bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of landslide-triggering rainfalls in a typhoon-prone region of the Philippines
Authors: Abancó Clàudia , Medina Vicente , Bennett Georgina L. , Matthews Adrian J. , Hürlimann Marcel
Published: March 2022

The rain that falls weeks or months before the occurrence of landslides can play a major role in the failure process, therefore it is crucial to account for it in hazard assessments and warning systems. It is especially relevant in tropical areas, where the amount of water that falls during wet seasons can be very high. In the Philippines, rainfall and typhoon events trigger Multiple-Occurrence Regional Landslide Events (MORLEs, Crozier, 2005), which cause hundreds of fatalities and significant economic damage every year.

Satellite-based rainfall measurements (IMERG GPM) associated with three typhoons that triggered MORLEs in the area of Itogon (Benguet, Philippines) and water infiltrated into the soil during the previous months are analysed. Data from the three typhoons are compared with 560 high intensity rainfall events (from period 2000-2020) that did not trigger regional landslide events. Results show that landslides occurred when typhoon rainfall exceeds 300 mm and the water infiltrated was higher than 1000 mm in the previous months. For one specific landslide-triggering typhoon event, satellite-based soil moisture data (1 m top soil layer) are analysed and compared to other non-landslide triggering rainfalls. Results do not show a clear correlation of critical rainfall and soil moisture values that triggered landslides.

The findings of this work highlight that the antecedent rainfall, and in particular its infiltration below the top soil layer, plays a major role in the triggering process of landslides, especially in tropical regions.

 Crozier, M.J. Multiple-occurrence regional landslide events in New Zealand: Hazardmanagement issues. Landslides 2, 247–256 (2005). https://doi.org/10.1007/s10346-005-0019-7
Attributing compound events to anthropogenic climate change
Authors: Zscheischler Jakob , Lehner Flavio
Published: March 2022

Extreme event attribution answers the question whether and by how much anthropogenic climate change has contributed to the occurrence or magnitude of an extreme weather event. It is also used to link extreme event impacts to climate change. Impacts, however, are often related to multiple compounding climate drivers. Because extreme event attribution typically focuses on univariate assessments, these assessments might only provide a partial answer to the question of anthropogenic influence to a high-impact event. We present a theoretical extension to classical extreme event attribution for certain types of compound events. Based on synthetic data we illustrate how the bivariate fraction of attributable risk (FAR) differs from the univariate FAR depending on the extremeness of the event as well as the trends in and dependence between the contributing variables. Overall, the bivariate FAR is similar in magnitude or smaller than the univariate FAR if the trend in the second variable is comparably weak and the dependence between both variables is moderate or high, a typical situation for temporally co-occurring heatwaves and droughts. If both variables have similarly large trends or the dependence between both variables is weak, bivariate FARs are larger and are likely to provide a more adequate quantification of the anthropogenic influence. Using multiple climate model large ensembles, we apply the framework to two case studies, a recent sequence of hot and dry years in the Western Cape region of South Africa and two spatially co-occurring droughts in crop-producing regions in South Africa and Lesotho.
Observations of contrail cirrus in ice-subsaturated environments and implications for mitigating the climate impact of aviation
Authors: Li Yun , Mahnke Christoph , Rohs Susanne , Bundke Ulrich , Spelten Nicole , Dekoutsidis Georgios , Groß Silke , Voigt Christiane , Schumann Ulrich , Petzold Andreas , Krämer Martina
Published: March 2022

Contrail cirrus, including line-shaped contrails, cause a net warming effect to the Earth’s climate. Of great importance to estimate their radiative effect is the coverage and mean optical thickness, which are closely associated with the conditions affecting the formation and microphysical properties of contrail cirrus.

This study focuses on contrail cirrus observations over central Europe and the Northeast Atlantic from the airborne ML-CIRRUS campaign in 2014. To identify contrail cirrus in the dataset of cloud observations, the following method is used: (1) the Schmidt-Appleman-Criterion is calculated, determining whether the environmental conditions are suitable for contrail formation, (2) an aircraft plume detection algorithm is adapted, identifying if a measured air mass originated from aircraft exhaust and (3) based on (1) and (2), statistical analyses are performed, resulting in a description of the general characteristics of contrail and natural cirrus.

Applying this method, not only are contrail cirrus and natural cirrus separated by their different microphysical properties (mean mass radius, ice crystal number and ice water content), but the favorable spatial occurrence conditions of contrail cirrus are also detected: Contrail cirrus occur with rather high frequency at the cruising altitude, where the atmospheric pressure ranges from 200 to 245 hPa (ambient temperature 207 – 218 K). Of particular interest is the occurrence of contrail cirrus in slightly ice-subsaturated environments, where the relative humidity with respect to ice (RHice) centers around 90 % instead of ice supersaturation as believed hitherto. This also differs from the in-cloud RHice centering at 100 % in natural cirrus. Inspecting the occurrence frequency of air masses with RHice > 90 % in comparison to RHice > 100 % from passenger aircraft observations above Europe and the North Atlantic during the IAGOS-MOZAIC period from 1995 to 2010, about 45 % of the air masses are prone to contrail cirrus formation instead of 30 % found in merely ice-supersaturated environments. Considering this finding in the routing of passenger flights, the avoidance of slightly ice-subsaturated to ice-supersaturated conditions might lead to a reduction of the occurrence of contrail cirrus and thus to a possible mitigation of their climate impact.

