bluuebunny/crossref_metadata_2025 huggingface dataset:
The extraordinary 2019/20 Australian bushfire season: contributing processes and environmental impacts
Authors: van Dijk Albert , Yebra Marta
Published: March 2020

The recent Australian summer witnessed bushfire at a scale that is without historical precedent. We analysed the scale and severity of the fires, the main processes contributing to their scale, and environmental consequences that have already become apparent.  We did this by combining satellite-derived information of vegetation cover, biomass and history, of soil and vegetation moisture content, and of fire extent and severity. More than 80,000 km2 was burnt, much of it native forest. Fire severity varied, but was overall greater than in preceding years. A critical factor contributing to fire conditions was a multi-year drought in Eastern Australia, which culminated in 2019 with the hottest and driest year in more than a century. During the fire season, fire danger conditions were further exacerbated by oceanic modes in the Indian and Southern Oceans, which limited circulation and caused excessive heating of the Australian land mass. Fuel availability in forests was unusually high. Reasons for this were several, including afforestation and regrowth as well as effective fire suppression in preceding years, while a contributing role for CO2 fertilisation is also plausible. Combined with the drought and associated vegetation mortality, this created a high and flammable fuel load. The fires strongly affected Australia’s total living carbon pool, which was already depleted by several years of below-average rainfall. Greenhouse gas releases associated with drought and bushfires are not considered in official emission accounts, but are of comparable magnitude. The smoke emissions also caused direct health impacts, affecting cities like Sydney, Melbourne and Canberra for prolonged periods. Most of the burnt forests are resilient to fire and will regenerate, assuming rainfall conditions improve. The severity, scale and connectedness of some of the fire complexes suggest ecological recolonization may be very slow, while a number of threatened species may not recover. Perhaps most concerning, some of the forests affected had burnt only years before, whereas other areas contained vegetation communities not experiencing fire for centuries, raising questions about their ability to regenerate and possibly permanent ecological regime shifts.
The Impacts of soil moisture over the Tibetan Plateau on Summer Precipitation in China
Authors: Lai Xin , Yuan Yuan
Published: March 2020

The Community Land Model version 4.5(CLM4.5), driven by the atmospheric forcing dataset CRUNCEP, was used to simulate the spatial and temporal characteristics of soil moisture(SM) across the Tibetan Plateau (TP) from 1981 to 2016. This study reveals the relationship between SM on the TP in May and summer precipitation in eastern China and the physical mechanism for the impact of SM on summer precipitation. To investigate the relationship between SM on the TP in May and the summer precipitation in eastern China, this study used the monthly mean SM data from CLM4.5 and monthly precipitation data from CN05.1 for the period from 1981 to 2016. Singular value decomposition (SVD) analysis shows that the surface SM in the south-central TP was positively related to the summer precipitation in South China and negatively related to that in the middle and lower reaches of the Yangtze River and Northeast China. The SM in the western TP was the opposite of that in the south-central region. The wetter the surface SM in the south-central TP in May was, the lower the surface temperature, sensible heat flux and net longwave radiation flux, and the higher the latent heat flux and net shortwave radiation flux, leading to weaker surface heating. In contrast, lower surface SM in the western TP led to stronger surface heating. This led to a weaker western Pacific subtropical high and a more northerly rain belt. The weather in South China was controlled by large cyclonic circulations forming convergences and updrafts that led to more rainfall in South China. The precipitation in the middle and lower reaches of the Yangtze River and Northeast China was less under the control of a single summer monsoon than that in South China.
Quasi-Biweekly Oscillation over the tropical western Pacific in boreal winter： Its climate influences on North America
Authors: Dong Zizhen , Wang Lin
Published: March 2020

The Quasi-Biweekly Oscillation (QBWO) mode with 10-20-day time scale over the tropical western Pacific (TWP) in boreal winter (December-February), characterized by westward-northwestward propagation from the dateline to the east coast of Philippines (EPH) identified by the first two EEOF modes, is investigated based on the daily mean OLR and ERA-Interim reanalysis datasets from 1979 to 2015. The suppressive (active) QBWO-related convection heating located near EPH at peak day (day 0), results in anomalous divergence (convergence) wind to the south of Japan at upper troposphere due to the heat release. The divergent circulations can advect climatological absolute vorticity, then leads to positive (negative) Rossby wave source, which could propagate eastward. Therefore, a Rossby wave train (RWT) with equivalent barotropical structure over Pacific originated from the south of Japan is observed one/two days later. This wave train propagates northeastward into Alaska and then southeastward into southern North America. The meridional wind associated with the cyclonic/anticyclonic anomalies of RWT advects climatological thermal condition dominating the local temperature tendency over North America. Thus, a significant warming (cooling) over central North America is found at day +4 consistent to the anomalous southerlies (northerlies). In addition, both the barotropical energy conversion (CK) and baroclinic energy conversion (CP) contribute to the RWT on a time scale of 10-20 days maintained against dissipation.
The improvement of the planetary boundary layer simulation over the central Tibetan Plateau
Authors: Xu Lujun , Liu Huizhi , Du Qun , Liu Yang
Published: March 2020

