bluuebunny/crossref_metadata_2025 huggingface dataset:
S-wave velocity structure in Kenyan potential geothermal fields inferred from ambient seismic noise data analysis
Authors: Chhun Chanmaly , Tsuji Takeshi , Ikeda Tatsunori
Published: March 2022

To reveal the seismic velocity structure and anisotropy in potential geothermal fields, Kenya, we analyzed ambient noise data from nine vertical components of broadband seismometer stations. Our analysis is based on the cross-correlation of ambient noise data by extracting phase velocity dispersion curves via the zero-crossing method and then applying surface-wave inversion to estimate S-wave velocity structures. The results for both phase velocity and S-wave velocity structures show a clear velocity contrast in volcanic systems (i.e., Korosi-Paka-Silali) in the Kenyan Great Rift (KGR). The phase velocity structure (i.e., 1400 - 2200 km/s) significantly drops in the Silali trachytic shield volcano and the Pleistocene Paka shield volcano. Such velocity contrasts are also observed where they are parallel and perpendicular to the geological structure of the KGR. Most decreasing seismic velocities are normal to abundant faults and fractures in the inner trough of the KGR. This direction is aligned with local extension direction, linked to divergent plate boundaries. The resulting S-wave velocity structures further disclose the anomaly features that can indicate permeable or non-permeable layers. Permeable layers are extensively existing that can provide potential geothermal fluid accumulations. Most potential areas are below the rift floor between the Paka and Silali volcanoes, involved in intense faulting/fractures and young porous rocks (i.e., intercalated pyroclastic, trachyte, and basalt lavas). The lithocap zones are mostly less than 1 km. The magma heat sources are most likely deeper than 3 km at Paka and 4 km at Silali. Therefore, geothermal reservoirs can be relatively interconnected due to shallow magma-volcanic systems, existing groundwater, porous volcanic rocks (i.e., pumice) and intensive fractures controlled by main graben faults in the KGR, regardless of impermeable volcanic rocks or (ore) mineralization in this study area. This work was supported by Leading Enhanced Notable Geothermal Optimization (LENGO) of SATREPS (JICA-JST), Japan.

Keywords: ambient noise, S-wave velocity, seismic anisotropy, shallow magma-reservoir systems, rifting and volcanism
Large eddy simulation of boundary-layer turbulence over heterogeneous underlying surfaces in the northeastern Tibetan Plateau
Authors: Zhang Yunshuai , Huang Qian , Ma Yaoming
Published: March 2022

The source region of the Yellow River (SRYR) is located in the northeastern of the Tibetan Plateau and is known as the “water tower” of China because it contains 48 lakes. Daytime lake breezes are proved by ERA-Interim reanalysis data in the SRYR. We use the Large Eddy Model to depict the effect of the circulations induced by surface anomaly heating (patches) on the boundary-layer turbulence. A set of 1D tests of strip-like surface heat flux distribution are carried out, which based on observations in the Ngoring Lake basin in the summer of 2012. The simulations show that for the cases without background wind, patch-induced circulations (SCs) promote the growth of convective boundary layer (CBL), enhance the turbulent kinetic energy (TKE), and then modify the spatial distribution of TKE. Based on phase-averaged analysis, which separates the attribution from the SCs and the background turbulence, the SCs contribute no more than 10% to the vertical turbulent intensity, but their contributions to the heat flux can be up to 80%. The thermal internal boundary layer reduces the wind speed and forms the stable stratification, which produces the obvious change of turbulent momentum flux and heat flux over the heterogeneous surfaces. The increased downdrafts, which mainly occur over the lake patches, carry more warm, dry air down from the free atmosphere. The background wind inhibits the SCs and the development of the CBL; it also weakens the patch-induced turbulent intensity, heat flux, and convective intensity.
Dual isotopes evaluation of nitrate contamination and their relative contribution of multiple sources in Daejeong, Jeju island, South Korea
Authors: Kim Changmin , Lee Juyeon , Kim Subin , Yang Minjune
Published: March 2022

Nitrate (NO3–) is the final product of the microbial nitrification process in the subsurface environment and can play a significant factor in potential contamination, causing seasonal hypoxia or eutrophication in the aquatic ecosystem. Excessive nitrogen (N) input by anthropogenic activities is well known as one of the major nitrogen sources such as dissolution of organic or synthetic (NH4+, NO3–) fertilizer, leakage of the municipal and industrial landfill, and manure or septic wastewater. This study implemented dual nitrate isotopes approach to investigate the spatial distribution of nitrate contamination and its relative contribution of multiple nitrate sources in Daejeong region, Jeju island, South Korea. A total of 26 groundwater samples were collected from Sangmo, Hamo, and Dongil areas in Daejeong region and their nitrate concentrations were measured. The isotope ratios of N (δ15 NNO3) and O (δ18 ONO3) were analyzed using a denitrifier which converts the dissolved nitrate in the groundwater sample into gaseous nitrous oxide (N2O). The NO3-N concentration above the DWS (drinking water standard, 10 mg/L) was found in 11 out of 19 wells only in Sangmo, while the average NO3-N concentrations of Hamo and Dongil were 2.95 and 2.58 mg/L, respectively. More than 80% of land use in Daejeong region was reported as agricultural farming, and massive synthetic fertilizer usage was expected. However, the δ15 NNO3 ranged from 8.3‰ to 10.2‰, with an average of 9.22‰ and δ18 ONO3 ranged from 3.2 to 6.9‰ with an average of 5.58‰, which are similar values of manure and septic wastewater. Thus, further investigation on land use changes, historical fertilizer consumption and its isotopic shifting in Daejeong region need to be considered for the relative contribution of nitrate sources.
The adsorption characteristics of Cr and Pb by various particle sizes of microplastics high-density polyethylene (HDPE)
Authors: Ha Taejung , Park Suhyeon , Yang Minjune
Published: March 2022