[Note: This work is carried out under the EU H2020 Research and Innovation Action “Advancing the Science for Aviation and Climate (ACACIA)”, funded by the European Union under the Grant Agreement No. 875036.]
Langmuir waves associated with magnetic holes in the solar wind
Authors: Boldu-O´Farrill Treviño Joan Jordi , Graham Daniel , Morooka Michiko , Karlsson Tomas , Khotyaintsev Yuri , André Mats , Souček Jan , Maksimovic Milan
Published: March 2022

Langmuir waves (electrostatic waves near the electron plasma frequency) are often observed in the solar wind, playing an important role in the energy dissipation of electrons. The largest amplitude waves are typically associated with type II and III solar radio bursts and planetary foreshocks. However, Langmuir waves not connected with radio bursts are also found in the solar wind. The causes of these Langmuir waves are not well understood. Langmuir waves are also found around magnetic holes, a localised depression of the magnetic field strength. This study aims to investigate the relationship between Langmuir waves and magnetic holes in the solar wind using electric and magnetic field measurements performed by the Solar Orbiter’s RPW and MAG instruments during 2020 and 2021. We identified a large set of Langmuir wave events from the RPW/TDS (Time Domain Sampler) waveform data using the plasma density estimated from the spacecraft’s potential obtained by RPW, showing that ~7% of them have been spotted inside magnetic holes. We will compare these events with local plasma conditions analysing the electron distribution functions, and discuss the mechanisms that may lead to the generation of Langmuir waves associated with magnetic holes in the solar wind.
Coupling sorption and biodegradation of Emerging Organic Compounds with geochemical modeling
Authors: Rodriguez-Escales Paula , Canelles Arnau , Sanchez-Vila Xavier
Published: March 2022

Understanding the fate of Emerging Organic Compounds (EOCs) is quite complex. It depends on several direct processes (e.g. sorption or biodegradation) but also on indirect ones (e.g. reduction oxidation processes, soil-water interaction). For that, modeling is a useful tool to evaluate it. Nevertheless, most of the models in literature are quite simple. Most of them are completely disconnected from the geochemical conditions of the environmental systems and it has been widely proved that both sorption and degradation of EOCs depends on that, specially, on pH and reduction oxidation dynamics. For that, in this work we have evaluated different conceptual models of EOC’s fate in the context of Managed Aquifer Recharge. The tested models were from the simplest one (fully disconnected from the geochemistry) to the more complex one (coupling both EOC’s sorption and biodegradation to the geochemistry). The models were validated with a column experiment, which reproduced the fate five EOC’s (paracetamol, diuron, benzophenone-3, carbamazepine and sulfamethoxazole)  in an infiltration pond with a reactive barriers made up of compost (3 types of columns, 0% of compost, 10% and 50%) (Modrzyński et al., 2021). The EOC’s models were also coupled with a previous geochemical model focused in carbon and nitrogen cycle and validated with the same experiments (Canelles et al., 2021). Our results demonstrate that a better reproduction is achieved when both sorption and biodegradation are coupled with a geochemical reactive transport, specially for systems with a higher presence of organic carbon.   

This work was financially supported by the Catalan Research Project RESTORA (ACA210/18/00040), by the Spanish Ministry of Science and Innovation through MONOPOLIOS (RTI2018-101990-B-100, MINECO/FEDER), as well as the EU project MARADENTRO (PCI2019-103425). 
Suitability of Environmental Tracers as groundwater dating tools in the next decade
Authors: Sültenfuß Jürgen
Published: March 2022

In the last decade a large and various set of groundwater modelling tools were developed and provide wide range of applications. In contrast, the number of tools for field studies remains limited. One of the tools are Environmental Tracers: substances of natural or anthropogenic origin which enter the groundwater system and were traced on their way to the discharge zone. Methods to interpret the tracer concentrations and how groundwater dynamics could be derived were published also in textbooks by now. One parameter to describe groundwater dynamics is residence time, age or flow velocity. All these terms are interchangeable.

Here, I will present an overview on applied Environmental Tracers to determine groundwater ages and assess their current limitation. Specially, I will make some predictions on the applicability for the near future. This includes some estimates about the concentration changes for the input of the tracers for younger groundwater and the consequences for reliability of the derived ages.

