bluuebunny/crossref_metadata_2025 huggingface dataset:
Managing Carbon Emissions to Avoid the Next Ice Age
Authors: Pretis Felix , Kaufmann Robert
Published: March 2020

There is considerable uncertainty about how the rapid, recent rise in greenhouse gas concentrations driven by anthropogenic emissions will interact with on-going changes in orbital position to affect climate in the very long run – the next several thousand years. Here we study the evolution of climate over the next hundred thousand years using a statistical climate model estimated on the paleo record that represents physically consistent relations between orbital position and climate. This climate model is able to use orbital position alone to simulate the timing, magnitude, and saw-toothed pattern of ice volume, CO2 concentrations, and other climate time series both in- and out-of-sample. The model is used to run experiments that simulate climate with- and without human intervention in the global carbon cycle. Without human intervention, the next glacial maximum is forecast to occur in about 20,000 years. This result is relatively unaffected by the current anthropogenic spike in CO2 concentrations. Conversely, the glacial maximum can be avoided - and the current climate maintained - by geo-engineering carbon concentrations to stabilize at around 325 ppm. The emissions needed to sustain these concentrations can be generated from known resources of fossil fuels. This suggests that CO2 is a cost effective control variable that - if managed carefully - can be used to sustain a hospitable climate in the short-run (by reducing emissions) and the long-run (by stabilizing concentrations).
Recent observations of magnetic cavities: from MHD to kinetic scale
Authors: Shi Quanqi , al Et
Published: March 2020

Magnetic cavities, also termed magnetic holes, dips or depression structures, have an observable magnetic field decrease in a short time span and have been widely observed in the solar wind plasmas, comet magnetospheres, terrestrial/planetary magnetosheaths, magnetospheric cusps and magnetotail plasmas since 1970s. In early observations, the structures were found in MHD scale, from tens to thousands of ρi (proton gyroradius) with corresponding temporal scales from seconds to tens of minutes. Later, kinetic scale magnetic cavities were detected in the earth’s magnetotail and magnetosheath, with size less than ρi and sometimes close to several ρe (electron gyroradius) and often associated with a significant electron vortex around the structure. Surprisingly, it has been found that such a small structure contains an abundance of phenomena, including different kinds of ion and electron distributions, electron or ion vortices, various types of waves, and even particle acceleration and declarations. In this presentation, we will show our recent observations of magnetic cavities from MHD scale to kinetic scale in the solar wind, magnetosheath, cusp and magnetotail. In the magnetosheath, downstream of the bow shock, the mirror mode instability can generate magnetic dip and peak trains. Using data from the new NASA satellite constellation MMS, we have found that electrons exhibit a new ‘donut’ shaped distribution function related to particle deceleration processes. Using boundary normal and velocity determination techniques, we found that MHD scale magnetic cavity structures can expand or shrink, and they can enter the cusp regions along with the entry plasmas. In the turbulent magnetosheath and quiet magnetotail, we have observed kinetic scale magnetic cavity structures with scales comparable or less than one ρi. An EMHD model and other theories will also be introduced and compared. We found that in the sheath the electron scale magnetic cavity has a circular cross section and it is a magnetic bottle in 3-D. We have also found that these structures shrink due to increases in the surrounding magnetic field, and this shrinkage of the small scale magnetic cavity can induce an electric field that accelerates the electrons to a significantly higher energy. Qualitatively distinct from other acceleration mechanisms, this process indicates a new type of non-adiabetic acceleration, and has been confirmed by the observed electron distribution function and test particle simulations. This discovery in space physics also has implications for understanding energy conversion in astrophysical plasmas, the origin of cosmic high-energy particles and plasma turbulence.
Study of a high activity eruption sequence of Kadovar volcano, Papua New Guinea, using data recorded by the CTBT International Monitoring System
Authors: Matsumoto Hiroyuki , Zampolli Mario , Haralabus Georgios , Stanley Jerry , Robertson James , Meral Özel Nurcan
Published: March 2020

The analysis of hydroacoustic signals originating from marine volcanic activity recorded by a remote hydroacoustic (HA) station, HA11 at Wake Island, of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System (IMS) is presented in this study. The events studied pertain to an eruption series at Kadovar Island, Papua New Guinea during the period January to February 2018. Local visual observations determined that the Kadovar volcano began to erupt at the summit of the island, and then created new vent spots near the coast. The events included the collapse of a lava dome on 9 February 2018. Directions-of-arrivals of the hydroacoustic signals detected at HA11 were evaluated using a cross-correlation technique, this allowed discrimination between hydroacoustics signals originating from the Kadovar volcanic activity and other numerous hydroacoustic signals generated by general seismic activity in the Pacific. Discrimination between volcanic activity and seismicity was achieved by examining the time-frequency characteristics of the hydroacoustic signals, i.e. associating short duration broadband bursts with volcanic eruptions, in line with criteria generally applied for such events. Episodes of high volcanic activity with as many as 80 detections per hour were identified on two occasions, separated by a one-month period of relative quiet. Some of the hydroacoustic signals were characterized by broadband frequency content and high received levels (i.e. ca. 30 dB higher than the ocean microseismic background). It was found that corresponding non-hydroacoustic signals could not be identified by other regional IMS stations, this providing an indication of the likely submarine origin of these events. Long duration bursts recorded on the day when the lava dome collapsed have been identified and characterized in time-frequency space. This study provides a further example of the added value of CTBT IMS hydroacoustic station remote monitoring of marine volcanic events.
2D crust-upper mantle velocity structure along a seismic section in Nanling, South China
Authors: xi Jia-ji , jiang Guo-ming , zhang Gui-bin , he Xiao-long
Published: March 2020