The planetary boundary layer (PBL) parameterization schemes play a critical role in the weather and climate models, while they describe physical processes associated with the momentum, heat and humidity exchange between land surface and atmosphere. The sensitivity of boundary layer variables to eight PBL parameterization schemes (three non-local and five local closure schemes), available in the Weather Research and Forecasting(WRF) model, is evaluated over the central Tibetan Plateau with field measurements of the Third Tibetan Plateau atmospheric scientific experiment (TIPEX III) in July. Model results showed acceptable behavior, but no particular scheme produced the best performances for all observation stations and meteorological parameters. All PBL schemes underestimated the surface temperature over the central Tibetan Plateau. The BouLac scheme showed the minimum cold bias of the surface temperature. For the surface energy budget components, it was found that the sensible heat flux and the downward longwave radiation were the main factors causing the lower surface temperature. The sub-grid scale gravity wave drag was added to reduce biases result from unresolved topography over the central Tibetan Plateau. It led to smaller cold bias, causing warmer lower-tropospheric temperature, smaller water vapor content and higher PBL height. The modified model results show more close to the observation.

 
Skillful prediction of the winter North Atlantic Oscillation
Authors: Fan Ke
Published: March 2020

The winter North Atlantic oscillation (NAO), is a crucial part of our understanding of Eurasian and Atlantic climate variability and predictability. However, both the statistical forecast model and the coupled model showed the limited forecasting skill for the winter NAO. In this study, we developed effective prediction schemes based on the interannual increment prediction method and verified their performance based on the climate hindcasts of the coupled ocean–atmosphere climate models（DEMETER, ENSEMBLES，CFSV2）. This approach utilizes the year-to-year increment of a variable (i.e. a difference in a variable between the current year and the previous year, e.g. DY of a variable) as the predictand rather than the anomaly of the variable. The results demonstrate that the new schemes can generally improve prediction skill of the winter NAO compared to the raw coupled model’s output（DEMETER, ENSEMBLES，CFSV2）. Also, the new schemes show higher skill in prediction of abnormal NAO cases than the climatological prediction. Scheme-I uses just the NAO in the form of year-to-year increments as a predictor that is derived from the direct outputs of the models. Scheme-II is a hybrid prediction model that contains two predictors: the NAO derived from the coupled models, and the observed preceding autumn Atlantic sea surface temperature in the form of year-to-year increments. Scheme-II shows an even better prediction skill of the winter NAO than Scheme-I. Besides, a new statistical forecast scheme was also developed using observed North Atlantic sea surface temperature and Eurasian snow cover in the preceding autumn to predict the upcoming winter NAO. The statistical prediction model showed high predictive skill in reproducing the interannual and interdecadal variability of NAO in boreal winter.
Determination of formation paleo-pressure and evolution process using gaseous hydrocarbon inclusions
Authors: Zhang Cunjian , Liu Jingdong , Jiang Youlu
Published: March 2020

Research on overpressure evolution and its formation mechanisms is of great significance for revealing reservoir formation mechanisms and predicting formation pressures in oil and gas reservoirs before drilling. However, research methods addressing overpressure evolution are not without issues. The fluid inclusion PVT simulation and basin simulation can be used to investigate the paleo-pressure.

The homogenization temperatures of inclusions were tested. The accuracy of the microscopic laser Raman spectroscopy analysis is too limited to fully test the components of gaseous hydrocarbon inclusions so that the organic components of the natural gas in the present-day gas reservoirs represented the gaseous hydrocarbon inclusions. In addition, the vapor-liquid ratio of gaseous hydrocarbon inclusions cannot be measured by CLSM. Firstly, A series of images at different slice depths was obtained by adjusting the focal length of a high-resolution microscope. Secondly, CorelDRAW software was used to calculate the areas of inclusions and bubbles; fitting functions were established between the inclusion areas and slice depths, and between the bubble areas and slice depths. Finally, the inclusion and bubble volumes were integrated to obtain the vapor-liquid ratios of the inclusions. PVTsim software can calculate the trapping pressures of inclusions. Combined with basin simulation, the evolution of paleo-pressure can be determined.

