bluuebunny/crossref_metadata_2025 huggingface dataset:
Point markers in replacement of odometer driven positioning: effects and possible problems
Authors: Persico Raffaele
Published: March 2020

It is widely known that, in GPR prospecting [1-2], sometime it is not possible to make use of the customary odometer for the recording of the position of the measurement points along the observation line. Consequently, in these cases the human operator is compelled to make use of point markers placed at known positions (measured with a tape) along the observation line. In particular, this can happen on the sand of a desert and on the polar ice [3], but it might happen also just due to some ill-functioning of the odometer. Notwithstanding, quite rarely the effects of the use of the point markers have been examined on the basis of some experimental test. At the conference, we will show an experiment where the same observation line has been gone through several times, first making use of the odometer included in the exploited GPR system and then making use of marker points. A third time, the same path was still travelled without odometers and taking the marker points without making use of any laptop command. These were replaced just by stopping for some seconds the GPR in any marker point (but keeping it switched on). This option can be useful in cases where e.g. the command has to be given through a touchscreen. The observation line was 15 m long, and was placed on a flat smooth and tough floor. This means that the line offered favourable conditions for the use of the odometer, and so the positions of the anomalies identified making use of the odometer are considered as the correct positions of the buried targets. This has allowed a quantification of the displacements from the correct position of the buried anomalies when making use of marker points taken with a step of one meter from each other. A  larger and deeper dealing is available in [4].

References

[1] R. Pierri, G. Leone, F. Soldovieri, R. Persico, "Electromagnetic inversion for subsurface applications under the distorted Born approximation" Nuovo Cimento, vol. 24C, N. 2, pp 245-261, March-April 2001.

[2] R. Persico, M. Ciminale, L. Matera, A new reconfigurable stepped frequency GPR system, possibilities and issues; applications to two different Cultural Heritage Resources, Near Surface Geophysics, vol. 12, n. 6, pp. 793-801 (doi: 10.3997/1873-0604.2014035), December 2014.

[3] H. Jol, Ground Penetrating Radar: Theory and applications, Elsevier, 2009.

[4] R. Persico, Ground Penetrating Radar: Physics and Practical Aspects, Springer Handbook of Cultural Heritage Analysis, edited by Sebastiano D’Amico and Valentina Venuti, Springer, 2020.
Empirical Rainfall Thresholds for Occurrence of Landslides in Wayanad, India
Authors: Abraham Minu Treesa , Satyam Neelima , Rosi Ascanio
Published: March 2020

Rainfall Induced landslides are one among the major natural disasters which cause destruction to lives and properties across the world. Wayanad (Kerala, India) is a region characterized by highly destructive landslides during monsoons. During the recent past, in 2018 and 2019, substantial damage to lives, agricultural land and properties have occurred due to landslides in the region. To minimize the effect of such events, a Landslide Early Warning System (LEWS) should be developed for Wayanad at the earliest. Being the major triggering factor, it is essential to study the relationship between the rainfall parameters and occurrence of landslides. Understanding the historical rainfall parameters which resulted in landslides will help to identify the critical conditions which are potent to initiate landslides in future in the study area and can effectively contribute to a LEWS. As an initial step towards achieving this goal, a study was conducted to develop regional scale rainfall threshold for the region using Intensity and Duration conditions which resulted in landslides in the recent history (2010-2018) in Wayanad. A catalogue has been prepared for the study area, collecting details of landslides happened during 2010 - 2018. Analysis has been carried out using two different statistical approaches, Bayesian and Frequentist, using 123 landslide events considered for the analysis. It is observed that both the methods are complementary and the Bayesian threshold is comparable with the Frequentist threshold with 5% exceedance probability where an intensity of 0.97mmh-1 can trigger landslides in the region when the duration of rainfall is 24h. Further studies can be conducted for the region using advanced methods also, to find the best suited approach to define a regional scale threshold and hence an effective LEWS.
Gender differences in farmers’ livelihood capital in Dazu District, China
Authors: Kuang Foyuan , Jin Jianjun , Liu Xuemin , Wang Yuhai
Published: March 2020

Livelihood capital is the basis for farmers to maintain livelihood sustainability and to make farming decisions. A major assertion that has been demonstrated with limited empirical evidence in the capital literature is the gender difference dichotomy. Using rural Dazu District as a case study, this paper constructs the evaluation index system of livelihood capital and carries on the comprehensive evaluation from a gender perspective. A stratified random sampling technique and household questionnaire survey were used to collect data from Dazu District, China. An asset index was used to compute the capital levels, while the independent sample t test and the ordinary least square (OLS) model were employed to compare the differences between gender in livelihood capital. The results show that there were significant gender differences in farmers’ livelihood capital. Specifically, male farmers have better livelihood capital than female farmers. Furthermore, the results reveal that the livelihood capital of male and female farmers is influenced by different sets of factors. Age, happiness, planting structure, agricultural policy support and cooperatives are main factors affecting livelihood capital of female farmers, while main influencing factors of male farmers are education, years of farming, health, risk preference, planting structure and cooperatives. These results imply that specific gender intervention programs are necessary be implemented in order to maintain farmers’ livelihood sustainability and to overcome gender gaps in agriculture.
The gullies of southeast Nigeria: an ecogeomorphic investigation
Authors: Osumgborogwu Ikenna , Wainwright John , Turnbull-Lloyd Laura
Published: March 2020