    There exists an important polymetallic ore belt in Nanling of the southeastern China. Previous studies suggest that the mineralization of Nanling is probably related to the bottom intrusion of magmatic rocks in the late Mesozoic. In this study, a natural seismic section was installed by using 81 portable stations with an interval of 5 km from July 2017 to August 2019, which runs across the Nanling belt in the south of Fujian and Jiangxi provinces. As a result, we have picked up 3,818 relative residual data from 215 teleseismic events with magnitude greater than 5.5. And we have applied the teleseismic full-waveform tomography and the teleseismic travel-time tomography to study the crust and the mantle velocity structure beneath the Nanling metallogenic belt, respectively. Our preliminary results show that: (1) a clear low-velocity anomaly exists in the crust beneath the Zhenghe-Dapu fault and its east side, which might be related to the rich ore deposits in Nanling; (2) some high-velocity anomalies in the uppermost mantle beneath the Wuyi metallogenic belt may be relevant to the igneous rock cooling and the lithospheric thickening; (3) there are obvious low-velocity anomalies at the upper mantle beneath the Wuyi and Nanling metallogenic belts, which are speculated to be hot materials from asthenosphere upwelling into the bottom of the lithosphere. Our results provide a new insight for investigating the deep structures and deep dynamic processes of Nanling tectonic belt.
Synthetic Wind Generation Records for Australian Wind Farms
Authors: Titova Evgenia , Mittal Rashmi
Published: March 2020

In this study, we present methodology to create synthetic multi-year wind generation dataset at minute-scale granularity at the existing and future Australian wind farms. The purpose of the dataset  is to assist studies of penetration of large scale and distributed renewable generation into the electricity systems and its impact on power system security in the National Energy Market (NEM).

Synthetic historical records are based on a spatial and temporal blend of reanalysis datasets with the minute-scale wind speeds observations at Bureau of Meteorology weather station network. Strengths and weaknesses of reanalysis data are illustrated and a correction methodology discussed. A method to introduce minute-scale and sub-hourly fluctuations absent in the reanalyses records is presented. Expected statistical properties of sub-hourly fluctuations in the wind generation records are derived from the characteristics of the background atmospheric state in the vicinity of the wind farms.

The accuracy of the dataset is validated in terms of  power spectra and ramping frequencies in the simulated timeseries against existing minute-scale observations of wind generation at Australian Wind farms. The statistical properties of the observed and simulated timeseries match reasonably well, overall making the dataset suitable for the investigations of  the implications of wind ramping on energy demand and generation at the existing and foreseeable infrastructure build in the NEM.
The Use of Stable Isotope-Based Water Age to Evaluate a Hydrodynamic Model
Authors: Gross Edward
Published: March 2020

Transport time scales are common metrics of the strength of transport processes. Water age is the time elapsed since water from a specific source has entered a study area. An observational method to estimate water age relies on the progressive concentration of the heavier isotopes of hydrogen and oxygen in water that occurs during evaporation. The isotopic composition is used to derive the fraction of water evaporated, and then translated into a transport time scale by applying assumptions of representative water depth and evaporation rate. Water age can also be estimated by a hydrodynamic model using tracer transport equations. Water age calculated by each approach is compared in the Cache Slough Complex, located in the northern San Francisco Estuary, during summer conditions in which this region receives minimal direct freshwater inflow. The model’s representation of tidal dispersion of Sacramento River water into this backwater region is evaluated. In order to compare directly to isotopic estimates of the fraction of water evaporated (“fractional evaporation”) in addition to age, a hydrodynamic model-based property tracking approach analogous to the water age estimation approach is proposed. The age and fractional evaporation model results are analyzed to evaluate assumptions applied in the field-based age estimates. The generally good correspondence between the water age results from both approaches provides confidence in applying the modeling approach to predict age through broader spatial and temporal scales than are practical to assess using the field method, and discrepancies between the two methods suggest aspects of both approaches that may be improved. Model skill in predicting water age is compared to skill in predicting salinity. Compared to water age, salinity observations are shown to be a less useful diagnostic of transport in this low salinity region in which salt inputs are poorly constrained.
Optimal allocation of water resources under natural and social complexities in Lincang, a border city of China and Burma
Authors: Chen DongNi , Cai YanPeng
Published: March 2020

