bluuebunny/crossref_metadata_2025 huggingface dataset:
Predicting Dengue Hemorraghic Fever Cases in Metro Manila, Philippines
Authors: Necesito Imee , Jung Jaewon , Bae Young Hye , Kim Soojun , Kim Hung Soo
Published: March 2020

Researchers have been looking for methods to prevent, control and provide lifelong protection to humans against dengue disease which is brought by the dengue-carrying mosquito called the Aedes Aegypti. However, such prevention, control and protection will best be aided by a dengue case prediction model. This study used the Negative Binomial Regression to forecast the dengue case incidence in Metro Manila, Philippines using principal components as explanatory variables. To ensure that the dengue cases are predictable, close returns plot (CRP) was performed.   The logarithm of dengue case incidence which were assigned as response variables have showed higher value of variance over the mean which validates the use of negative binomial regression. Principal Component Analysis utilizing Nino 3.4 sea surface temperature (SST), precipitation and minimum temperature was used in the study. The acquired principal components (PC1, PC2, PC3 and PC4) were used as the explanatory variables for the negative binomial regression to calculate the number of the logarithm of dengue case incidence. However, to improve the calculated value of DHF cases in comparison to its actual value, residuals from the negative binomial regression were treated using moving average approach. The data used in this study were from 1994-2010 climatological data. Results for both negative binomial and moving average were combined to get the forecasted dengue incidence. Forecasted values showed a maximum of 12% difference from the actual DHF cases indicating a high forecasting performance. This study which focused on predicting the possible dengue incidence in the central districts of the Philippines  is believed to be essential to create plans of action to prevent and control this disease.
Detecting dynamical anomalies in time series from different palaeoclimate proxy archives using windowed recurrence network analysis
Authors: Donner Reik , Lekscha Jaqueline
Published: March 2020

Analysing palaeoclimate proxy time series using windowed recurrence network analysis (wRNA) has been shown to provide valuable information on past climate variability. In turn, it has also been found that the robustness of the obtained results differs among proxies from different palaeoclimate archives. To systematically test the suitability of wRNA for studying different types of palaeoclimate proxy time series, we use the framework of forward proxy modelling. For this, we create artificial input time series with different properties and compare the areawise significant anomalies detected using wRNA of the input and the model output time series. Also, taking into account results for general filtering of different time series, we find that the variability of the network transitivity is altered for stochastic input time series while being rather robust for deterministic input. In terms of significant anomalies of the network transitivity, we observe that these anomalies may be missed by proxies from tree and lake archives after the non-linear filtering by the corresponding proxy system models. For proxies from speleothems, we additionally observe falsely identified significant anomalies that are not present in the input time series. Finally, for proxies from ice cores, the wRNA results show the best correspondence with those for the input data. Our results contribute to improve the interpretation of windowed recurrence network analysis results obtained from real-world palaeoclimate time series.
Episodic occurrence of field-aligned energetic ions on the dayside
Authors: Yue Chao , Bortnik Jacob , Zou Shasha , Nishimura Yukitoshi , Foster John C.
Published: March 2020

The tens of keV ion populations observed in the ring current region at L~ 3- 7, generally have pancake-shaped pitch angle distributions (PADs), that is, peaked at 90 degrees. These pancake PADs are formed due to a combination of betatron and Fermi acceleration when they are transported from the tail plasma sheet, where the major ring current plasma originates. However, in this study, by using the Van Allen Probe observations from 2012 to 2018 on the dayside, unexpectedly we have found that about 5% of the time, protons with energies of ~30 to 50 keV show two distinct populations according to their PADs, having an additional population of field-aligned ions overlapping with the original pancake population. The newly appearing field-aligned populations have higher occurrence rates at ~12-16 MLT during geomagnetically active times. In particular, we have studied eight such events in detail and traced back these ions to their source regions according to the energy-dependent dispersion signatures caused by the differences in drift velocities. We found that the source regions are located around 12 to 18 MLT which coincides with the high occurrence rate region of 12-16 MLT. Based on the ionospheric and LANL geosynchronous observations of these eight events, it is suggested that these energetic ions with field-aligned PADs most probably are accelerated in the post-noon sector in association with ionospheric disturbances that are triggered by tail injection. These results provide evidence of another important source of the ring current ions.
Dealing with “too much data”: Automated Structure-from-Motion Processing of Time Lapse Imagery at Nùłàdäy Glacier, Yukon, Canada
Authors: Bash Eleanor , Dow Christine , McDermid Greg
Published: March 2020

