bluuebunny/crossref_metadata_2025 huggingface dataset:
Compensated root water uptake by split-rooted tomatoes
Authors: Ben-Gal Alon , Tzohar Dov
Published: March 2021

Compensation occurs when reduced uptake in regions of the root-zone due to stress-causing conditions (ie: lack of water, high salinity, lack of oxygen) is countered by augmented uptake from roots in areas with good conditions. A plant's ability to compensate may depend on actual conditions in the soil, transpiration demand, and on biological signaling and stomatal response. The most popular models of macro-uptake by roots in soils handle compensation empirically, through mathematical correction, without consideration of mechanistic processes.

We hypothesized that plant roots could fully compensate for reduced uptake due to partial root-zone stress-causing conditions, as long as sufficient good conditions and available water were maintained in some other part of the root-zone. We implemented a novel research platform to quantify compensative uptake including split-root weighing-drainage lysimeters in a greenhouse where short-term (less than one day) salinity was induced in half the roots of tomato plants. The system allowed for partial root-zone stress-causing conditions and quantification of uptake from areas with poor and good conditions separately.

In response to changes in salinity in half of the root zone, uptake was immediately reduced in the salinized part and increased in the non-salinized part. When added salt concentration was relatively low, compensation was quantified up to tens of percent increase in non-salty and equivalent decrease in salty parts, even in cases where uptake was not effected in control plants where both sides received the salt solution. When salinity was higher, plant-scale transpiration was reduced by exposure to salinity on one side but much less than for cases where both sides were exposed. The plant scale reductions in one-sided salinized root zones lasted only a few days and eventually returned to be equal to non-salinized control plants. There was no evidence of signaling and stomatal closure from the stressed areas.

Tomato plants were found to have a mechanism for short-term compensative response to spatially variable conditions of available water in the root zone. When zones of more available water exist, uptake increases relatively in them, allowing decreased uptake in zones having lower available water. As long as there is no hydraulic restriction for uptake in other areas of the root zone, temporal reduction in water availability in some part of the root zone will not affect plant scale transpiration or plant activity. The results suggest that mechanistic based approaches to uptake and stress, including compensation, should improve uptake components of soil-water-plant models.  
Downstream grain-size changes using PebbleCounts in the south-central Andes: Relations to channel steepness and SAR observations
Authors: Purinton Benjamin , Bookhagen Bodo
Published: March 2021

Grain-size data are imperative for understanding erosional and fining processes in steep terrain as rivers are the primary conduits for sediment transport. However, collecting hundreds of pebble measurements at multiple channel bed survey sites in steep and dynamic high-mountain river settings remains a challenging roadblock in studying downstream variations in grain-size. Using PebbleCounts (https://github.com/UP-RS-ESP/PebbleCounts), we survey large (~1,000+ m2) channel cross sections and measure thousands of grains per survey to build robust grain-size distributions in the Quebrada del Toro, Northwest Argentina. Because of imagery resolution considerations, we only examine the grain sizes in the ≥ 2.5 cm fraction of the distribution. We gather measurements via a careful counting and validation process to constrain uncertainties, which highlights the dominant over- and under-segmentation errors that occur in PebbleCounts in this challenging geographic setting. Despite uncertainties, we are able to study downstream changes in grain-size percentiles at seven survey sites along a 100-km stretch of the trunk stream, which traverses a steep topographic and environmental gradient. We find that only the upper-most percentiles (≥ 95th) are sensitive, whereas the 50th and 84th percentiles show little downstream variability in this rapidly eroding catchment. In particular, we note a strong relation between increases in these upper percentiles and the along-channel junctions with large, oversteepened tributaries, where extreme channel steepness reaches are > 200 m0.8 (θ=0.4). Furthermore, independent spaceborne synthetic aperture radar (SAR) coherence and amplitude observations show clear relations to mass transfer and channel bed roughness changes, which also relate to the grain-size variability that we find.
Attribution of high-impact extreme sea surface temperature events
Authors: Barkhordarian Armineh , Baehr Johanna
Published: March 2021

We evaluate whether anthropogenic influence has affected the observed extreme sea surface temperature (SST), defined as discrete events of anomalously warm or cold ocean temperatures, over the last decades. To this end we utilize three large ensembles of coupled climate models and use two methods. The ﬁrst method analyzes the observed long-term spatiotemporal changes of extreme SST to detect the presence of a signal beyond changes solely due to natural (internal) variability and to attribute the detected changes to external climate drivers. The second method is based on single event attribution, which determines how an external forcing have changed the likelihood of high-impact extreme SST events, such as the north Atlantic cold blob, the northeast Pacific warm blob, Tasman Sea marine heatwave, etc. In this study we further combine observations and model simulations under present and future forcing to assess how internal variability and anthropogenic climate change modulate extreme SST events.
Rupture process of the 7 May 2020 Mw 5.0 Tehran earthquake and its relation with the Damavand stratovolcano, and Mosha Fault
Authors: Büyükakpınar Pınar , Jamalreyhani Mohammadreza , Rezapour Mehdi , Donner Stefanie , Nooshiri Nima , Hassanzadeh Mirali , Marzban Pouria , Maleki Asayesh Behnam
Published: March 2021

