bluuebunny/crossref_metadata_2025 huggingface dataset:
Drought monitoring in mountain areas with high resolution precipitation products
Authors: Naumann Gustavo , Avanzi Francesco , Ercolani Giulia , Ponziani Denise , Stevenin Hervè , Ratto Sara Maria , Gabellani Simone
Published: March 2022

Drought is a recurrent climatic phenomenon associated with a deficient availability of water resources over a large geographical area and lasting for a significant period. The effects of drought usually accumulate slowly over a considerable period and may persist for several years, even after the drought has ended. In mountain areas, the effects of drought can be evident in the disruption of ecosystems, hydropower production, and may even affect economic activity such as agriculture and tourism.

The main limitation for developing effective real-time drought monitoring systems in mountainous areas is the lack of reliable and up-to-date precipitation data. A sparse distribution of rain gauges and short or incomplete rainfall historical records pose further problems. This lack of information may lead to significant errors in the estimation of statistical parameters for deriving water supply indices from the precipitation time-series. Procedures for drought detection and assessment have a particular level of uncertainty associated to the data and models used.

To better understand the extent, severity, and impact of a drought in a region, it is first necessary to improve the quality of these procedures using the best available data, theoretical assumptions, and model formulations. The main objective of this study is to assess the uncertainties due to sample size associated with the estimation of the Standardised Precipitation Index (SPI) and their impact on the possible level of confidence in drought monitoring in the Western European Alps (Aosta Valley, Italy).
Monitoring of Unlit Flares using Sentinel-2: A Global Emissions Inventory for 2021 
Authors: Conrad Bradley , Johnson Matthew
Published: March 2022

Immediate-term reductions of methane emissions are widely seen as a critical step toward holding global warming below 1.5–2°C. The oil and gas sector is a dominant source of anthropogenic methane emissions and numerous stakeholders have implicated gas flaring at upstream production sites as a key source to mitigate. Flaring is the process whereby OG producers destroy spurious yet significant volumes of methane-rich natural gas via open-air combustion. During their lifetime, gas flares may intermittently become extinguished in which case the flare, which generally reduces greenhouse gas emissions by converting methane to carbon dioxide, effectively becomes a direct vent of methane to atmosphere. Recently, ground-, air-, and satellite-based instruments have identified a troubling regularity with which these so-called unlit flares may exist in some jurisdictions. Unlit flares may genuinely be accidental – resulting from equipment malfunctions, extreme wind conditions, or unpredictable emergency scenarios – or deliberate – to support maintenance operations, due to poor operating practices, or to obscure volumes of flared gas. Regardless of intent, the frequency with which flares are unlit and, critically, the global scale of the associated methane emissions are poorly understood.

In this work, publicly available imagery data from the multispectral instrument on-board the Sentinel-2 satellites are leveraged to develop a global emissions inventory for unlit flaring during 2021. Sentinel-2 data are processed with published methane retrieval algorithms and a novel plume detection algorithm to identify and estimate emission rates of detected unlit flares. Detected emissions are subsequently considered in the context of scene-specific probabilities of detection, which permits extrapolation of available data to infer a first-ever global emissions inventory for unlit flares. A Monte Carlo analysis is used to robustly characterize uncertainties of this approach.
Influence of pre-stress conditions in 2D plane strain simulations of a dynamic rupture with off fault damage
Authors: Jeandet Ribes Louise , Thomas Marion , Bhat Harsha
Published: March 2022

Understanding the mechanical properties of the off-fault medium and its interactions with earthquake rupture is essential for a better understanding of the behavior of fault zones. In this framework, two-dimensional, plane strain models are often used to investigate the interplay between seismic rupture propagation and inelastic deformation in the damage zone. The role of pre-stress conditions for faulting and damage has been studied, in particular the influence of Y, the angle between the largest principal stress and the fault strike. However, in plane strain conditions, the out-of-plane stress is often ignored when setting up the initial stress field, and its influence on dynamic rupture and stress evolution has not been inferred. In this study, we explore the role of the out-of-plane pre-stress for a 2D in-plane model in plane strain conditions. We model a 1D right-lateral, strike-slip vertical fault featuring slip-weakening friction law. We first demonstrate theoretically that if the out- of-plane stress is not considered properly in the initial stress field, pre-stress conditions may not correspond to actual strike-slip faulting. We then investigate how changing the initial stress field can influence the rupture and the stress evolution in the off-fault medium. Our results show that if it does not influence significantly the rupture dynamics, the out-of-plane stress is essential in controlling the evolution of the off-fault medium, especially the localization and extend of areas affected by plastic yielding. Therefore, our results demonstrate the importance of considering properly the initial out-of-plane stress to infer the extend, magnitude and distribution of damage in 2D plane strain simulations with off fault plastic deformation.
Water Tariffs and Affordability in Urban Water Supply and Wastewater Systems 
Authors: Xenarios Stefanos , Buurman Joost , Araral Eduardo
Published: March 2022