The above methods were used to investigate the paleo-pressure of the Upper Triassic Xujiahe Formation in the northeast portion of the Sichuan Basin. Overpressure began to develop in the Middle Jurassic period. Due to hydrocarbon generation taking place, the formation pressure increased rapidly from the Middle Jurassic period to the early Late Cretaceous period. Since the early Late Cretaceous period, the formation pressure has gradually decreased due to tectonic uplift and erosion. From the Oligocene period to the present, the formation pressure have increased again in local areas due to tectonic compression.
The Simulation of Drifting Dead Pigs in the Sea
Authors: Lin Yong-Jun , Wen Chih-Chung , Ke Kai-Yuan , Tan Yih-Chi
Published: March 2020

In 2017, dead pigs infected with African swine fever were found on the beach of Tianpu, Kinmen, an offshore island of Taiwan. After the event, the Kinmen government carried out a thorough pig farm quarantine. However, none infected pig was found in any of the pig farms. This study aims to identify where the dead infected pig came from. Affected by ocean currents, marine drifts can often reach hundreds or thousands of kilometers away from their origins. During the winter, ocean currents across the north of the Taiwan Strait from west to east may transport the pigs from the coast of Fujian and Zhejiang, China, to the coast of north-central Taiwan. Another possible driven force is the near-shore current of western China. In order to analyze the possible drifting path of pigs, the hydrodynamic model and the particle tracking model were applied. Pigs were simulated as mass particles. The simulation domain includes sea area nearby Kinmen and China where pigs may originate. Considering the effect of the currents and wind from 2018/12/26 to 2019/1/3, three possible drift scenarios were set for analysis, including (S1): originated from Weitou Bay; (S2): originated from Jiulong River estuary; (S3) originated from the coast of Quanzhou. The results showed that the most possible scenario is S3.
Factors influencing the sorption of polycyclic aromatic hydrocarbons, cadmium and mercury to biochars – a surface response methodology approach
Authors: Chaudhuri Sampriti , Sigmund Gabriel , von Rautenkranz Hary , Hueffer Thorsten , Hofmann Thilo
Published: March 2020

Biochar is a versatile soil additive and CO2 neutral or negative “green” sorbent. Biochar can improve the soil quality, water retention capacity, and is effective in binding contaminants. Previous studies showed that biochar is a suitable remediation option at sites with residual contamination and that it is particularly favorable in immobilizing organic polycyclic aromatic hydrocarbons (PAHs) and cadmium. To achieve remediation goals, however, careful assessment of the soil geochemistry (pH, background ions, organic carbon content), the nature of the contaminant, and the application rate need to be carried out. We have screened the sorption affinity of 11 different types of biochars and 2 activated carbons for selected heavy metals and ionizable and non-ionizable PAHs. The biochars differed in the starting feedstock material (rice husk, wheat straw pellets, mixed softwood pellets, oil seed rape straw, miscanthus straw pellets), temperature of production (550°C, 700°C), and elemental composition. The target contaminants included acenaphthene, dibenzofuran, carbazole, dibenzothiophene, 2-hydroxybiphenyl, cadmium, and mercury. The sorption of the organic contaminants was driven by the carbon content, specific surface area, and aromatic nature of the biochars. Sorption of cadmium was higher onto biochars with greater inorganic fractions, whereas for mercury no specific trends could be observed. Based on the results of the initial screening, a novel approach to statistically design experiments using the Box-Behnken model was employed for selected biochars. Using this method, experiments were conducted to systematically investigate the influence of four factors (pH, dissolved organic carbon, ionic strength and contaminant concentration) on sorption at three different levels (-1, 0, +1). The results from the surface response modeling approach provides fundamental new insight into the applicability of these biochars at contaminated sites and can help identify scenarios favorable for remediation with biochar. Our results will help in the development of a remediation strategy with an overall low environmental footprint for contaminated soils.
Detecting the landslide vulnerability in the epicentre of Wenchuan Earthquake via SBAS-InSAR method
Authors: Zhang Wenjiang
Published: March 2020

Valleys in the epicentre of Wenchuan Earthquake (Sichuan Province, China) are severely subjected to landside risks partially due to the persistent influences of the serious earthquake in 2008. Without enough regionally in-situ monitoring measures, the method of multi-temporal, differential interferometric synthetic aperture radar (D-InSAR) provides an efficient to monitor the surface subsidence and thus the landslide vulnerability. In this study, we used the Sentinel Satellite Images (2015-2018) to extract the subsidence information along river valleys near the Wenchuan Earth epicentre, which was well validated by the in-situ observation of one GPS station (RSME=1.6 cm, p<0.01). Our results showed the persistent ground subsidence (1.5 mm yr-1, p<0.01) at many places, which was also related to terrain aspect besides to the well-proved conditions of slope, vegetation cover and soil layer. This fact that implied the terrain aspect should be taken into accounts in landside vulnerability analyses, because precipitation is locally more abundant in windward places. Results emphasized the higher vulnerability of landslide in summer, which could be attributed to more precipitation during summer in the study area. Our study extracted over 100-km valleys (and especially ~50 places) with high landslide vulnerability (subsidence rate > 1.20 mm yr-1), which should be paid high-prior careful attentions so as to avoid potential geological disasters.
Drivers of carbon fluxes in high-altitude Alpine Critical Zone: a novel data-based model
Authors: Magnani Marta , Baneschi Ilaria , Giamberini Mariasilvia , Raco Brunella , Mosca Pietro , Provenzale Antonello
Published: March 2020