Also, I give an overview on the state of the measurement capacities and the possible development. It will be estimated how the analytical errors affect the ages. These constraints must be recognized for planning of field studies for groundwater age determination.
The exoplanetary magnetosphere extension in Sun-like stars based on the solar wind and solar UV emission
Authors: Reda Raffaele , Giovannelli Luca , Alberti Tommaso , Berrilli Francesco , Bertello Luca , Del Moro Dario , Di Mauro Maria Pia , Giobbi Piermarco , Penza Valentina
Published: March 2022

The solar activity in form of coronal mass ejections or solar wind disturbances, such as slow or high speed streams, affects the circumterrestrial electromagnetic environment, with a primary effect on the magnetosphere, compressing and perturbing it. Here, in order to connect the long-term solar activity variations to solar wind properties, we use measurement of a proxy for chromospheric activity, the Ca II K index, and solar wind OMNI data for the time interval 1965-2021, which almost entirely covers the last 5 solar cycles. By using both a cross correlation and a mutual information approach, a 3.6-year mean lag has been found between Ca II K index and solar wind dynamic pressure. This result allows us to obtain a relationship between the solar UV emission and the solar wind dynamic pressure, enabling us to derive the Earth’s magnetospheric extension over the last 5 solar cycles.
Moreover, the advantage of having used the Ca II K index proxy is that the relation found for the Sun can be easily extended to other stars with similar properties (i.e. Sun-like stars). To this scope, the model is then used to study the effect of stellar wind dynamic pressure on the magnetosphere of Earth-like planets orbiting at 1 AU around a sample of Sun-like stars.
Clustering of groundwater hydrographs to reveal common patterns for the Baltic region
Authors: Retike Inga , Bikše Jānis , Kalvāns Andis , Popovs Konrāds , Haaf Ezra
Published: March 2022

The aim of this study is to identify salient patterns of groundwater level dynamics in the Baltic region. The study investigates correspondence between (grouped) groundwater level dynamics and catchment, well and physiographic site characteristics. The analysis was carried out in five consecutive steps. Firstly, 1691 groundwater hydrographs were collected from Baltic surveys responsible for national groundwater level monitoring (Latvain Environment, Geology and Meteorology Centre; Estonian Environment Agency; Geological Survey of Lithuania). Observation wells represent both unconfined and confined aquifers. Groundwater level time series were checked for errors and treated according to an approach proposed by Retike et al., 2021. Secondly, the dataset was limited to the time period when daily groundwater level measurements were available in all three countries. The resulting time period covers 8.5 years at 689 wells. Then, the acceptable amount of missing values was defined as the balance between most complete hydrographs, the number of retrained hydrographs and spatial coverage of the wells. Gaps (if present) in the remaining 283 wells were filled with missForest (Stekhoven and Bühlmann, 2012). The results were visually inspected to identify groundwater hydrographs with suspicious modeling patterns and five wells were removed from further analysis based on expert judgment. Finally, 278 groundwater hydrographs (136 from Latvia, 58 from Lithuania and 86 from Estonia) were retained and clustered using Hierarchical Cluster Analysis. The identified clusters of groundwater level times series were then explained using descriptive geological (like aquifer lithology, thickness), hydrological (distance to the nearest stream), climatic (precipitation, seasonality) and anthropogenic (land use) characteristics. This research is funded by the Latvian Council of Science, project “Spatial and temporal prediction of groundwater drought with mixed models for multilayer sedimentary basin under climate change”, project No. lzp-2019/1-0165.

References:

Retike, I., Bikše, J., Kalvāns, A., Dēliņa, A, Avotniece, Z., Zaadnoordijk, W.J., Jemeljanova, M., Popovs, K., Babre, A., Zelenkevičs, A., Baikovs, A. (2022) Rescue of groundwater level time series: How to visually identify and treat errors. Journal of Hydrology, 605, 127294. https://doi.org/10.1016/j.jhydrol.2021.127294

Stekhoven, D.J., Bühlmann, P. (2012) Missforest-Non-parametric missing value imputation for mixed-type data. Bioinformatics, 28, 112–118. https://doi.org/10.1093/bioinformatics/btr597
Multi-objective trade-off analysis in operating dams for the environment: The case of the Lower Volta River
Authors: Owusu Afua , Zatarain Salazar Jazmin , Mul Marloes , van der Zaag Pieter , Slinger Jill
Published: March 2022

Historically, overcoming energy deficits or increasing water security has translated into a demand for more dams. However, the construction and conventional operation of dams have had contradictory outcomes, negatively impacting natural riverine ecosystems and riparian communities. In the Lower Volta River Basin in Ghana, the construction of the Akosombo dam, with a residence time of 3.9 years, led to the formation of the largest artificial lake by surface area and the resettlement of 80,000 people. Furthermore, the riverine ecosystem changed, as did the lives of the downstream communities who lost their traditional livelihoods. In contrast, the Akosombo dam is credited for powering Ghana’s industrialization and making it one of the more developed countries in West Africa. Thein lies the issue: there exists a trade-off between anthropogenic water demands such hydropower, irrigation or recreation on the one hand, and water for river ecosystems and services on the other. A transparent approach to managing these trade-offs between multiple water users is therefore needed to operate dams equitably. In this study, an Evolutionary Multi-Objective Direct Policy Search (EMODPS) is applied to case of the Lower Volta River Basin to identify the multi-sectorial trade-offs that exists between water users.  A designer environmental flow is incorporated as an objective rather than as a constraint and additionally, different policy framings and scenarios encompassing climate change and varying energy futures are investigated. This study highlights the challenges faced by dam operators in balancing water demands, and also identifies synergies and opportunities for compromise in the Lower Volta River.
Performance of Deep Learning pickers in routine network processing applications
Authors: Fernandez-Prieto Luis M. , García José Enrique , Villaseñor Antonio , Sanz Verónica , Ammirati Jean-Baptiste , Díaz Eduardo , García Carmen
Published: March 2022