Microplastics were defined as plastics that measure less than 5 mm and have strong hydrophobicity, small particle sizes, and large specific surface areas. Microplastics can serve as a carrier of heavy metals and a potential hazard in the ecosystem by biological accumulation. This study investigated the adsorption characteristics of chromium (Cr) and lead (Pb) onto microplastics based on various particle sizes. The high-density polyethylene (HDPE) was categorized into three particle size ranges (2.5 – 1 mm, 1 – 0.3 mm, and less than 0.3 mm), and batch adsorption tests were conducted with five different concentrations (0, 0.5, 1, 10, and 30 mg/L) of Cr and Pb solutions. In this study, the adsorption behaviors of Cr and Pb on all three particle sizes of HDPE were more suitable for the Langmuir model (R2 > 0.99) than the Freundlich model (R2 > 0.90). The maximum adsorption amount of Cr and Pb on HDPE (Qm = 0.09 mg/g for Cr and 0.05 mg/g for Pb) was found in the size of less than 0.3 mm, indicating that the high specific surface area may affect adsorption capacities. For three different particle sizes, the adsorption of Pb on HDPE was higher than that of Cr. This result could be attributed to the higher adsorption binding strength of Pb (1.04) on the surface of HDPE than that of Cr (0.06) due to the larger ionic radius and higher electronegativity of Pb2+ than those of Cr6+.
Impact of land-use/cover changes due to urbanization on groundwater recharge by precipitation in South Korea
Authors: Heo Junyong , Jeong Seongwoo , Jang Seoggan , Kim Linn , Kwon Daewoong , Yang Minjune
Published: March 2022

Due to urbanization, land use and cover change (LUCC) are considered one of the concerns in groundwater recharge by precipitation because urban development increases impermeable surfaces. The main objective of this study is to investigate the effects of LUCC on groundwater recharge by precipitation in South Korea. Ten monitoring wells were selected based on a significant difference in LUCC using Arc-GIS software. Then lag-time between precipitation and groundwater level response was estimated based on correlation coefficients computed from cross-correlation function (CCF) and moving average (MA) for 3 years before and after LUCC. As a result of the estimated lag-time, monitoring wells were classified into two groups: group Ⅰ (n = 3) with more than 30% increase in the impermeable surface and group Ⅱ (n = 7) with less than 30% increase in the impermeable surface. Group I showed a significant increase in lag-time computed from MA (28 to 127 days) and CCF (6 to 19 days), while group II showed no significant difference in lag-time. The results of this study indicate that groundwater recharge is regulated by the occurrence of the impermeable surface, interrupting direct groundwater recharge from rainwater infiltration.
Trend analysis of Changing Temperature over the Time Period of 1979 to 2014 in Uttarakhand, Western Himalaya, India
Authors: Palni Sarita , Parashar Deepanshu , Pandey Arvind
Published: March 2022

Himalayan mountain region lying in the northern part of Indian sub-continent is among those zones which bears the most ecologically sensitive environments and is also a repository of biodiversity, fresh water storage and ecosystem services. Over the last three decades, land transformation related to exploitative land uses is among the main drivers of changing snow cover, vegetation cover and productivity in western Himalayas region. In a region where field-based research is challenging due to heterogenous relief and high altitude, quantifying the changes in temperature pattern using Remote Sensing Techniques can provide essential information regarding variating trends in different elements relating to temperature. This paper studies the trend analysis of changing temperature patterns using SWAT data (1979–2014) over Uttarakhand Himalayas and its association with altitudinal gradient. This paper investigates the trends in maximum (Tmax), minimum (Tmin) & mean (Tmean) temperatures in the annual, seasonal and monthly time-scales for 55 stations in the 5 regions of Uttarakhand’s Western Himalayan region which are categorized on the basis of elevation, from year 1979-2014. Statistical approaches are used to examine the effect of change in pattern of temperature upon the phenology of vegetation in the region under study, fresh water ecosystems, agricultural productivity, decreasing snow line & increasing tree line, change in duration of the seasons etc.
Optical, physical and chemical characteristics of Australian aerosols associated with fire events from 2002 to 2019
Authors: Yang Xingchuan , Zhao Chuanfeng
Published: March 2022