In high mountains, the Critical Zone (CZ) is a thin layer sustaining the whole local ecosystem. Here, however, the effects of climate change are manifesting most rapidly than in the surrounding lowlands. This is especially critical for the high-altitude carbon cycle, for which our knowledge is still patchy and new feedbacks could possibly be triggered. In particular, models of the processes that control carbon fluxes in mountain grasslands and Alpine tundra need to be improved. To contribute to fill this knowledge gap, in 2017 a new Critical Zone Observatory was established at the valley of the Nivolet Plain (CZO@Nivolet) in the Gran Paradiso National Park (GPNP), in the western Italian Alps, at about 2700 m asl. Three measurement sites were identified along the flanks of the valley.  The sites are characterized by soils developed over carbonate rocks, gneiss rocks and glacial deposits. Since 2017, every year, from July to October, fluxes of carbon dioxide (CO2) were measured using a portable accumulation chamber, together with basic meteo-climatic and environmental variables, such as soil and air temperature and moisture, air pressure and solar radiation. This work is focused on a novel empirical model that uses unbiased and rigorous statistical analysis of these data to identify the environmental variables that control CO2 fluxes in Alpine tundra. The modelling approach is applied to the full dataset of simultaneous in situ measurements of the net exchange, ecosystem respiration and environmental variables for the three sites and the three measurement years. Since a large year-to-year variability in the dependencies on solar irradiance and environmental temperature is observed, a multi-regressive model has been implemented, where additional variables are introduced as perturbations of the standard functions. The multi-regressive model identifies the main drivers, highlighting the crucial role of soil moisture, and largely explains the temporal variability of the fluxes, with explained variance up to 90%. This model provides a basis for estimating future scenarios of carbon fluxes in high-altitude Alpine ecosystems.
An integrated research infrastructure concept with multidisciplinary observations on climate change
Authors: Bäck Jaana , Petäjä Tuukka , Pihlatie Mari , Levula Janne , Vesala Timo , Kulmala Markku
Published: March 2020

The observations on global warming or elements relevant to climate change are frequently performed in isolation, which results in insufficient understanding of the whole Earth system functioning and feedbacks. Frequently CO2 emissions, atmospheric concentrations of greenhouse gases and the global air temperature records are pooled together to obtain statistical relationships and correlations between them. However, forecasting future changes and designing tools for mitigating their deleterious effects would require a more holistic and comprehensive observation scheme. We propose a concept of an integrated research infrastructure, where the feedbacks can be analysed with multidisciplinary and comprehensive observations. The SMEAR concept (Station for Measuring Earth system-Atmosphere Relations) has been developing into a powerful tool, allowing detection of trends in key climate, atmosphere and ecosystem parameters, providing detailed process understanding of atmosphere and ecosystem structure and functions, and facilitating deep insights on feedbacks between the ecosystems and atmosphere. The presentation gives examples of recent novel results, especially in the perspective of climate change feedbacks and mitigation in forest ecosystems.
A millennium-length temperature reconstruction for the eastern Mediterranean
Authors: Esper Jan , Klippel Lara , Krusic Paul J. , Konter Oliver , Raible Christoph , Xoplaki Elena , Luterbacher Jürg , Büntgen Ulf
Published: March 2020

The Mediterranean has been identified as particularly vulnerable to climate change, yet a high-resolution temperature reconstruction extending back into the Medieval Warm Period is still lacking. Here we present such a record from a high-elevation site on Mt. Smolikas in northern Greece, where some of Europe’s oldest trees provide evidence of warm season temperature variability back to 730 CE. The reconstruction is derived from 192 annually resolved, latewood density series from ancient living and relict Pinus heldreichii trees calibrating at r1911-2015 = 0.73 against regional July-September (JAS) temperatures. Although the recent 1985-2014 period was the warmest 30-year interval (JAS Twrt.1961-90 = +0.71°C) since the 11th century, temperatures during the 9-10th centuries were even warmer, including the warmest reconstructed 30-year period from 876-905 (+0.78°C). These differences between warm periods are statistically insignificant though. Several distinct cold episodes punctuate the Little Ice Age, albeit the coldest 30-year period is centered during high medieval times from 997-1026 (-1.63°C). Comparison with reconstructions from the Alps and Scandinavia shows that a similar cold episode occurred in central Europe but was absent at northern latitudes. The reconstructions also reveal different millennial-scale temperature trends (NEur = -0.73°C/1000 years, CEur = -0.13 °C, SEur = +0.23°C) potentially triggered by latitudinal changes in summer insolation due to orbital forcing. These features, the opposing millennial-scale temperature trends and the medieval multi-decadal cooling recorded in Central Europe and the Mediterranean, are not well captured in state-of-the-art climate model simulations.
Combining SEM, EDS & EBSD: Challenges and considerations in the micro-analysis of rock thin sections
Authors: Stavropoulou Alexandra , Hiscock Matthew , Kamber Balz , Rodriguez-Blanco Juan-Diego
Published: March 2020

Quantitative modal analysis of rock thin sections or liberation analysis of minerals processing plant materials can be very complex as grain sizes can vary by more than 7 orders of magnitude: Thin sections of rocks may contain extremely coarse grains (mm-sized crystals) down to glassy material with no long-range order (ordered domains <1 nm).