In recent years there have been a great progress in earthquake detection and picking arrival times of P and S phases using Deep Learning algorithms. However, the general adoption of these methods for the routine processing of monitoring networks has been held back by factors such as the availability of well documented software, computational resources, and a gap in knowledge of these methods. We have analyzed recent available Deep Learning pickers, comparing the results against data picked by a human operartor and against non-Deep Learning programs. We have used data recorded in several locations, with different characteristics and triggering mechanisms, such as volcanic eruptions, induced seismicity and local eartquakes, recorded using different types of instruments. We have found that the Deep Learning algorithms are able to achieve results comparables to a human operator, and several times better than a classical program, specially in data with a low signal to noise ratio. They are very efficient at ignoring large amplitude transient noise and at picking S waves, a task that is often difficult even for experienced analysts, and they require very few parameters to tune (often only the probability threshold) so an in-depth knowledge of neural networks is not required. (This research has been funded by  Spanish Ministry of Science and Innovation MICINN/AEI/10.13039/501100011033 grants CGL2017-88864-R and PRE2018-084986).
Revisited Rainfall Threshold In the Indonesia Landslide Early Warning System 
Authors: Yuniawan Ragil A , Rifai Ahmad , Faris Fikri , Westen Cees van , Jetten Victor , den Bout Bastian , Subiyantoro Andy , Muntohar Agus , Musthofa Akhyar , Hidayat Rokhmat , Hidayah Alidina , Ridwan Banata , Priangga Eka , Satyaningsih Ratna , Sutanto Samuel
Published: March 2022

Landslides are one of the most disastrous natural hazards that frequently occur in Indonesia. Since 2017, Balai Sabo has developed an Indonesia Landslide Early Warning System (ILEWS) by utilizing a single rainfall threshold for an entire nation. This condition might lead to inaccuracy of the landslide prediction. Therefore, this study aims to improve the accuracy of the system by updating the rainfall threshold. This study focused on Java Island, where most of the landslides in Indonesia occur. We analyzed 420 landslide events with the one-day and three-day cumulative rainfall for each landslide event. Rainfall data were obtained from the Global Precipitation Measurement (GPM), which is also used in the ILEWS. We propose four methods to derive the thresholds, 1st is the existing threshold applied in the Balai Sabo-ILEWS, the 2nd and the 3rd use the average and minimum of rainfall that trigger landslides, respectively, and the 4th uses the minimum values of rainfall that induce major landslides. We employed the Receiver Operating Characteristic (ROC) analysis to evaluate the predictability of the rainfall thresholds. The 4th method shows the best result compared to the others, and this method provides a good prediction of landslide events with a low error value. The chosen threshold will be used as a new threshold in the Balai Sabo-ILEWS.
Richard’s equation revisited – the challenge to reconstruct non-equilibrium field retention data with soil hydraulic models
Authors: Wöhling Thomas , Mietrach Robert
Published: March 2022

The origins of the Richard’s equation date back more than a century but it is still the most commonly used model to describe variably saturated soil water movement. It requires the specification of the characteristic relationships between soil water content, tensiometric pressure and hydraulic conductivity, which can be subsumed as soil hydraulic models. Numerous soil hydraulic models and variants thereof have been developed to mimic the behaviour of natural soils, including hysteresis, macro-pore flow, and dynamic non-equilibrium flow. Despite the progress being made, it is often difficult to accurately simulate retention data derived from undisturbed field soils.

This work presents a benchmark inverse modelling study for 1D soil water movement and field retention data from a wetting-drying cycle using state-of-the-art soil hydraulic models. The main aim is to test the ability of the different models to reproduce the field data. The soil hydraulic models tested are, among others, the van Genuchten-Mualem model (VGM, 1976, 1980), VGM with hysteresis (Kool and Parker, 1987), Brooks-Corey (1966), Dual porosity (Durner, 1994) and the non-equilibrium flow model by Diamantopoulus (2015).

In our study, we used an implementation of the Richards equation with the highly efficient and numerically stable Methods-of-Line scheme. Best-fit estimates and parameter posterior distributions were derived using the Markov-Chain Monte Carlo sampling algorithm DREAM_ZS and time series of soil water content and tensiometric pressure. The field data shows clear signs of non-equilibrium flow. It originates from an intensively studied, inverted-lysimeter site with Pumice soils under grass from the central part of the North Island of New Zealand.