Gully erosion was unknown in the Orlu area of Southeast Nigeria before the Nigerian civil war (from 1967 to 1970) but has now become endemic and continues to present day.  Human activities are central to this acceleration of erosion due to their intervention with ecogeomorphic processes. This paper aims to improve understanding of ecogeomorphic drivers of gully erosion using case studies from the Orlu area of southeast Nigeria, and to achieve this aim, focus-group meetings and analyses of remotely sensed data were adopted. High-resolution (0.61 – 5 m) satellite imagery for 2009 and 2018 were acquired from different platforms and used for gully mapping and monitoring while ASTAR DEM was used to estimate topological parameters. Upslope contributing areas were produced for two gullies; A and U, while gully evolutions between 2009 and 2018 were related to changes in contributing areas during same time span. Ecogeomorphic and climatic drivers such as vegetation-cover change, slope angle, elevation, rainfall, and nearness to roads and rivers were studied and their associations with gullying established. Vegetation cover was classified into three: non-vegetated, open vegetation and trees while daily surface runoff between 2009 and 2018 was estimated for these vegetation classes using the Curve Number approach. Results from focus-group meetings show that both gullies started in 1969 during the civil war as a result of increase in population density arising from the influx of refugees as well as other military activities. Gully growth was sustained after the civil war was a result of land use changes. Average gully headcut retreat rate between 2009 and 2018 was 64 m yr-1 and 12.2 m yr-1 for gully A and U respectively, while a positive correlation was recorded between change in vegetation cover in contributing areas and increase in gullied area with Pearson’s correlation of 0.6 and r2 of 0.4. The runoff model predicted runoff for only the non-vegetated areas with runoff coefficients ranging from 11.5 % to 22 %. Slope angle, profile and plan curvature had positive associations with gullies while elevation, nearness to rivers and nearness to roads recorded negative correlations with gullies. In conclusion, while geomorphic drivers such as slope angle are preparatory factors, human activities including civil wars and land-use changes are forcing factors of gully erosion. This study has implications for gully remediation especially as regards land use management of upslope contributing areas.

Keywords: Gully erosion, Ecogeomorphology, upslope contributing area, south east Nigeria
Volcanic degassing along the enigmatic South Sandwich volcanic arc
Authors: Liu Emma , Wood Kieran , Aiuppa Alessandro , Giudice Gaetano , Bitetto Marcello , Pering Tom , Wilkes Thomas , McGonigle Andrew , McCormick Kilbride Brendan , Fischer Tobias , Nowicki Scott , Mason Emily , Richardson Tom , Hart Tom
Published: March 2020

The South Sandwich Islands (SSI) are a chain of active volcanoes in the Southern Ocean and remain one of the most remote and enigmatic island arcs on Earth. The relatively recent development of the SSI over the past 20 million years has been closely linked with the formation of the Drake Passage, making this one of the youngest known volcanic arcs and therefore one of the most critical for understanding the early stages of arc geochemical evolution. Recent volcanic eruptions in the SSI have had significant impacts on local terrestrial and marine ecosystems, including some of the largest penguin colonies ever observed, through tephra deposition and from sustained volcanic degassing. Rare cloud-free satellite images over the last two decades have indicated that the summit of Mt Michael (Saunders) hosts a sustained lava lake, but until now these observations have not been ground-truthed by in-situ measurements. Long-term persistent passive outgassing at many of these volcanoes, even between eruptive phases, suggests that the SSI volcanic arc could be a significant source of volatiles to our atmosphere, and yet we lack any constraints on the degassing budgets of this volcanic arc. Here, we present novel measurements of gas chemistry, aerosol composition, and carbon isotope signature from along the South Sandwich Island arc. By combining ground-based measurements of SO2 flux with in-situ samples of plume composition using Unoccupied Aerial Systems (UAS), we present multi-species volatile fluxes for the major along-arc degassing sources. Further, by evaluating the carbon to sulfur ratio (C/ST) and carbon isotope composition in emitted gases together with petrological constraints from erupted tephra, we aim to test the hypothesis that carbon is supplied to the SSI by subduction of oceanic carbonated serpentinite, and thus contribute to our understanding of carbon recycling at subduction zones.
The progress on the observation and modeling of surface heat fluxes and evapotranspiration over heterogeneous landscapes of the Third Pole region
Authors: Ma Yaoming
Published: March 2020