The current study attempts to identify the role of the most widely used physical, economic and institutional parameters that may affect water tariffs and affordability across several cities in high and upper-middle income countries. Differential inferential statistical methods were employed to explore potential associations of the water consumption, variable and fixed costs, utility management, and minimum wage, with the economic affordability on household level. The findings indicate a loose association of the tariffs with the above indicators which may not lead to certain assumptions. Although the results may be uncertain and inconclusive, however, there have only few studies till now exploring and comparing water affordability of urban water systems in high and upper-middle income countries. The findings could trigger further research on the better comprehension of affordability and water tariffs by improving social inclusion of low-income households on urban water accessibility and usage.
Species competition and dispersal drive vegetation dynamics in tidal salt marshes
Authors: Bertuzzo Enrico , Finotello Alvise , D'Alpaos Andrea , Marani Marco
Published: March 2022

Salt marshes are among the most common morphological features found in tidal landscapes and provide ecosystem services of utmost importance.

The ability of salt marshes to counteract changes in external forcings depends on the complex dynamic interactions between physical and biological processes. In particular, salt-marsh evolution, both in the horizontal and vertical directions, is critically affected by the presence of halophytic vegetation that colonizes the marsh platform.

Despite their importance, however, modeling vegetation dynamics in intertidal marshes remains a major challenge both at the theoretical and practical/numerical levels. Improving our current understandings of the mechanisms driving halophytes zonation is of critical importance to enhance projections of salt-marsh response to changes in climate and relative sea level.

Here we present a new bi-dimensional, spatially explicit ecological model aimed to simulate the spatial dynamics of halophytic vegetation in tidal saline wetlands. Vegetation dynamics are treated differently compared to previous models, which employed relatively simple deterministic or probabilistic mechanisms, dictated only by the ability of different species to adapt to different topographic elevations. In our model, in contrast, spatial vegetation dynamics depend not only on the local habitat quality but also on spatially explicit mechanisms of dispersal and competition among multiple, potentially interacting species. The temporal evolution of vegetation biomass at each site depends on death and colonization processes, both local and resulting from dispersal. These processes are modulated for each species by the habitat quality of the considered site.

Results indicate that our model can predict realistic diversity and species-richness patterns. More importantly, the model is also able to effectively reproduce the outcome of classical ecological experiments, in which a species is transplanted to an area outside its optimal niche. A direct comparison clearly shows how previous models not accounting for dispersal and interspecific competitions are unable to reproduce such dynamics.

Coupled with a hydro- and morphodynamic module, our model can contribute to improving our ability to model salt marsh evolution numerically and allow for cost-effective ecological community-level studies, providing useful insights on the ecomorphodynamics of marsh landscapes that are of interest to the community of coastal scientists and managers as a whole.
Assessing Climate Impacts Against Groundwater Pumping Impacts on Stream Flow with Statistical Analysis
Authors: Pyschik Jonas , Harter Thomas , Stahl Kerstin
Published: March 2022