Wildfires are an important contributor to atmospheric aerosols in Australia and could significantly affect regional and even global climate. This study investigates the impact of fire events on aerosol properties along with the long-range transport of biomass burning aerosol over Australia using multi-year measurements from Aerosol Robotic Network (AERONET) at ten sites over Australia, satellite dataset derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), reanalysis data from Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2), and back-trajectories from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT). The fire count, FRP, and AOD showed distinct and consistent interannual variations with high values during September-February (Biomass Burning period, BB period) and low values during March-August (non-Biomass Burning period, non-BB period) every year. Strong correlation (0.62) was found between fire radiative power (FRP) and aerosol optical depth (AOD) over Australia. Furthermore, the correlation coefficient between AOD and fire count was much higher (0.63-0.85) during October-January than other months (-0.08-0.47). Characteristics of Australian aerosols showed pronounced difference during BB period and Non-BB period. AOD values significantly increased with fine mode aerosol dominated during BB period, especially in northern and southeastern Australia. Carbonaceous aerosol was the main contributor to total aerosols during BB period, especially in September-December when carbonaceous aerosol contributed the most (30.08-42.91%). Aerosol size distributions showed a bimodal character with both fine and coarse aerosols particle generally increased during BB period. The mega fires during the BB period of 2019/2020 further demonstrated the significant impact of wildfires on aerosol properties, such as the extreme increase in AOD for most southeastern Australia, the dominance of fine particle aerosols, and the significant increase in carbonaceous and dust aerosols in southeastern and central Australia, respectively. Moreover, smoke was found as the dominant aerosol type detected at heights 2.5-12 km in southeastern Australia in December 2019 and at heights roughly from 6.2 to 12 km in January 2020. In contrast, dust was detected more frequently at heights from 2 to 5 km in November 2019, January, and February 2020. A case study emphasized that the transport of biomass burning aerosols from wildfire plumes in eastern and southern Australia significantly impacted the aerosol loading, aerosol particle size, and aerosol type of central Australia.
No effect of long-term soil warming on diffusive soil inorganic and organic nitrogen fluxes in a temperate forest soil
Authors: Inselsbacher Erich , Heinzle Jakob , Tian Ye , Kwatcho-Kengdo Steve , Shi Chupei , Borken Werner , Wanek Wolfgang , Schindlbacher Andreas
Published: March 2022

The capacity of forest plants to sequester C is closely linked to soil nitrogen (N) availability, a major control of plant growth and ecosystem functioning. An increase of soil temperature caused by climate change affects C and N cycling in forest soils, but implications for plant available N have remained largely unclear. In recent short-term laboratory incubation studies, an increase in soil temperature has not only led to a significant increase in diffusive N fluxes, but also to a concomitant shift in bioavailable N quality for plant and microbial uptake, i.e. towards a higher proportion of inorganic N forms compared to small organic N forms such as amino acids. However, long-term effects of soil warming on diffusive soil N fluxes in situ remain largely unknown. Applying the microdialysis technique, we quantified in situ diffusive fluxes of amino acids, ammonium and nitrate at the long-term soil warming experimental site Achenkirch (Tyrol, Austria). This site is one of the few climate manipulation experiments operational for more than 15 years and has already provided a wealth of novel insights into the potential effects of global warming on forest ecosystem responses. Results from four sampling campaigns (n = 1152 microdialysis samples) during the growing season showed no effect of warming on diffusive N fluxes. Diffusive ammonium fluxes increased from spring towards autumn while nitrate fluxes followed an opposite trend. Compared to other temperate and boreal forest soils, the proportion of amino acids in the total diffusive N flux in this carbonate soil was low (13 - 30%), while the proportions of ammonium (21 – 67%) and nitrate were high (19 – 58%). In conclusion, our results suggest that in situ diffusive N fluxes, as well as the proportions of different N forms, were unaffected after 15 years of soil warming.  Accordingly, warming may not be expected to increase diffusive soil N supply for root uptake in the topsoil in the long run. Diffusive N availability was mainly determined by seasonal effects and by the small-scale heterogeneity of the soil matrix.
Development of a first local landslide early warning system in Slovenia 
Authors: Peternel Tina , Zupan Matija , Šegina Ela , Jemec Auflič Mateja , Šinigoj Jasna
Published: March 2022

The fact that Slovenia is highly exposed to landslides underlines the need for preventive measures to reduce the hazard associated with landslides. For this reason, in 2011 the Geological Survey of Slovenia (GeoZS) started developing the MASPREM system to predict landslides hazard due to increased rainfall at the national level.

In 2021, the MASPREM system was upgraded to a local landslide early warning system which was specifically developed for landslide-prone area in the hinterland of the settlement of Koroška Bela (Karavanke mountain, NW Slovenia). This area is known by numerous landslides, that represent the source area of a potential debris flows that could pose a threat to the settlement bellow. The triggering mechanisms behind this kind of landslides are related to various environmental conditions (e.g. geological conditions, tectonic settings, topography, etc.) and triggering factors such as prolonged and/or intense precipitation, changes in groundwater levels, erosion and earthquakes.

Since we cannot avoid the risk of landslides and have to adapt, it is important to understand and predict landslide behaviour. With the help of landslide monitoring early landslide activity can be detected and landslide impacts can be reduced.

To meet this need, we have implemented real-time geotechnical (extensometers), hydrometeorological (piezometers, rain gauges) and geodetic (GNSS antennas) sensors that enable temporal prediction of landslide dynamics. Based on analyses of monitoring data and reconstruction of previous event, threshold values (precipitation, displacements) were determined.