Material characterisation and modal analysis have traditionally been carried out with a combination of solid-state, microscopic and spectroscopic techniques (e.g., optical / scanning electron microscopy, powder X-ray diffraction, X-ray fluorescence spectroscopy). These techniques require different sample preparation routines, data acquisition and evaluation - a time-consuming process that may be considered too complex to implement in mineral processing plants despite requiring the relevant sample preparation equipment. Scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS provides an opportunity to carry out this characterisation in a more rigorous and, in certain cases, automated way. This process includes image thresholding (setting of grey levels of present phases by the analyst) and X-ray data collection with EDS. EDS is an ideal analytical technique for this work as it offers high acquisition speeds and the collection of the whole energy spectrum with a single detector, not requiring the selection of a fixed element list prior to data acquisition. Characterisation of coarse-grained rocks requires larger areas to be scanned in order to ensure representativity.

The analytical workflow can be further optimised by combining SEM-based analytical techniques for in situ, non-destructive, and potentially simultaneous bulk analysis. Electron backscatter diffraction (EBSD) is an SEM-based technique which can be used to determine the crystallographic properties and orientation of mineral grains, as well as to perform fabric analyses on polycrystalline materials. EBSD allows for crystallographic data to be collected simultaneously with chemical data and does not require powdered samples. As a result, the texture of the material can be fully preserved. The sample preparation requirements of the technique are similar to those for standard SEM-EDS, with an additional final polishing step, essential for the removal of surface imperfections, as the EBSD signal is generated on the sample surface. The coupling of EDS and EBSD datasets permits the enhanced interpretation of feature analysis data, allowing for a deeper understanding of the compositional, structural and textural properties of the sample. This, highly-efficient, in-situ, bulk material characterisation, is key for the mining industry, as it provides insights for optimising downstream procedures thereby saving time and resources and bolstering throughput and efficiency.
Mechanisms of formation of multiple current sheets in the heliospheric plasma sheet
Authors: Maiewski Evgeniy , Malova Helmi , Kislov Roman , Popov Victor , Petrukovich Anatoly , Zelenyi Lev
Published: March 2020

When spacecraft cross the heliospheric plasma sheet (HPS) that separates large-scale magnetic sectors of the opposite direction in the solar wind, multiple rapid fluctuations of a sign of the radial magnetic field component are observed very often, indicating the presence of multiple current sheets occurring within the HPS. Possible mechanisms of formation of these structures in the solar wind are proposed. Taking into accout that the streamer belt in the solar corona is believed to be the main source of the slow solar wind in the heliosphere, we suggest that the effect of the multi-layered HPS is determined by the extension of many streamer-belt-borne thin current sheets oriented along the neutral line of the interplanetary magnetic field. Within the framework of a proposed MHD model, self-consistent distributions of the key solar wind characteristics which depend on streamer propreties are investigated. It is shown that both single and multiple streamers that are capable of reaching a remote boundary surface can form the observed multiple current sheets with azimuthal currents alternating in direction inside the HPS. The implications of these results for the interpretation of observations in the solar wind are discussed.
Crustal Structure and Earthquakes beneath the Jammu and Kashmir Himalaya
Authors: Mitra Supriyo , Sharma Swati , Powali Debarchan , Priestley Keith , Wanchoo Sunil
Published: March 2020