In May 2020 an earthquake with Mw 5.0 struck at ~40 km east of Tehran metropolis and ~15 km south of the Damavand stratovolcano. It was responsible for 2 casualties and 23 injured. The mainshock was preceded by a foreshock with Ml 2.9 and followed by a significant aftershock sequence, including ten events with Ml 3+. The occurrence of this event raised the question of its relation with volcanic activities and/or concern about the occurrence of larger future earthquakes in the capital of Iran. Tehran megacity is surrounded by several inner-city and adjacent active faults that correspond to high-risk seismic sources in the area. The Mosha fault with ~150 km long is one of the major active faults in central Alborz and east of Tehran. It has hosted several historical earthquakes (i.e. 1665 Mw 6.5 and 1830 Mw 7.1 earthquakes) in the vicinity of the 2020 Mw 5.0 Tehran earthquake’s hypocenter. In this study, we evaluate the seismic sequence of the Tehran earthquake and obtain the full moment tensor inversion of this event and its larger aftershocks, which is a key tool to discriminate between tectonic and volcanic earthquakes. Furthermore, we obtain a robust characterization of the finite fault model of this event applying probabilistic earthquake source inversion framework using near-field strong-motion records and broadband seismograms, with an estimation of the uncertainties of source parameters. Due to the relatively weak magnitude and deeper centroid depth (~12 km), no static surface displacement was observed in the coseismic interferograms, and modeling performed by seismic records. Focal mechanism solution from waveform inversion, with a significant double-couple component, is compatible with the orientation of the sinistral north-dipping Mosha fault at the centroid location. The finite fault model suggests that the mainshock rupture propagated towards the northwest. This directivity enhanced the peak acceleration in the direction of rupture propagation, observed in strong-motion records. The 2020 moderate magnitude earthquake with 2 casualties, highlights the necessity of high-resolution seismic monitoring in the capital of Iran, which is exposed to a risk of destructive earthquakes with more than 10 million population. Our results are important for the hazard and risk assessment, and the forthcoming earthquake early warning system development in Tehran metropolis.
IMF BX and Dipole Tilt Dependence on Transpolar Arcs
Authors: Thor Simon , Kullen Anita , Cai Lei
Published: March 2021

Transpolar arcs (TPAs) are predicted by many models to appear in both hemispheres, as so-called conjugate TPAs. However, some observations have suggested that this is not always the case, and that there is an IMF Bx dependence on whether TPAs appear on both hemispheres or not. Specifically, it has been suggested that TPAs only appear on the northern hemisphere for negative IMF BX and vice versa for positive IMF BX. Furthermore, a positive Earth dipole tilt is predicted to have a similar effect on TPA occurrences as a negative IMF BX and vice versa. It is also known that TPAs appear on different locations on the auroral oval, i.e., dawn-, dusk- or both sides of the oval, depending on IMF BY. However, the role of IMF BX and IMF BZ for the TPA location remains unclear, with some previous observations suggesting a correlation with IMF BX.

In this study, we investigate the influence of IMF BX and dipole tilt on TPAs by statistically analyzing observational data. We analyze TPA datasets from four previous studies, as well as our own TPA dataset, created from DMSP satellite measurements. At first glance, the data suggests that there is a strong correlation between both IMF BX and dipole tilt, and TPA observations in a specific hemisphere. However, when normalizing the data to the solar wind distribution and when taking observational bias into account, this correlation disappears. We therefore conclude that there is no clear correlation between neither IMF BX nor dipole tilt and in which hemisphere a TPA appears. We further analyze four of the five datasets with respect to dawn-dusk appearances of TPAs and its correlation to IMF BX, BY and BZ. Here, the results for the datasets mostly agree with previous observations. Finally, we discuss the potential causes for the few non-conjugate TPAs, by studying our own TPA dataset in further detail.
Tectonic ledges at the bottom of Lake Ladoga
Authors: Anokhin Vladimir , Dudakova Dina , Dudakov Mikhael
Published: March 2021