Additionally, we set up customised dashboards that allow access to all real-time monitoring sensors. In this way, GeoZS emergency service and stakeholders can access daily updated data presented on webpage at any time. In the future, we plan to upgrade the local warning system with emails alerts sent to registered users when determined threshold values will be exceeded.

Acknowledgement:  The research was funded by the Slovenian Research Agency (Research Program P1-0419, project Z1-2638, Infrastructure programme I0-0007), the Administration of the Republic of Slovenia for Civil Protection and Disaster Relief, the Ministry of Environment and Spatial Planning, and the Municipality of Jesenice.
Comparison between towed absolute and shipborne 3C fluxgate magnetic measurements in shallow water. Applications for marine geophysical surveys.
Authors: Reiller Hugo , Oehler Jean-François , Lucas Sylvain , Marquis Guy , Rouxel Didier , Munschy Marc
Published: March 2022

We compare marine magnetic measurements simultaneously acquired with absolute and three-component fluxgate sensors to evaluate their respective benefits for marine geophysical mapping and detection surveys.

Shom collected the data in shallow waters, in the Bay of Brest (France) and in the Iroise Sea, during two cruises in the Fall 2021. As per standard practice, an absolute Overhauser magnetometer was towed 180 m behind the 60 m-long Laplace and Lapérouse hydrographic vessels. In addition, two vector magnetometers were temporarily installed at the top of the ship’s mast and on the roof of a 10 m-long launch. Scalar data were processed following Shom’s standards: shift to sensor position, layback adjustments, removal of gyrations and spikes, filtering and calculation of magnetic anomalies by removing the IGRF model (Alken et al., 2021) and reducing external variations measured at a local reference station. Vector data were corrected for the strong magnetic fields generated by the hull and other steel components of the ship by the application of a “scalar compensation” using a least-squares regression analysis (Leliak, 1961) on data from figures of merit. The compensated vector data then need to be low-pass filtered to remove uncorrected variations of attitude and heading. Magnetic anomalies were finally computed by removing the median value for each profile and reducing external variations from the same local reference station.

Our first results show that maps of total-field anomalies derived from vector data acquired on the ship are very close to those of the absolute data upward-continued to the altitude of the mast. This similarity suggests that it is possible to perform good-quality magnetic surveys without the constraint of having to tow an instrument. The different processing steps however raise the detection threshold for anthropogenic objects lying on the seafloor or partially buried. Vector data acquired on smaller launchs are much more complicated to compensate as ranges of pitch, roll and heading variations are greater than for a large ship and potentially imperfectly sampled by the figures of merit.
Estimation of hourly actual evapotranspiration over the Tibetan Plateau by random forest model
Authors: Wang Xian , Zhong Lei , Ma Yaoming , Ma Weiqiang , Han Cunbo
Published: March 2022

Actual evapotranspiration (ETa) is a key variable in the energy and water cycle of the earth climate system. Evapotranspiration product with high temporal resolution and accuracy is of great significance to the effective use of water resources and regulation of local climate. Here, one–year hourly ETa over the entire Tibetan Plateau (TP) was estimated by a combination use of satellite data from Fengyun-4A and Random Forest (RF) model. The validation against in situ measurements from six stations equipped with eddy-covariance instruments shows a root mean square error (RMSE) of 32.24 mm month-1 and a correlation coefficient of 0.85. Compared with results from surface energy balance system (SEBS) with a RMSE value of 59.13 mm month-1, Maximum Entropy Production (MEP) with a RMSE value of 62.28 mm month-1 and the European Centre for Medium-Range Weather Forecasts Reanalysis-5 (ERA5) with a RMSE value of 53.64 mm month-1, the ETa results from RF model have the highest accuracy. The annual spatial average RF ETa over the whole TP was about 387.34 mm. Thus, the total ETa of the TP was about 1039.85 km3 yr−1. The annual average ETa in the eastern (long. > 95°E), central (95°E ≥ long. > 85°E) and western (long. ≤ 85°E) parts of the TP are 478.63 mm, 356.94 mm and 279.67 mm, respectively. In addition, diurnal averaged and monthly averaged ETa over different land cover types and different climate zones over the TP were also clearly identified. The ETa over cropland and the humid area is the highest with the largest variation range.
A two-year record of INP concentration measurements at the Sonnblick Observatory (3106 m): Insight into seasonal variability
Authors: Bogert Pia , Graf Johannes , Lacher Larissa , Höhler Kristina , Ludewig Elke , Möhler Ottmar
Published: March 2022

In mixed-phase clouds, primary ice formation occurs only in the presence of ice-nucleating particles (INPs) [Vali et al., 2015], which are a very rare subset of the aerosols in the atmosphere. INPs are an important part of the earth climate system, as they can initiate the formation of precipitation [Mülmenstädt et al., 2015] and have an influence on the cloud radiative properties [Murray et. al, 2021]. In the last decades, different INP measurements have been performed within the atmospheric boundary layer at mixed-phase clouds conditions [Kanji et. al, 2017]. INP measurements in the free troposphere are challenging, as they can only be conducted by aircraft-based measurements or at high altitude mountain stations. However, it is important to study long-term INP concentrations at different altitudes and geographical locations to get a better understanding of the presence of INPs in the atmosphere.