Results demonstrate that none of the models was able to accurately mimic soil water content and tensiometric pressure data simultaneously at all times. Model deficiencies were identified particularly for the two wetting events, where all models underestimated soil water content while tensiometric pressure matched the data closely. We hypothesise that at least part of the discrepancies relate to an oversimplification of the hydraulic conductivity function for non-equilibrium flow.

This study is limited to a single data set and by several assumptions that are commonly made in inverse parameter estimation studies. The better assessment and implementation of measurement error (structures) might alleviate (or mask) some of the discrepancies between model simulations and data. However, this is apparently not the solution to the problem. Dynamic non-equilibrium flow has been observed in natural soils in several well-conducted field experiments. Our results are just one example that demonstrates the need to improve soil hydraulic modelling by revisiting the physics of fundamental processes in natural soils. 
Greenhouse gas emissions and global warming potentials of four paludiculture plants in a fen peatland in southern Germany 2019
Authors: Bockermann Carla , Eickenscheidt Tim , Drösler Matthias
Published: March 2022

The concept of paludicultures is growing in importance as a promising sustainable alternative to current agricultural use of organic soils. Besides agricultural and economic viability, quantifying the climatic effects of paludicultures is essential to give reliable policy advice and facilitate sustainable management decisions with regard to climate change. Emission factors (EFs) of the relevant greenhouse gases (GHG) carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) for a variety of potential paludiculture plants are still rare, especially from comparable treatment and site conditions.

In 2016, different temperate fen plant species (Carex acutiformis, Phragmites australis, Phalaris arundinacea, Typha latifolia) were established as paludicultures at a former grassland on fen peatland in the Freisinger Moos within the scope of the MOORuse-project. Three years after plant establishment, we measured fluxes of CO2, CH4 and N2O to obtain a one-year budget (2019) using manual closed chambers. Besides gas flux measurements we observed vegetation parameters and biomass development including a winter harvest. In 2019, the annual mean water level in these four plant treatments were between 5 to 10 cm below surface. We are currently analysing the data and will give an overview of the complete GHG balances and resulting global warming potentials of the four paludiculture plants. With these values we start to fill an important gap of knowledge for assessing the climate protection potential of paludicultures.

The MOORuse-project is funded by the European Union (European Regional Development Fund) and the Bavarian State Ministry of the Environment and Consumer Protection [funding code: 64b-U8639.1-2015/8-14].
(Li,Na)-P substitution in garnet as an indicator of UHP conditions 
Authors: Racek Martin , Jeřábek Petr , Štípská Pavla , Závada Prokop , Svojtka Martin , Hasalová Pavlína , Veselovský František
Published: March 2022

Findings of coesite and diamond in quartzo-feldspathic rocks confirmed the idea that continental crust, despite its buoyancy, can be subducted to ultra-high pressure (UHP) conditions. In addition to these index minerals, UHP conditions can be reflected by specific minor elements incorporated in major minerals, which was well demonstrated in mantle rocks, but poorly explored in continental crust. Here, we investigate garnet with coesite inclusions from subducted metagranites of the Eger Crystalline Complex, Bohemian Massif. The garnet shows chemically distinct concentric domains with minor amounts of P, Na, and Li. From the correlation of these elements, we infer (Na,Li)1P1M2+-1Si-1 substitution, where the Na deficiency is compensated by Li in a 2:1 ratio. This is the first time that such coupled substitution in garnet has been defined and clearly connected to UHP conditions in natural samples, proving itself as a new tool to reveal UHP conditions in garnet. In addition, garnet in subduction zones needs to be considered as an important Li carrier, able to transport significant amounts of Li into the Earth's mantle.
How to avoid mass deaths in the emergency avoidance process of mountain disasters: Lessons from the mountainous areas of western China
Authors: Chen Rong , Tan Rongzhi , Zhang Jianqiang
Published: March 2022

The impact of mountain disasters on human society continues to increase under the background of climate change and social economy development, especially for the developing countries or regions with relatively backward social and economic development level and fragile natural ecological environment. China is one of the countries suffered most serious mountain disasters in the world. In particular, after Wenchuan earthquake in 2008, the frequency and scale of secondary mountain disasters caused by heavy rainfall and the earthquake increased significantly, which seriously threatens the life and property safety and post-disaster reconstruction in earthquake-hit areas. Therefore, some events with mass deaths and injuries occurred. For example, on July 10, 2013, the massive landslide in Sanxi Village, Zhongxing Town, Dujiangyan City, Sichuan Province caused 166 deaths or missing. On June 24, 2017, the high mountain collapse in Xinmu Village, Dixi Town, Maoxian County, Sichuan Province buried 62 farm houses, caused 10 deaths, 73 missing and 3 injures. What’s more, mountain disasters also caused mass deaths and injuries in some areas less affected by Wenchuan earthquake. On June 28, 2012, the large debris flow occurred in Aizi Gully, Ningnan County, Sichuan Province, China was the annually most serious debris flow in construction site in China, resulting in 40 deaths or missing. On June 28, 2020, debris flow caused 17 deaths or missing in Caogu Township, Mianning County, Liangshan Prefecture, China. Lots of disaster cases show that disaster awareness and emergency capacity are the base of scientific emergency avoidance，which  is one of the important ways to reduce the casualties of mountain disasters in high-risk areas. Through the analysis of disaster cases, the experience and lessons of mountain disasters in western China were summarized and the measures to avoid mass deaths and injuries in the process of mountain disaster emergency avoidance were explored. So this research aims to  provide a scientific basis for the reduction of casualties in mountain disasters in similar areas.
Selecting Good Quality Official and Citizen Science Rain Gauge Data and Blending with Radar for More Accurate Rainfall Representation 
Authors: O'Hara Tess , Lewis Elizabeth , McClean Fergus , Fowler Hayley , Parkin Geoff
Published: March 2022

