pickup ions (PUI) and electrons. In such multi-ion plasma, two fast magnetosonic wave modes exist: the low-frequency fast mode that propagates in the thermal ion component and the high-frequency fast mode that propagates in the suprathermal PUI component [Zieger et al., 2015]. Both fast modes are dispersive on fluid and ion scales, which results in nonlinear dispersive shock waves. In this talk, we briefly review the theory of dispersive shock waves in multi-ion collisionless plasma. We present high-resolution three-fluid simulations of the TS and the heliosheath up to 2.2 AU downstream of the TS. We show that downstream propagating nonlinear magnetosonic waves grow until they steepen into shocklets (thin current sheets), overturn, and start to propagate backward in the frame of the downstream propagating wave, as predicted by theory [McKenzie et al., 1993; Dubinin et al., 2006]. The counter-propagating nonlinear waves result in fast magnetosonic turbulence far downstream of the shock. Since the high-frequency fast mode is positive dispersive on fluid scale, energy is transferred from small scales to large scales (inverse energy cascade). Thermal solar wind ions are preferentially heated by the turbulence. Forward and reverse shocklets in the heliosheath can efficiently accelerate both ions and electrons to high energies through the shock drift acceleration mechanism. We validate our three-fluid simulations with in-situ high-resolution Voyager 2 magnetic field and plasma observations at the TS and in the heliosheath. Our simulations reproduce the magnetic turbulence spectrum with a spectral slope of -5/3 observed by Voyager 2 in frequency domain [Fraternale et al., 2019]. However, since Taylor’s hypothesis is not true for fast magnetosonic perturbations in the heliosheath, the inertial range of the turbulence spectrum is not a Kolmogorov spectrum in wave number domain. 
Semi-continuous measurements of water-soluble inorganic ions over a high-altitude background site in central Taiwan
Authors: Singh Atinderpal , Chen We-Ren , Lee Chung-Te
Published: March 2020

To better understand the abundance and sources of water-soluble inorganic ions (WSIIs), semi-continuous measurements of WSIIs were performed during autumn 2015 and spring 2016 at a high-altitude background station (2,862 m above sea level) on the summit of Mt. Lulin in central Taiwan. During autumn, the mass concentration of PM2.5, major WSIIs, and CO increased significantly from 12:00 to 18:00 hrs local standard time (LST), whereas the visibility and concentration of O3 decreased at the same time. The backward trajectories analyses showed that the sampling site was under the influence of lifted air masses by the upslope wind from 12:00 to 18:00 hrs. Thus the mountain-valley (M-V) circulation could be the major driving force for the observed aerosol diurnal patterns over the study region during autumn. In sharp contrast to autumn, five high aerosol loading events were observed during spring with each event lasting for a few days. These events were synchronized with the long-range transport of biomass burning (BB) smoke emissions from the Indochina region, as revealed from the fire count map and backward trajectories. The plumes appear to mask their characteristic diurnal features that are driven by the local M-V circulation. These plumes also affected the acidity of ambient aerosol. During BB events, aerosol was found to be relatively more alkaline in nature as revealed by higher molar ratio of [NH4+]calc/[NH4+]meas during BB events (0.88 ± 0.25) than that of the whole spring season (0.81 ± 0.33). The third BB event (BB3), March 29 to April 04, 2016, was the most prominent one among all BB events. During BB3, the mass concentration of PM2.5, NH4+, K+, NO3- and SO42- increased from 8.3 to 29, 0.01 to 2.0, 0.02 to 0.4, 0.01 to 1.6, and 0.4 to 4.1 μg m-3, respectively as compared to before the event. A fog event (March 31; 0:00 to 10:00 LST) was also observed during the BB3 event that decreased the mass concentration of all the species significantly. It suggested that aerosol scavenging and cloud-active processing may occur in this fog event.
State of the art of Seasonal and Subseasonal Wind and Wind Power Forecasting for the Iberian Peninsula and the Canary islands
Authors: Añel Juan A. , Bayo-Besteiro Susana , García-Rodríguez Michael , Labandeira Xavier
Published: March 2020