We use P-wave receiver function (P-RF) analysis of broadband teleseismic data recorded at twenty two stations spanning the Jammu-Kishtwar Himalaya, Pir Panjal Ranges, Kashmir Valley, and Zanskar Ranges in Northwest Himalaya to model the seismic velocity structures of the crust and the uppermost mantle. Our network extends from the Shiwalik Himalaya (S) to the Tethyan Himalaya (N), across the major Himalayan thrust systems and litho-tectonic units. We perform Vp/Vs-Depth stacking of P-RF and joint inversion with surface wave dispersion data. Our analysis show that the underthrust Indian crust, beneath the Jammu-Kishtwar Himalaya, has an average thickness of ~40 km and dips northward at ~7-9º. The overlying Himalayan wedge increases in thickness northward from the Shiwalik Himalaya (~8–10 km) to the Tethyan Himalaya (~25–30 km). The underthrust Indian crust Moho is marked by a large positive impedance contrast and lies at a depth of ~45 km beneath the Shiwalik Himalaya and ~65 km beneath the Higher Himalaya, deepening northward beneath the Tethyan Himalaya. We observe Moho flexure across the Mandli-Kishanpur Thrust (MKT), in the Shiwalik Himalaya, and beneath the Kishtwar window. Each time to Moho deepens by ~10 km, from ~45 km to ~55 km, and from ~55 km to ~65 km, respectively. The Moho is remarkably flat at ~56 km beneath the Pir Panjal Ranges, from its southern foothills to the northern flank in the Kashmir Valley. North of the Kashmir Valley the Moho dips steeply underneath the Zanskar Ranges from ~56 km to ~62 km. Along the Jammu-Kishtwar common conversion point (CCP) profile the Main Himalayan Thrust (MHT) is highlighted by the low velocity layer (LVL) at a depth of ~8 km beneath the Shiwalik Himalaya to ~25 km beneath the Higher Himalaya. The average dip on the MHT is ~9º and has a frontal ramp beneath the Kishtwar window. The MKT, MBT and MCT are marked by LVLs which splays updip from the MHT. Average crustal Vp/Vs shows that beneath the Shiwalik Himalaya, west of the MFT anticline the crust is mafic in nature while towards the east the crust is felsic in nature. Beneath the Lesser Himalaya the crust is largely felsic, while beneath the Pir Panjal range the crust is intermediate to mafic. North of the Kashmir Valley, beneath the Zanskar range the crust is felsic to intermediate in nature. We compare the source mechanism of the 2013 Kishtwar earthquake (Mw 5.7) and hypocentral location of small-to-moderate earthquake beneath Kishtwar region with the CCP profile. Our results show that these earthquakes occurred on or above the MHT in the unlocking zone, between the frictionally locked shallow segment and deeper creeping segment of the MHT. This marks the zone of stress build-up on the MHT in the interseismic period and is possibly the zone of megathrust initiation.
An assessment of groundwater and surface water geochemistry in a limestone forest, Langkawi Island, Malaysia
Authors: Reading Lucy
Published: March 2020

In 2007, Langkawi Island in Malaysia was awarded UNESCO Global Geopark status, partly due to its diverse geological setting which includes tropical karst limestones. Whilst extensive studies of the geological setting at Langkawi Island have been carried out, the hydrogeochemistry and hydrogeology of the karst systems in this region have received little attention.

At the Penarak Nature Centre on Langkawi Island, the early stages of construction for an ecotourism resort within a limestone forest are taking place. At this site, water sampling and analyses were carried out, with a team of undergraduate science students, to characterise the baseline surface water and groundwater chemistry. Samples were collected from 10 locations at the limestone forest site. As no groundwater monitoring bores were available at the site, samples were instead collected from 4 identified groundwater seepage sites, in addition to 5 surface water sites and 1 seawater site. Field measurements of pH, EC, redox potential, dissolved oxygen and temperature were obtained. Samples from each site were also analysed for δ18O, δ2H and major ions.

Through a combination of geochemical plots and multivariate data analysis (Principal Components Analysis and Cluster Analysis), relationships between the water composition from different sites were identified. The water type for all of the groundwater seepage and surface water sites was Ca-HCO3, indicating a high degree of groundwater-surface water interaction and rock dissolution. The multivariate data analysis results also provided an indication that groundwater sites located less than 300 meters apart may be flowing through separate karst conduits. One of the groundwater seepage sites, located close to construction, was identified as having higher concentrations of magnesium, calcium and sodium when compared with all of the other groundwater seepage and surface water sites. As there is little known about the karst hydrogeology and hydrochemistry on Langkawi Island, it is not clear whether the chemical differences identified at this construction site are occurring due to local heterogeneities in the karst system or due to anthropogenic impacts.

This study has been able to provide some baseline geochemical data and preliminary insights into groundwater and surface water interactions in a limestone forest at Langkawi Island. Recommendations for further research include a program of geophysical/hydrogeological mapping of the karst system and the establishment of a water monitoring network within the limestone forest.
 

 
Variations of Subpolar Ocean Gyres Observed by the GRACE Time-Variable Gravity: Antarctic Ross/Weddell and Arctic Beaufort Gyres
Authors: Gao Chunchun , Chao Benjamin Fong
Published: March 2020

The mesoscale ocean gyres within polar oceans, including Ross Gyre (RG), Weddell Gyre (WG) and Beaufort Gyre (BG), are important features of the polar climate and ocean systems. However, they are not well observed by satellite altimetry because of their high latitudes and wintertime sea-ice coverage. We employ the GRACE satellite’s time-variable gravity (TVG) dataset from the Centre National d'Etudes Spatiales/Groupe de Recherches de Géodésie Spatiale (CNES/GRGS) Release 03 solutions at nominal 10-day sampling between July 2002 to June 2016, to investigate the non-seasonal and high-frequency variations of the three gyres, a feat demonstrated in a previous work by Yu and Chao (2018) for studying the Argentine Gyre. We solve the empirical orthogonal functions (EOF) and confirm their barotropic structure and find the sea level variations in the RG and WG are strongly correlated with the Antarctic Oscillation (AAO) and the El Nino-Southern Oscillation (ENSO), and that in the BG is correlated with salinity changes and ENSO. Different from the Argentine Gyre, there are no short-period oscillations of dipole pattern within the three subpolar gyres based on the complex EOF (CEOF) analysis from GRACE data. The fact that GRACE does observe these signals, while the de-aliasing background ocean model (whose predictions were removed before-hand in the employed GRACE data) fails to, ascertains that GRACE TVG data can shed light on the ocean gyre variabilities unavailable by satellite altimetry and at spatial and temporal resolutions higher than practiced hitherto.
Synergized magnetic and gravity measurements probe the detailed structure of the gas giants' deep atmospheres
Authors: Galanti Eli , Kaspi Yohai
Published: March 2020