Recent advances in camera sensors, data storage, and structure-from-motion (SfM) processing are opening new possibilities for monitoring glacier processes through time series imagery. With SfM processing, internal and external camera parameters can be estimated in a bundle adjustment, alleviating problems associated with camera stability in the field. Orienting points in real world coordinates, however, still requires manual intervention in the form of ground control identification in imagery when dealing with two camera systems. We are introducing a new automated method of orienting point clouds from two-camera time lapse set ups to allow for fast processing of large numbers of frames. We accomplish this by leveraging several algorithms developed for computer vision and apply them to an analysis of glacier surface elevation change. Two time lapse systems were installed overlooking Nùłàdäy (Lowell Glacier), Yukon, Canada, on July 13, 2019. Each system consisted of a Nikon D5600 and a DigiSnap Pro, recording images at 2-hour intervals. On July 1, 2019 a manned aircraft flight collected imagery of the glacier using a Nikon D850 with a differential GPS collecting high precision locations for each image. The July 1 imagery was processed using Agisoft Photoscan Professional through the Python API to produce a target point cloud for orientation of unregistered time lapse imagery. Using Photoscan Professional’s 4D capability, a time series of images from each time lapse camera were aligned in a one-step bundle adjustment to produce a series of dense point clouds at each time step. Point clouds from time lapse imagery were coregistered to the target point cloud using a Fast Point Feature Histograms and a color-enhanced point cloud alignment based on Rusu et al. (2009) and Park et al. (2017). The M3C2 algorithm (Lague et al., 2013) was used to difference point clouds in the timeseries and derive a time series of elevation change at Nùłàdäy with an uncertainty of 1.5 m2.  All steps in the workflow are executed through Python, allowing for easy automated execution of data processing. With streamlined processing it is possible to integrate more time steps into SfM analysis of glacier surface elevation change and integrate the data into modelling efforts of glacier evolution.
The impact of iodine on ozone trends in the lower stratosphere
Authors: Chipperfield Martyn , Feng Wuhu , Dhomse Sandip , Li Yajuan , Hossaini Ryan , Pfeilsticker Klaus
Published: March 2020

Depletion of the stratospheric ozone layer by chlorine and bromine species has been a major environmental issue since the early 1970s. Following controls on the production of the long-lived halocarbons which transport chlorine and bromine to the stratosphere, the ozone layer is expected to recover over the course of this century. Decreases in the stratospheric loading of chlorine and bromine have been observed and there are signs of this resulting in an increase in ozone in the upper stratosphere and the Antarctic lower stratosphere. However, in contrast to this expectation of increasing stratospheric ozone, Ball et al. (ACP doi:10.5194/acp-18-1379-2018, 2018, ACP doi:10.5194/acp-19-12731-2019, 2019) have reported evidence for an ongoing decline in lower stratospheric ozone at extrapolar latitudes between 60°S and 60°N. Chipperfield et al. (GRL, doi:10.1029/2018GL078071, 2018) analysed these results using the TOMCAT 3-D chemical transport model (CTM). They reported that much of the observed ozone decrease could be explained by dynamical variability. Furthermore, they investigated the potential role for bromine and chlorine from very short-lived species (VSLS) but found only a small contribution.

Very recently, Koenig et al. (PNAS, doi:10.1073/pnas.1916828117, 2020) have reported quantitative observations of almost 1 pptv iodine in the lower stratosphere. They show that this iodine is an important contribution to the local iodine loss budget and speculate that a trend in iodine could therefore explain the observed downward trend in ozone.

Here we use an updated version of the TOMCAT CTM to investigate the impact of iodine on lower stratospheric ozone trends. We repeat the simulations of Chipperfield et al. (2018), using both ERA-Interim and ERA5 reanalyses (to compare the quantification of the dynamical contribution). We use assume trends in the stratospheric injection of iodine to quantify the possible impact of this on global ozone trends through both gas-phase chemistry and novel heterogeneous processes.

 
Geoarchaeology and chronology of Sodicho – insights into site formation processes and human activity in a volcanic rock shelter, SW Ethiopia
Authors: Hensel Elena A. , Vogelsang Ralf , Noack Tom , Bubenzer Olaf
Published: March 2020

Rock shelter and cave sites can be suitable archives for archaeological remains and environmental records if the right conditions are complied with. There are a few sediment stratigraphies in the Horn of Africa that preserved information about human occupation during the Upper Pleistocene and Holocene. Unfortunately, little is known about human settlement in Ethiopia during the period corresponding to MIS 2 due to discontinuous archaeological records. The project A1, within the framework of the Collaborative Research Centre 806 (CRC 806 – “Our Way to Europe”), focuses on Late Pleistocene stratigraphies and paleoenvironments of northeast African sites. In this context, during excavations at the Sodicho Rockshelter in the southwestern Ethiopian Highlands, a complex stratigraphy with evidence of several human occupation phases was exposed.

This poster presents the latest research results of the Sodicho Rockshelter. It displays first radiocarbon ages and the site formation processes according to a selection of sedimentological and geochemical methods to understand human settlement history in this tropical environment. A multi-proxy approach has been chosen to detect possible rapid or gradual changes in depositional conditions in the rock shelter. The sedimentological records suggest that the depositional and post-depositional processes varied significantly over time in response to external environmental changes and the use of the shelter by humans. For instance, lithic assemblages in anthropogenic influenced layers alternate with thick volcanic ash layers. In addition, a sterile, clayish horizon refers to a period of increased precipitation and could thus provide evidence for an African Humid Period. The Sodicho Rockshelter could validate the current state of research and possibly close the chronostratigraphic gap.
New seismological insights from the analyses of historical and recent earthquakes at Ischia Island (Southern Italy)
Authors: Carlino Stefano , Convertito Vincenzo , Tramelli Anna , De Novellis Vincenzo , Pino Nicola Alessandro
Published: March 2020