Renewable energy plays a key role to play in the transition towards a low-carbon society and many countries have been investing in R&D and deployment of renewables over the last few decades. Despite its importance, relatively little attention has been focused on the crucial impact of weather and climate on energy demand and supply, or on the seasonal forecast generation or operational planning of renewable technologies. In particular, to improve the operation and longer-term planning of renewables it is essential to consider seasonal and subseasonal weather forecasting. Unfortunately, reports that focus on these issues are not common in the scientific literature.
Here we present a systematic review of the seasonal forecasting of wind and wind power for the Iberian peninsula and the Canary Islands, a region leading the world in the development of renewable energies (particularly wind), and thus an important illustration in global terms. To this end, we consider the scientific literature published over the last eleven years (2008-2018). An initial search of this literature produced 8355 documents, but our review suggests that only around 0.3% are actually relevant to our purposes. The results show that the teleconnection patterns (NAO, EA, and SCAND) and the stratosphere are important sources of predictability in the Iberian Peninsula and that GloSea5 is an effective model for seasonal wind forecasting for the region. We conclude that the existing literature in this crucial area is very limited, which points to the need for increased research efforts. Moreover, the approach and methods developed here could be applied to other areas for which systematic reviews might be either useful or necessary.
The diurnal cycle of lightning and storms during the pre-Meiyu, Meiyu and post-Meiyu period over Yangtze-Huaihe River Basin, China
Authors: Yang Ji
Published: March 2020

Using 5 years of operational Doppler radar, cloud-to-ground lightning observations and NECP reanalysis data, this study, for the first time for such a purpose, examines the spatial and temporal characteristics of and correlations between summer storm and lightning over the Yangtze-Huaihe River Basin (YHRB), with a special emphasize on their diurnal cycles. The sub-seasonal variability of the lifetime, storm top, max reflectivity and cell-based vertical integrated liquid (VIL) water of storms are also investigated using the Storm Cell Identification and Tracking algorithm. Results show that storms over YHRB occur most frequently during the Meiyu period. Storms are largely associated with Meiyu fronts during the period and show a fast-moving speed and moderate intensity (proxies including storms top, max reflectivity and VIL). The diurnal variations of storms embedded in Meiyu front are weak. The storm intensity becomes much stronger in the post-Meiyu period due to the increased atmospheric instability. Higher occurrence frequency of CG lighting can also be found during the post-Meiyu period. The diurnal cycles of storm and CG lightning in the post-Meiyu period show a unimodal pattern with an afternoon peak corresponding to solar heating effect. An inverse correlation between the lightning numbers and the mean value of peak current (MPC) for the negative CG lightning is found during the pre-Meiyu and Meiyu periods. The diurnal variation of MPC for the negative CG lightning agrees well with the storm intensity to some extent.
Stepwise modeling and the importance of internal fluxes validation to improve hydrological model realism: three case studies in cold regions of China
Authors: Gao Hongkai , Ren Ze , Duan Zheng
Published: March 2020

Model realism testing is of vital importance in science of hydrology, in terms of realistic representation of hydrological processes and reliability of future prediction. We conducted three modeling case studies in cold regions of China, i.e. the upper Heihe River basin, the Urumqi Glacier No.1 basin, and the Yigong Zangbu River basin, to test the importance of stepwise modeling and internal fluxes validation to improve model realism.

In the upper Heihe River basin, we used four progressively more complex hydrological models (FLEXL, FLEXD, FLEXT0 and FLEXT), to stepwisely account for distributed forcing inputs, tailor-made model structure for different landscapes, and the realism constraints of parameters and fluxes. We found that the stepwise modeling framework helped hydrological processes understanding, and the tailor-made model structure and realism constraints improved model transferability to two nested basins.