The Sonnblick Observatory (SBO) in the Austrian Alps is located at an altitude of 3106 m above sea level and is an ideal location to investigate the INP concentration in the free troposphere, as the measured INPs are directly relevant for ice formation. Since August 2019, we continuously measure the INP concentration at the SBO via filter collection and offline analysis with INSEKT (Ice Nucleation Spectrometer of the Karlsruhe Institute of Technology) [Schneider et. al, 2020]. The analysis of the sampled aerosols gives us the temperature dependent number concentration of INPs at temperatures above -25°C with a time resolution of one week. In order to receive a better insight into short-term fluctuations, we performed additional measurements with the online INP measurement PINE (Portable Ice Nucleation Experiment) [Möhler et al., 2021], since the end of July 2021. PINE has a time resolution of 5 – 6 min and usually measures at a constant temperature of ~ -23°C. In addition, INP activity screenings in the range from -15°C to -30°C are performed in regular intervals and during interesting meteorological periods such as Saharan dust events. The overlap in temperature ranges of INSEKT and PINE enables a comparison between the two measuring instruments.

Our results show that there are significant seasonal variations in the INP concentration. Especially during the summer time, strong diurnal variations in the INP concentration were observed, which could be explained by the influence of convectively lifted air from the boundary layer during the day. Correlations of the measured INP concentrations to meteorological parameters, aerosol properties and boundary layer stability will be discussed. In addition, we will present a case study of a dust event, which shows a sudden, strong increase in the INP concentration.
High-frequency waves driven by pickup ion ring-beam distributions in the outer heliosheath
Authors: Liu Kaijun , Mousavi Ameneh , Sadeghzadeh Sina
Published: March 2022

Scattering of pickup ion ring-beam distributions in the outer heliosheath is a fundamental element in the spatial retention scenario of the energetic neutral atom (ENA) ribbon observed by the Interstellar Boundary EXplorer (IBEX). According to our earlier linear instability analysis, pickup ion ring-beam distributions trigger magnetic field-aligned, right-hand polarized unstable waves in two separate frequency ranges which are near and far above the proton cyclotron frequency, respectively. We have performed hybrid simulations to study the unstable waves near the proton cyclotron frequency. However, the high-frequency waves well above the proton cyclotron frequency are beyond the reach of hybrid simulations. In the present study, particle-in-cell simulations are carried out to investigate the parallel- and anti-parallel-propagating high-frequency waves excited by the outer heliosheath pickup ions at different pickup angles as well as the scattering of the pickup ions by the waves excited. In the early stages of the simulations, the results confirm the excitation of the parallel-propagating, right-hand polarized high-frequency waves as predicted by the earlier linear analysis. Later in the simulations, enhanced anti-parallel-propagating modes also emerge. Furthermore, the evolution of the pickup ion ring-beam distributions of the selected pickup angles reveals that the high-frequency waves do not significantly contribute to the pickup ion scattering. These results are favorable regarding the plausibility of the spatial retention scenario of the IBEX ENA ribbon.
Air temperature variability of the Hrubý Jeseník and Králický Sněžník Mountains peaks
Authors: Dolák Lukáš , Láska Kamil , Řehoř Jan , Štěpánek Petr , Zahradníček Pavel , Lahoda Marek
Published: March 2022

Air temperature is one of the most significant meteorological variables. Reconstruction of air temperature is necessary to analyse temperature variability during the recent global warming. So far, significant attention has been paid to the study of air temperature variability in Central European mountain regions. However, only minimum studies dealt with the Hrubý Jeseník and Králický Sněžník Mountains (the Czech-Polish border, northern Moravia). The paper aims to reconstruct mean, maximal and minimal air temperatures of four mountain stations above 1 000 m a. s. l. in the Jeseníky and Králický Sněžník Mountains between 1961–2020 and reveal the possible trends. To compile a consistent input dataset both in time and space, input data for the interpolation underwent thorough data quality control, homogenisation and filling of missing data. Input values were interpolated employing regression kriging via the SoilClim model into maps in 500m spatial resolution on a daily scale. Short-term temperature series had been reconstructed back to 1961 and consequently compared to Vysoká hole station (1463 m a. s. l.). Statistical significant increasing 10year annual and seasonal temperature trends were proved in the 1961–2020 period. However, the temperature of mountain peaks of the Hrubý Jeseník and Králický Sněžník within 10year annual trend increased slower in comparison with lowlands (0.3°C, respectively 0.4°C). The results highlight the importance of air temperature analysis in the mountain regions and contribute to a better understanding of temperature variability in the recent global warming.
Impact of heavy metals (Cu, Fe, Pb, Zn) on carbon and nitrogen uptake of the diatom-bearing benthic foraminifera Heterostegina depressa d'Orbigny 1826
Authors: Bubl Mario , Wanek Wolfgang , Heinz Petra , Hofmann Thilo , Lintner Michael
Published: March 2022