The exchange of heat and water vapor between land surface and atmosphere over the Third Pole region (Tibetan Plateau and nearby surrounding region) plays an important role in Asian monsoon, westerlies and the northern hemisphere weather and climate systems. Supported by various agencies in the People’s Republic of China, a Third Pole Environment (TPE) observation and research Platform (TPEORP) is now implementing over the Third Pole region. The background of the establishment of the TPEORP, the establishing and monitoring plan of long-term scale (5-10 years) of it will be shown firstly. Then the preliminary observational analysis results, such as the characteristics of land surface energy fluxes partitioning and the turbulent characteristics will also been shown in this study. Then, the parameterization methodology based on satellite data and the atmospheric boundary layer (ABL) observations has been proposed and tested for deriving regional distribution of net radiation flux, soil heat flux, sensible heat flux and latent heat flux (evapotranspiration (ET)) and their variation trends over the heterogeneous landscape of the Tibetan Plateau (TP) area. To validate the proposed methodology, the ground measured net radiation flux, soil heat flux, sensible heat flux and latent heat flux of the TPEORP are compared to the derived values. The results showed that the derived land surface heat fluxes over the study areas are in good accordance with the land surface status. These parameters show a wide range due to the strong contrast of surface feature. And the estimated land surface heat fluxes are in good agreement with ground measurements, and all the absolute percent difference in less than 10% in the validation sites. The sensible heat flux has increased slightly and the latent heat flux has decreased from 2001 to 2016 over the TP. It is therefore conclude that the proposed methodology is successful for the retrieval of land surface heat fluxes and ET over heterogeneous landscape of the TP area. Further improvement of the methodology and its applying field over the whole Third Pole region and Pan-Third Pole region were also discussed.
Overland runoff erosion dynamics on steep slopes with forages under field simulated rainfall and inflow
Authors: Li Changjia , Pan Chengzhong
Published: March 2020

Although numerous studies have acknowledged that vegetation can reduce erosion, few process-based studies have examined how vegetation cover affect runoff hydraulics and erosion processes. We present field observations of overland flow hydraulics using rainfall simulations in a typical semi-arid area in China. Field plots (5 m × 2 m) were constructed on a loess hillslope (25°), including bare soil plot as control and three plots with planted forage species as treatments—Astragalus adsurgens (A. adsurgens), Medicago sativa (M. sativa) and Cosmos bipinnatus (C. bipinnatus). Both simulated rainfall and simulated rainfall + inflow were applied. Forages reduced soil loss by 55–85% and decreased overland flow rate by 12–37%. Forages significantly increased flow hydraulic resistance expressed by Darcy-Weisbach friction factor by 188–202% and expressed by Manning’s friction factor by 66–75%; and decreased overland flow velocity by 28–30%. The upslope inflow significantly increased overland flow velocity by 67% and stream power by 449%, resulting in increased sediment yield rate by 108%. Erosion rate exhibited a significant linear relationship with stream power. M. sativa exhibited the best in reducing soil loss which probably resulted from its role in reducing stream power. Forages on the downslope performed better at reducing sediment yield than upslope due to decreased rill formation and stream power. The findings contribute to an improved understanding of using vegetation to control water and soil loss and land degradation in semi-arid environments.
A Geodesist's Involvement Into Archaeology; A Beginning of Huge Discoveries
Authors: Hawarey Mosab
Published: March 2020

Geodesists have a different mindset; major or minor involvement in mapping, navigation, positioning, surveying, gravity, coordinate frames and systems, geographical information systems, photogrammetry, 3D laser scanning, satellite orbit determination, orbital mechanics, interferometry and many other fields all help in the grand builtup of a resilient scientist who can emerge with an explorer attitude towards various facets of life; archaeology being one of them, needless to say. If this hybrid composite of mindset and attitude is combined with disciplined and smart usage of geophysical 3D imaging instrumentations deployed frequently by treasure hunters, geodesists might be in a very unique position to make a big bang in the world; finding archaeological Black Swans that might serve to rewrite certain narratives of ancient history is something geodesists must consider deeply. In this presentation, an approach and a discovery will be presented.
Stable Isotope Evidence for Recent Global Warming Hiatus
Authors: Wang Rui , Liu Zhongfang
Published: March 2020

Global mean surface air temperature (SAT) has remained relative stagnant since the late 1990s, a phenomenon known as global warming hiatus. Despite widespread concern and discussion, there is still an open question about whether this hiatus exists, partly due to the biases in observations. The stable isotopic composition of precipitation in mid- and high-latitude continents closely tracks change of the air temperature, providing an alternative to evaluate global warming hiatus. Here we use the long-term precipitation δ18O records available to investigate changes in SAT over the period 1970–2016. The results reveal slight decline in δ18O anomaly from 1998 to 2012, with a slope of -0.0004‰ decade-1 which is significantly different from that of pre-1998 interval. This downward δ18O anomaly trend suggests a slight cooling for about -0.001°C decade-1, corroborating the recent hiatus in global warming. Our work provides new evidence for recent global warming hiatus and highlights the potential of utilizing precipitation isotope for tracking climate changes.
Inner-core dynamics during the rapid intensification of Hurricane Wilma (2005) with a steady radius of the maximum wind
Authors: Qin Nannan , Zhang Da-Lin , Miller William , Kieu Chanh
Published: March 2020