In the Urumqi Glacier No. 1 basin, with 52% of the area covered by glaciers, we developed a conceptual glacier-hydrological model (FLEXG) and tested its performance to reproduce the hydrograph, and separate the discharge into contributions from glacier and nonglacier areas, and establish estimates of the annual glacier mass balance (GMB), the annual equilibrium line altitude (ELA), and the daily snow water equivalent (SWE). We found that the FLEXG model, involving effects of topography aspect, was successfully transferred and upscaled to a larger catchment without recalibration.

In the Yigong Zangbu River basin, with 41.4% glacier area, we designed three models (FLEXD, FLEX-S, FLEX-SG) to stepwisely understand the impact of snow, glacier to reproduce historic streamflow. We found that by involving snow and glacier modules, the model performance was dramatically improved. Although the daily streamflow of FLEX-SG reached up to 0.93 Kling-Gupta Efficiency (KGE) in calibration, it significantly overestimated snow cover area (SCA) and glacier mass balance (GMB). With satellite measured precipitation lapse rate, we improved FLEX-SG model realism not only to reproduce hydrography but also SCA and GMB.
Machine learning-based dynamical seasonal prediction of summer rainfall in China
Authors: Wang Jialin , Yang Jing , Ren Hongli , Li Jinxiao , Bao Qing , Gao Miaoni
Published: March 2020

The seasonal prediction of summer rainfall is crucial for regional disaster reduction but currently has a low prediction skill. This study developed a machine learning (ML)-based dynamical (MLD) seasonal prediction method for summer rainfall in China based on suitable circulation fields from an operational dynamical prediction model CAS FGOALS-f2. Through choosing optimum hyperparameters for three ML methods to reach the best fitting and the least overfitting, gradient boosting regression trees eventually exhibit the highest prediction skill, obtaining averaged values of 0.33 in the reference training period (1981-2010) and 0.19 in eight individual years (2011-2018) of independent prediction, which significantly improves the previous dynamical prediction skill by more than 300%. Further study suggests that both reducing overfitting and using the best dynamical prediction are imperative in MLD application prospects, which warrants further investigation.
Numerical simulation of bubble deformation in various velocity profiles across a conduit
Authors: Ohashi Masatoshi , Ichihara Mie , Maeno Fukashi , Kennedy Ben , Gravley Darren
Published: March 2020

Tube pumice is characterized by aligned highly elongated bubbles and is a common product of explosive silicic eruptions. The relative abundance of tube pumice and non-tube pumice in the stratigraphy has been interpreted as resulting from temporal and spatial variations in a conduit flow. Therefore, understanding the formation mechanism of tube pumice is valuable, but still debated. Most previous studies interpret tube pumice forming from simple shear deformation, assuming a parabolic velocity profile across a conduit. However, simple shear cannot explain the observation that tube pumice is rare in plinian falls but frequent in ignimbrites (interpreted to have wider vents).

In this study, we combine a bubble deformation model with a quasi-two-dimensional steady conduit flow model. A bubble is deformed by the velocity gradient while moving within the conduit flow. The conduit flow model is calculated for the 1.8 ka Taupo plinian eruption, which produced a high proportion of tube pumice in the ignimbrite phase. In this abstract, we explain results from two rheological models showing distinct velocity profiles. In the Newtonian isothermal fluid, the velocity profile across the conduit becomes parabolic. In a fluid that allows viscous heating, the temperature near the conduit wall rises up sharply, leading to a strong reduction in viscosity, and the velocity profile changes from a parabolic shape to a plug-like shape. The parabolic velocity profile produces highly elongated bubbles mainly by simple shear, while the plug-like velocity profile is dominated by pure shear and accumulates less strain to elongate bubbles. The bubble shape at the fragmentation surface depends significantly on the velocity profile and its change along the conduit.