For the last several years, the Institute of Limnology RAS has been conducting geological and geomorphological studies of the bottom of Lake Ladoga, the largest lake in Europe. Beginning in 2018, these studies began to use underwater photo and video camera, created at INOZ RAS. The use of this new research tool led to the discovery of a number of new facts of the structure of the bottom of Lake Ladoga. In particular, during the 2020 field season, the authors discovered in several areas of Lake Ladoga the existence of underwater subvertical scarps, composed of bedrocks. At the same time, the submarine towing boat stood in one place, and the camera vertically upward from depths of about 100 - 120 meters to depths of 20 - 30 meters. During this entire rise, the camera recorded the bedrock ledge with vertical and even negative angles. No traces of glacier processing were found, which indicates the Holocene age of the found scarps. In 2020, such ledges were found in 3 regions of Lake Ladoga: in a depression near the  Pitkyaranta in the northeastern part of the lake, in the Suuri-Viroluoto trench in the northern part of the lake and on the western underwater slope of Valaam Island. A mention of the possibility of the existence of such ledges (up to the first tens of meters in height) in the northern part of Lake Ladoga is found in the works of V.A. Rumyantsev and V.N. Rybakina (2012), A.V. Amantov (2014), Bolshiyanov (2018). M.A.Naumenko, who studied the underwater slope of Valaam Island, considered the maximum angle of this slope to be 60 degrees (2019). We found sub-vertical ledges up to 100 meters high. In addition, these scarps are in spatial relationship with the existing tectonic faults, confirming their significant fault component. The presence of young vertical high ledges at the bottom of Lake Ladoga indicates powerful young tectonic movements in this region.
Estimating cumulative catchment streamflow depletion from abstractions
Authors: Rajanayaka Channa , Booker Doug , Yang Jing
Published: March 2021

Abstraction from surface and groundwater bodies alters river flow regimes. The economic and social benefits of abstraction need to be balanced against their consequences for hydrology dependent ecological functions, ecosystem services, cultural values and recreation. However, impacts of an abstraction on flow regimes are often assessed in isolation and so cumulative impacts of many spatially distributed abstractions on the catchment are not understood. While spatially distributed, high-resolution model(s) (e.g. MODFLOW) can be developed to understand the cumulative impacts of abstractions, this is cost prohibitive and the demand for data is high (e.g., system properties, hydroclimatic) to develop such a model at regional scales and, further, such site specific models cannot be transferred to other spatial locations. We have developed a model to estimate cumulative streamflow depletion at given locations of a stream network resulting from both surface and groundwater abstractions. The surface water abstractions directly deplete the nearest river segment with which the abstraction is associated. However, depletion owing to each groundwater take, response times of which can extend to weeks, months or even years following the abstractions, was associated with all river segments which were within a 2 km radius of the groundwater take. The proportion of depletion from each river segment owing to a groundwater take is dependent on distance between well and segment, flow (based on the naturalised 7-day mean annual low flow) and length of the segment within 2 km radius of the well. Two aquifer parameters (transmissivity and storativity) are used for calculating the streamflow depletion. Field tests can be used to measure these parameters but observations are not available for all necessary locations. We used Random Forest statistical techniques to estimate the aquifer parameters at unmeasured locations. Results of the streamflow depletion model are displayed using an interactive application (app). The model can be used to obtain timeseries of cumulative stream depletion at any location in the river network from many spatially distributed abstractions.
A large tectonic-controlled subglacial lake with ocean drainage in Princess Elizabeth Land, East Antarctica
Authors: Yan Shuai , Blankenship Donald D. , Young Duncan A. , Greenbaum Jamin S. , Li Lin , Rutishauser Anja , Guo Jingxue , Roberts Jason L. , Ommen Tas D van , Sun Bo
Published: March 2021

The Princess Elizabeth Land (PEL) sector of the East Antarctic Ice Sheet, one of the largest grounded ice reservoirs in Antarctica, is adjacent to regions that experienced significant change during the last glacial maximum. The identification of subglacial water in PEL (to date only inferred from satellite image data) would provide important constraints on our estimation of the basal thermal condition in this region. Also, the existence of a large subglacial hydrology system in PEL comes with potential impacts on the basal melting rate and stability of downstream ice shelves, such as the West Ice Shelf. Here we present geophysical evidences confirming the existence of a large subglacial lake in PEL, hereby referred as Lake Snow Eagle (LSE), for the first time, using recently acquired aerogeophyscial data by international collaborations. We estimate LSE to be about 42 km in length and 370 km2 in area, making it one of the largest subglacial lakes in Antarctica. LSE is shown to lie in a subglacial canyon system that is linked to the coastal ice shelves, which makes LSE the first known major Antarctic interior water body that has a potential direct hydrological pathway into the ocean. We then systematically investigate its geological characteristics and bathymetry by 2-D geophysics modellings. We estimate the water volume of LSE to be about 21 km3, while the sediment volume to be about 20 km3. Our geophysical modelling results also suggest that LSE is located along a compressional geologic boundary, indicating possible tectonic controls over LSE.
The value of expedition-based science for capturing otherwise unobtainable Arctic oceanographical data
Authors: McCallum Adrian , Suara Kabir
Published: March 2021

High spatial and temporal resolution oceanographic data from across the Arctic Ocean are essential to better constrain climate models. Ongoing satellite measurements and mooring and autonomous profiler data are valuable, but many regions and temporal periods are inadequately surveyed, particularly outside summer months.

Over-ice scientific research expeditions can address these deficiencies because they are cost-effective and can be utilised at almost any time and at any location to obtain high spatiotemporal resolution data; unique peer-reviewed findings from such expeditions are now being published. For example, recently examined data from the Makarov Basin, obtained in April, during the 2011 Catlin Arctic Survey (McCallum and Suara, 2020) shows a surface mixed layer extending to a depth of ~40 m and buoyancy frequencies exceeding 0.025 s−1, indicating very strong thermohaline stratification, probably due to spring ice melt.