Declining summer streamflow is observed in Pacific Northwest catchments, impacting endangered salmon species which need sufficient flow to reach their spawning grounds. Groundwater pumping for irrigation is generally considered the cause of low summer flow. However, it is unclear, how much water is lost due to water use or climatic factors, as there often is no data on pumping-volume. In this study we assess the lost amount of streamflow during summer low flows and quantify the shares attributable to climate change and agricultural water-consumption, only using streamflow data. As a case study we focused on the Scott River catchment, California, having 7% agricultural land use. We compared summer streamflow, snow water equivalent and precipitation between historic (1940-1976), intermediate (1977-1999) and modern (2000-2020) timeframes. Snow water equivalent showed negative significant trends at lower elevations (1600-1800 m). We also observed significant negative trends in mean and minimum streamflow as well as earlier starting and longer lasting low flow season. Using a paired-basin approach we were able to detect a mean 38.5% (37.5 +/- 3 Mm³) streamflow decrease from historic to modern timeframe years, where 14.6% (14.25 +/- 1.4 Mm³) were attributable to agricultural water consumption and 23.9% (23.2 +/- 1.4 Mm³) to climate change. These results demonstrate that agriculture substantially impacts streamflow; however, the influence of climate change dominates. Therefore, stopping water use in summer to increase low flows is insufficient. A possibility to ensure enough flow for endangered salmon could be artificial aquifer recharge during high flows to top of low flow season.
Aligning earthworm activity and microbial necromass formation in mineral soil
Authors: Angst Gerrit , Frouz Jan , van Groenigen Jan Willem , Scheu Stefan , Kögel-Knabner Ingrid , Eisenhauer Nico
Published: March 2022

Microbial necromass is regarded as a central pool of soil organic carbon, whose management is critical in efforts to reduce atmospheric CO2 concentrations and mitigate climate change. However, recent concepts on soil organic matter formation have ignored one of the most important factors for the formation and stabilization of microbial necromass in many soils: earthworms. Based on recent evidence, we conceptualize how the ingestion and mixing of mineral particles and organic matter by earthworms temporarily convert the egested soil to a hotspot of quick and efficient microbial growth and turnover, in which increased amounts of necromass tightly bind to mineral surfaces and stabilize within aggregates. We further stress the low dependence of this process on the quality of pre-existing soil organic matter (in contrast to the assumptions of recent concepts) and its high relevance to the resilience of soil carbon to external disturbances in extensive regions of the soil remote from classical hotspots of microbial necromass formation. We finally provide suggestions on how to close remaining research gaps.
Advances on submarine geomorphology at the Fjord system of Gran Campo Nevado (~52°S)
Authors: Veloso-Alarcón Mario , Iason-Zois Gazis , Geiger Alessa , Sebastien Bertrand , Rodrigo Cristián
Published: March 2022

The glacial history of Patagonia has been built from paleoclimate records found at the margin of the former Patagonian Ice-sheet. However, current deglaciation models of Patagonia still have spatio-temporal gaps to be filled. In this direction, the study of the submerged paleo-climate records at the Patagonian Fjord system and pro-glacial lakes could fill these gaps and enhance our knowledge on deglaciation in Patagonia. However, the exploration of such remote areas is hindered by logistic challenges and rough weather conditions.

In November of 2018 we collected the first high-resolution swath multibeam echosounder (MBES) bathymetry of Senos Icy and Glacier, the southern section of Canal Gajardo and Estero Portaluppi, which are fjords located at the flanks of Gran Campo Nevado. In this work, we present this new bathymetry and its first geomorphological interpretation. The analysis revealed a heterogeneous seafloor with geomorphological features related to glacial dynamics. The data interpretation is supplemented by shallow sub-bottom profiles that have been also acquired during that survey. We think that such information is the baseline for future exploration of these fjords focused on the already identified submerged glacial bedforms and their chronology.  
The role of Rossby wave breaking for annual and extreme precipitation in (semi)arid regions
Authors: De Vries Andries Jan , Armon Moshe , Klingmüller Klaus , Portmann Raphael
Published: March 2022