Rainfall data collected by citizen scientists is typically regarded as low quality and therefore remains underused in hydrological applications. Conversely, official data collected by professional organisations is often treated as more reliable than it really is. Here we demonstrate that value can be extracted from citizen science rainfall data by applying automated statistical quality control combined with manual checks. We also consider the pros and cons of citizen science rain observations.

Carefully selected rain data from official and citizen science gauges have been blended with radar.  Examples of how rainfall depths vary depending on the data inputs are presented, highlighting the benefit of incorporating all available data sources. This approach is particularly important when determining rainfall during spatially and temporally variable convective storms. The research is concerned with convective storms that resulted in pluvial flooding in urban areas of the UK between 2014 – 2018, however, the methodology could be implemented in any location where hourly (or shorter interval) rain gauge data and radar are available.  
Spatio-temporal Analysis of the Southern Ocean Storms Using the Australian Seismic Arrays
Authors: Pandey Abhay , Tkalčić Hrvoje
Published: March 2022

The microseismic energy of the Earth is ubiquitously present and recorded on seismographs around the globe. It has been observed that the Rayleigh waves in the 20-50 s period band are excited due to the large oceanic storms (stormquakes). Although surface waves associated with the ocean-wave activity are well documented and have been used, the interaction between the storms and the ocean can also generate energy that propagates as seismic body waves. Such body waves traverse through the Earth’s deep interior and interact with the internal boundaries in very much the same way as the waves generated by earthquakes. The primary motivation of our study is to investigate the feasibility of utilizing stormquakes in a similar way we utilize earthquakes in passive seismology. The first step is to identify and detect permanent and moving sources in near real-time seismic recordings, considering their different natures.

We process continuous waveforms recorded by the Australian arrays of different apertures using state-of-the-art array-processing technique, the Capon method. Firstly, we infer the source location and characteristics of body-wave seismic signals generated throughout the entire life cycle of the oceanic storms in the southern hemisphere. Then we validate the source location of the seismic signals from the storms with the back-projection method. We further benchmark the observations via synthetic experiments by modelling the seismic sources generated by oceanic storms. These experiments help determine the method's strengths and weaknesses to detect stormquake body-wave signals. The location of the body-wave sources associated with the distant storms may provide new datasets which can be utilized and complement seismic data for surveying the Earth’s interior structures.
​​The role of cold pools and microphysics schemes in the organization of convection
Authors: Casallas Alejandro , Tompkins Adrian , Thompson Gregory
Published: March 2022

Convective self-aggregation can spontaneously appear in radiative-convective equilibrium (RCE) simulations using idealized experiments with cloud-resolving models and it has been suggested that cold pools could play an important role in the development of organization, by delaying its onset when the cold pools have larger radii. Cold pool radius is determined by the amount of precipitation produced by microphysical schemes (precipitation efficiency) and the strength of the evaporation. We demonstrate this using idealized RCE experiments with the WRF model that convective cold pool characteristics can differ dramatically between 5 of the standard schemes commonly used in the model. We then systematically increase/decrease the cold pool size by changing the evaporation of rain in the 5 microphysics schemes to observe the impact on convective aggregation. One complication in interpreting the results of such experiments is that a change in the evaporation of rain also produces a change in the profile of net convective heating that could also impact organization. To isolate this effect,  a second set of experiments is performed by artificially increasing (decreasing) the horizontal wind speed used in the surface flux calculation for all grid points determined to lie within cold pool interiors to produce a faster (slower) cold pool recovery and impact their ultimate radii. The ensembles of the experiments show that the larger the cold pool radii, the larger the spatial variance of the water vapor path is in the equilibrium state and they also demonstrate how the cold pool size impacts the strength and even the sign of the surface latent heat contribution to aggregation. Nonetheless, the strong forcing of aggregation by radiation feedbacks in these experiments means that the cold pool changes do not produce large modifications to the aggregation onset time. Thus the aggregation onset may be more strongly impacted by the microphysical processes that determine the convective anvil size and low-level cloud cover, and thus ultimately the cloud-radiative forcing. This is under investigation in ongoing experiments that modify the ice fall speed and the autoconversion of cloud water to rain in the 5 microphysical schemes, which will also be reported in the presentation.
Crustal and upper mantle 3D Vs structure of the Pannonian Region from joint earthquake and ambient noise Rayleigh wave tomography
Authors: Timkó Máté , El-Sharkawy Amr , Wiesenberg Lars , Fodor László , Wéber Zoltán , Lebedev Sergei , Meier Thomas ,   AlpArray Working Group
Published: March 2022