We also conduct a quantitative and statistical bubble shape analysis of pumice erupted at Taupo volcano. It shows that the plinian pumices have a single peak in the bubble shape distribution, while the ignimbrite pumices have a broad distribution and contain highly elongated bubbles. The comparison of the distribution of pumice textures with the simulation results suggests that the velocity profile of the plinian phase is close to a plug-like shape. We also calculate bubble deformation for the Taupo ignimbrite eruption, using the viscous-heating model. We model a　wider conduit for the ignimbrite phase which leads to lower shear rate around the conduit walls and a higher proportion of the conduit experiencing parabolic flow compared to the plinian phase. This increased proportion of parabolic velocity profile in the conduit can explain a large number of tube pumice in the Taupo ignimbrite.
Evaluating the precipitation regime of the Great Lakes Region in CMIP6 models
Authors: Minallah Samar , Steiner Allison
Published: March 2020

The Laurentian Great Lakes region has a distinct precipitation seasonality, with highest magnitudes in the summer months of June to September and drier conditions in the winter months (December to March). The region also exhibits a ‘mid-summer drying’ behaviour, where the precipitation magnitude drops from July to August by approximately 7% and recovers in September before declining again in the autumn season. The distinct precipitation seasonal cycle modulates the land hydrological budget and has significance for regional water resources. This study aims to understand the precipitation seasonality in 20 CMIP6 models for historical (1980 – 2014) and mid-century (2030 – 2060) SSP2-4.5 scenario. Seasonal wet/dry biases in historical data are computed using CRU TS4.03 precipitation data as baseline.

CMIP6 models show a myriad of different patterns, none of which conform to the observed precipitation seasonality. Some models show a singular skewed peak with the maxima in either June or July flowed by slow tapering off until December (e.g., MRI-ESM2.0, CanESM, GFDL-CM4). Various models show a spring and winter-time wet bias (NUIST-NESM3, ACCESS-ESM1-5) and/or underestimation of the summer-season magnitudes (FGOALS-f3-L, NCAR-CESM2, NorESM2-MM). In general, the precipitation seasonality exhibited by the CMIP6 models is not characteristic of the region. We also find that while some models are wet or dry throughout the year, others show only seasonal biases indicating that their convective parameterization and/or microphysics schemes fail to adequality capture precipitation patterns in these seasons. While most CMIP6 models and reanalysis datasets show a gaussian convective precipitation cycle with the annual maxima in July, some models (e.g., BCC-CSM2-MR, NCAR-CESM2) show strong biases in it, indicating issues with their convective schemes.

These biases and anomalous precipitation cycle can be propagated or even amplified in the future climate model simulations, significantly altering the projections. Therefore, identifying the models that best represent the regional precipitation spatiotemporal characteristics can assist in better assessment of the future changes in the region’s hydroclimate.
Coarse particle motion and resting times during bedload in a glacier-fed mountain stream of the central Chilean Andes
Authors: Mao Luca , Carrillo Ricardo , Brardinoni Francesco , Toro Matteo , Fraccarollo Luigi
Published: March 2020

Coarse bed load transport is a crucial process in river morphodynamics, but it is difficult to monitor in mountain streams. Predicting bed load is a difficult task especially in steep step-pool streams, where the critical dimensionless shear stress is affected by local channel slope and relative submergence, and only part of the flow energy is available to entrain and transport sediments as some is dissipated in local hydraulic plunging and jumps. Here we present a new sediment transport dataset obtained from two years of field-based monitoring (2014-2015) at the Estero Morales, a high-gradient stream in the central Chilean Andes. This stream features step-pool bed geometry and a glacier-fed hydrologic regime characterized by abrupt daily fluctuations in discharge. Bed load was monitored directly using Bunte samplers and by surveying the mobility of passive integrated transponder (PIT) tags. We used the competence method to quantify the effective slope, which is the fraction of the total slope responsible for bed load transport. This accounts for only 10% of the total slope, confirming that most of the energy is dissipated on macroroughness that characterize step-pool stream. We used the displacement lengths of PIT tags to derive the statistics of flight and resting times, observing that the average length of a flight scales inversely with grain size.
Quantifying contributions of uncertainties in physical parameterization schemes and model parameters to overall errors in Noah-MP land modeling using observations from eddy flux sites
Authors: Li Jianduo , Chen Fei
Published: March 2020