A two-stage interval fuzzy credibility constraint programming method is proposed to deal with the uncertainties of fuzzy variables, discrete intervals and probability distributions, and to reflect the dynamic uncertainties and related decision-making processes. Lincang City is located in the southwest border of China. It is a frontier window and an important channel for China to face the "radiation center" of Southeast Asia and South Asia. It is the only intersection of the Tropic of cancer and the geographic water distribution lines of the Pacific Ocean and the Indian Ocean. Its hydrological and water resources are unique.Considering lincang city, yunnan province as the research object, and considering the uncertainty of the amount of available water resources within the region, a two-stage fuzzy credibility constraint programming model was built to optimize the allocation of regional water resources.The objective function of the model is to maximize the economic returns of the system. Fuzzy variables, discrete intervals and probability distribution are introduced to represent the multiple uncertainties in the system. The confidence level is set to solve the problem of fuzzy risk with violation probability. The results show that the model can effectively deal with the uncertainty of the allocation system, and reflect the trade-off between the system benefits and risks, so as to reduce the risk of water shortage and low economic penalty, and achieve efficient allocation of water resources.
Paleohydrology of high magnitude floods from upper Kaveri basin, Southern India: Implication to late Holocene climate variations
Authors: Goswami Kartika , Jaiswal Manoj K , Kale Vishwas
Published: March 2020

In recent times global climatic changes are gaining due importance. One of the ways in which climate change affects humankind is the frequent occurrence of extreme climatic disruptions, such as high magnitude climate-flooding events. In order to understand the present and future trend and pattern of the changing climate, it is important to identify high magnitude palaeoflood events and reconstruct the palaeohydrology. Instrumental/historic records have helped to understand the extreme flood-climate relationship in the modern environment. However, to understand their long-term relation (102-103 years) studying sedimentological archives of large magnitude floods (eg. slack water deposits) is important, also, leading us to understand the future climatic disruptions even more effectively. Robust estimation of palaeoflood discharges and frequencies will also lead to the formulation of better flood-related policies.

Current study is undertaken in the upper reaches of Kaveri basin, Southern India and shows noteworthy link between the major climatic transitions (from fluvial dormancy to sudden outburst of monsoons around 2 ka, onset of Little Ice Age (LIA) in the 14th century, end of LIA in the 19th century and then the 20th century) and increased frequency of large magnitude floods. Detailed flood chronology was established using the optically stimulated luminescence (OSL) dating technique. OSL dates the last daylight exposure of the sediment. In addition, palaeoflood discharge estimations were made based on Manning’s equation. Together with numerical dating, it allowed the reconstruction of flood magnitude and frequency over an extended period of time. The study suggests that the magnitudes of recent flood events are higher than the palaeoflood magnitudes in the study area. We also observe that the two major flood events of the 20th century reported from the upper Kaveri were produced by high-intensity short-duration storm events. Rainfall precipitation analyses of the last 10 years (2010-2019) demonstrate the increase in erraticity of rainfall also causing extreme floods. Analyses of other hydrological variables such as soil moisture, basin shape, and size in producing floods in the study area suggest that rainfall alone may not always be the ultimate proxy for subsequent flooding.
Development of 10-minute interval analysis and prediction system in KMA
Authors: Kim Minyou , Lee Keunhee , Lee Yong Hee
Published: March 2020

To be well prepared for rapidly-developing meteorological hazards in advance, quick and qualified information on real-time and very-short range (within 6 hours) forecasts is required. KLAPS (Korea Local Analysis and Prediction System) was developed for the operational very-short range forecasts in KMA (Korea Meteorological Administration), based on the LAPS (Local Analysis and Prediction System) from NOAA and WRF from NCAR in 2009. Recently, KLAPS is updated to use new observation datasets and physics schemes from KIM (Korea Integrated Model) to improve its very-short range precipitation forecast skills. New observation data sources (geostationary satellite, RADAR, ground-based GNSS(Global Navigation Satellite System), ceilometer, local radiosonde, etc.) are ingested into KLAPS in real-time to resolve rapidly developing mesoscale systems. Physics schemes (WDM7, KSAS(Kiaps SAS), RRTMG, Shing-Hong PBL, etc.) based on KIM physics package are implemented in KLAPS to support the high-resolution physics. The new KLAPS is now operated in 10-minute interval, so that it could provide 10-minute interval precipitation forecasts to the public(www.weather.go.kr) every 10 minutes. The advantages of 10-minute interval analysis and forecast system will be presented.
Modeling of a forested study site with the Community Land Model version 5 using climate projections for the 21st century.
Authors: Strebel Lukas , Goergen Klaus , Naz Bibi S. , Bogena Heye , Vereecken Harry , Hendricks Franssen Harrie-Jan
Published: March 2020

Modeling forest ecosystems is important to facilitate adaptations in forest management approaches necessary to address the challenges of climate change, particularly of interest are ecohydrological states and fluxes such as soil water content, biomass, leaf area index, and evapotranspiration.