Precipitation can have large dual societal impacts in regions with a dry climate. On the one hand, extreme precipitation can induce catastrophic floods, and on the other hand, replenish scarce fresh water resources. In contrast to wet extratropical regions, the atmospheric processes that lead to precipitation formation in the dry subtropics are often overlooked by the scientific community. In this study we address the role of Rossby wave breaking for annual and extreme precipitation in (semi)arid regions. To this end, we quantify the contribution of Rossby wave breaking to extreme precipitation days and annual precipitation amounts in regions with different degrees of aridity. Rossby wave breaking is represented by potential vorticity (PV) streamers and cutoffs on isentropic surfaces using ERA-Interim reanalysis data, while precipitation is used from the global precipitation measurement (GPM) integrated multi-satellite retrieval product IMERG for the period of 2001-2018. We show that the relevance of Rossby wave breaking for precipitation increases from humid to hyper arid regions. More specifically, equatorward breaking Rossby waves contribute to a large fraction of annual and extreme precipitation in regions on the pole-westward flanks of world’s most arid regions where most precipitation occurs in the cool season. In contrast, precipitation in the equator-eastward parts of these arid regions has a negative association with Rossby wave breaking, implying that the tropical forcing governs the precipitation formation which occurs in these regions predominantly in the warm season. The results suggest that breaking Rossby waves are of key importance for precipitation in (semi)arid regions that undergo a drying in a warming climate, underlining the need to better understand the response of wave breaking to global warming.
Catch me if you can: Evaluating sampling methods for airborne ultrafine particles’ composition analysis
Authors: Eckenberger Elisabeth , Das Anusmita , Gawlitta Nadine , Kernchen Sarmite , Orasche Jürgen , Schnelle-Kreis Jürgen , Sklorz Martin , Jakobi Gert , Zimmermann Ralf , Nölscher Anke C.
Published: March 2022

Airborne particles affect air quality, weather and climate. The continuing urbanization is expected to expose a growing fraction of the world’s population to still increasing levels of anthropogenic emissions of airborne particles and precursors of secondary aerosols. These anthropogenically emitted particles are dominated in number by ultrafine particles (UFP; diameter less than 100 nm), which therefore are common in urban air. Their size and chemical composition determine whether the particles impose a risk to human health or the environment. Thus, in-depth knowledge about airborne UFPs' sources and atmospheric fate is essential for environmental risk assessment. A detailed chemical analysis of UFPs aids to better understand environmental processes in the atmosphere and possible effects on human health.

Despite the need of learning more about the origin, behaviour, mobility, fate, and toxicity of UFPs, attempts to analyze their chemical composition in the atmosphere are still rare. Considering their low mass, partial volatility and dynamic character, it is still a great challenge to separate, catch and analyze UFPs in the atmosphere.

Impactors are important tools to separate and collect environmental particles from the air with the aim of analyzing their chemical composition. Herein, we report our evaluation of commercially available and frequently deployed cascade impactors for their applicability of sampling airborne UFPs. We tested the following criteria: (1) A precise size separation or cut‑off in the ultrafine range to enable size-dependent chemical analysis, (2) The collection of the greatest as possible particle mass (high sampling volume) while minimizing evaporation losses of semi-volatile fractions (small pressure drop). Therefore, different impactors were connected in line between a customizable particle generation source, a flow reactor for dilution, mixing and ageing, and a mobility particle size spectrometer (MPSS). So far, our results indicate a significant variability among impactors of the same model and highlight the difficulty of combining all these requirements in one device. However, after careful physical characterization, we developed a strategy to optimize the particle sampling for atmospheric UFPs chemical composition analysis.

This project is financed by the Bavarian Ministry of the Environment and Consumer Protection.
Relatively-relocated seismicity during the 2021 Fagradalsfjall dyke intrusion, Reykjanes Peninsula, Iceland: Detailed evolution of a lateral dyke, and comparison to Bárðarbunga-Holuhraun
Authors: Southern Esme Olivia , Greenfield Tim , Winder Tom , Ágústsdóttir Þorbjörg , Brandsdóttir Bryndís , Fischer Tomas , Doubravová Jana , Rawlinson Nick , White Robert , Gudnason Egill Árni , Hersir Gylfi Páll , Hrubcova Pavla , Bacon Conor
Published: March 2022

The 2021 Fagradalsfjall eruption on Iceland’s Reykjanes Peninsula was preceded by more than 12 months of elevated activity, beginning around November 2019. This dominantly consisted of episodes of intense seismic swarms, but also featured inflationary episodes in both the Svartsengi and Krísuvík volcanic systems. On 24th February 2021, an exceptionally intense episode of seismicity covering the length of the Peninsula marked the initiation of a dyke intrusion, which continued to develop until the 19th of March, when melt first erupted at the surface. The fissure eruption lasted 6 months, ending on 18th September 2021.