Recent studies show that some hurricanes may undergo rapid intensification (RI) without contracting the radius of maximum wind (RMW). A cloud-resolving WRF-prediction of Hurricane Wilma (2005) is used herein to examine what controls the RMW contraction and how a hurricane could undergo RI without contraction. Results show that the processes controlling the RMW contraction are different within and above the planetary boundary layer (PBL). In the PBL, radial inflows contribute to contraction, with frictional dissipation acting as an inhibiting factor. Above the PBL, radial outflows and vertical motion govern the RMW contraction, with the former inhibiting it. A budget analysis of absolute angular momentum (AAM) shows that the radial AAM flux convergence is the major process accounting for the spinup of the maximum rotation, while the vertical flux divergence of AAM and the frictional sink in the PBL oppose the spinup. During the RI stage with no RMW contraction, the local AAM tendencies in the eyewall are smaller in magnitude and narrower in width than those during the contracting RI stage. In addition, the AAM following the time-dependent RMW decreases with time in the PBL and remains nearly constant aloft during the contracting stage, whereas it increases during the non-contracting stage. These results reveal different constraints for the RMW contraction and RI, and help explain why a hurricane vortex can still intensify after the RMW ceases contraction
Numerical Air Quality Forecast over East China: Advance, Uncertainty and Future
Authors: Zhou Guangqiang
Published: March 2020

Air pollution is severely focused due to its distinct effect on climate change and adverse effect on human health, ecological system, etc. Eastern China is one of the most polluted areas in the world and many actions were taken to reduce air pollution. Numerical forecast of air quality was proved to be one of the effective ways to help to deal with air pollution. This abstract will present the advance, uncertainty and thinking about the future of the numerical air quality forecast emphasized in eastern China region. Brief history of numerical air quality modeling in Shanghai Meteorological Serveice (SMS) will be reviewed. The operational regional atmospheric environmental modeling system for eastern China (RAEMS) and its performance on forecasting the major air pollutants over eastern China region will be introduced. And uncertainty will be analyzed meanwhile challenges and actions to be done in the future are to be suggested for better service of numerical air quality forecast.
Variability assessment of Irrigation Requirement for Winter Wheat Cropping Under Changing Climate.
Authors: Gujjanadu Suryaprakash Kaushika , Kotnur Suryanarayana Rao Hari Prasad
Published: March 2020

India is primarily an agronomic country and most of the cropping in the Rabi season depends on the rainwater availability. With the ill effects of climate change cropping up, the agriculture sector is expected to take a major hit. This study takes a technical approach on the impact of climate change on the irrigation requirement of wheat cropping by studying the future irrigation requirement based on the temperature and rainfall that can be expected to occur in the future timelines. A root water uptake model involving the solution of the non-linear Richards equation to assess the root-zone moisture movement is formulated and validated. The inputs of the model include the crop data, which, in this case is obtained by field experimentation at the irrigation field laboratory at IIT Roorkee and weather data, which is obtained from the CANESM2 General circulation model for the historical and projected timescales. The historical GCM data for thirty years is bias corrected using the observed data from the India Meteorological department (IMD). The validated root water uptake model is applied to the historical and projected data for a 60 year span for two emission scenarios for RCP 4.5 and 8.5. The output was obtained as soil moisture profiles and frequencies of irrigation required. It was seen that for both the mild and high emission scenarios, the number of irrigation events per cropping period increased. This increase is assessed using variability analysis and for its impacts on the water resources management systems. The variability assessment showed the variation of the irrigation water requirement on annual and decadal scales. This is useful in understanding the historical and expected crop water requirement in view of the climate change effects.
Resistivity-depth imaging of airborne transient electromagnetic method based on an artificial neural network
Authors: Zhang Jifeng , Feng Bing , Li Dong
Published: March 2020

An artificial neural network, which is an important part of artificial intelligence, has been widely used to many fields such as information processing, automation and economy, and geophysical data processing as one of the efficient tools. However, the application in geophysical electromagnetic method is still relatively few. In this paper, BP neural network was combined with airborne transient electromagnetic method for imaging subsurface geological structures.

We developed an artificial neural network code to map the distribution of geologic conductivity in the subsurface for the airborne transient electromagnetic method. It avoids complex derivation of electromagnetic field formula and only requires input and transfer functions to obtain the quasi-resistivity image section. First, training sample set, which is airborne transient electromagnetic response of homogeneous half-space models with the different resistivity, is formed and network model parameters include the flight altitude and the time constant, which were taken as input variables of the network, and pseudo-resistivity are taken as output variables. Then, a double hidden layer BP neural network is established in accordance with the mapping relationship between quasi-resistivity and airborne transient electromagnetic response. By analyzing mean square error curve, the training termination criterion of BP neural network is presented. Next, the trained BP neural network is used to interpret the airborne transient electromagnetic responses of various typical layered geo-electric models, and it is compared with those of the all-time apparent resistivity algorithm. After a lot of tests, reasonable BP neural network parameters were selected, and the mapping from airborne TEM quasi-resistivity was realized. The results show that the resistivity imaging from BP neural network approach is much closer to the true resistivity of model, and the response to anomalous bodies is better than that of all-time apparent resistivity numerical method. Finally, this imaging technique was use to process the field data acquired by the airborne transient method from Huayangchuan area. Quasi-resistivity depth section calculated by BP neural network and all-time apparent resistivity is in good agreement with the actual geological situation, which further verifies the effectiveness and practicability of this algorithm.
Seasonal Variations of Arctic Low‐Level Clouds and Its Linkage to Sea Ice Seasonal Variations
Authors: Yu Yueyue , Taylor Patrick , Cai Ming
Published: March 2020