The community land model in its current version 5 (CLM5) simulates a broad collection of important land-surface processes; from moisture and energy partitioning, through biogeophysical processes, to surface and subsurface runoff. Additionally, CLM5 contains a biogeochemistry model (CLM5-BGC) which includes prognostic computation of vegetation states and carbon and nitrogen pools. However, CLM5 predictions are affected by uncertainty related to uncertain model forcings and parameters. Here, we use data assimilation methods to improve model performance by assimilating soil water content observations into CLM5 using the parallel data assimilation framework (PDAF).

 

The coupled modeling framework was applied to the small (38.5 ha) forested catchment Wüstebach located in the Eifel National Park near the German-Belgian border. As part of the terrestrial environmental observatories (TERENO) network, the SoilNet sensors at the study site provide soil water content and soil temperature measurements since 2009.

CLM5 simulations for the period 2009-2100 were made, using local atmospheric observations for the period of 2009-2018 and an ensemble of regional climate model projections for 2019-2100. Simulations illustrate that data assimilation of soil water content improves the characterization of past model states, and that estimated model parameters and default model parameters result in different trajectories of ecohydrological states for 2019-2100. The simulations also illustrate that this site is hardly affected by increased water stress in the future.

The developed framework will be extended and applied for both ecosystem reanalysis as well as further simulations using climate projections across forested sites over Europe.
Inertia-Gravity Wave Generation Near Upper Jets in the Australian Region
Authors: Reeder Michael , Morgan Adam
Published: March 2020

During rapid extratropical cyclogenesis in the Australian region, distinctive striated, triangular-shaped clouds commonly form on the poleward side of the jet exit near the axis of inflection between an upstream trough and downstream ridge. These clouds are called striated deltas and the striations are shown here to be caused by radiating inertia-gravity waves. An analysis of 28 striated delta clouds shows that the striated deltas have a mean length of 1034 km and width of 537 km, and a striation wavelength of 74 km. Large parcel accelerations, nonlinear flow imbalance and active convection within the striated delta are features of the composite upper-tropospheric environment. Patterns of Q-vector illustrates the unique shape of striated delta clouds to be coincident with a delta-shaped forcing of adiabatic ascent in the poleward jet exit. One of the extratropical cyclones analysed and its associated striated delta is simulated with WRF-ARW both with and without diabatic heating. Both simulations produce pronounced gravity wave packets along the surface cold front, along the downstream upper jet axis and a delta-shaped packet in the lower stratosphere above the jet exit. Ray tracing identifies the source region of the waves in the stratosphere to be the upper jet. Vertically-radiating gravity waves originating in the vicinity of the jet during rapid extratropical cyclogenesis, propagate both upwards and downwards, imprinting striations onto the cloud in the jet exit and setting the spacing between the convective bands.
Extensive fires in southeastern Siberian permafrost linked to preceding Arctic Oscillation
Authors: Kim Jin-Soo , Kug Jong-Seong , Jeong Su-Jong , Park Hotaek , Schaepman-Strub Gabriela
Published: March 2020

Terrestrial Arctic is a critical region for positive carbon-climate feedback because of the release of considerable organic carbon from the permafrost buried in the soil. Fires rapidly transfer carbon to the atmosphere. Thus, carbon release through boreal fires could considerably accelerate Arctic warming; however, boreal fire occurrence mechanisms and dynamics remain largely unknown. Here, we analyze fire activity and relevant large-scale atmospheric conditions over southeastern Siberia, which has the largest burned area fraction in the circumboreal and high-level carbon emissions due to high-density peatlands. It is found that the annual burned area increased when a positive Arctic Oscillation (AO) takes place in early months of the year, despite peak fire season occurring 1 to 2 months later. A local high-pressure system linked to the AO drives a high-temperature anomaly in late winter, causing premature snowmelt. This causes earlier ground surface exposure and drier ground in spring due to enhanced evaporation, promoting fire spreading. Recently, southeastern Siberia has experienced warming and snow retreat; therefore, southeastern Siberia requires appropriate fire management strategies to prevent massive carbon release and accelerated global warming.
Plate speeds modulated by sediment subduction: insights from numerical models
Authors: Behr Whitney , Holt Adam , Becker Thorsten , Faccenna Claudio
Published: March 2020

Tectonic plate velocities predominantly result from a balance between the potential energy change of the subducting slab and viscous dissipation in the mantle, bending lithosphere, and slab–upper plate interface. A range of observations suggest that slabs may be weak, implying a more prominent role for plate interface dissipation than previously thought. Behr & Becker (2018) suggested that the deep interface viscosity in subduction zones should be strongly affected by the relative proportions of sedimentary to mafic rocks that are subducted to depth, and that sediment subduction should thus facilitate faster subduction plate speeds. Here we use fully dynamic 2D subduction models built with the code ASPECT to quantitatively explore how subduction interface viscosity influences: a) subducting plate sinking velocities, b) trench migration rates, c) convergence velocities, d) upper plate strain regimes, e) dynamic topography, and f) interactions with the 660 km mantle transition zone.  We implement two main types of models, including 1) uniform interface models where interface viscosity and slab strength are systematically varied, and 2) varying interface models where a low viscosity sediment strip of finite width is embedded within a higher viscosity interface. Uniform interface models indicate that low viscosity (sediment-lubricated) slabs have substantially faster sinking velocities prior to reaching the 660, especially for weak slabs, and also that they achieve faster ‘steady state’ velocities after 660 penetration. Even models where sediments are limited to a strip on the seafloor show accelerations in convergence rates of up to ~5 mm/y per my, with convergence initially accommodated by trench rollback and later by slab sinking. We discuss these results in the context of well-documented plate accelerations in Earth’s history such as India-Asia convergence and convergence rate oscillations along the Andean margin.