During the intrusion, melt first propagated northeast towards Mt Keilir, then to the southwest, eventually forming a 10 km-long dyke. This was marked by more than 80,000 microearthquakes, recorded by a dense local seismic network and detected and located using QuakeMigrate[1].

We present high precision relative relocations of the seismicity, and tightly constrained focal mechanisms of earthquakes which are dominantly located along the base of the dyke. We compare the Fagradalsfjall seismicity to the 2014-2015 Bárðarbunga-Holuhraun intrusion and eruption seismicity [2], in the context of the contrasting tectonic settings, and markedly different precursory activity.

1: Winder, T., Bacon, C., Smith, J., Hudson, T., Greenfield, T. and White, R., 2020. QuakeMigrate: a Modular, Open-Source Python Package for Automatic Earthquake Detection and Location. https://doi.org/10.1002/essoar.10505850.1

2: Woods, J., Winder, T., White, R. S., and Brandsdóttir, B., 2019. Evolution of a lateral dike intrusion revealed by relatively-relocated dike-induced earthquakes: The 2014–15 Bárðarbunga–Holuhraun rifting event, Iceland. https://doi.org/10.1016/j.epsl.2018.10.032
Quality check of ground-based hourly measurements of downwelling surface solar irradiance in China
Authors: Chen Xuemei , Tournadre Benoît , Blanc Philippe , Saint-Drenan Yves-Marie , Gschwind Benoît
Published: March 2022

Ground-based measurements of downwelling surface solar irradiance (DSSI) play an important role in many topics, such as the design and operation of solar energy systems, the study of the Earth radiation budget, and the validation of gridded DSSI products such as those derived from satellite imagery and reanalyses. For our purpose of validating satellite-based estimates of DSSI over China, we use ground-based hourly measurements at 99 stations operated by China Meteorological Administration (CMA). The measurements might not be perfect, including outliers, biases, sudden shifts or slow instrumental drifts that an extended quality check (QC) can detect. Physical threshold methods like the one proposed by Long and Dutton (2002) are frequently used to detect some of the physically impossible data records on an hourly or sub-hourly basis. However, in our case, we observed many inconsistent measurements that can pass such threshold-based QC. This is especially because diffuse and/or direct components of DSSI are not measured for most CMA stations and only global irradiance-based check for DSSI can be realized.

To detect drifts or jumps that might last for weeks or months in the time series of measured DSSI, we carried out the QC by comparing the clearness indices (i.e., the ratio between DSSI and horizontal irradiance at the top of atmosphere) from measurements with those from the ERA-5 reanalysis, in a similar approach to Urraca et al. (2017). Consistency of ERA-5's clearness indices was checked at first by comparison with high quality measurements from Baseline Surface Radiation Network. The same quality check was then applied to the hourly datasets at CMA stations. Over the years 2017-2018, our QC method led us to keep 52 stations fully and 19 stations partly.

Reference:

Long C.N. and Dutton E.G. BSRN Global Network recommended QC tests, V2.0, BSRN Technical Report, pp 3, 2002.

Urraca R., Gracia-Amillo A., Huld T., et al. Quality control of global solar radiation data with satellite-based products, Solar Energy 158, pp 49-62, 2017. https://doi.org/10.1016/j.solener.2017.09.032.
Stream lithium isotope ratios record antecedent and transient hydrological conditions in catchment weathering exports
Authors: Golla Jon , Bouchez Julien , Didon-Lescot Jean-François , Domergue Jean-Marc , Grard Nadine , Ayral Pierre-Alain , Josselin Didier , Druhan Jennifer
Published: March 2022