Foraminifera are protists thriving in marine and estuarine environments. They occupy all sorts of habitats, from nearly fresh water to the abyssal ocean. In this study we investigated the uptake of inorganic carbon (C) and nitrogen (N) with respect to the presence of heavy metals (Cu, Fe, Pb, Zn) on the photosymbiont-bearing benthic coral reef foraminifera H. depressa d'Orbigny 1826. This species does not ingest food, it feeds exclusively on the products of its symbionts. Recent studies demonstrated the vulnerability of this species in the context of shifting environmental parameters (e.g. pCO2, temperature). Here, we analyzed the impact of heavy metal contamination on the metabolism of these diatom-hosting foraminifera. Incubation experiments were accomplished with artificial seawater enriched with heavy metals at 50 μg/L and 500 μg/L. Additionally, the stable isotopes 13C (sodium bicarbonate) and 15N (ammonium chloride) were added into the water to trace their assimilation. Seven individuals of H. depressa were used per replicate, placed in crystallization dishes and incubated for several time points (1d, 3d, 5d, 7d). Furthermore, Microscopy-PAM measurements were performed. The fluorometer consisting of a modified epi-fluorescence microscope equipped with a modulated LED light source and a photomultiplier for detection of modulated chlorophyll fluorescence was applied to monitor the heavy metal effects on the photosymbiont activity. We saw that copper exhibited the greatest toxicity, while iron increased symbiotic activity. Lead caused biased results, forming dark, brown spots in the cultures. While low concentrations of zinc promoted the growth and metabolism of the foraminifera, high concentrations were toxic.
RiverRunner: a low-cost sensor prototype for continuous dissolved GHG measurements
Authors: Dalvai Ragnoli Martin
Published: March 2022

The role of freshwater ecosystems in the global carbon budget has yet to be accurately quantified. Substantial uncertainties remain in estimation of greenhouse gas (GHG) fluxes to the atmosphere due to heterogeneity, temporal variability and small scale of many systems. Additionally, methods to measure dissolved gases involve expensive equipment and/or are time consuming, making fine scale resolution challenging. We here present a self-made low-cost (~ 250 €) sensor unit which can measure carbon dioxide (CO2) and methane (CH4) in the water phase, allowing inexpensive continuous in-situ logging of GHG concentrations with little manpower.

The electronic hardware of the sensor unit is integrated into a polypropylene tubing with two parts: The sensor body is completely waterproof and houses electrical hardware and battery. The sensor head houses the gas sensors and is separated from the water phase by a semipermeable PTFE membrane that is hydrophobic but permeable to gases, thereby allowing the gaseous phase in the sensor head to equilibrate with the water phase.

For CO2, we use a miniature non-dispersive infrared sensor; data from the factory-calibrated sensor can be read via I2C serial communication. For CH4, we use a semiconductor gas quality sensor from the Figaro sensor family. Originally developed for explosion warning systems, these sensors were shown to detect CH4 near ambient concentration. Incorporated into a voltage divider, sensor output voltage can be measured and translated into CH4 concentration. Electrical resistance of this sensor varies in presence of combustible gases but also with temperature and humidity. Additional sensors provide pressure, temperature and relative humidity; and mathematical models fitted to calibration data allow to adjust for reference output voltage at background concentration levels, thereby allowing measurement of CH4 concentration. As a microprocessor, we use an Arduino mini board in combination with a real-time clock, a voltage regulator and a micro SD-card module. The microprocessor is programmed using Arduino´s integrated development environment. Data is stored on the internal SD card and powered by two Li-Ion 18650 batteries connected in series. The sensor is able to measure continuously for 24 hours.

Our low-cost, yet accurate-enough sensor can help to address the major bottlenecks in better quantification of GHG fluxes: continuous measurements to capture natural temporal variability, as well as spatially replicated measurements to map carbon sources and sinks across heterogeneous ecosystems with little investment costs. 
Advanced retrieval of sulfur dioxide over Asia using TROPOMI and GEMS satellite sensors
Authors: Theys Nicolas , De Smedt Isabelle , Fayt Caroline , van Gent Jeroen , Lerot Christophe , Lee Hanlim , Park Jeonghyeon , Hong Hyunkee , Van Roozendael Michel
Published: March 2022

The high spatial resolution TROPOspheric Monitoring Instrument (TROPOMI) launched in 2017 onboard the Sentinel-5 Precursor (S5P) platform provides important information on global volcanic and anthropogenic SO2 emissions, with an unprecedented level of details. More recently, the Geostationary Environmental Monitoring System (GEMS) was launched onboard the GEO-KOMPSAT-2B satellite in February 2020. GEMS has the unique capability of sensing SO2 over Asia at hourly resolution, offering great perspectives in monitoring and understanding emission process and pollution transport in the atmosphere. GEMS is the first satellite sensor of a geostationary constellation with the European (Sentinel-4) and US (TEMPO) counterparts.

In a recent study (Theys et al., 2021), we proposed an approach called Covariance-Based Retrieval Algorithm (COBRA), different from the classical Differential Optical Absorption Spectroscopy (DOAS). Application of COBRA to TROPOMI SO2 column retrievals leads to a significant reduction of the retrieval noise and biases as compared to the TROPOMI operational (DOAS-based) SO2 product. COBRA even reveals new emission sources in long-term averaged SO2 maps.

In this presentation, we apply COBRA for the retrieval of SO2 from GEMS spectra. The resulting SO2 vertical columns are presented and evaluated against different satellite data sets (GEMS L2 SO2 operational product, and TROPOMI SO2 COBRA and operational products) and ground-based measurements.  While GEMS measures the same location several times per day, it is crucial to understand the retrieval bias and how it varies under varying observation geometry. This aspect and possible corrections will be discussed extensively.