References: Behr, W. M., & Becker, T. W. (2018). Sediment control on subduction plate speeds. Earth and Planetary Science Letters, 502, 166-173.
In Honour of Distinguished Scientist and Seminal Hydrogeologist Professor Ghislain de Marsily
Authors: Simmons Craig T.
Published: March 2020

Professor Ghislain de Marsily is an internationally renowned scientist famed for his contributions to groundwater hydrology and water management. He is a pioneer in the development of stochastic hydrogeology. This presentation will outline and explore the significant contributions made by de Marsily to hydrogeology as a whole and to stochastic hydrogeology in particular. It will examine the effect of his work on defining the discipline of hydrogeology as we know it today, and will go on to show the significant impact his students and colleagues continue to have, inspired by his passion, ideas and enthusiasm for a more sustainable, equitable future for all.
Combing deep learning and multi-source data to promote subjective perception of ecosystem services in urban landscape
Authors: Chen Yugang , Qiu Yeshan , Che Shengquan
Published: March 2020

Subjective perception of ecosystem services is an emerging topic to better understand nature-based solutions for human and natural sustainability. Survey-based methods for subjective perception has the difficulty to move their conclusions beyond site-specific applications. Potential data sources for subjective perception exist in many sources such as geo-tagged social media and street-view photos. In this paper, we develop a combined deep-learning, survey, and multi-source data big data approach to study and promote subjective ecosystem service perceptions beyond site-specific applications. Specifically, we use machine learning models trained to predict human perception from a large dataset of images to rate urban landscape photos from social media and street-view maps. The predictors include CNN-engineered photo features, geographic information, survey-based ratings as well as public ratings from social media and street-view maps. The method of this study can be applied to understand subjective perception of ecosystem services for a wide range of urban landscape site. The results contribute to a better understanding of connections between subjective perception and objective evaluation of ecosystem services value for urban landscape so that nature-based solutions can be better implemented for human well-being and sustainability.

Key Words: Deep learning; Multi-source big data; Subjective perception; Ecosystem services; Social media
Estimation of aboveground biomass in North China using Sentinel-1 and 2 datasets
Authors: Wang Yueting , Zhang Xiaoli
Published: March 2020

Forest aboveground biomass (AGB) plays an important role in measuring forest carbon reserves. Accurate mapping AGB is important for monitoring carbon stocks and will contribute to achieve the goal of sustainable development. In this study, we explored the potential of mapping AGB in north China using a three-year monthly time series of Senitinel-1 (S1) and Sentinel-2 (S2) data. The backscattering and indices of SAR S1 combined with spectral reflectance, vegetation indices and biophysical parameters from multispectral S2 imagery were evaluated for AGB prediction in a Random Forest regression. Three scenarios were conducted with different datasets to determine: (1) the potential of using S1 and S2 to estimate AGB, (2) optimal variables selection for AGB mapping, (3) contribution of time series datasets to improving the accuracy of AGB mapping. Random forest regression was used to develop forest AGB estimation models, which was divided into three types of modeling using only S1, only S2, and a combination of S1 and S2. Compared to S1 (RMSE = 65.7 Mg/ha), S2 achieved better prediction accuracy (RMSE = 58.4 Mg/ha), although the combination of S1 and S2 time series datasets estimated the best AGB results (RMSE = 42.3 Mg/ha). The research implied that incorporation of SAR and multispetral data considerably improved AGB mapping performance when compared with the use of SAR or multispectral data alone. This proposed approach provides a new insight in improving the estimation accuracy of forest AGB in north China.
The Central European droughts of 2018 and 2019 observed with GRACE-Follow-On
Authors: Boergens Eva , Güntner Andreas , Dobslaw Henryk , Dahle Christoph
Published: March 2020

In this study we investigate the ability of GRACE-FO (Gravity Recovery and Climate Experiment Follow-On) to quantify the two consecutive summer droughts of 2018 and 2019 in Central Europe. The GRACE-FO mission was launched in May 2018 as the successor of GRACE (2002-2017) and thus, allows us to relate the droughts of the last two years to former droughts in 2003 and 2015.

The water mass deficit in 2018 was 90±18.5 Gt and in 2019 even 116±18 Gt compared to the long term climatology. These deficits are 60% and 76% of the annual mean variations which is so severe that a fast recovery of the water storage cannot be expected within one year. The drought of summer 2019 was more severe than the European-wide drought of 2003 with a water deficit of 85±16 Gt and had the largest water deficit in the whole GRACE and GRACE-FO time span.