A model for such expedition-based science might comprise: a sympathetic and supportive scientific community, government bureaucracies willing to support and enable more ‘risky’ ventures, and funding bodies, including private industry, who are willing to sponsor and support, relatively inexpensive, high quality polar science.

Future acceptance and utilisation of over-ice scientific research expeditions has the potential to enable the collection of otherwise unobtainable glaciological, oceanographical and meteorological data in poorly sampled spatiotemporal regimes to allow better constraining and development of regional and global climate models.
Supercooled Southern Ocean Waters
Authors: Haumann F. Alexander , Moorman Ruth , Riser Stephen C. , Smedsrud Lars H. , Maksym Ted , Wong Annie P. S. , Wilson Earle A. , Drucker Robert , Talley Lynne D. , Johnson Kenneth S. , Key Robert M. , Sarmiento Jorge L.
Published: March 2021

In cold polar waters, temperatures sometimes drop below the freezing point, a process referred to as supercooling. However, observational challenges in polar regions limit our understanding of the spatial and temporal extent of this phenomenon. We here provide observational evidence that supercooled waters are much more widespread in the seasonally ice-covered Southern Ocean than previously reported. In 5.8% of all analyzed hydrographic profiles south of 55° S, we find temperatures below the surface freezing point (‘potential’ supercooling), and half of these have temperatures below the local freezing point (‘in-situ’ supercooling). Their occurrence doubles when neglecting measurement uncertainties. We attribute deep coastal-ocean supercooling to melting of Antarctic ice shelves, and surface-induced supercooling in the seasonal sea-ice region to winter-time sea-ice formation. The latter supercooling type can extend down to the permanent pycnocline due to convective sinking plumes—an important mechanism for vertical tracer transport and water-mass structure in the polar ocean.
Synergistic Effects of Unsaturated Flow and Soil Organic Matter on Retention and Transport of PPCPs in Soils
Authors: Chen Xijuan , Dai Yuanyuan , Zhuang Jie
Published: March 2021

This study examines the effects of soil organic matter (SOM) and water content on the transport of five selected pharmaceutical and personal care products (PPCPs, ibuprofen, carbamazepine, bisphenol A, tetracycline, and ciprofloxacin) in four natural soils with different SOM contents. Batch isotherm experiment results showed that SOM effect was very significant for positively charged tetracycline and ciprofloxacin, relatively significant for non-dissociated carbamazepine and bisphenol A and insignificant for negatively charged ibuprofen in the soils. Transport results showed that neither tetracycline nor ciprofloxacin moved through the saturated and unsaturated soil columns, demonstrating their very limited mobility in soils as a result of significant electrostatic attraction independent of SOM and water conditions. Overall, higher SOM content and lower water content were favorable to the retention of ibuprofen, carbamazepine and bisphenol A in the soils. The effect of water content was not significant in the SOM-removed soils. The SOM could increase the kinetic (type 2) adsorption of PPCPs at the solid-water interface (SWI), and the air phase could increase the instantaneous (type 1) adsorption of PPCPs at the air-water interface (AWI). This result suggests that lowering water content could greatly enhance the adsorption of PPCPs that had high affinities to soils and vice versa. This study provides an important implication that AWI and SWI might have a nonlinear relationship in promoting the adsorption and reducing the mobility of PPCPs under unsaturated flow conditions.
Pitch angle scattering of an energetic magnetized particle by a circularly polarized electromagnetic wave
Authors: Bellan Paul M.
Published: March 2021

The interaction between a circularly polarized electromagnetic wave and an energetic gyrating particle is described [1] using a relativistic pseudo-potential that is a function of the frequency mismatch,  a measure of the extent to which ω-kzvz=Ω/γ is not true. The description of this wave-particle interaction involves a sequence of relativistic transformations that ultimately demonstrate that the pseudo potential energy of a pseudo particle adds to a pseudo kinetic energy giving a total pseudo energy that is a constant of the motion. The pseudo kinetic energy is proportional to the square of the particle acceleration (compare to normal kinetic energy which is the square of a velocity) and the pseudo potential energy is a function of the mismatch and so effectively a function of the particle velocity parallel to the background magnetic field (compare to normal potential energy which is a function of position). Analysis of the pseudo-potential provides a means for interpreting particle motion in the wave in a manner analogous to the analysis of a normal particle bouncing in a conventional potential well.  The wave-particle  interaction is electromagnetic and so differs from and is more complicated than the well-known Landau damping of electrostatic waves.  The pseudo-potential profile depends on the initial mismatch, the normalized wave amplitude, and the initial angle between the wave magnetic field and the particle perpendicular velocity. For zero initial mismatch, the pseudo-potential consists of only one valley, but for finite mismatch, there can be two valleys separated by a hill. A large pitch angle scattering of the energetic electron can occur in the two-valley situation but fast scattering can also occur in a single valley. Examples relevant to magnetospheric whistler waves are discussed. Extension to the situation of a distribution of relativistic particles is presented in a companion talk [2].