Concentration-discharge relationships have been extensively utilized to infer the routing of water and pathways of (bio)geochemical reactions in the Critical Zone. To date, relatively little complementary development of stable isotope ratio - discharge relationships has been made, despite the fact that these tracers are commonly used to disentangle weathering reactions in the fluids draining from headwater systems. A process-based understanding of the extent to which fluid flow rates, antecedent hydrological conditions, and water age distributions impact these isotopic signatures in stream or river exports would present a pivotal advancement in the quantitative analysis of Critical Zone structure and function. Here, we explore how these factors regulate variations in stable lithium isotope ratios (expressed as δ7Li) of streamflow and the underlying water-rock interactions recorded by this signal during periods of hydrological transience. We present novel data sets collected during two distinct flooding events in Sapine Creek, a small, granitic catchment located on the southern flank of the Mont-Lozère, France and part of a Critical Zone Observatory within the French OZCAR Research Infrastructure. The data from this site are used to parametrize and validate an isotope-enabled, multicomponent reactive transport model capable of running transient simulations designed to mimic two sampling conditions at Sapine: (1) a storm preceded by a low-flow period and (2) a storm event during the wet season. The models are initiated from an unweathered granite subject to steady state uplift and infiltration. From this point, two synthetic storm events are simulated. Simulation of a storm event ending a period of dry conditions results in a net increase in streamflow lithium isotope ratios due to enhanced secondary mineral formation promoted by relatively long water residence times. In contrast, when the model is used to simulate a succession of relatively larger (~2 times greater in magnitude) storms during a wet season, a net decrease in δ7Li is observed. These lower isotope ratios are a consequence of attenuated secondary mineral formation. These preliminary results and trends demonstrate the influence of antecedent hydrological conditions and storm intensity on the magnitude and duration over which stream δ7Li is perturbed and, hence, the seasonal dependence of this signal as a record of transient behavior.
The Relationship between Desroziers and Three-Cornered Hat Methods
Authors: Todling Ricardo , Semane Noureddine , Anthes Rick , Healy Sean
Published: March 2022

This note examines the relationship between what at first sight looks like two unrelated methods for estimating second order statistics of relevance to data assimilation. The first method is due to Desroziers et al. (2005) and relies on residual statistics readily available from data assimilation applications. The second method, due to Gray and Allan (1974), only recently making its appearance in atmospheric sciences, is generally formulated to use three data sets and seems in principle capable of deriving estimates of observation, background and analysis just as well. The usefulness of either method lies in them not requiring knowledge of the true value of the quantities at play. Desroziers derives its results by relying explicitly on the constraints associated with the data assimilation minimization problem; the 3CH method is general and its estimates hold as long as random errors in the three data sets of choice are independent. Establishing the relationship between the methods amounts to identifying the data sets of 3CH with be the observation, background, and analysis associated with Desroziers. The choice of observation and background for two of the data sets of 3CH is acceptable under the typical assumption of independence in their errors. Specifying the third data set of 3CH as the analysis seems unreasonable for analysis errors are by construction dependent on errors in both observations and background. This note finds that when the assumption of optimality required of Desroziers is applied to 3CH the latter method recovers the Desroziers error estimates for observation and background. More interestingly, in contrast with Desroziers estimate of errors in the analysis, the remaining corner of 3CH obtains the negative of the analysis error variance. An illustration of this finding is provided by deriving various uncertainties in bending angle.

 
The Cascading Foreshock Sequence of the Ms 6.4 Yangbi Earthquake in Yunnan, China
Authors: Zhu Gaohua , Yang Hongfeng , Tan Yen Joe , Jin Mingpei , Li Xiaobin , Yang Wei
Published: March 2022

Foreshocks may provide valuable information on the nucleation process of large earthquakes. The 2021 Ms 6.4 Yangbi, Yunnan, China, earthquake was preceded by abundant foreshocks in the ~75 hours leading up to the mainshock. To understand the space-time evolution of the foreshock sequence and its relationship to the mainshock nucleation, we built a high‐precision earthquake catalog using a machine-learning phase picker—EQtransformer and the template matching method. The source parameters of 17 large foreshocks and the mainshock were derived to analyze their interaction. Observed “back-and-forth” spatial patterns of seismicity and intermittent episodes of foreshocks without an accelerating pattern do not favor hypotheses that the foreshocks were a manifestation of a slow slip or fluid front propagating along the mainshock’s rupture plane. The ruptured patches of most large foreshocks were adjacent to one another with little overlap, and the mainshock eventually initiated near the edge of the foreshocks’ ruptured area where there had been a local increase in shear stress. These observations are consistent with a triggered cascade of stress transfer, where previous foreshocks load adjacent fault patches to rupture as additional foreshocks, and eventually the mainshock.
Does Caribbean SST drive decadal to centennial-scale variability in the Central American Monsoon? Evidence from stalagmites from Mona Island, Puerto Rico 
Authors: Cozadd Claudia , Lachniet Matthew , Warken Sophie , Li Hanying , Winter Amos
Published: March 2022

This research is based on broader study investigating drivers of decadal to centennial-scale variations in the Central American Monsoon (CAM), a sub-region of the broader North American Monsoon. In the context of the Global Monsoon system, the precipitation patterns of CAM are of particular interest because of the placement/shifting of the ITCZ through time, its proximity to the AMOC system, and that existing precipitation records from this area have revealed a heterogenous pattern throughout the past 2 kyr.