The strong zonal flows observed at the cloud-level of the gas giants extend thousands of kilometers deep into the planetary interior, as indicated by the Juno and Cassini gravity measurements. However, the gravity measurements alone, which are by definition an integrative measure of mass, cannot constrain with high certainty the detailed vertical structure of the flow below the cloud-level. Here we show that taking into account the recent magnetic field measurements of Saturn and past secular variations of Jupiter's magnetic field, give an additional physical constraint on the vertical decay profile of the observed zonal flows in these planets. In Saturn, we find that the cloud-level winds extend into the planet with very little decay (barotropically) down to a depth of around 7,000 km, and then decay rapidly, so that within the next 1,000 km their value reduces to about 1% of that at the cloud-level. This optimal deep flow profile structure of Saturn matches simultaneously both the gravity field and the high-order latitudinal variations in the magnetic field discovered by the recent measurements. In the Jupiter case, using the recent findings indicating the flows in the planet semiconducting region are order centimeters per second, we show that with such a constraint, a flow structure similar to the Saturnian one is consistent with the Juno gravity measurements. Here the winds extend unaltered from the cloud-level to a depth of around 2,000 km and then decay rapidly within the next 600 km to values of around 1%. Thus, in both giant planets, we find that the observed winds  extend unaltered (baroctropically) down to the semiconducting region, and then decay abruptly. While is it plausible that the interaction with the magnetic field in the semiconducting region is responsible for winds final decay, it is yet to be understood whether another mechanism is involved in the process, especially in the initial decay form the strong 10s meter per seconds winds.
A critical look at studying the interplanetary drivers of the magnetospheric disturbances
Authors: Yermolaev Yuri , Lodkina Irina , Dremukhina Lidia , Yermolaev Michael , Khokhlachev Alexander
Published: March 2020

Although the main types of solar wind (the so-called interplanetary drivers), which may contain the southward component of the interplanetary magnetic field (Bz <0) and cause disturbances in the magnetosphere, have long been known, it has only recently been discovered that different types of drivers cause a different reaction of the magnetosphere for identical field variations (Borovsky and Denton,2006, Yermolaev et al., 2013). This discovery led to a significant increase in the number of investigations studying the response of the magnetosphere-ionosphere system to various drivers. At the same time, the number of incorrect approaches in this direction of research has increased. These errors can be attributed to 4 large classes. (1) First class includes works whose authors uncritically reacted to previously published works and use incorrect results to identify types of drivers. (2) Some authors independently incorrectly identified driver types. (3) Very often, authors associate the perturbation of the magnetosphere-ionosphere system caused by a complex driver (a sequence of single drivers) with one of the drivers, ignoring the complex nature. For example, a magnetic storm is often caused by a compression region Sheath in front of an interplanetary CME (ICME), but the authors consider the ICME to be a cause of disturbance, not Sheath. (4) Finally, there is a “lost driver” of magnetospheric disturbances: some authors simply do not consider the Sheath compression region before ICME if there is no interplanetary shock (IS) before Sheath, although this type of driver, “Sheath without IS”, generates about 10% of moderate and strong geomagnetic storms (Yermolaev et al., 2017, 2020). These errors lead to numerous mistakes and incorrect conclusions.
The work is supported by the RFFI grant 19-02-00177а. 

References
Borovsky, J. E., and M. H. Denton (2006), Differences between CME‐driven storms and CIR‐driven storms, J. Geophys. Res., 111, A07S08, doi:10.1029/2005JA011447

Yermolaev, Y. I., N. S. Nikolaeva, I. G. Lodkina, and M. Y. Yermolaev (2012), Geoeffectiveness and efficiency of CIR, sheath, and ICME in generation of magnetic storms, J. Geophys. Res., 117, A00L07, doi:10.1029/2011JA017139

Yermolaev, Y.I., Lodkina, I.G., Nikolaeva, N.S. et al. (2017), Some problems of identifying types of large-scale solar wind and their role in the physics of the magnetosphere, Cosmic Res. 55: 178. https://doi.org/10.1134/S0010952517030029

Yermolaev, Y.I., Lodkina, I.G., et al. (2020), Some problems of identifying types of large-scale solar wind and their role in the physics of the magnetosphere. 4. Lost driver, Cosmic Res. 59, in press

 
Topographic and geomorphological features of a hydrothermal field in submarine Mienhua Volcano offshore northeastern Taiwan
Authors: Chen Tzu-Ting , Hsu Ho-Han , Su Chih-Chieh , Liu Char-Shine , Chen Song-Chuen , Chen Yu-Huang
Published: March 2020