Using CALIPSO‐CloudSat‐Clouds and the Earth's Radiant Energy System (CERES)‐Moderate Resolution Imaging Spectrometer (MODIS) (C3M) dataset, this study documents the seasonal variation of sea ice, cloud, and atmospheric properties in the Arctic (70°N–82°N) for 2007–2010. A surface type stratification—consisting Permanent Ocean, Land, Permanent Ice, and Transient Sea Ice—is used to investigate the influence of surface type on low-level Arctic cloud liquid water path (LWP) seasonality. The results show significant variations in the Arctic low-level cloud LWP by surface type linked to differences in thermodynamic state. Subdividing the Transient Ice region (seasonal sea ice zone) by melt/freeze season onset dates reveals a complex influence of sea ice variations on low cloud LWP seasonality. We find that lower tropospheric stability (LTS) is the primary factor affecting the seasonality of cloud LWP. Our results suggest that variations in sea ice melt/freeze onset have a significant influence on the seasonality of low-level cloud LWP by modulating the lower tropospheric thermal structure and not by modifying the surface evaporation rate in late spring and mid-summer. We find no significant dependence of the May low-level cloud LWP peak on the melt/freeze onset dates, whereas and September/October low-level cloud LWP maximum shifts later in the season for earlier melt/later freeze onset regions. The Arctic low cloud LWP seasonality is controlled by several surface-atmosphere interaction processes; the importance of each varies seasonally due to the thermodynamic properties of sea ice. Our results demonstrate that when analyzing Arctic cloud-sea ice interactions, a seasonal perspective is critical.
Podiform and stratiform chromitite with PGE in Paleoproterozoic (2.1 Ga) Pados-Tundra ultramafic (ophiolite) complex (N-E part of the Fennoscandian Shield, Arctic region)
Authors: Bayanova Tamara , Pavel Serov , Evgeniy Kunakkuzin , Ekaterina Steshenko , Elena Borisenko
Published: March 2020

Pados-Tundra ultramafic complex belong to Serpentinite belt in the northern Fennoscandian Shield and composed of dunite-harzburgite-orthopyroxenite with 7 rhythms and 4 Cr layers. The associated massif named as Malyi Pados are considered as a satellite intrusion (Mamontov, Dokuchaeva, 2005) or dislocated block detached according by (Barkov et al., 2016). Nevertheless the complex includes of Dunite Zone with podiform and stratiform chromitite with Ir subgroup PGE (Ru, Os, Ir – IPGE) and associated with chromian spinel in ophiolite (Joban, 2006). Fiestly unusual microtextures and mineralogical features with clinochlore, laurite and native Ru was found (Barkov et al., 2017).

Isotope U-Pb data on baddeleyite in core of zircon from mafic gabbronorite rocks of the Malyi Pados gave 2083±7 Ma and are coeval to ages of Cu-Ni Pechenga (1980 Ma) and PGE Bushveld deposits. Notably are measured new U-Pb ages with 2087±3 Ma for baddeleyite and metamorphic rutile with 1804±10 Ma from hornblendite dyke which are cutted ultramafic rocks of the Pados-Tundra complex.

New Sm-Nd mapping data for the main rocks of the complex are reflected model TDM ages of primary protolith from 2.78 Ga to 2.36 Ga and 3.13 Ga for host rock with positive εNd values from +2.7 to +2.1. New Sm-Nd investigations to podiform chromitites of the Pados-Tundra complex are similar to Sopcheozerskoe Cr-deposit (Dunite Block) of the Monchegorsk ore region with positive εNd and young protolith ages about 2.7 Ga for primary magma sources instead of Paleoproterozoic Co-Cu-Ni and PGE layered intrusions of the Fennoscandian Shield with 2.4 Ga to 2.5 Ga for origin and 3.2 - 3.5 Ga of the protolith EM-1 enriched mantle plume reservoir (Bayanova et al., 2009, 2014, 2018). All new U-Pb on baddeleyite and Sm-Nd studies to whole rocks of the Pados-Tundra complex infer about ophiolite (spreading or oceanization of the crust) and presence diamond in podiform chromitites according to new highlights of (Ballhause et al., 2017).

All investigations are supported by RFBR 18-05-70082 (Arctic resources), 18-35-00152, 18-35-00246, Scientific Research Contract N0.0226-2019-0053 and Program of Presidium RAS 8.48.
Studying the bottom landscapes of Lake Ladoga with use of underwater vehicles
Authors: Anokhin Vladimir , Dudakova Dina , Dudakov Mikhael
Published: March 2020

In 2019, the Institute of Limnology of the Russian Academy of Sciences (IL RAS) carried out geological and geomorphological studies of the bottom and shores of Lake Ladoga within the framework of the State project of the IL RAS No. 0154-2018-0003 / 5. The research included the study of the bottom landscapes of Lake Ladoga with help of a series of underwater vehicles Limnoscout, designed and assembled at the IL RAS.

Underwater photo and video of the bottom in the coastal zone was carried out by the Limnoscout-230 vehicle from a boat. Each video filming polygon  included 2 continuous video profiles of 1-2 km normal to the shore, and 1 connecting profile parallel to the shore of 200-400 m, in the deep part.