Here we present new carbon and oxygen isotopic records of two speleothems, MO-AL-3 and MO-CU-2, recently collected from Mona Island, Puerto Rico. These speleothems together cover the last 2 kyr BP, thus significantly expanding the hydrologic history of the Northeastern Caribbean from speleothem records. Previous studies, mostly from the Western Caribbean, have revealed that Caribbean SSTs as well as solar and volcanic forcing are involved, to different degrees, as driving mechanisms determining the strength of the InterAmerican monsoon systems over the late Holocene. The study of precise, independent chronologies extracted from speleothems, and comparing them to local and regional coral/sclerosponge SST reconstructions, allows for an improved understanding of precipitation patterns of the Caribbean overtime. This new record allows the investigation of decadal to centennial-scale precipitation variability, as well as its linkage to past human civilizations. There is also potential to contribute to the recent discussion of whether the AMO is an internal oscillation or externally forced.  
Evaluation of the spatiotemporal representation of the GPM satellite precipitation products over diverse climatic regions in Ireland
Authors: Mohammed Safa , Nasr Ahmed , Mahmoud Mohammed
Published: March 2022

In response to recent major flood events in Ireland, the authorities have prioritised the development of a national flood forecasting model for use as a tool in flood risk management. Accurate flood predictions by this model require high resolution spatiotemporal rainfall data. One source for this type of data is the remote sensing estimated precipitation provided by the Global Precipitation Measurement (GPM) satellite. The GPM has ability to detect and estimate all forms of precipitation using a range of advanced instruments, including Microwave and Radar technologies. This study evaluates the accuracy of detecting the large rainfall events which occurred in Ireland during the period 2014-2021 by three Integrated Multi-satellitE Retrievals for GPM (IMERG) precipitation products (i) early run ; (ii) late run; and (iii) final run. The satellite estimates of these events have been assessed using five statistical indices applied to various temporal scales; hourly, daily, and monthly. The results showed that, for satellite detection, all of the three IMERG products had an acceptable detection accuracy of the large rainfall events. In particular, the calibrated product – final run product – outperformed the other near-real-time products in terms of estimation error and bias. Overall, the results indicate that IMERG satellite precipitation products can be used with confidence to detect large events over high latitude areas such as Ireland. Besides, they have a high potential for coupling with in-situ data to improve the accuracy of the integrated flood forecasting model.
Quantifying soil carbon sequestration by multi-source constraints
Authors: Tao Feng , Luo Yiqi
Published: March 2022

Soil carbon cycle is a large yet poorly understood component of the global carbon cycle under climate change. The transient behaviour of the soil carbon cycle is fully determined by four elements, which are carbon input, residence time,carbon pool size (or state), and the net carbon flux. Many of the past studies focused on one subset of the four elements to quantify soil carbon sequestration under climate change, often leading to contradictory conclusions. Here we assimilated data of respired soil 14C, soil 14C profile, and soil organic carbon (SOC) profile from Harvard Forest (i.e., a mid-latitude hardwood forest) into a vertically resolved process model (i.e., Community Land Model version 5, CLM5) together with estimated carbon input to fully constrain soil carbon dynamics during 1900 to 2010. Our results suggested litter pools instead of the mineral soil pools contributed to the majority of the carbon sequestration in history. Different sources of constraints effectively informed parameters of their corresponding elements in the soil system. Yet, single data constraints only provided part of the features of soil carbon cycle and cannot lead to a comprehensive interpretation of its historical dynamics. Using 14C data alone as the constraints resulted in overestimated soil carbon residence time and more sensitive responses of soil carbon sequestration to changing climate. In the future, multi-source data constraints from different global databases are essential in understanding soil carbon dynamics and accurately quantifying soil sequestration in response to the changing climate across the globe.
Analyses of convective event climatology in the Arabian Peninsula and forecast opportunity at S2S time scale  
Authors: Chang Hsin-I , Castro Christopher L , Luong Thang M , Risanto Christoforus Bayu , Hoteit Ibrahim
Published: March 2022