There is a high potential of hydrothermal mineral deposits in the Southern Okinawa Trough offshore northeastern Taiwan. This study aims to integrate bathymetry data, water column images, seabed image, sub-bottom profiles and ROV observations to better understand a hydrothermal field, submarine Mienhua Volcano (MHV). A repeated mapping survey equipped with EM-712 was conducted to see if significant bathymetric changes took place since 50 days in MHV. The volcano of 2 km width and 240-m relief height is present at about 1300-m water depth near Mienhua Canyon. The volcano combines with several small and rugged mounds. From ROV observations, two of the mounds show active hydrothermal vents covered by white tubeworms and a white smoker with some mussels, respectively. In addition, active water column gas flares are observed on the southeastern part of MHV. Based on the identification of sub-bottom profiles, the special distribution of acoustic blanking zone shows the southeastern part is more narrow than the northwestern area. However, comparing the bathymetry mapped in two times, no obvious overall morphological changes are detected, except on the volcano rim. Seabed image also reveals similar backscatter intensity within the rugged mounds, suggested they may be at similar stages of morphological development. We consider that the hydrothermal vents are variable. In addition, the preliminary results indicate the fluid migration is the important process to influence the evolution of the hydrothermal field in MHV. Therefore, we also applied more seafloor images, geochemical and geophysical data which have been reported in MHV. Our results could evaluate the relationship between the flare activities, geomorphological features and the location of the blanking zone in the sedimentary strata.
Cost-effective recreational-grade single beam echosounder with side scan sonar system in imaging bubbly coastal submarine groundwater discharge
Authors: Gabuyo Mary Rose , Siringan Fernando , Sarmiento Keanu Jershon , Flores Paul Caesar
Published: March 2020

Submarine groundwater discharge (SGD) is any direct flow of fluid across the seafloor, which forms bubbly or leaky springs and seeps from the intertidal zone to the deep sea. SGDs can significantly alter physico-chemical conditions of seepage zones. Identifying and mapping SGD is crucial to further recognize its influence in both marine and terrestrial ecosystems. However, mapping this phenomenon has been a continuing challenge, mainly due to the difficulty in its detection and quantification. This study explores the capability and applicability of an inexpensive, commercially available, recreational-grade combination of depth meter and side scan sonar system to image different types and identify point sources of coastal SGDs. Standard and systematic methodologies for efficient imaging and processing were established. The utility of the recreational-grade system was assessed and validated using a research-grade side scan sonar. SCUBA diving and CTD casting were conducted for ground-truthing and further characterization. Lower frequency sonars (83/200 kHz) showed more distinct acoustic signatures of discrete and dispersed bubbly SGDs, than the higher frequency system (455 kHz and 780 kHz research-grade unit). Sonar images showed that SGD plumes can be indicated by near seafloor to midwater cloud-like features. Spring-type SGDs tend to form cloud features with a funnel-shaped morphology. In sites where SGDs are dispersed, the acoustic signature is a curtain-like cloud, with higher bubble density in the upper water column. This is consistent with diver-based observation of increasing bubble sizes (<1 mm to ~30 mm) from point source to water surface. CTD casts indicate that the SGDs have recirculated seawater, with increasing temperature and salinity with depth. In the assessment of system and data processing requirements, and costing, a recreational-grade unit provides a good alternative for coastal SGD works.
Environmental Education in Primary School
Authors: Fratti Panagiota Alexandra
Published: March 2020

This paper is an educator’s perspective on nine-year-old students' participation in the environmental project “Climate Detectives”, an initiative that engages students with space science and space engineering themes, including curricular and extra-curricular activities. Climate Detectives is an ESA school project for students between 8 and 15 years old. Students are challenged to ‘make a difference’ in understanding and protecting Earth’s climate by identifying a climate problem by observing their local environment and be tasked to investigate it.
     The project aims at developing and reinforcing students’ STEM skills and at stimulating their creativity, critical thinking and initiative to improve their understanding of climate issues and positively changing behaviors that can have an influence on such issues. In our school’s participation, we focused on the satellites that the European Space Agency (ESA) is using in order to monitor water pollution. We investigated how this technology was used during the horrific environmental disaster that occurred back in 2017 next to our island, Salamina, when an oil spill was formed after an accident.
     During the first phase of our project, we investigated what satellites are and why they are the necessary for Earth sciences. We built our own satellites, using LEGO We Do 2.0 and we wrote code in order to program them to move near our inflated Earth. We also found data (pictures from the Copernicus / Sentinel satellites) in order to investigate how large the oil split was and which parts of our island and other areas of Attica were affected.  During the second phase of our project, we read interviews from people in our island acknowledging  how they felt about the oil spill and how it affected their lives and we wrote a letter to our island’s mayor to express our thoughts. Furthermore, we organized two kids workshops, one in co-operation with a children’s books writer, member of a major environmental organization and one by a representative of the European Commision "Energy Savings Team" to learn about the effects of the oil spill and our energy options.