Quantifying contributions of errors in model structure and model parameters to biases in a land surface model (LSM) is critical for model improvement, but has not been done systematically for many global land surface models. This paper investigates the uncertainties in the Noah with multiparameterization (Noah-MP) LSM with dynamic vegetation by examining the interactions between imperfect parameterization schemes (PSs) and improper parameter values (PVs). A number of Noah-MP physical ensemble simulations were conducted at 92 eddy flux sites to quantitatively assess the impacts of the PS uncertainties on model performance, and then the key parameters in the two combinations of schemes with significant differences were calibrated. The results show that five subprocesses—the surface exchange coefficient (SFC), soil moisture threshold, radiation transfer (RAD), runoff and groundwater, and surface resistance to evaporation—have the most significant influence on the performances of simulated sensible heat flux, latent heat flux, net absorbed radiation and gross primary productivity in the Noah-MP LSM with dynamic vegetation, and that the interaction between SFC and RAD contributed up to 80% of the variation in the model performance at some sites. It is also shown that tuning the PSs and optimizing the PVs should be jointly applied to reduce the errors in the Noah-MP LSM, although compared to tuning PSs, parameter optimization happens to make less robust model improvement. Finally, this study emphasizes that reducing the significant uncertainties in soil parameters and exploring the errors caused by missing physical features are crucial to improving LSMs with dynamic vegetation.
Water in MgSiO3-majorite at high temperatures and pressures: Incorporation mechanisms and thermoelastic properties
Authors: Zhang Zhigang , Lou Yancheng , Stackhouse Stephen , Walker Andrew
Published: March 2020

As the major component of garnet, the second most abundant phase in Earth’s transition zone, MgSiO3-majorite (Mgmj) may be an important reservoir of water. Previous works at ambient conditions show that water is incorporated in Mgmj by substituting Si with H in the Si-O tetrahedra. Due to the challenges of experiments and simulations, there are still very limited data on hydrous MgSiO3-majorite at simultaneously high temperatures and pressures.

In this study, we have carried out extensive first principles calculations to determine the properties of hydrous MgSiO3-majorite up to 2000 K and 40 GPa. We systematically considered all possible incorporation mechanisms with seven substitutional reactions. By solving the equations of equilibrium constants of the reactions, we obtained the ratios of various polyhedral substitutions and their temperature and pressure dependences. Our results show that the occupations of water (hydrogen) in Mgmj change mainly with temperature and are generally pressure-independent. Almost all of hydrogen occupy in the Si-O tetrahedra at 300 K, but the ratio of Mg-O dodecahedra increases remarkably with temperature and is the highest at 2000 K, which suggests that water in Mgmj under mantle conditions would be different from that observed at ambient conditions and implies the importance of in-situ measurements of high-TP experiments.

We have also calculated the elastic velocities and anisotropies of two types of hydrous Mgmj which caused by substitutions of Mg and Si. Our results show that ~1 wt% water in Si vacancy would decrease wave velocities of Mgmj by ~3% in both VP and VS, while the same amount of water in Mg vacancy would more effectively decrease the velocities by ~6%. In addition, water in Mg vacancy would noticeably improve the seismic anisotropy and the dlnVs/dlnVP of Mgmj while water in Si vacancy shows much smaller effects.
Mass balance of radiocaesium derived from Fukushima accident and estimation of latest fluxes among atmosphere, land and ocean
Authors: Aoyama Michio , Tsumune Daisuke , Inomata Yayoi , Tateda Yutaka
Published: March 2020