We report here a first comparative analysis between recent and historical earthquakes, occurred in the island of Ischia (Southern Italy), which produced heavy damages and thousands of fatalities. The island of Ischia is located in the Gulf of Naples, and represents a peculiar case of resurgent caldera in which volcano-tectonic earthquakes, with low magnitude, have generated large damages and catastrophic effects, as is the case for the 4 March 1881 (Imax8-9 MCS) and the 28 July 1883 (Imax10-11 MCS) events. Both the earthquakes struck the northern area of the island, similarly to the recent 21 August 2017 earthquake. The results allowed us to assess the location, as well as the possible dimension and the related maximum magnitude of the seismogenic structure, located in the northern sector of the island, and responsible of damaging earthquakes. Our results also provide an additional framework to interpret mechanisms leading to earthquakes associated with dynamics of calderas.

 
Exploring and reducing biases in sub-ice-shelf melt rates in an Earth system model
Authors: Asay-Davis Xylar , Begeman Carolyn , Comeau Darin , Hoffman Matthew , Lin Wuyin , Petersen Mark , Price Stephen , Roberts Andrew , Veneziani Milena , Wolfe Jonathan
Published: March 2020

Sub-ice-shelf melting plays a critical role in the dynamics of the Antarctic Ice  Sheet and also feeds back on the regional climate, transforming ocean properties (e.g., affecting deep-water production and sea-ice formation).  A full understanding of these processes, as well as the ability to project their response to a changing climate, requires Earth System Models (ESMs) that include coupling with ice-sheet processes.  However, biases in regional Antarctic climate can be amplified through sub-ice-shelf melting, and biased melt rates can have significant adverse effects on ice-sheet model initialization and evolution.  In preparation for inclusion of dynamic ice sheets in ESMs, this presentation discusses our recent experience in understanding the causes of biases in ocean properties on the Antarctic continental shelf and their relationship to ice-shelf melting.  Differences in model behavior across configurations and simulations using the Energy Exascale Earth System Model (E3SM) demonstrates a sensitivity of melt rates to climate. We assess the sensitivity of those melt rates to changes in the region’s climate, including freshening on the continental shelf and shoaling of the thermocline. We also show that ice-shelf meltwater feeds back onto the climate, for example, by affecting melting under neighboring ice shelves, sometimes dramatically so.  We demonstrate that significant reductions in melt-rate biases can be achieved through modifications to ocean model mixing parameterizations. This work charts a path forward for configuring ESMs to produce realistic Antarctic melt rates.
Land use change and water production function in the Karst Gabin Basin: A regional study from southwest China (1980-2015)
Authors: Yu Yang , Liu Hu , Zhang Weixin , Wu Xiuqin
Published: March 2020

Rocky desertification has long been identified as an adverse geo-environmental hazard to both humans and the environment. With increasing rocky desertification, karst ecosystem is one of the most severely-threatened ecosystems in the world due to its thin soil layer. As a typical karst landform, the Karst Gabin Basin in the southwest China is characterized by the presence of large arable land, frequent agricultural activities, and prominent soil and water loss. In this study, land use and land-cover change between 1980 and 2015 was investigated based on multi-temporal remote sensing images. InVEST model was used to calculate regional water production. The results showed that there was a decrease in the acreage of cultivated land and water body, but a slight increase in that of residential land. Meanwhile, there was an significant increase in forest land and grassland. During the study period, restored area was greater than degraded area. Water production area was divided into three ecological zones based on water yield capacity. Our finding showed that conservation strategy had a significant influence on land use change in this area, which also served as a basis for rational planning in the karst Gabin basin.
Risk assessment for tsunami events in the city of Siracusa, Italy
Authors: Pagnoni Gianluca , Armigliato Alberto , Tinti Stefano , Zaniboni Filippo
Published: March 2020

Siracusa is an important historical city of Greek origin, located on the southern part of the eastern coast of Sicily. The old town developed on the island of Ortigia, and expanded on the near mainland, but later it declined and during the Middle Ages it occupied only the island. The development of the built areas on the mainland restarted at the end of the nineteenth century, with the construction of a number of new quarters. Nowadays the island of Ortigia is connected to the rest of the town by two drive-over bridges. The history of Siracusa as well as of the eastern coast of Sicily is marked by destructive earthquake events that caused significant damage and many fatalities, and also by lethal tsunamis (occurred in the years 1169, 1693 and 1908). Indeed, this region is one of the coastal areas most prone to tsunami attacks in the Mediterranean Sea, being affected by local-source tsunamis and also by those generated by earthquakes in the Western Hellenic Arc.