[1] P. M. Bellan, Phys. Plasmas 20, Art. No. 042117 (2013)

[2] Y. D. Yoon and P. M. Bellan, JGR 125, Art. No. e2020JA027796 (2020)
Effects of container size and fruit load intensity on tomato under salt stress
Authors: Zhou Kaining , Lazarovitch Naftali , Ephrath Jhonathan
Published: March 2021

Container size and fruit load intensity are two common factors manipulated to regulate plant growth and development. As saline water is increasingly used for irrigation in arid and semi-arid regions, it is important to study effects of container size and fruit load intensity on tomato in both aboveground and belowground parts under salt stress. The experiment was conducted in a net house located in Sede Boqer Campus, Israel. Containers of four sizes (8-, 28-, 48-, and 200L with the same depth but vary in diameters), two salinity levels (1.5- and 7.5 dS m−1) and two crop load intensities (0% and 100%) were applied. Gas exchange parameters (i.e., stomatal conductance and CO2 assimilation rate), plant growth parameters (i.e., plant height and stem diameter), and root development were monitored periodically. Plant biomass and various root traits were measured at harvest. For aboveground part, results revealed that container size and salinity level significantly influenced gas exchange performance while fruit load intensity had no significant effect. Plants grown in larger containers without salt stress had higher stomatal conductance and CO2 assimilation rate. Plant height and stem diameter were significantly greater in plants grown in 200L than those in other containers despite salinity and fruit load levels. Moreover, plants grown in 200L containers exhibited significant increase of 56.3%, 152.9%, and 174.9% respectively in yield compared with those grown in 48-, 28- and 8L under salt stress. The increase magnitudes were greater when there was no salt stress: 109.0%, 430.8%, and 454.0% respectively. For belowground parts, increased container size leads to increased rooting depth. Besides, Minirhizotron data showed that in 200L containers, plants grown under low salinity without fruit developed the greatest total root length. More detailed root data will be presented.  It is concluded that container size has a pronounced effect on physiological behaviours of tomato plants. Therefore, properly increasing container size can alleviate yield reduction under saline irrigation.
Spatial representation of stochastically generated rainfall for derived flood frequency analysis
Authors: Thiele Luisa-Bianca , Pidoto Ross , Haberlandt Uwe
Published: March 2021

For derived flood frequency analyses, stochastic rainfall models can be linked with rainfall-runoff models to improve the accuracy of design flood estimations when the length of observed rainfall and runoff data is not sufficient. The stochastic rainfall time series, which are used as input for the rainfall-runoff model, can be generated with different spatial resolution: (a) Point rainfall, which is stochastically generated rainfall at a single site. (b) Areal rainfall, which is catchment rainfall averaged over multiple sites before using the single-site stochastic rainfall model. (c) Multiple point rainfall, which is stochastically generated at multiple sites with spatial correlation before averaging to catchment rainfall. To find the most applicable spatial representation of stochastically generated rainfall for derived flood frequency analysis, simulated and observed runoff time series will be compared based on runoff statistics. The simulated runoff time series are generated utilizing the rainfall-runoff model HBV-IWW with an hourly time step. The rainfall-runoff model is driven with point, areal and multiple point stochastic rainfall time series generated by an Alternating Renewal rainfall model (ARM). In order to take into account the influence of catchment size on the results, catchments of different sizes within Germany are considered in this study.  While point rainfall may be applicable for small catchments, it is expected that above a certain catchment size a more detailed spatial representation of stochastically generated rainfall is necessary. Here, it would be advantageous if the results based on areal rainfall are comparable to those of the multiple point rainfall. The stochastically generation of areal rainfall is less complex compared to the stochastically generation of multiple point rainfall and extremes at the catchment scale may also be better represented by areal rainfall.    
Is 2020 super Meiyu a result of changing annual cycle of East Asian monsoon?
Authors: Lu Mengqian , Pan Mengxin , Dai Lun , Cheng Tat Fan
Published: March 2021

2020 was exceedingly difficult for humans. As the world was experienced surge waves of COVID19, East Asia was also facing a one in a century, record-breaking flood,  as the result of a super 47-day Meiyu/Baiu stage of East Asian summer monsoon. As East Asian monsoons (EAM) follow a yearly cyclical pattern, we wonder which stage(s) were collateral damages of the extended Meiyu. Was it an early termination of the anomalous dry Spring, or was it a delayed northward propagation of the rain belt, i.e. late Mid-summer? The hypothesis stems from our recent finding (Dai et al., 2020) that the duration of the Spring stage is informative for the onset of Meiyu, while the duration of Meiyu is negatively correlated with that of Mid-summer, i.e., the longer the Meiyu, the shorter the Mid-summer. To verify this, we first positioned the 2020 pre-Meiyu, Meiyu, Mid-summer stages in the 40-year climatology annual cycle (Dai et al., 2020). Although neither the onset nor the termination was beyond the 40-year variance, Meiyu indeed hastened to arrive but postponed its departure. Rain belt stalled over the Yangtze river basin and southern Japan since mid-June; until the end of July, a planetary-scale anomalous high pressure band was in place encompassing the Arabian sea and north Pacific. It hindered the South Asian monsoonal flow to the South China Sea, curbing the northward propagation of the rain belt with assistance by both southeast-ward shift of South Asian High and lower level high pressure system persistent over the northern China. With these observations, we put forward a framework of ocean-atmosphere coupled mechanisms that traces back to the summer in 2019, and reveal the climate teleconnection and circulation systems that pave the road to the 2020 super Meiyu. With this study, we address the question of whether the 2020 super Meiyu was a “black swan” or a manifestation of ongoing systematic changes of the EAM annual cycle?