Regarding with amount of movement of 137Cs from domain to domain for several years after the accident, we also evaluated that the amount of 137Cs transported by the rivers might be 40 TBq which is corresponding to less than 1.3 % of deposited 137Cs. For resuspension, the annual deposition of 137Cs at Okuma during the period from 2014 to 2018 means that 4 TBq year-1to 10 TBq year-1should be amount of resuspension from land to atmosphere and this amount correspond to 0.1 % to 0.3 % of total deposition of 137Cs on land in Japan. The 137Cs activity concentration at 56N canal in 2016-2018 correspond to 137Cs discharge of 0.73 TBq year-1to 1.0 TBq year-1from FNPP1 site to open water. The integrated amount of FNPP1 derived 137Cs that entered the Sea of Japan, SOJ, until 2017 was 0.27 ± 0.02 PBq, which is 6.4 % of the estimated total amount of FNPP1-derived 137Cs in the STMW in the North Pacific. The integrated amount of FNPP1-derived 137Cs that returned to the North Pacific Ocean through the Tsugaru Strait from SOJ was 0.11 ± 0.01 PBq, 42 % of the total amount of FNPP1-derived 137Cs transported to the SOJ. As a result of decontamination works, 134 TBq of 137Cs was removed from surface soil until February 2019 which correspond to 4 % of deposited 137Cs on land in Japan. Therefore, the largest transport amount of 137Cs was 270 ± 2 TBq from STMW in the North Pacific to SOJ until 2017, and the second largest was decontamination work by which work about 134 TBq was removed from surface soil on land until Feb. 2019. Fluvial transport by rivers contributed about 40 TBq since June 2011 until 2016.
Deciphering taxonomic carbon exchange between plants and microorganisms using proteomics coupled with 13C tracers and spatially resolved protein extraction
Authors: Moran James , Lin Vivian , Zhu Ying , Tolic Nikola , Purvine Samuel , Rosnow Joshua , Lipton Mary
Published: March 2020

Clear elucidation of plant-microbe interactions within the rhizosphere and how these relationships change over time can be confounded by the large microbial biodiversity, shifting microenvironmental conditions, and extensive spatial constraints within these complex systems. Proteomics analysis of root or soil samples, when linked with metagenomic interpretation, can provide key insights to both the taxonomy and functional capability of microbial populations within a sample. Yet, existing proteomic approaches may not always be able to provide the needed temporal and spatial resolution to capture fine-scale and short-term interactions between plants and microorganisms. To remedy this limitation, we are developing a suite of methodological adaptations intended to leverage proteomic analysis to help identify key interactions between rhizosphere microorganisms and their host plant.

First, we are employing 13C tracers coupled with automated data analysis to identify specific organisms consuming both simulated and natural root exudates. We are specifically exploring microcosms constructed from natural soil (Kellogg Biological Station, Hickory Corners, Michigan, USA) and planted with switchgrass as a platform for developing the techniques. Multiple previous studies have linked key interactions between both free-living and epiphytic microbial members with improved performance of a switchgrass host under nutrient-depleted, natural field conditions. Providing evaluation of the amount and taxonomic recipient of switchgrass-supplied carbon under varying conditions may help link key taxonomic groups with improved plant performance and biomass production.

Second, we are leveraging a membrane extraction technique coupled with specialized sample digestion, purification, and analysis to enable non-destructive, spatially-resolved protein extraction from the root-soil interface within our constructed microcosms. Through its non-destructive nature, this approach permits timeseries analysis for tracking specific taxa and, in some cases, functions associated with rhizosphere processes both before and after a system perturbation as well as variations over plant growth phases during a growing season. The high sensitivity of this system enables spatial analysis at the one to two mm scale where samples can be manually selected based on proximity to specific root structure, metabolic hotspots in the system, or other parameter of choice. Spatial analysis can be leveraged to track taxonomic distribution within the rhizospheres associated with roots at different growth stages or levels of maturity.
Synergies and trade-offs for the SDGs in a deltaic socio-ecological system: Development of an Integrated Assessment Model
Authors: Marcinko Charlotte , Harfoot Andrew , Daw Tim , Clarke Derek , Hazra Sugata , Hutton Craig , Hill Chris , Lazar Attila , Nicholls Robert
Published: March 2020