For these reasons, in the last decade the need has developed to prepare adequate evacuation measures to respond to tsunami hazardous events. This work, using the method proposed by Pagnoni et al. (2020) and applied to the near town of Augusta, studies the tsunami risk for different inundation levels. The results are provided in terms of the Human Damage (HD), which is the number of people involved and the number of fatalities, and of the Economic Loss (EL), which returns the loss of economic value of buildings affected by tsunamis. Maps of HD and EL per each inundation scenario allow one to understand which areas of Siracusa are most involved and also to identify evacuation paths to potential safe collection areas and/or buildings for efficient emergency plans.
Exploring the effect of neighboring building on land surface temperature of central park
Authors: Han Dongrui , Yang Xiaohuan , Cai Hongyan , Xu Xinliang , Qiao Zhi , An Hongmin
Published: March 2020

Urban parks can effectively mitigate the urban heat island (UHI) effect. Many studies have investigated the relationship between the shape, size, interior components and cooling effect of the park, little attention have been given to explore the relationship between land surface temperature (LST) of central park and buildings in the neighboring areas. This study has explored the effect of the neighboring building on LST of central park, taking Beijing as the study area. The results showed that the cold island footprint of the park in summer was larger than that in winter (with an average area of 0.15 km2 larger). The components of building in cold island footprint of the park were dominated by middle-rese building (MRB). LSI of MRB and AREA_SD of LMB were identified as the key explanatory variables in summer and winter, respectively, which could explained 16.8% and 13.9% of the variance in the park’s LST. This study could extend scientific understanding of the effect of building on park’s LST, and could provide guidance to urban planners on how to mitigate the UHI effects through the rational allocation of buildings.
Ample and recurrent sea-level fluctuations during the Bajocian: A hint towards middle Jurassic glacio-eustatism
Authors: Bodin Stéphane , Danisch Jan , Mau Malte , Krencker Francois-Nicolas , Nutz Alexis , Kabiri Lahcen
Published: March 2020

Mesozoic sea-level fluctuations have been a matter of debate for several decades, especially the extend and origin of sea-level cycles that have a periodicity of about 1 Myr or less. The debate lies in the main driving mechanism for sequence development (global sea-level or sediment flux variations) as well as the reason behind water exchanges between the continents and the oceans (glacio- or aquifer-eustatism). In this study, we focus on the carbonate-dominated sedimentary record of the Bajocian (Middle Jurassic) in the Central High Atlas Basin of Morocco. Several aspects make this basin an appropriate location for discussing Middle Jurassic sea-level changes. Firstly, the outstanding exposures of the High Atlas Mountains, with continuous exposures for 10s of kilometres, allow to describe and track sedimentary packages and their bounding surfaces from proximal to distal settings. Moreover, a combination of ammonite and brachiopod biostratigraphy with carbon-isotopes chemostratigraphy allows to temporarily constrain their development, which permits to correlate and compare the Central High Atlas sedimentary record to other basins. Finally, due to high-subsidence rates, thick Bajocian sedimentary sequences have accumulated, minimizing condensation and hiatus that might prevail in other basins due to a lack of accommodation space creation. Two Bajocian long-term transgressive-regressive (T-R) packages are observed throughout the basin. They are modulated by several medium-term T-R packages, that have each an approximate duration of 1 Myr. These sequences can also be correlated on a basinwide scale. Combined with sedimentological and facies analyses, architectural evidence along proximal-to-distal transect illustrates that several of the medium-term sequences are characterized by the presence of a falling stage and lowstand systems tracts, demonstrating that medium-term T-R stacking patterns are not solely linked to fluctuation in sediment supply, but also to episodes of relative sea-level fall of at least 30m of amplitude. This is confirmed by backstripping analysis performed in a composite section from the center of the Basin. Comparison with Bajocian deposits from France and Scotland, where good biostratigraphic dating is also available, shows that similar contemporaneous sea-level fall can be observed, highlighting their potential global character. The two long-term Bajocian sequences are more difficult to correlate on a global scale, suggesting that they are rather primarily linked to fluctuation in regional sediment supply or dynamic topography processes. The exact cause of the Bajocian medium-term sea-level falls is currently unknown, but it is here interesting to note that a relatively cool globate climate has been postulated for the Middle Jurassic, suggesting that glacio-eustasy was their most likely driver.
Length of day fluctuations at long and short timescales. Geomagnetic drivers
Authors: Demetrescu Crisan , Dobrica Venera
Published: March 2020

We decompose the well known LOD time series provided by IERS, that shows so-called decadal variations, in fluctuations at several timescales, namely: sub-centennial (60-90 years), inter-decadal (20-35 years), decennial (~11 years) and intra-decennial (~6 years). A Hodrick and Prescott (1977) type of analysis is used, followed by the decomposition of the trend and oscillatory parts at the mentioned timescales using Butterworth filtering. Comparing the results to previously (e.g. Dobrica et al., 2018) known oscillations of the geomagnetic field (dD/dt), and carrying out a similar analysis for parameters describing the evolution of the magnetospheric ring current, suggest the latter is the ultimate driver of both geomagnetic and LOD variations. The probable mechanisms are discussed as well: Alfvén torsional oscillations in the outer core, triggered by variations in the magnetospheric ring current, or a direct control of geomagnetic declination by variations in the magnetospheric ring current. While the first one is long accepted for the long-term variations in D and LOD, a similar possibility for the 6-year variation is out of question due to the implied value of the geomagnetic field within the outer core (Gillet et al., 2010); for the latter we suggest the second mechanism.       
How drought modulates carbon-use efficiency and soil carbon formation in rhizosphere, detritusphere, and bulk soils
Authors: Sokol Noah , Blazewicz Steve , Foley Megan , Greenlon Alex , Pett-Ridge Jennifer
Published: March 2020