GRACE-FO total water storage data also allows the analysis of the spatio-temporal drought patterns. The largest water mass deficit in 2018 was detected in October and centred in South-Western Germany and neighbouring countries. However, the exact onset of the 2018 drought is not determinable due to missing data between July and October. The drought 2019 reached its largest deficit in July and was more evenly spread across Central Europe than the 2018 drought.

From the GRACE and GRACE-FO mass anomalies, we derive a drought index which is compared to an external soil-moisture drought index. Over the whole time series between 2002 and 2019 both indices show a high congruence. However, as the two indices do not describe the same hydrological compartments a time lag and a memory effect of TWS relative to soil-moisture is visible in the comparison.

Overall, the presented study proves the successful continuation of GRACE with GRACE-FO and thus the reliability of the observed Central European summer drought of 2019 as the most extreme water scarcity event since 2002.
Sensitive Detection of Ambient Formaldehyde by Incoherent Broadband Cavity Enhanced Absorption Spectroscopy
Authors: Liu Jingwei , Li Xin , Yang Yiming , Wang Haichao , Kuang Cailing , Zhu Yuan , Chen Mindong , Hu Jianlin , Zeng Limin , Zhang Yuanhang
Published: March 2020

Formaldehyde (HCHO) is the most abundant atmospheric carbonyl compound and plays an important role in the troposphere. However, HCHO detection via traditional incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) is limited by short optical path lengths and weak light intensity. Thus, a new light-emitting diode (LED)-based IBBCEAS was developed herein to measure HCHO in ambient air. Two LEDs (325 and 340 nm) coupled by a Y-type fiber bundle were used as an IBBCEAS light source, which provided both high light intensity and a wide spectral fitting range. The reflectivity of the two cavity mirrors used herein was 0.99965 (1 – reflectivity = 350 ppm loss) at 350 nm, which corresponded with an effective optical path length of 2.15 km within a 0.84 m cavity. At an integration time of 30 s, the measurement precision (1σ) for HCHO was 380 parts per trillion volume (pptv) and the corresponding uncertainty was 8.3%. The instrument was successfully deployed for the first time in a field campaign and delivered results that correlated well with those of a commercial wet-chemical instrument based on Hantzsch fluorimetry (R2 = 0.769). The combined light source based on Y-type fiber bundle overcomes the difficulty of measuring ambient HCHO via IBBCEAS in near-ultraviolet range, which may extend IBBCEAS technology to measure other atmospheric trace gases with high precision.
Exploring the role of risk perception in influencing flood losses over time
Authors: Ridolfi Elena , Albrecht Frederike , Di Baldassarre Giuliano
Published: March 2020

What implications do societies’ risk perceptions have for flood losses? This study uses a stylized, socio-hydrological model to simulate the mutual feedbacks between human societies and flood events. It integrates hydrological modelling with cultural theory and proposes four ideal types of society that reflect existing dominant risk perception and management: risk neglecting, risk monitoring, risk downplaying and risk controlling societies. We explore the consequent trajectories of flood risk generated by the interactions between floods and people for these ideal types of society over time. Results suggest that flood losses are substantially reduced when awareness raising attitudes are promoted through inclusive, participatory approaches in the community. In contrast, societies that rely on top-down hierarchies and structural measures to protect settlements on floodplains may still suffer significant losses during extreme events. This study illustrates how predictions formed through social science theories can be applied and tested in hydrological modelling.
One dimensional numerical modeling of land subsidence caused by seasonal groundwater level fluctuations in Kawajima, Japan
Authors: Akitaya Kento , Aichi Masaatsu
Published: March 2020

Land subsidence caused by seasonal fluctuation of groundwater level caused by agricultural groundwater use was numerically simulated in this study. In the study area, Kawajima, Saitama prefecture, Japan, the hydraulic head has been gradually increasing over time with seasonal fluctuations and the subsurface formations have repeated expansion and compaction. However, the land subsidence progressed because the compaction included the plastic deformation. In this study, vertically one-dimensional model to numerically simulate coupled groundwater flow and soil deformation in Kawajima was developed with modified cam-clay model. Because of the lack of subsurface information, it was difficult to set the physical properties such that the simulated subsidence and the observed subsidence are satisfactorily close to each other. This study applied a genetic algorithm in order to search the set of underground physical properties. The improved set of underground physical properties succeeded to reproduce the observed land subsidence in Kawajima.
Experimental approach to study the climate effects from drained peatland restauration
Authors: Ibrom Andreas , Pirk Norbert , Steenberg Larsen Klaus , Kindler Paula Anna , Larsen Poul
Published: March 2020

Peatlands have been traditionally drained to increase productivity. Aeration of the topsoil increases decomposition of peat, which results in increased CO2 emissions contributing to warming of the global climate. Peatland restauration tries to reestablish the natural state by blocking the drainage and increasing the ground water table. Two questions arise, whether the establishment of anaerobic conditions in the peat will increase methane production and whether the net CO2 uptake by plants will be reduced, both of which offsetting the anticipated positive climate effect from peatland restauration. In order to claim a positive climate effect from peatland restauration, the effect on the total greenhouse gas (GHG) balance must be demonstrated[VH1]  at different time scales.