 

 

 

Reference

Dai, L., Cheng, T. F., & Lu, M. (2020). Define East Asian monsoon annual cycle via a self‐organizing map‐based approach. Geophysical Research Letters, 47. e2020GL089542. https://doi.org/10.1029/2020GL089542
Nature-based sealing of leaky streams - Testing a bio-degradable bentonite mat for preventing infiltration losses in alpine stream
Authors: Zieher Thomas , Pfeiffer Jan , Polderman Annemarie , von Maubeuge Kent , Hochreiter Helmut , Ribis Christian , Lechner Veronika , Bergmeister Daniel
Published: March 2021

Deep-seated landslides can pose a serious threat to settlement areas and their assets in mountain regions across the world. An important step of a holistic landslide management is the implementation of suitable mitigation measures. However, technical mitigation measures against the impacts of natural hazards often rely on synthetic materials. Progress in materials science and development often makes it possible to replace synthetic components with renewable, bio-degradable materials that provide the same functionality. These alternative, nature-based solutions can simultaneously offer co-benefits such as environmental sustainability, less maintenance efforts and a greater societal acceptance. In this context, an experimental setup was installed in the upslope catchment area of an active deep-seated landslide in Vögelsberg (community of Wattens, Tyrol, Austria). At the chosen location the infiltration losses along the unconsolidated streambed potentially contribute to groundwater recharge, which is considered a main hydrological driver of the landslide. The goal of the experiment was to efficiently seal a 25 m long section of a stream without relying on synthetic materials. To reach this goal, a prototype of a bio-degradable bentonite mat was implemented as an impermeable layer in the subsurface of the leaky stream section. The efficacy of the mat is continuously monitored by several soil moisture probes installed below and above the layer and repeated measurements of subsurface characteristics with the help of electrical resistivity tomography. Furthermore, topographic changes due to erosion or sagging of the embankments are periodically monitored using a terrestrial laser scanner. Currently, the implemented solution must be considered a concept case to help raise awareness for this nature-based alternative to conventional engineering measures based on synthetic materials. If the experiment proves successful, it could be upscaled in the upstream catchment area of the landslide to prevent infiltration along leaky streams in the same way and reduce the hydrological forcing of the landslide.

The present study has been carried out in the OPERANDUM project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 776848.
Development of an interactive Cloud-based seismic network modelling application on a common Geophysical Processing Toolkit platform
Authors: Golodoniuc Pavel , Attanayake Januka , Jones Abraham , Bradley Samuel
Published: March 2021

Detecting and locating earthquakes relies on seismic events being recorded by a number of deployed seismometers. To detect earthquakes effectively and accurately, seismologists must design and install a network of seismometers that can capture small seismic events in the sub-surface.

A major challenge when deploying an array of seismometers (seismic array) is predicting the smallest earthquake that could be detected and located by that network. Varying the spacing and number of seismometers dramatically affects network sensitivity and location precision and is very important when researchers are investigating small-magnitude local earthquakes. For cost reasons, it is important to optimise network design before deploying seismometers in the field. In doing so, seismologists must accurately account for parameters such as station locations, site-specific noise levels, earthquake source parameters, seismic velocity and attenuation in the wave propagation medium, signal-to-noise ratios, and the minimum number of stations required to compute high-quality locations.

AuScope AVRE Engage Program team has worked with researchers from the seismology team at the University of Melbourne to better understand their solution for optimising seismic array design to date: an analytical method called SENSI that has been developed by Tramelli et al. (2013) to design seismic networks, including the GipNet array deployed to monitor seismicity in the Gippsland region in Victoria, Australia. The underlying physics and mechanics of the method are straightforward, and when applied sensibly, can be used as a basis for the design of seismic networks anywhere in the world. Our engineers have built an application leveraging a previously developed Geophysical Processing Toolkit (GPT) as an application platform and harnessed the scalability of a Cloud environment provided by the EASI Hub, which minimised the overall development time. The GPT application platform provided the groundwork for a web-based application interface and enabled interactive visualisations to facilitate human-computer interaction and experimentation.
Evaluation of the tropical water vapor of CMIP6 GCMs with ESA CCI+ “Water Vapor” climate data records: Insights from large-scale atmospheric circulation
Authors: Brogniez Helene , He Jia , Picon Laurence , Schroder Marc , Preusker René , Danne Olaf
Published: March 2021