Carbon use efficiency (CUE) is theorized to be positively associated with the formation of microbially-derived, mineral-associated soil carbon.  Yet few empirical studies have directly tested this relationship. Moreover, it is unclear: (1) how differences between distinct soil microbial communities (for example, differences in competitive interactions and/or growth rate among rhizosphere, detritusphere, and bulk soil communities) may yield different relationships between carbon-use efficiency and soil carbon formation, and (2) how microbial ecophysiology – such as physiological changes induced by drought – may modulate the strength and/or direction of the CUE-soil carbon relationship.

To investigate these questions, we conducted a 12-week 13C tracer study to track the movement of two dominant sources of plant carbon – rhizodeposition and root detritus – into soil microbial communities and carbon pools under normal moisture vs drought conditions. Using a continuous 13CO2-labeling system, we grew the Mediterranean annual grass Avena barbata in controlled growth chambers and measured the formation of organic matter from 13C-enriched rhizodeposition. As the plants grew, we harvested rhizosphere and bulk soil at three time points (4, 8, and 12 weeks) to capture changes in soil carbon pools and microbial community dynamics. In parallel microcosms, we tracked the formation of soil carbon derived from 13C-enriched A. barbata root detritus during 12 weeks of decomposition; harvesting detritusphere and bulk soil at 4,8, and 12 weeks. In all microcosms, we manipulated soil moisture to generate drought (7.8 ± 2.1 % soil moisture) and ‘normal moisture’ (15.1 ± 4.2 % soil moisture) treatments.

In all samples (over 150 observations), we measured CUE via the 18O-H2O method, and quantified the formation of different 13C-soil organic carbon pools via density fractionation. Here we will present data on how soil moisture influences CUE in rhizosphere, detritusphere, and bulk soil communities, and whether differences in CUE are correlated with the formation of mineral-associated soil organic carbon. These results will help to illustrate whether CUE acts as a lynchpin variable with predictive power for stable soil carbon formation, or whether other microbial traits may require consideration.

 

 
A semi-operational near-real-time Modelling Infrastructure for assessing GHG emissions in Munich using WRF-GHG
Authors: Zhao Xinxu , Chen Jia , Marshall Julia , Galkowski Michal , Gerbig Christoph , Hachinger Stephan , Dietrich Florian , Lan Lijuan , Knote Christoph , Denier van der Gon Hugo
Published: March 2020

Since the establishment of the firstly fully-automatic urban greenhouse gas (GHG) measurement network in Munich in 2019 [1], we are building a high-resolution modeling infrastructure which will be the basis for a quantitative understanding of the processes responsible for the emission and consumption of CO2, CH4, and CO in Munich. The results of our near-real-time modeling are expected to also provide guidance for local emission reduction strategies.

The precision of our transport modeling framework is assessed through comparison with surface and column measurements in August and October 2018, and the contributions from different emissions tracers are quantified to understand the sources and sinks of atmospheric carbon in the Munich area. A differential column approach [3] is applied for comparing models to observations independently of the biases from background concentration fields (Zhao, X. et al, 2019). Various tracers are separately included in the simulation to further analyze the contribution from different emission processes (e.g., biogenic emissions from wetlands, fossil fuel emissions, and biofuel emissions). Surface emissions are taken from TNO-GHGco v1.1 emission inventory at a resolution of 1 km (cf. Super, I. et al, 2019). Biogenic fluxes of CO2 are calculated online using the diagnostic VPRM model driven by MODIS indices. The initial and lateral tracer boundary conditions are implemented using Copernicus Atmosphere Monitoring Service (CAMS) data, with a spatial resolution of 0.8° on 137 vertical levels, with a temporal resolution of 6 hours.

The precision of our transport modeling framework is assessed through comparison with surface and column measurements in August and October 2018, and the contributions from different emissions tracers are quantified to understand the sources and sinks of atmospheric carbon in the Munich area. A differential column approach [3] is applied for comparing models to observations independently of the biases from background concentration fields (Zhao, X. et al, 2019).

[1] Dietrich, F. et al.: First fully-automated differential column network for measuring GHG emissions tested in Munich. In Geophysical Research Abstracts. 2019.

[2] Zhao, X. et al.: Analysis of total column CO2 and CH4 measurements in Berlin with WRF-GHG, Atmos. Chem. Phys., 19, 11279–11302, https://doi.org/10.5194/acp-19-11279-2019, 2019. 