The United Nations Sustainable Development Goals (SDGs) promote sustainable development and aim to address multiple challenges including those related to poverty, hunger, inequality, climate change and environmental degradation. Interlinkages between SDGS means there is potential for interactions, synergies and trade-offs between individual goals across multiple temporal and spatial scales. We aim to develop an Integrated Assessment Model (IAM) of a complex deltaic socio-ecological system where opportunities and trade-offs between the SDGs can be analysed. This is designed to inform local/regional policy. We focus on the Sundarban Biosphere Reserve (SBR) within the Indian Ganga Delta. This is home to 5.6 million often poor people with a strong dependence on rural livelihoods and also includes the Indian portion of the world’s largest mangrove forest – the Sundarbans. The area is subject to multiple drivers of environmental change operating at multiple scales (e.g. global climate change and sea-level rise, deltaic subsidence, extensive land use conversion and widespread migration). Here we discuss the challenges of linking models of human and natural systems to each other in the context of local policy decisions and SDG indicators. Challenges include linking processes derived at multiple spatial and temporal scales and data limitations. We present a framework for an IAM, based on the Delta Dynamic Emulator Model (ΔDIEM), to investigate the affects of current and future trends in environmental change and policy decisions within the SBR across a broad range of sub-thematic SDG indicators. This work brings together a wealth of experience in understanding and modelling changes in complex human and natural systems within deltas from previous projects (ESPA Deltas and DECCMA), along with local government and stakeholder expert knowledge within the Indian Ganga Delta.
Regression equations of probability plot correlation coefficient test statistics using machine learning
Authors: Ahn Hyunjun , Kim Sunghun , Lee Joohyung , Heo Jun-Haeng
Published: March 2020

In the extremes hydrology field, it is essential to find the probability distribution model that is most appropriate for the sample data to estimate the reasonable probability quantile. Depending on the assumed probability distribution model, the probability quantile could be estimated with quite different values. The probability plot correlation coefficient (PPCC) test is one of the goodness-of-fit tests for finding suitable probability distributions for a given sample. The PPCC test determines whether assumed probability distributions are acceptable for the sample data using correlation coefficients between sample data and theoretical quantiles of assumed probability distributions. The critical values for identification are presented as a two-dimensional table, depending on the sample size and the shape parameters of models, for a three-parameter probability distribution. In this study, the applicability and utility of machine learning in the hydrology field were examined. For the usability of the PPCC test, a regression equation was derived using a machine learning algorithm with two variables: sample size and shape parameter.
Introducing Sage: Cyberinfrastructure for Sensing at the Edge.
Authors: Collis Scott , Beckman Pete , Kelly Eugene , Catlett Charles , Sankaran Rajesh , Altintas Ikay , Olds Jim , Ferrier Nicola , Park Seongha , Kim Yongho , Papka Michael
Published: March 2020

There are many networks of sensors for earth system science. Most networks are local or regional in scale (eg mesonets). National weather services maintain networks for meeting stakeholder needs and responsibilities to the WMO Global Observing System. These systems are comprised of single task rigid sensors generally attached to logger systems. Sage [1] is a project which will deliver a cyberinfrastructure network allowing multi-tenant, multi-tasked sensor packages. In addition to traditional meteorological instrumentation and advanced static and pan-tilt-zoom cameras Sage nodes have powerful compute infrastructure allowing machine learning based phenomenology detection at the edge. This allows science question-based reconfiguration of sensor operation. A well described Application Programming Interface (API) will allow new algorithms to be pushed to the edge and new sensor packages to be added including those that have complex configuration spaces like LIDAR and Radar. This presentation will introduce Sage and present early example results such as using cameras for cloud classification, inundation caused by heavy rainfall and early wildfire ignition detection. 