Theys, N., Fioletov, V., Li, C., De Smedt, I., Lerot, C., McLinden, C., Krotkov, N., Griffin, D., Clarisse, L., Hedelt, P., Loyola, D., Wagner, T., Kumar, V., Innes, A., Ribas, R., Hendrick, F., Vlietinck, J., Brenot, H., and Van Roozendael, M.: A Sulfur Dioxide Covariance-Based Retrieval Algorithm (COBRA): application to TROPOMI reveals new emission sources, Atmos. Chem. Phys., 21, 16727–16744, https://doi.org/10.5194/acp-21-16727-2021, 2021.
Uncertainty in effects of anthropogenic aerosols on Sahel precipitation
Authors: Monerie Paul-Arthur , Dittus Andrea , Wilcox Laura J , Turner Andrew G
Published: March 2022

An increase in European and North American anthropogenic aerosol emissions in the 1970s and 1980s led to a decrease in Sahel precipitation during the same time. Although significant, the effect of anthropogenic aerosols on Sahel precipitation is uncertain across a set of CMIP6 single-forcing simulations. However, understanding the cause of this uncertainty in simulated effects of anthropogenic aerosols on West African precipitation in CMIP6 models is difficult, largely due to the relatively small number of large-ensembles with single-forcing simulations. Here, we use a single-model ensemble that spans much of the range in anthropogenic aerosol effective radiative forcing from the CMIP5 and CMIP6 multi-model ensembles. The simulations are performed with HadGEM3-GC3.1 and the different forcings are achieved by scaling emissions in anthropogenic aerosols. We show that changes in anthropogenic aerosols have strong effects on the drivers of the West African monsoon, and on precipitation extremes. Further, we show that the magnitude and even the occurrence of the West African drought (1970s-1980s) strongly depend on the simulated effective anthropogenic aerosol radiative forcing in the model simulations. Our results show that a better understanding of the effects of anthropogenic aerosols on climate is necessary to improve predictions of decadal trends in Sahel precipitation. 
Estimating the costs and benefits of landscape-based water retention measures as nature-based solutions to mitigating climate impacts in eastern Germany, the Czech Republic, and Slovakia
Authors: Susnik Janez , Masia Sara , Kravčík Michal , Pokorný Jan , Hesslerová Petra
Published: March 2022

In eastern Germany, the Czech Republic, and Slovakia, historic policies have led to large, monocropped agricultural landscapes resulting in degradation of traditional landscapes with impacts on the local water and climate cycles. In the last 20 years, the expansion of urban and industrial areas has added to this landscape degradation. The growing interest in nature-based solutions, including landscape-based water-retention measures, is a response to reversing landscape degradation, rejuvenating ecosystem services, and mitigating the impacts of large-scale commercial agriculture and climate change. In this study, the costs and benefits of water-retention measures in east Germany, the Czech Republic, and Slovakia are assessed. Results indicate that water-retention measures, should they be implemented throughout the study area, offer potentially increased water availability over all land use classes assessed, help to increase local crop productivity, and aid in local landscape cooling. Croplands are suggested as being the best value for money, offering the greatest volume potentials (mean = 88 million m3), cooling effects (mean = -1.6°C), and productivity gains (mean = €66 million yr-1), while also being the cheapest to implement per unit area. Differing policies in the three states will likely result in non-uniform selection or implementation of measures. Future research should focus on local-level studies offering greater practical messages beyond the regional-level analysis conducted in this work, as well as ways towards harmonising policy across the states. This work contributes to the growing body of literature assessing the costs and benefits of water-retention measures, including the potential for landscape cooling, lowering temperature gradients, and ecosystem restoration. As the world urbanises, and as more land is converted to homogeneous cropland, such measures may prove critical in mitigating climate change, landscape drying, flood runoff, and soil and nutrient loss.
Past and predicted climate change impacts on heat-related child mortality in Africa
Authors: Chapman Sarah , Birch Cathryn E , Marsham John H , Part Cherie , Kovats Sari , Hajat Shakoor
Published: March 2022

Children (< 5 years) are highly vulnerable during hot weather, however the impacts of past and future warming on child mortality has never been estimated. Here, we use CMIP6 global climate models to quantify, for the first time, the heat-related child mortality that has already occurred (1995 – 2020) in Africa due to climate change, as well as estimate future burdens (2020 – 2050). By 2009, heat-related child mortality was already double what it would have been without climate change and outweighed any contributions from general improvements in development. Under a high emission scenario (SSP585) mortality will double by 2049 compared to 2005 - 2014. Mitigation will save lives; if 2050 temperature increases are kept to 1.5ºC, approx. 3900 – 6300 children could be saved annually in Africa compared to the SSP585 scenario. Our findings support the need for urgent mitigation and adaptation measures to save lives now and in the future.
Effect of ocean carbon cycle feedbacks on the air-sea gas exchange of CO2 in CESM
Authors: Boot Amber , Von Der Heydt Anna , Dijkstra Henk
Published: March 2022