[3] Chen, J. et al: Differential column measurements using compact solar-tracking spectrometers, Atmos. Chem. Phys., 16, 8479–8498, https://doi.org/10.5194/acp-16-8479-2016, 2016.
Salt water intrusion in the Pearl River networks, China
Authors: Zhang Wei , Zhou Rongxiang , Ji Xiaomei
Published: March 2020

The Pearl River networks is a typical river networks system with channel density ranging from 0.81-0.88m/m2. Recent years, with the rapid development of economy, the intensive human activities have great impacts on the networks system. Sand excavation is the most severe one, which directly led to the averaged 4-6m riverbed downcutting over the Pearl River networks. Consequently, salt water intrusion has become much serious than it was before. In this study, a coupled 1-D river networks and 3-D estuarine combined numerical model has been established to evaluate the influence of bathymetry changes and sea level rising on the salt water intrusion in the river networks. Two period of bathymetries in 1990s and 2000s have been used to simulate the length of salt water intrusion (LSR). It is found that the LSR in 2000s was 24 km farther upstream than that in 1990s. However, the LSR is no more than 3 km when sea level rises by 30 cm. This implies that impact of bathymetry changes overwhelms the sea level rise on LSR. The result also shows that LSR has the negative and positive correlation with river discharge and tide range respectively, which means that LSR will decrease and increase with river discharge and tidal range increasing. Furthermore, it is quite interesting to notice that the LSR is also quite relative to the flow ratio at the apex of the delta. With the same river discharge from the upper stream, the more the discharge come from the West River, the less LSR will happen, which would be quite useful to the authority to transfer the water to control the salt water intrusion in Pearl River networks.
Latest Advances in Fractional Snow Cover Mapping on MODIS Data by Machine Learning Algorithms
Authors: Kuter Semih , Akyurek Zuhal
Published: March 2020

Spatial extent of snow has been declared as an essential climate variable. Accurate modeling of snow cover is crucial for the better prediction of snow water equivalent and, consequently, for the success of general circulation and weather forecasting models as well as climate change and hydrological studies. This presentation mainly focuses on the representation of the latest findings of our efforts in fractional snow cover mapping on MODIS images by data-driven machine learning methodologies. For this purpose, a dataset composed of 20 MODIS - Landsat 8 image pairs acquired between Apr 2013 and Dec 2016 over European Alps were employed. Artificial neural networks (ANN), multivariate adaptive regression splines (MARS), support vector regression (SVR) and random forest (RF) models were trained and tested by using reference FSC maps generated from higher spatial resolution Landsat 8 binary snow maps. ANN, MARS, SVR and RF models exhibited quite good performance with average R ≈ 0.93, whereas the agreement between the reference FSC maps and the MODIS’ own product MOD10A1 (C5) was slightly poorer with R ≈ 0.88.
The Information Entropy Prisms on Riverine Water Quality Evolution
Authors: Pang Tianrui , Jiang Jiping , Sivakuamr Bellie , Zheng Yi , Zheng Tong
Published: March 2020

Information entropy theory has been largely applied in hydrological modeling and engineering optimization. Recently the entropy description and explanation of reactive solute mixing and transport process has received increasing attentions. Literatures mainly focus theoretical analysis on hypothetical cases, however, the direct observation and calculation with field datasets are hardly reported.

This work studied the change of information entropy in surface water solute transport system with field data. A comprehensive information entropy based analysis framework were proposed, which works like a combined optical system with Optical Sources-Filters-Prisms-Images. We established four basic probability space, leading to four basic information entropy indexes: Dilution index (E), Flux index (F), Spatial entropy index (Gx) , and Temporal entropy index (Gt).

The evolution characteristic of information entropy in one-component solute diffusion system is studied by using the method of discrete information entropy analysis. In the system boundary definition of fixed observation, the information entropy appears a peak in time and space dimension, and the peak value of information entropy appears in the first 20%-30% of the fixed observation interval, while in the system boundary definition of dynamic observation, information entropy decreases continuously with the increase of time and space distance. Through the local sensitivity analysis of the hydrodynamic parameters of the above analytical solutions, it is found that the sensitivity of information entropy H to diffusion coefficient Dx is relatively constant, and the greater the degradation coefficient k is, the more sensitive the monitoring time t is to k, the more sensitive the spatial change of information entropy is to the change of flow velocity ux with the increase of distance, while the change of time is insensitive to ux.

Furthermore, the evolution characteristic of information entropy in complex water quality process of rivers is studied. The Guangming section of Maozhou River in Shenzhen is taken as the research area. BOD-DO and nitrogen elements (NH3-N, NO3-N, Org-N) water quality process were selected, and one-dimensional S-P model and WASP_EUTRO water quality model were constructed respectively. After model calibration and verification, the changing characteristics of information entropy, mutual information and information transfer index are analyzed under the system definition of fixed observation. It was found that the transformation reaction process gradually replaced the diffusion process in the complex water quality process as the main factor affecting the change of information entropy, and the information entropy change law in the single component diffusion process no longer exists in the complex water quality process.
Learning geology using VR: student feedbacks on the VirtuaField applications
Authors: Viseur Sophie , Civet François , Lamarche Juliette , Rizza Magali , Benedetti Lucilla , Fleury Jules , Jorda Laurent , Groussin Olivier , Borgomano Jean , Léonide Philippe
Published: March 2020

Aix-Marseille University launched the VirtuaField project whose objective is to integrate DOMs into a VR application to provide students with a pedagogical tool enabling learning field practice.