 

[1]  https://www.research.northwestern.edu/world-watchers/
Potential Tropical Cyclone Disaster Loss Assessment based on Multiple Hazard Indicators
Authors: Li Jian
Published: March 2020

Tropical cyclones could cause large casualties and economic loss in coastal area of China. It is of great importance to develop a method that can provide pre-event rapid loss assessment in a timely manner prior to the landing of a tropical cyclone. In this study, a pre-event tropical cyclone disaster loss assessment method based on similar tropical cyclone retrieval with multiple hazard indicators is proposed. Multiple indicators include tropical cyclone location, maximum wind speed, central pressure, radius of maximum wind, forward speed, Integrated Kinetic Energy (IKE), maximum storm surge, and maximum significant wave height. Firstly, the track similarity is measured by similarity deviation considering only the locations of tropical cyclone tracks. Secondly, the intensity similarity is measured by best similarity coefficient using central pressure, radius of maximum wind, maximum wind speed, moving speed, wind, storm surge, and wave intensity indices. Then, the potential loss of current tropical cyclone is assessed based on the retrieved similar tropical cyclones loss. Taking tropical cyclone Utor (2013) that affected China as an example, the potential loss is predicted according to the five most similar historical tropical cyclones which are retrieved from all the historical tropical cyclones. The method is flexible for rapid disaster loss assessment since it provides a relatively satisfactory result based on two scenarios of input dataset availability.
Characteristics of the secondary circulations in the convective boundary layer over two-dimensional heterogeneous surfaces
Authors: Xiang Zixuan , Sun Jianning , Zou Jun
Published: March 2020

Large-eddy simulations are performed to investigate the effects of background wind on the secondary circulations (SCs) in the convective boundary layer. Heterogeneities are produced by a prescribed two-dimensional surface sensible heat flux pattern of chessboard-type and have a size which is a bit larger than the boundary layer height.

When the wind blows along the diagonal of the chessboard-like pattern, the roll-like SCs are observed even when the background wind speed is as large as 10m/s, with whose axes are oriented along the diagonal of the pattern. Another case with wind direction along neither the diagonal nor the side of the chessboard-like pattern and weak wind speed shows the roll-like SCs still exist but lack symmetry. The SCs become much weaker and change their axes orientation when the wind speed increases.

Meanwhile, the results are different when the Coriolis force is considered. When the background wind is weak, the asymmetry of the SCs become more significant with the development of boundary layer when the Coriolis force is considered, while the SCs tend to be symmetrical without the Coriolis force. When the background wind strengthens, the SCs are more difficult to maintain in the case of Coriolis force.

Further analysis through rotational and divergent decomposition suggests which part contributes more to the maintenance of the SCs.
Seasonal controls of soil water content spatial pattern in a steep forested catchment: A modeling approach
Authors: Han Xiaole , Liu Jintao
Published: March 2020

Characterizing soil volumetric water content (VWC) dynamics at different soil depth plays a key role in hydrological modeling and is essential for effective catchment management. However, our understanding of how critical zone structure (topography and soil) and rainfall affect VWC dynamics is limited. Therefore, the objective of this study was to investigate the effects of the hillslope structure and rainfall on VWC dynamics in a steep forested, zero-order catchment. VWC was measured from soil surface to soil-bedrock interface at five soil layers (0-8, 8-40, 40-70, 70-110, and 110-160 cm) for a complete water year, and covering various landscapes such as an ephemeral stream, riparian, and different hillslope positions. A total of 13 environmental indices, including eight DEM-derived terrain attributes and five soil attributes, were used to investigate the relationships between soil-terrain attributes and VWC. An all-possible-subsets regression model was adopted to construct the soil water content prediction model (SWPM). A geophysical method (ground penetrating radar, GPR) was used to investigate the soil depth to assist in the establishment of SWPM. The results demonstrate that the all-possible-subsets regression model performed well for predicting VWC. Additionally, the strength of the relationships between soil-terrain attributes and VWC could be different through time. For instance, the relationships between the topographic wetness index (TWI) and VWC were all significant (P<0.05) from August to October, whereas the correlation between TWI and VWC was not significant (P≥0.05) at approximately 25% of measurement days from November to February. The results also show that the high correlation between terrain-related attributes and VWC usually occurs in the measurement days with high catchment storage state, whereas the high correlation between soil-related attributes and VWC more often occurs in the measurement days with low catchment storage state. Therefore, the control factors of VWC spatial organization vary from humid (controlled by topographic redistribution of water) to arid (controlled by vertical processes such as evapotranspiration) seasons.