To avoid tipping points in the Earth system, it is important to keep warming of our planet to a maximum of 1.5 to 2°C. To be able to make policy for this goal, it is important to know what our carbon budget is for the coming decades. Unfortunately, the Earth system is a complicated system with multiple feedbacks, which make it difficult to assess this budget. One of the feedbacks is between atmospheric CO2 concentration and the Atlantic Meridional Overturning Circulation (AMOC). The AMOC is an important component of the global ocean circulation and plays a role in regulating the climate of the Northern Hemisphere. Simulations with earth system models project that the AMOC strength will decrease in the future. Changes in the AMOC influence the distribution of tracers such as heat, salt, nutrients and carbon in the ocean. These tracers all affect the marine carbon cycle by, for example, influencing the solubility of CO2, and biological production in the surface ocean, and thus the air-sea gas exchange of CO2. Therefore, changes in the AMOC may be relevant for the maximum emission levels. In this presentation, we discuss the relation between the AMOC and the air-sea CO2 exchange in the Community Earth System Model v2 (CESM2). By using results of CESM2 simulations, accompanied by the results of a box model, the Simple Carbon Project Model v1.0 (SCP-M), we find that the AMOC-CO2 feedback is positive, i.e. higher atmospheric CO2 concentrations result in a weaker AMOC, which leads to less CO2 uptake by the ocean. The mechanisms behind this feedback, related to changes in the solubility, soft tissue pump and phytoplankton composition, will be presented as well as the impact of this feedback on atmospheric CO2 concentration.
Geological perspectives of offshore underground hydrogen storage in Ireland
Authors: Xiao Zhipeng , Desmond Cian , Stafford Paul , Li Zili
Published: March 2022

Rapid development of renewable sources (e.g., wind turbines and geothermal energy) has been increasing the market share of renewable energy in electricity production in Ireland with a target of 70% by 2030. However, the production of renewable energy is usually fluctuating, which necessitates the strategies and technologies to match intermittent electricity generation surplus with time-varying market demand. Hydrogen gas generated from surplus renewable electricity has been acknowledged to be a promising energy carrier for balancing this energy gap. In particular, underground hydrogen storage in geological formation emerges as an economically effective and reliable method to store the gas on a large scale. To this end, it is essential to develop a comprehensive understanding of the suitable geological settings for underground hydrogen storage.

This paper investigates various geological settings in Ireland for different types of offshore underground hydrogen storage (e.g., salt caverns, depleted hydrocarbon fields, and aquifers). For each Irish offshore basin, an assessment is conducted to evaluate the potential application of underground storage methods and associated safety & serviceability concerns. The result confirms some prospective areas for different options of hydrogen underground storage at specified conditions. In particular, the offshore sedimentary basins of western and southern Ireland are considered to be suitable UHS geological settings. These shortlisted suitable geological settings deserve further investigation in greater details for the subsequent design & construction of hydrogen underground storage projects.
Overview of the seafloor geodetic observation conducted by the Japan Coast Guard using the GNSS-Acoustic ranging combination technique
Authors: Nakamura Yuto , Ishikawa Tadashi , Watanabe Shun-ichi , Yokota Yusuke
Published: March 2022

The Japanese Islands lie along subduction zones where the Pacific Plate and the Philippine Sea Plate subduct, making the islands one of the most seismically active zones in the world. Japan, prone to earthquake disasters throughout its history, has constructed numerous seismic and geodetic observation networks to elucidate the mechanism of catastrophic megathrust earthquakes that occur along the plate boundary near the subduction zones.

The Hydrographic and Oceanographic Department of the Japan Coast Guard (JCG) is one of the government branches that conduct geodetic observations to advance megathrust earthquake research. JCG conducts seafloor geodetic observation using the GNSS-Acoustic ranging combination technique (GNSS-A). GNSS-A enables us to measure the global coordinates of a seafloor reference point in precision of centimeters by simultaneously conducting GNSS observation of a sea surface platform (i.e., survey vessel, buoy, autonomous vehicle…) and trilateration of seafloor benchmarks using acoustic ranging. As of now, JCG regularly conducts GNSS-A observations at 27 seafloor sites along the Japan Trench and the Nankai Trough, named the Seafloor Geodetic Observation Array (SGO-A).

JCG has been conducting GNSS-A seafloor geodetic observation since 2000, and numerous technological advancements have been made in the past 20 years, significantly improving the observation frequency and positioning precision. The observation system currently operated by the JCG using survey vessels enables us to measure 3-4 times per year per seafloor site (Ishikawa et al. 2020, Front. Earth Sci.). Recently, we have developed an open-source GNSS-A analysis software named “GARPOS”, which simultaneously estimates sound speed perturbation and seafloor benchmark positions using empirical Bayesian inversion (Watanabe et al. 2020, Front. Earth Sci.).

Our regular observation at the SGO-A sites along the Japan Trench has revealed co- and postseismic processes of the 2011 Tohoku-oki Earthquake (Watanabe et al. 2021, EPS). Along the Nankai Trough, we have elucidated heterogeneous interplate coupling (Yokota et al. 2016, Nature) and shallow slow slip events (Yokota and Ishikawa 2020, Sci. Adv.). In this presentation, we review our observation and analysis methods, tectonic phenomena revealed from our observation, and the latest observation results at our SGO-A sites.