Underwater video filming of the bottom in the open water area of ​​the lake was carried out by the Limnoscout-50 vehicle from the board of the r/v “Poseidon”, by point diving, in which the bottom was shot within a radius of 2-4 m from the dive point.

Maximal deep of studies was 117 m.

All underwater surveys were accompanied by echo-sounding surveys and GPS tracking.

In total, 24 underwater video filming  polygons in the coastal zone and 23 underwater video filming points in the open water area of ​​the northern part of Lake Ladoga were worked out.

The collected extensive photo and video materials made it possible to make preliminary typology of the bottom landscapes of Lake Ladoga and evaluate their condition.

Several new important facts of the structure of the bottom of Lake Ladoga and biota distribution were discovered, in particular:

- For the first time on the bottom of Lake Ladoga, an invasive species of mollusk Dreissena polymorpha was discovered, which in other large lakes has a significant impact on ecosystems.

- For the first time at the bottom in the northern part of the lake, outlets of presumably Riphean sandstones were discovered, which significantly complements the geological picture of the area.

- For the first time at the bottom in the northeastern part of the lake an abnormally deep occurrence of coarse deposits was discovered, which is likely to be associated with the intense activity of glaciers.

The use of underwater photo and video in combination with traditional methods for studying the bottom landscapes of Lake Ladoga has shown the high efficiency of these methods. The studies will be continued.
Grain size of deposits in different plantation dunes on the eastern shore of Qinghai Lake
Authors: Tian Lihui , Zhang Dengshan , Yu Yang
Published: March 2020

Soil particles are related to vegetation growth and source of depositsc in arid and semi-arid desert. It is worth mentioning that plantation is the one the most effective ways improving desert soil conditions. The sandy land on the eastern shore of Qinghai Lake is the biggest area in the desertified land of Qinghai Lake Basin. Some measures have been taken to prevent and control desertification in Kutu district since 2008. We chose the dunes that planted Salix cheilophila、Hippophae rhamnoides、Pinus sylvestris、Populus simonii and Hedysarum scoparium as study sites, then collected deposits from topsoil to the depth of 60 cm to probe into the change of grain size features. The results show that: (1) All study dunes primarily are made up of medium materials for mean particle size (M) is medium sand widely distributed from 0.27mm to 0.31mm which are presented uniform. (2) The sorting coefficient of sediments is concentrated between 0.5 and 0.9 with better performance. The skewness value is between 0 and 1, which shows nearly symmetrical and positive skewness. The kurtosis is between wide and medium. (3) The vertical change of particle size composition at different depths of 60 cm indicates that plantation significantly changed the distribution of the surface sediments in the dunes, whereas particle compositions at different depths did not have obvious rules of different plants. (4) The vegetation recovery time in study area was short, therefore, interactions between wind sorting, terrain fluctuations and vegetation growth might affect the grain size features of surface sediments in study area.
Glacier sliding set by self-regulating feedback between friction and drainage efficiency
Authors: Gilbert Adrien , Gimbert Florent , Thøgersen Kjetil , Schuler Thomas , Kääb Andreas
Published: March 2020

Glacier basal sliding accommodates most of glacier motion and is the main process behind glacier dynamic variability, able to substantially modulate glacier response to climate change. In particular, it controls glacier instabilities, surges, ice stream development and flow speeds of most glaciers on Earth. Paradoxically, glacier sliding remains one of the least understood processes in glacier physics due to the difficulty of accessing and observing the sub-glacial environment. In numerical models, sliding of glaciers is traditionally determined by friction laws interlinking basal shear stress, sliding velocity and water pressure. However, assessing the effects of water pressure on sliding remains a challenge due to the sparsity of appropriate data to validate coupled ice-flow/subglacial-hydrology models. We unify here the description of subglacial cavities transient dynamic for basal friction and sub-glacial hydrology and show how it interacts as a self-regulating coupled system. Our results are in striking agreement with observation from a unique multi-decadal record of basal sliding and water discharge in Argentière Glacier (French Alps). We show that sliding speed of hard-bedded glaciers is set by the drainage efficiency necessary to accommodate the melt water supply rather than being driven by water pressure. We suggest that liquid water supply at the glacier base rather water pressure should be used to develop friction laws that include the effect subglacial hydrology. This will make glacier dynamical response to climate change more predictable.
Water sustainability: the prospect of transfer projects in China
Authors: Abbasi Naseer Ahmed , Xu Xiangzhou
Published: March 2020