The Pannonian basin is a continental back-arc basin in Central Europe, surrounded by the Alpine, Carpathian, and Dinaric mountain ranges. To better understand this area's tectonic affinity and evolution, a high-resolution model of the crust, the mantle lithosphere, and the asthenosphere is essential. The region's crustal structures are well documented, e.g., classical active seismic, receiver functions, and ambient noise surface wave studies, but consistent imaging of the entire lithosphere remains a challenge. Here we present a new high-resolution 3D shear wave velocity model of the crust and upper mantle of the broader Pannonian region using joint tomographic inversion of ambient noise and earthquake data.

For this purpose, we collected continuous waveform data from more than 1280 seismic stations for ambient noise cross-correlation measurements from a region centered to the Pannonian Basin and encompassing the rimming orogenic chains. This dataset embraces all the permanent and temporary stations operated in the time period from 2005 to 2018. We calculated Rayleigh wave ambient noise phase velocity dispersion curves using the phase of the noise cross-correlation functions of the vertical components in the period range from 5 to 80 s. Then we combined this dataset with existing measurements from earthquake data in the period range of 8-300 s.

At lower periods (< 50 s) and shorter interstation distances, there is a well-documented systematic discrepancy between the dispersion measurements collected by the two methods. The phase-velocity curves measured by the noise-based method are slower on average than the dispersion curves extracted by the earthquake-based method. A correction term is defined by comparing phase velocity curves from both data sets for the same station pairs. Phase velocity maps are then calculated from 5 s to 250 s periods using ambient noise and earthquake measurements.

Local dispersion curves extracted along each grid node of the 2D phase velocity maps are inverted for depth velocity models using a newly implemented Particle Swarm Optimization (PSO) algorithm to obtain the 3D distribution of the shear-wave velocities. The shear wave velocity structure reveals pronounced variations of the lithospheric thickness and physical properties related to deep tectonic mechanisms operated in the region.
Revisiting the relationship between the pore water carbon isotope gradient and bottom water oxygen concentrations
Authors: Bradbury Hal , Thomas Nicola , Hodell David
Published: March 2022

Reconstructing the oxygen content at the base of the ocean provides insight into ocean circulation, carbon storage in the deep ocean and hence, the global carbon cycle. The microbial breakdown of organic carbon within marine sediment through aerobic respiration consumes oxygen in the pore fluid and releases dissolved inorganic carbon. The offset in the carbon isotopic composition of epifaunal and infaunal foraminifera is related to the respiration of the organic carbon and can be used to reconstruct the oxygen content of the bottom water. Previous work has provided a data-derived calibration which is valid for oxygen reconstructions between 55–235 micromolar. In this study, we apply a biogeochemical reactive transport model (RTM) to extend and update the calibration, which allows for the reconstruction of oxygen concentrations up to ~400 micromolar. Using the RTM and new data from the Iberian Margin, we also demonstrate that the calibration between the carbon isotope gradient and bottom water oxygen concentrations must account for the coupled changes in all aspects of the carbon system due to the respiration of organic carbon. We apply the improved calibration to reconstruct the changes in oxygen content in the North Atlantic over the past 1.4 Myr.
A multidecadal decline of Weddell Sea Bottom Water volume forced by wind-driven sea ice changes
Authors: Zhou Shenjie , Meijers Andrew , Meredith Michael , Abrahamsen Povl , Silvano Alessandro , Holland Paul , Sallée Jean-Baptiste , Østerhus Svein
Published: March 2022

Antarctic Bottom Water (AABW) is one of the most important deep water masses contributing to the lower limb of the global overturning circulation, which modulates the deep ocean ventilation and oceanic heat/carbon exchanges on multidecadal to millennial timescales. Weddell Sea Bottom Water (WSBW) is a key precursor of the AABW exported from the Weddell Sea. Its formation involves intense air-sea-ice interaction on the continental shelf that releases brine from sea ice formation, and occurs mostly in the austral winter. Here we report a distinct long-term volume decline of WSBW revealed by data collected along repeat occupations of World Ocean Circulation Experiment (WOCE) hydrographic sections. We estimate a >20% reduction of WSBW volume since the early 1990s and a resultant widespread deep Weddell Sea warming associated with a basin-scale deepening of isopycnal surfaces. With the most significant volume reduction concentrating within the densest classes of WSBW and a concurrent decline of sea ice formation rate (>30%) over the southwestern Weddell continental shelf inferred from remote-sensed sea ice concentration data, we propose that the observed WSBW volume reduction is likely to be driven by a multidecadal weakening of dense shelf water production due to the sea ice changes. Reanalysis atmospheric data and ice drift data suggest that the reduction of sea ice formation rate is predominantly linked to changes in wind-driven sea ice convergence in front of Ronne Ice Shelf and Berkner Bank, as a response to a vigorous Amundsen Sea Low deepening that is teleconnected to tropical Pacific SST variability, and associated with the local radiative forcing from long-term ozone depletion.
Thermodynamic Scaling of Extreme Daily Precipitation over the Tropical Ocean
Authors: De Meyer Victorien , Roca Rémy , Fiolleau Thomas
Published: March 2022