Indeed, students have few occasions to train in the field during their academic curricula. Field trips are expensive and require a complex logistics. Nowadays, the photogrammetry or LIDAR techniques allow geoscientists to obtain High-Resolution 3D representations of outcrop geometries and textures, often termed as Digital Outcrop Models (DOM). DOMs are already used as pedagogical supports for practical exercises on computers such as fault throw or seismic occurrence calculation, or modelling 3D geological structures from outcrop interpretations. However, these exercises do not cover all required skills to gain autonomy and consistence in the field, such as the pertinent observation sampling. The computer engines are not convenient support for that task because the visualization, although in 3D, still depends on a 2D screen and does not preserve the 1:1 scale, which is of paramount importance for Geoscience interpretations.

The Virtual Reality (VR) technique is the ultimate way to provide a full 3D view, which can preserve the 1:1 scale, while benefiting from the numerical nature of the support (DOMs, DEM).

First prototypes were provided by the VR2Planets company from the case study of La Fare les Oliviers (SE France), which shows diffuse fractures and fracture corridors, in addition to sedimentological and geomorphological structures. The prototypes have been tested in training experiences with volunteer students. Surveys have been performed in order to obtain feedbacks from students on the ability of the VirtuaField application to gain field skills, but also on the more pertinent way to design the pedagogical tools. The synthesis of these feedbacks will be presented as well as a first outline of the pedagogical guidelines on using VR tools for educational purposes.
Active surface deformation in the south-central Andes revealed by multiple-sensor InSAR, GNSS and field observations
Authors: Bookhagen Bodo , Strecker Manfred R. , Weiss Jonathan R. , Alonso Ricardo N.
Published: March 2020

With an average elevation of about 3.7 km the semi-arid to arid Central Andean Plateau (Altiplano-Puna) constitutes the world’s second largest orogenic plateau. The internally drained region is characterized by compressional basin-and-range topography. Many of the basins in the Argentine sector of the plateau (Puna) are presently evaporitic salt pans, but during the Pleistocene the basins have repeatedly experienced high lake-level phases during pluvial periods. Due to protracted sedimentary infilling and sustained internal drainage conditions the basins have thick sedimentary sequences that have partially coalesced. The basins are bordered by reverse-fault bounded ranges, reaching 5 to 6 km elevation, but the history and extent of tectonic deformation in this region is not very well known. Global Navigation Satellite System (GNSS) data have been used to estimate decadal-scale tectonic shortening rates but the spatiotemporal pattern of surface deformation is complex and includes the compounding effects of subduction zone megathrust earthquake transients.

Here, we use a combination of field observations, cosmogenic nuclide dating of deformed alluvial-fan surfaces, Interferometric Synthetic Aperture Radar (InSAR), and GNSS data time series to quantify Quaternary to decadal-scale tectonic deformation. The arid mountain ranges provide ideal conditions to observe deformation from multiple sensors, including TerraSAR-X, Sentinel-1, ALOS2, and ENVISAT. Furthermore, we rely on 12 m TanDEM-X topographic data to characterize 103-106 yr surface deformation using cosmogenic nuclide exposure dating and digital elevation model analysis.

 The Puna has been previously characterized as a region with little tectonic activity including very low levels of seismicity despite evidence for strike-slip and extensional faulting accompanied by mafic volcanism. The eastern plateau margins in particular record this type of kinematic regime, while the adjacent foreland is characterized by a higher level of seismicity and ongoing contraction. Here, we present evidence of ongoing contraction during the past two decades compatible with tectono-geomorphic phenomena that support the notion of tectonic shortening in the central Puna Plateau. For example, tilted shorelines associated with former lake-highstands along the flanks of an anticline and Neogene-Pleistocene growth strata associated with this structure indicate that shortening in this region has been sustained since the Neogene. InSAR and GNSS time series analysis permit the identification and characterization of previously unrecognized tectonic activity in adjacent sectors of the intermontane basins, thus helping to improve our understanding of crustal dynamics in the Central Andes.
Fast short-term lava flow hazard assessment with graph theory
Authors: Centorrino Veronica , Bilotta Giuseppe , Cappello Annalisa , Ganci Gaetana , Corradino Claudia , Del Negro Ciro
Published: March 2020

We explore the use of graph theory to assess short-term hazard of lava flow inundation, with Mt Etna as a case study. In the preparation stage, we convert into a graph the long-term hazard map produced using about 30,000 possible eruptive scenarios calculated by simulating lava flow paths with the physics-based MAGFLOW model. Cells in the original DEM-based representation are merged into graph vertices if reached by the same scenarios, and for each pair of vertices, a directed edge is defined, with an associated lava conductance (probability of lava flowing from one vertex to the other) computed from the number of scenarios that reach both the start and end vertex. In the application stage, the graph representation can be used to extract short-term lava flow hazard maps in case of unrest. When a potential vent opening area is identified e.g. from monitoring data, the corresponding vertices in the graph are activated, and the information about lava inundation probability is iteratively propagated to neighboring vertices through the edges, weighted according to the associated lava conductance. This allows quick identification of potentially inundated areas with little computational time. A comparison with the deterministic approach of subsetting and recomputing the weights in the long-term hazard map is also presented to illustrate benefits and downsides of the graph-based approach.
DiG-DAG: Didactic Game for Divulgation of Understandable Geophysics
Authors: D'Addezio Giuliana , Lombardo Valerio , Conte Stefania , De Santis Anna
Published: March 2020