Water vapor is one of the fundamental elements in the atmosphere. Its distribution is strongly associated with large-scale atmospheric circulation. Here the new global water vapor climate data records (CDR) generated within the ESA Water Vapor CCI+ project (WV_cci) is used to perform a comprehensive evaluation of total column water vapor provided by 21 global climate models (CMIP6 framework). The ESA WV_cci CDRs cover the period 2002-2017 with a daily frequency and a regular 0.5° spatial resolution. The focus is on the tropical region (30°S - 30°N). The observational diagnostic relies on the decomposition of the tropical atmosphere into large-scale dynamical regimes using the 500 hPa atmospheric vertical velocity w500 (in hPa/day) as a proxy. The ESA WV_cci and the CMIP6 data are then sorted according to dynamical regimes (intervals of 10 hPa/day) allowing to study the evolution of the regimes in terms of frequency of occurrence and is linked to water vapor variation. While the basic picture of the tropical atmosphere is properly represented by the models (moister in ascending branches, drier in subsiding branches) there are noticeable differences in the patterns that will be discussed. The inter-annual variation of water vapor for both observation and the models will be analyzed, and the trend significance are assessed using Mann-Kendall test. This highlights the interest of water vapor climate data records for model evaluation.
Climate forcing due to the snow albedo effect in the regional climate models from the CORDEX Flagship Pilot study LUCAS.
Authors: Daloz Anne Sophie , Schwingshackl Clemens , Mooney Priscilla , Strada Susanna , T. Lund Marianne , Breil Marcus , M. Cardoso Rita , Davin Edouard , Hoffmann Peter , Katragkou Elena , C.A. Lima Daniela , Meier Rony , de Noblet-Ducoudre Nathalie , Rechid Diana , M. M. Soares Pedro , Sofiadis Giannis , Strandberg Gustav , H. Toelle Merja
Published: March 2021

In the Northern Hemisphere, the seasonal snow cover plays a major role in the climate system via its effect on albedo and surface fluxes, influencing the variations in near surface temperature. Across climate models, the parameterization of the snow-albedo relationship remains a source of high uncertainty, often leading to large biases in the representation of local and global climate.

In this work, we analyze regional climate model outputs from the flagship pilot study (FPS) Land Use and Climate Across Scales (LUCAS) of the European branch of the Coordinated Downscaling Experiments EURO-CORDEX. These experiments include land use change forcing to identify robust biophysical impacts of land use changes on climate across regional to local spatial scales and at various time scales from extreme events to multi-decadal trends.

Here, we evaluate the ability of this ensemble of regional climate models combined with different land surface models to capture the climate forcing from the snow albedo effect in Europe, by comparing their representation of the Snow Atmosphere Sensitivity Index (SASI) with reanalyses and satellite observations. A specific focus is given to three sub-regions: Scandinavia, East Baltic and East Europe. For all regions, during the accumulation period, the models tend to largely agree on the representation of SASI. However, during the ablation period, there are large disparities, which are related to differences in the representation of the snow cover fraction in the models. This suggests that the choice of the land model is more critical for the representation of the climate forcing from the snow albedo effect than the atmospheric model. These differences in SASI leads to discrepancies in the simulated surface temperature. 
Water masses variability in inner Kongsfjorden during 2010-2020
Authors: De Rovere Francesco , Chiggiato Jacopo , Langone Leonardo , Schröeder Katrin , Miserocchi Stefano , Giglio Federico
Published: March 2021

Kongsfjorden is an Arctic fjord situated in the Svalbard archipelago. The fjord hydrography is influenced by the warm and saline Atlantic water from West Spitsbergen Current (WSC) flowing northward on the shelf slope and the cold and fresh polar waters circulating on the shelf. Once several conditions are satisfied, Atlantic waters from the WSC can extensively flood the fjord. These intrusions are majorly confined to the summer season although some strong events have been identified also in winter. In this study, a decade of continuous observations is used to examine changes in water properties and water masses variability in inner Kongsfjorden, with a special focus on Atlantic water intrusions. Data have been gathered by the National Research Council of Italy (CNR) through the Mooring Dirigibile Italia (MDI) in addition to summer CTD surveys. MDI was deployed in September 2010 at 100m depth and comprises various temperature and salinity sensors placed at different depths. Analysis of the longest temperature series reveals a positive linear trend since 2010. However, both temperature and salinity present a peak at the beginning of 2017 and decreasing values toward the end of the series. No significant trends were found when considering the monthly water column temperature as average of few sensors’ measurements. Yet, differentiating the seasonal contributions reveals that summer temperatures feature a fast warming (0.26 °C/yr) whereas winters do not show a statistically significant linear trend. Temperature and salinity observations gathered at 25 and 85m depth are used to depict water masses variability accorfing to previous water masses classifications. Some evidences are noted: first, events of Atlantic water intrusions are always confined near the bottom and they are never seen at 25m, whilst summer freshwater is found only in the near surface. Second, the timing of occurrence of these two water types seems to be related: the presence of large freshwater volumes close to the surface are preceded by the arrival of warm and saline waters. This evidence is interpreted as the melting signal of Kronebreen, the largest tidewater glacier in Kongsfjorden, triggered by the intrusion of Atlantic water. As a result, the large freshwater input manages to dilute the Atlantic water settled near the bottom. Third, the temperature and salinity peaks at the beginning of 2017 are associated to a massive Atlantic water flooding in the inner fjord lasting several months in summer/autumn 2016 and 2017. After this period, Atlantic water is seen only for few months in summer 2019. CTD measurements are used to depict the summer hydrography of Kongsfjorden and the focus is drawn on the characterisation of the seasonal cycle for each available year of measurements. Finally, the drivers of Atlantic water intrusion events are examined, as the presence of low pressure systems and the wind patterns in the region.
EASYDAB (Earth System Data Branding) for FAIR and Open Data
Authors: Ganske Anette , Kaiser Amandine , Kraft Angelina , Heydebreck Daniel , Lammert Andrea , Thiemann Hannes
Published: March 2021