In a new project in Norway (close to Trysil, Innlandet), we established a paired plot design in an ombrotrophic bog, where one of the two plots will be restored, while the other will remain drained. The two sites differ slightly in elevation and lie 1.5 km apart from each other. We report results from the first phase of the experiment, i.e. examining the comparability of the two plots. We use eddy covariance and ecosystem chambers to measure CO2, CH4 and N2O fluxes.

While the CO2 fluxes are remarkably similar between the two plots, the CH4 fluxes tend to be slightly higher in the lower of the two plots. With flux footprint simulations and spatio-temporal analysis of the chamber flux measurements it is examined, whether these differences are caused by small scale horizontal heterogeneity, i.e. by CH4 emission hotspots, or whether these are a general feature of the lower experimental site. Options to improve the comparability of the two experimental plots, namely source area filtering versus relational approaches will be discussed.

The methodology that is developed in the project is relevant for monitoring, reporting and verification of climate change mitigation measures within terrestrial ecosystems.

Acknowledgements:

The project is funded by the Norwegian Environment Agency (Miljødirektoratet), Oslo, Norway, (project number 18088061).
CO2 fluxes and carbon balance of an agricultural grassland in southern Finland
Authors: Heimsch Laura , Lohila Annalea , Kulmala Liisa , Tuovinen Juha-Pekka , Korkiakoski Mika , Laurila Tuomas , Liski Jari
Published: March 2020

Agriculture is globally a significant source of carbon emissions to the atmosphere. Main causes for these high emissions are conventional intensive management practices which include such as frequent ploughing, monocropping and high use of agrochemicals. These practices contribute to the loss of biodiversity and soil organic matter, as well as to the CO2 emissions from land use. Recently, it has been recognised that agriculture functioning on the basis of regenerative practices is one of the most potential tools to mitigate climate change.

It is well known that topsoil layer and especially humus-rich soils can store more carbon than atmosphere and vegetation together. Therefore, increasing the amount of soil organic matter in the agroecosystems, by applying enhanced management practices such as reduced tillage, high biodiversity and cover cropping, agricultural soils would not only help to mitigate climate change but also to restore soil quality and fertility. To understand the carbon dynamics on different agricultural sites, factors affecting and comprising the carbon balance, and to verify soil carbon and ecosystem models, continuous long-term monitoring of the GHG fluxes is essential at such managed ecosystems. Here we present results from a new eddy covariance (EC) flux study site located in southern Finland.

Continuous CO2 flux measurements using the EC method have been conducted at Qvidja farm on mineral (clay) soil forage grassland in Parainen, southern Finland (60.29550°N, 22.39281°E) since the spring 2018. Based on the flux and biomass data, the annual carbon balance was estimated to be negative, i.e. the site acted as an overall sink of carbon even in the dry and hot year 2018. However, the seasonal CO2 fluxes were greatly dependent on weather conditions and management procedures. Results from 2019 show that the growing season accompanied with more mature and dense grass, a bit higher precipitation and lower temperatures, as well as higher cutting height was more favorable for carbon uptake in Qvidja as compared to year 2018.
Decoupling the crustal and mantle gravity signature at subduction zones with satellite gravity gradients: case study Sumatra
Authors: Root Bart , van der Wal Wouter , Fullea Javier
Published: March 2020

The GOCE satellite mission of the European Space Agency has delivered an unprecedented view of the gravity field of the Earth. In this data set, the strongest gravity gradient signals are observed at subduction zones in the form of a dipole. Despite numerous studies on subduction zones, it is still unclear what is causing this strong signal. Is the source of the observed dipole situated in the crust, mantle, or a combination of these?

We have constructed a 3D geometry of the Sumatra slab using the global SLAB1.0 model. This geometry is substituted in a global upper mantle model WINTERC5.4, a product of the ESA Support to Science Element: 3DEarth. The density in the subducting crust, mantle, or a combination of both is fitted to the gravity gradients at satellite height. Lateral varying Green’s functions are used to compute the gravity gradients from the densities. In the case of a combined crust/mantle model, spectral information of the sensitivity of satellite gradients is used to construct a weighted inversion.

Preliminary results show that crustal mass transport (mostly from the overriding plate) in the direction of the subducting plate is mostly responsible for the negative anomaly observed in between the trench and the volcanic arc. This signal is, however, not visible along the complete subduction zone. Most crustal transport is seen where normal subduction takes place. Oblique subduction shows less crustal transport and more intra-crustal faulting. The satellite gravity gradients show high sensitivity to this particular crustal signature and therefore can be used to analyze subduction zones globally.
Soil organic carbon stability of urban soils and of floodplain soils under different hydrothermal conditions
Authors: Brianskaia Inna , Vasenev Vyacheslav , Brykova Ramilla
Published: March 2020