Affected by global climate change, water shortages and other extreme weather, water scarcity in world is alarming sign. China is suffering from severe water shortage in northern areas due to multiple reasons such as declining of runoff of main rivers to northern areas and serious rainfall shortage. This article provides the evidences regarding the feasibility and their technical, financial, political, socioeconomic, environmental from the aspects of two projects, Tunnel and Tianhe projects. The Tianhe water diversion project is expected to bring 2.5 billion cubic meters of precipitation in the Sanjiangyuan area, 200 million in the Qilian Mountains area and 120 million in the Qaidam area every year. On the other hand, the Tibet-Xinjiang Tunnel, which would be the longest water divert tunnel in the world, plan to divert the water from Tibet to Xinjiang using a 1000-kilometer tunnel. The project is expected to turn Xinjiang into California, which could carry 10 to 15 billion tons of water each year. These two projects are anticipated to solve the problem of water, food and drought in the country. In addition, the integrated telecoupling helps to promote ecosystem services research and governance, identify knowledge gaps, guide research design, and strengthen the interaction between researchers and stakeholders.
Summer crops and the impact of pesticides on surface and underground water in the southeast of the province of Buenos Aires, Argentina.
Authors: Costa José Luis , Angelini Hernan , De Geronimo Eduardo , Aparicio Virginia
Published: March 2020

Agricultural land is the first pesticide recipient after application. Even if the pesticides are applied in accordance with the regulations, only a smaller amount reaches their objectives (weed or pest), while the rest represents possible environmental pollutants (Hvězdová et al., 2018). In this case, the pesticides they become the non-point source of contamination.

The objective of this work was to evaluate the impact of summer crop practices on the concentration of pesticides in surface water and groundwater. In soybean and corn crops, next to surface water courses, 2 freatimeters were installed. Groundwater depth was evaluated in six moments (19/12/2018, 4/1/2019, 14/1/2019, 8/2/2019, 15/2/2019 and 25/2/2019). Water samples were extracted and the concentration of 45 organic molecules (pesticides and degradation products) was determined with a UPLC MS / MS. Once the concentration of each molecule was quantified, it was added to establish the proportion corresponding to the total of a) glyphosate + AMPA; b) Atrazine + hydroxy-atrazine + desetyl-atrazine + desisopropyl-atrazine; c) 2,4D and d) other molecules.

The groundwater was always at a depth greater than 1.30 m in the freatimeters. On average, the proportion of the sum of molecules was: glyphosate metabolite > atrazine metabolite > 2.4D > other organic molecules. The sum of molecules ranged from 0.17 to 39.1 µg l-1. On the other hand, the sum of molecules ranged from 1.3 to 12.5 µg l-1 during the evaluation period. On average, the proportion of the sum of molecules was: glyphosate + metabolite > Atrazine + metabolite > 2.4D  other organic molecules.

These preliminary results indicate that the grain production system generates an impact evidenced by the presence of synthetic organic molecules in the water. It is important to adjust crop management practices to avoid and / or minimize that impact and its environmental consequences.
Valuing System Flexibility Through adding Pumped Hydro Energy Storage in the New England Electricity System
Authors: Nock Destenie , Baker Erin
Published: March 2020

As energy transition pushes the world towards low-carbon or high renewable economies, the share of renewables supplying electricity continues to increase. Due to their intermittent nature, as the share of renewables increases so does the demand for flexibility in power systems. Pumped hydro energy storage (PHES) is one method of enhancing power system flexibility due to its ability to regulate power output from renewables, acting as a supplier and consumer, and enhance overall system sustainability through enhancing the capacity factor of renewables and being a low emission technology. In this paper we estimate the trade-offs of PHES additions to a regions power system using an electricity dispatch model tied with multi-criteria decision analysis considering the three pillars of sustainability (i.e. social, environmental, and economical). We rank various low carbon generation portfolios, which contain a mix of PHES, wind, solar, natural gas, nuclear, and oil, under nine illustrative preference scenarios. In this work we find that using PHES to support renewables increases sustainability in the New England Power System. We find that the optimal strategy to enhance flexibility and sustainability of power systems may be to simply add storage to the system due to its ability to reduce GHG emissions and support renewables.
The Greenland Geodetic Network (GNET)
Authors: Brunt Kelly , Hawley Robert
Published: March 2020

The Greenland Geodetic Network (GNET) consists of 58 global navigation satellite systems (GNSS) installed on the bedrock around the perimeter of the island. Much of the network was installed between 2007 and 2009, providing a long time series of GNSS data for much of Greenland. The network is currently owned and maintained by the Danish Agency for Data Supply and Efficiency (SDFE), while the National Science Foundation (NSF) provides support for data transport from the deep field. Here, we present a new resource (go-gnet.org) intended to be a clearinghouse to foster international collaborations and to encourage new and innovative use of these data.
Why do Geodetic Data need DOIs? First ideas of the GGOS DOI Working Group
Authors: Elger Kirsten , Coetzer Glenda , Botha Roelf ,   GGOS DOI Working Group
Published: March 2020

Only four years after the implementation of digital object identifiers (DOIs) for unambiguously identifying and linking to online articles, the first DOI for digital datasets was registered in 2004. Originally developed with the purpose of providing permanent access to (static) datasets described in scholarly literature (to allow reproducibility and scrutiny of research results), DOIs today are increasingly used for dynamic datasets (e.g. time series from observational networks, where new data values are added frequently given that the originally published data will not change), collections or networks. These DOIs (and other persistent identifiers) are mainly assigned for providing a citable and traceable reference to various types of sources (data, software, samples, equipment) and means of rewarding the originators and institutions.