As in many scientific disciplines, there are a variety of activities in Earth system sciences that address the important aspects of good research data management. What has not been sufficiently investigated and dealt with so far is the easy discoverability and re-use of quality-checked data. This aspect is taken up by the EASYDAB label.

EASYDAB1 is a currently developed branding for FAIR and open data from the Earth System Sciences. The branding can be adopted by institutions running a data repository which stores data from the Earth System Sciences. EASYDAB is always connected to a research data publication with DataCite DOIs. Data published under EASYDAB are characterized by a high maturity, extensive metadata information and compliance with a comprehensive discipline-specific standard. For these datasets, the EASYDAB logo is added to the landing page of the data repository. Thereby, repositories can indicate their efforts to publish data with high maturity.

The first standard made for EASYDAB is the ATMODAT standard2, which has been developed within the AtMoDat3 project (Atmospheric Model Data). It incorporates concrete recommendations and requirements related to the maturity, publication and enhanced FAIRness of atmospheric model data. The requirements are for rich metadata with controlled vocabularies, structured landing pages, file formats (netCDF) and the structure within files. Human- and machine-readable landing pages are a core element of the ATMODAT standard and should hold and present discipline-specific metadata on simulation and variable level. 

The ATMODAT standard includes checklists for the data producer and the data curator so that the compliance with the standard can easily be obtained by both sides. To facilitate automatic checking of the netCDF files headers, a checker program will also be provided and published with DOI. Moreover, a checker for the compliance with the requirements for the DOI Metadata will be developed and made openly available. 

The integration of standards from other disciplines in the Earth System Sciences, such as oceanography, into EASYDAB is helpful and desirable to improve the re-use of reviewed, high-quality data. 

 1www.easydab.de

2https://cera-www.dkrz.de/WDCC/ui/cerasearch/entry?acronym=atmodat_standard_en_v3_0

3www.atmodat.de
On the possibility of an intra-Earth source of Sq-variations of the Earth's magnetic field
Authors: Zhumabayev Beibit , Vassilyev Ivan
Published: March 2021

Analysis of the direction of motion of the vector of Sq-variations of the Earth's magnetic field, depending on the time of day and season of the year, shows that the observed Sq-variation is similar to the magnetic field created by a negatively charged spherical body moving in space. Transformations of the Sq-variation vector from the local coordinate system of the magnetic observatory to the ecliptic coordinate system are performed. A possible connection between the origin of the Sq-variation and the electric dipole moment of quartz molecules oriented towards the center of the Earth during the crystallization of the mineral and causing the electric and dipole magnetic fields of the Earth is considered. A scheme for conducting an experiment that allows us to separate the effects of extraterrestrial and extraterrestrial sources of Sq-variations is proposed.
Consistent large-scale response of hourly extreme precipitation to temperature variability
Authors: Ali Haider , Fowler Hayley , Lenderink Geert
Published: March 2021

Hourly precipitation extremes can intensify with higher temperatures at higher rates than theoretically expected from thermodynamic increases explained by the Clausius-Clapeyron (CC) relationship (~6.5%/K), but local scaling with surface air temperature is highly variable. Here, we use daily dewpoint temperature, a direct proxy of absolute humidity, as the scaling variable instead of surface air temperature. Using a global dataset of over 7000 hourly precipitation gauges, we estimate the at-gauge local scaling across six macro-regions; this ranges from CC to 2xCC for more than 60% of gauges. We find positive scaling in subtropical and tropical regions in contrast to previous work. Moreover, regional scaling rates show surprisingly universal behaviour at around CC, with higher scaling rates in Europe. Our results show a much greater consistency of scaling across the globe than previous work, usually at or above the CC rate, suggesting the relevance of dewpoint temperature scaling to understand future changes.   