Пожалуйста, вставьте свой абстрактный HTHigh anthropogenic impact and the rate of urbanization result in a decrease of urban soils’ capacity to perform ecosystem services. Carbon sequestration is an important soil-based ecosystem service, which can be assessed through quantity and quality soil carbon stocks. The stability of soil organic matter (SOM) is characterized by the resistance of its constituent components to biological, chemical and physical destruction. In the study, SOME stability in peat-sand mixture used for urban soils’ construction; floodplain soil was analyzed in response to temperature-moisture conditions. The decomposition rate of various soils was assessed. Decomposition was assessed through studying microbial production of CO2. In the research the CO2 emissions were studied under following temperatures and moisture conditions: temperature – 7°C, 22°C, 30°C and 40°C and moisture – 0.2 WHC, 0.4 WHC, 0.6 WHC, 0.8 WHC, 1 WHC. Moisture affects the amount and activity of microbial biomass, controls the availability of oxygen to microorganisms, causes periods of water microbial stress and also can destabilize organic matter, resulting in increased availability of carbon to soil microorganisms. Different patterns of moisture and temperature impacts on the soil organic carbon (SOC) decomposition rates were observed. It was concluded that, depending on the qualitative composition of carbon, the impact of hydrothermal conditions on the emission of carbon dioxide changed.ML здесь.
Geological map services as a tool for natural risk management in Finland: Geochemical baselines and acid sulfate soils
Authors: Pihlaja Jouni
Published: March 2020

Geological Survey of Finland (GTK) provides data on assessing risks related to soil geochemical baselines and acid sulfate soils. The results are published as map services and they can be used for example to aid land use planning, environmental impact assessments, evaluation of soil contamination and soil remediation actions. Acid sulfate soil data can also be utilized in water protection planning.

Geochemical baseline samples are gathered from the most common minerogenic soil parent materials in urban areas, industrial environments and in the surroundings of mine sites. In the map service data 17 elements are presented in total and it is possible to calculate the regional soil baseline values from a desired area.

The acid sulfate soil map service contains survey data on the properties of acid sulfate soils in the coastal regions of Finland. It is possible to study the general maps of the probable presence of acid sulfate soils and survey-point specific information based on drilling and analysis results.

Both map services mentioned above are free to view at the GTK web pages.
The possible formation mechanism of the Subtropical Countercurrent in the Pacific Ocean
Authors: Zhang Zhichun , Xue huijie
Published: March 2020

            Based on a nonlinear reduced gravity model simulation, formation cause of Subtropical Countercurrent(STCC) in the Pacific Ocean are investigated. The model reproduces well the characteristics of circulation of thermocline in the North pacific Ocean. The results suggest that the variation of the west boundary topography, especially the witdh of the luzon strait, play a key role on the formationg of STCC as well as the wind sress meridional gradient. When the witdh of the luzon strait gradually decrease, the STCC increase . the model results also reveal that the wind stress dipole curl of west ot the hawaii islands is key to the HLCC formation.
New insights on controls of piping distribution in degraded blanket bog
Authors: Regensburg Taco , Holden Joseph , Chapman Pippa , Pilkington Michael , Evans Martin
Published: March 2020

As part of the EU-funded MoorLIFE2020 project, which examines strategies to restore degraded blanket bog in the Peak District of northern England, we investigated natural soil pipes. These pipes are a cause of concern to peatland restoration practitioners who are unsure whether to block them to reduce erosion and flood risk when conducting restoration work. Soil pipes often occur in complex networks with varying channel sizes, undulating through the soil profile. Their prevalence is often linked to controls such as topographic location, slope, aspect, vegetation cover, climate, and properties of the surrounding soil. Such relationships are poorly understood for degraded blanket bog. A before-after-control treatment study was designed to examine the effects of pipe blocking on fluvial carbon removal and streamflow in Upper North Grain (UNG), a small headwater catchment located between 490 m and 541 m above sea level. The catchment has a blanket peat cover up to four meters thick at places, with a branching network of deep gullies that incise into the bedrock. This experimental design was envisaged to address the following hypotheses: (i) the severity of degradation of UNG is a dominant control on pipe density; (ii) blocking of pipe outlets impairs pipe-to-stream connectivity. Our results point towards a rejection of both hypotheses. An initial field survey used to locate and characterize pipe outlets, resulted in 353 individual outlet recordings with a density of 13.79 per km of surveyed gully bank. Southeast, south, southwest and west-facing gully banks accounted for more than 75% of identified pipe outlets. The experimental design compares water and aquatic carbon fluxes in two streams - in one catchment the active pipe outlets (n=25) were blocked by closing off the void behind the pipe outlet with peat and stones, wooden screens or plastic pilling, while in the other catchment the pipes were left open. Areas on the gully bank around original outlets were photographed every two weeks. This analysis showed that within the first month after blocking, all treated pipes had formed bypass routes around the block and initiated new pipe outlets. New outlets were found both above and below the original pipe outlet at distances up to 1 meter from the original pipe outlet regardless of bank aspect, suggesting the networks behind a pipe outlet to be a porous system that connects in both vertical and horizontal directions when issuing onto gully banks. Further results will be presented from the ongoing monitoring showing effects of pipe blocking on streamflow storm responses and the export of particulate and dissolved organic carbon from pipes and streams.