As a result of international groups, like the Coalition for Publishing Data in the Earth and Space Sciences (COPDESS) and the Enabling FAIR Data project, datasets with assigned DOIs are now fully citable in scholarly literature - many journals require the data underlying a publication to be available before accepting an article. Initial metrics for data citation are available and allow data providers to demonstrate the value of the data collected by institutes and individual scientists – which makes them even more attractive.

This is especially relevant in the framework of evaluation criteria for institutions and researchers, that usually only consider scientific output in the form of scholarly literature and citation numbers. Compared to other scientific disciplines, geodesy researchers appear to be producing less “countable scientific” output. Geodesy researchers, however, are much more involved in operational aspects and data provision than researchers in other fields might be. Geodesy data and equipment therefore require a structured and well-documented mechanism which will enable citability, scientific recognition and reward that can be provided by assigning DOI to data, data products and scientific software.

To address these challenges and to identify opportunities for improved coordination and advocacy within the geodetic community, the International Association of Geodesy’s (IAG) Global Geodetic Observing System (GGOS) has established a Working Group on “Digital Object Identifiers (DOIs) for Geodetic Data Sets”. The GGOS DOI Working Group (with more than 20 members) officially started with a first meeting during December 2019, co-located to the AGU Fall Meeting. Beginning with an assessment of DOI minting strategies that are already implemented, the GGOS DOI Working Group is designated to establish best practices and advocate for the consistent implementation of DOIs across all IAG Services and in the greater geodetic community.
Estimability in Rank-Defect Mixed-Integer Models: Theory and Applications
Authors: Teunissen Peter
Published: March 2020

G1.1 Session: Recent Developments in Geodetic Theory

 

Estimability in Rank-Defect Mixed-Integer Models: Theory and Applications

 

PJG Teunissen1,2

1GNSS Research Centre, Curtin University, Perth, Australia

2Geoscience and Remote Sensing, Delft University of Technology, The Netherlands

Email: p.teunissen@curtin.edu.au; p.j.g.teunissen@tudelft.nl

 

Although estimability is one of the foundational concepts of todays’ estimation theory, we show that the current concept of estimability is not adequately equipped to cover the estimation requirements of mixed-integer models, for instance like those of interferometric models, cellular base transceiver network models or the carrier-phase based models of Global Navigation Satellite Systems (GNSSs). We therefore need to generalize the estimability concept to that of integer-estimability. Next to being integer and estimable in the classical sense, functions of integer parameters then also need to guarantee that their integerness corresponds with integer values of the parameters the function is taken of. This is particularly crucial in the context of integer ambiguity resolution. Would this condition not be met, then the integer fixing of integer functions that are not integer-estimable implies that one can fix the undifferenced integer ambiguities to non-integer values and thus force the model to inconsistent and wrong constraints.

In this paper we present a generalized concept of estimability and one that now also is applicable to mixed-integer models. We thereby provide the operationally verifiable necessary and sufficient conditions that a function of integer parameters needs to satisfy in order to be integer-estimable. As one of the conditions we have that estimable functions become integer-estimable if they can be unimodulair transformed to canonical form. Next to the conditions, we also show how to create integer-estimable functions and how a given design matrix can be expressed in them. We then show how these results are to be applied to interferometric models, cellular base transceiver network models and FDMA GNSS models.

 

Keywords: Estimability, S-system theory, Mixed-integer Models, Integer-Estimability, Admissible Ambiguity Transformation, Interferometry, Global Navigation Satellite Systems (GNSSs)

 
Lower hybrid waves at the magnetosheath separatrix region
Authors: Tang Binbin , Li Wenya , Graham Daniel , Wang Chi , Khotyaintsev Yuri ,   MMS team
Published: March 2020

Lower hybrid waves are investigated at the magnetosheath separatrix region in asymmetric guide-field reconnection at Earth’s magnetopause by using MMS observations. These waves are found in a limited region, depending on the density gradient across the separatrix, and they are driven by the lower hybrid drift instability. Properties of these waves are presented: (1) the waves propagate towards the x-line due to the out-of-plane magnetic field, consistent with the electron drift direction; (2) the wave potential is about 20% of the electron temperature. These drift waves effectively produce cross-field particle diffusion, enabling the entry of magnetosheath electrons into the exhaust region.
Proto-dune formation under a bimodal wind regime
Authors: Delorme Pauline , Wiggs Giles , Baddock Matthew , Nield Joanna , Best James , Christensen Kenneth , Bristow Nathaniel , Valdez Andrew , Claudin Philippe
Published: March 2020

Early-stage aeolian bedforms develop into sand dunes through complex interactions between flow, sediment transport and surface topography. Depending on the specific environmental and wind conditions the mechanisms of dune formation, and ultimately the shape of the nascent dunes, may differ. Here, we investigate the formation of a proto-dune-field, located in the Great Sand Dunes National Park ( Colorado, USA), using a three dimensional linear stability analysis.

We use in-situ measurements of wind and sediment transport, collected during a one-month field campaign, as part of a linear stability analysis to predict the orientation and wavelength of the proto-dunes.

We find that the output of the linear stability analysis compares well to high-resolution Digital Elevation Models measured using terrestrial laser scanning. Our findings suggest that the bed instability mechanism is a good predictor of proto-dune development on sandy surfaces with a bimodal wind regime.