The theory of extreme precipitation has come to a more mature state over the last decade and highlights the balance between the change in extreme precipitation and in surface humidity with warming. The latter is further constrained by the changes in surface temperature. The analytically derived scaling coefficient based on the Clausius-Clapeyron derivative is ~6 %.K−1 under typical tropical surface conditions. While frequently confronted with observations over land, the theory has so far only been marginally evaluated against precipitation data over the ocean. Using an ensemble of satellite-based precipitation products and a suite of satellite-based sea-surface temperature (SST) analyses at 1°-1day resolution, extreme scaling is investigated for the tropical ocean (30°S – 30°N). The focus is on the robust features common to all precipitation and SST products. It is shown in this study that microwave constellation-based precipitation products are characterized by a very robust positive scaling over the 300 – 302.5K range of 2-days-lagged SST. This SST range corresponds to roughly 60 % of the amount of tropical precipitation. The ensemble mean scaling lies around the theoretically expected rate of 6 %.K−1 regardless of the extreme indices computed or the length of the period considered. The robustness of the results confirms the suitability of the current generation of constellation-based precipitation products for extreme precipitation analysis. Furthermore, the ability of the RCEMIP models to properly simulate the observed behavior with tropical SST is discussed.
Relations between multifractal soil pore characteristics and soil properties. A case study in coastal saline soils.
Authors: Sun Xiaoqin , Tarquis Ana , She Dongli , Han Xiao , Wang Hongde , Tang Shengqiang
Published: March 2022

Soil salinization is one of the significant constraints to food security. Anthropogenic activities such as improper agricultural practices and poor drainage systems can accelerate salinization. The reclamation of these saline areas, such as the coastal areas in Jiangsu province (China), is vital to produce sufficient food, fodder, and fibre sustainably.

Soil washing was applied at Rudong location (Jiangsu) in 2007 as a method of soil reclamation. The monitoring of coastal saline soil improvement at three different depths (0-20, 20-40, 40-60 cm) has been followed through physical, chemical, and biological measures.

At the same time, soil samples collected by plastic rings were scanned, obtaining a central region of interest (ROI) of 512×512×512 voxels. These grey images, and their binary images, were analyzed in 2D and 3D using multiscaling techniques extracting standard multifractal parameters.

The results found different relationships between laboratory measures and image analysis parameters in which soil depth influences. Grey images parameters showed a stronger relation compared to binary images.

ACKNOWLEDGEMENTS

This research has been partially founded by the National Natural Science Foundation of China through Grant no. 42177393, MICINN through project no. Project No. PGC2018-093854-B-I00 of the Spanish Ministerio de Ciencia Innovación y Universidades of Spain, the funding from the Comunidad de Madrid (Spain), the Structural Funds 2014-2020 512 (ERDF and ESF), through project AGRISOST-CM S2018/BAA-4330.
Identification of conceptual rainfall-runoff models of large drainage basins based on GRACE and in-situ data
Authors: Douch Karim , Saemian Peyman , Sneeuw Nico
Published: March 2022

Since 2002, estimates of the spatio-temporal variations of Earth’s gravity field derived from the Gravity Recovery and Climate Experiment (GRACE and now GRACE-FO) mission measurements have provided new insights into large scale water redistributions at inter-annual, seasonal and sub-seasonal timescales. It has been shown for example that for many large drainage basins the empirical relationship between aggregated Terrestrial Water Storage (TWS) and discharge at the outlet reveals an underlying dynamic that is approximately linear and time-invariant.

In this contribution, we further analyse this relationship in the case of the Amazon basin and sub-basins by investigating different physically interpretable, lumped-parameter models for the TWS-discharge dynamics. To this end, we first put forward a linear and continuous-time model using a state-space representation. We then enhance the model by introducing a non-linear term accounting for the observed saturation of the discharge. Finally, we reformulate the model by replacing the discharge by the river stage at the outlet and add a prescribed model of the rating curve to obtain the discharge. The suggested models are successively calibrated against TWS anomaly derived from GRACE data and discharge or river stage records using the prediction-error-method. It is noteworthy that one of the estimated parameters can be interpreted as the total amount of drainable water stored across the basin, a quantity that cannot be observed by GRACE alone. This quantity is estimated to be on average 1,750 km³ during the period 2004-2009. These models are eventually combined with the equation of water mass balance, in order to obtain a consistent representation of the basin-scale rainfall-runoff dynamics suited to data assimilation.