Geophysics is the application of the laws and techniques of physics to disclose knowledge about the Earth’s dynamic processes and subsurface structure. It explores phenomena such as earthquakes, volcanoes, tsunamis to improve our understanding of the Earth’s physical processes. Effective mitigation of risks from catastrophic geophysics hazards requires knowledge and understanding of natural processes. Scientific divulgation deals with the communication of knowledge previously produced in scientific contexts to a non-expert massive audience.  One of the difficulties science divulgators need to overcome is to explain specific concepts, even complex, from a given discipline in a language simple and understandable, maintaining scientific correctness, and enhance skills, knowledge and competences of their interlocutors.

Considering that, nowadays, digital technologies play a large role in young people’s lives and games are directly connected to the life of adolescents, we realized an educational videogame to teach geophysics and Earth sciences to low and high-school students; an educational computer game, serious game, where electronic medium with all the characteristic of a gaming environment convey formative outcomes. The starting point is that technologies are systems of open possibilities that can be effectively integrated with innovative methods of education necessary to promote more effective, efficient, attractive and durable learning. In fact, the ardour and enthusiasm that digital games evoke in teenagers has brought many researchers, school leaders and teachers to the question “how video games” can be used to engage young people and support their learning.

A first stage of the project of Virtual Reality, "Journey inside the volcano", were presented at several scientific divulgative events, such as the ESA Living Planet Symposium, The National Geographic Festival delle Scienze, the September 29th INGV Open Day, involving more that a thousand users and receiving appreciation from the public. We present the serious game and the relate appreciation analysis based on guestbook comments compiled at the end of the experience. The comments reveal a great level of appreciation, involvements and emotions, and margins of improvement. The results foster us to improve the project developing other geophysical topics.
Algorithm for 2D Modeling of the Propagation of a Sound Wave in an N-layer Elastic Medium with Inclusions with Various Physical-Mechanical Properties of a Hierarchical Type Located in an Oil Reservoir
Authors: Khachay Andrey
Published: March 2020

A new method has been developed for modeling acoustic monitoring of a layered-block elastic medium with several inclusions of various physical, mechanical and phase hierarchical structures. An iterative process is developed for solving the direct problem for the case of three hierarchical inclusions of l, m, s-th ranks based on the use of 2D integral-differential equations. The degree of hierarchy of inclusions is determined by the values â€‹â€‹of their ranks, which can be different. Hierarchical inclusions are located in one layer: the first is anomalously dense, the second is anomalously plastic, and the third is anomalously elastic and fluid-saturated density. The degree of filling with inclusions of each rank for all three hierarchical inclusions is different. The simulation results can be used in monitoring studies of the control of fluid return from oil fields developed as part of horizontal drilling.

 
Spherical and ellipsoidal surface mass change from GRACE time-variable gravity data
Authors: Šprlák Michal , Ghobadi-Far Khosro , Han Shin-Chan , Novák Pavel
Published: March 2020

The problem of estimating mass redistribution from temporal variations of the Earth’s gravity field, such as those observed by GRACE, is non-unique. By approximating the Earth’s surface by a sphere, surface mass change can be uniquely determined from time-variable gravity data. Conventionally, the spherical approach of Wahr et al. (1998) is employed for computing the surface mass change caused, for example, by terrestrial water and glaciers. The accuracy of the GRACE Level 2 time-variable gravity data has improved due to updated background geophysical models or enhanced data processing. Moreover, time series analysis of ∼15 years of GRACE observations allows for determining inter-annual and seasonal changes with a significantly higher accuracy than individual monthly fields. Thus, the improved time-variable gravity data might not tolerate the spherical approximation introduced by Wahr et al. (1998).

A spheroid (an ellipsoid of revolution) represents a closer approximation of the Earth than a sphere, particularly in polar regions. Motivated by this fact, we develop a rigorous method for determining surface mass change on a spheroid. Our mathematical treatment is fully ellipsoidal as we concisely use Jacobi ellipsoidal coordinates and exploit the corresponding series expansions of the gravitational potential and of the surface mass. We provide a unique one-to-one relationship between the ellipsoidal spectrum of the surface mass and the ellipsoidal spectrum of the gravitational potential. This ellipsoidal spectral formula is more general and embeds the spherical approach by Wahr et al. (1998) as a special case. We also quantify the differences between the spherical and ellipsoidal approximations numerically by calculating the surface mass change rate in Antarctica and Greenland.

 

References:

Wahr J, Molenaar M, Bryan F (1998) Time variability of the Earth’s gravity field: Hydrological and oceanic effects and their possible detection using GRACE. Journal of Geophysical Research: Solid Earth, 103(B12), 30205-30229.