Severe weather associated with organized convective systems is becoming more intense globally and is also observed in the Arabian Peninsula (AP). The extreme rainfall-associated flooding in low soil infiltration region like the AP often lead to significant social and economic losses within a very short period. Improving forecast capability at sub-seasonal to seasonal (S2S) timescale can potentially assist disaster risk mitigation, and water resource management.

 

A series of S2S regional climate model reforecasts were completed using the Weather Research and Forecasting Model (WRF) at convective-permitting resolution (4 km) for the AP. We dynamically downscale 20 years of winter season from the European Centre of Medium-range Weather Forecasts (ECMWF) S2S reforecast product. WRF simulations were initialized weekly with 1-month simulation duration between November and April.  A total of 191,400 hindcast days have been generated to evaluate the predictability of winter rainfall associated with convective activities.

 

Methods designed to evaluate the S2S forecast skills considers the probability of detection of precipitation at neighboring grids, determining the rate of forecast agreements between ensemble members, and running evaluation of the probability of forecast from 1-week to 4-week lead time. We evaluated all rain gauge measurement and gridded precipitation datasets available for the study period and determined the following datasets as our ground-base reference: satellite based Global Precipitation Mission (GPM) and 4-km reanalysis data produced by the King Abdullah University of Science and Technology (KAUST-RA). The WRF S2S downscaled reforecasts significantly improved from the driving ECMWF reforecast climatology, as evaluated against  the GPM and the KAUST-RA dataset. Our WRF results also produced reasonable winter precipitation climatology over the AP as compared to the satellite observations and high-resolution reanalysis products, at 1-week, 2-week, 3-week and 4-week forecast lead times.
Seasonal and interannual variations of carbon fluxes at the Amazon Tall Tower Observatory site in 2014-2019
Authors: Komiya Shujiro , Carioca de Araújo Alessandro , V. Lavric Jost , Nelson Bruce , Sörgel Matthias , Weber Bettina , Botia Santiago , Gomes-Alves Eliane , Walter David , de Oliveira Sá Marta , Wolff Stefan , M. Pinho Davieliton , Kondo Fumiyoshi , Trumbore Susan
Published: March 2022

The vegetation and soils of the Amazon contain large amounts of carbon that may be vulnerable to loss given ongoing climate and land use change in the Amazon basin. Previous studies predicted that the Amazon rainforest would start to act as a net carbon source to the atmosphere by 2030-2040, and that it has switched from being a sink to source over the last decade. Using data from eddy covariance and vertical carbon dioxide profile measurement systems installed at the 80 m walk-up tower in the Amazon Tall Tower Observatory (ATTO) site, located in well-preserved central Amazon upland rainforest, we assessed net ecosystem exchange (NEE), gross primary productivity (GPP), and ecosystem respiration (Reco) for the period 2014-2019. The NEE results indicate that the central Amazon upland rainforest was carbon neutral or a source during this 6-year period. Seasonal GPP variations were related to soil water availability and vapor pressure deficit. The strong 2015-2016 El Niño event decreased both GPP and Reco due to the unusually long dry period, but also contributed to carbon flux dynamics in post El Niño periods. In the 2017-dry season, we measured higher dry-season GPP compared with the other years, which we hypothesize was triggered by photosynthesis activation in sub-canopy and understory trees. This is supported by the minimum green crown fraction at upper canopy trees, indicating more light availability in lower canopy trees, and the higher fraction of absorbed photosynthetically active radiation, both recorded during the dry-season of 2017. Our results show that the ground-based measurement setup at ATTO is well suited to investigate the local carbon fluxes on seasonal to interannual time scales.
Ensemble strategy for decision-support tool : a case study of the Alex storm in 2020 in la Roya and la Vésubie valleys
Authors: Wacheux Christophe
Published: March 2022

Best allocation of ressources from stakeholders that face fast-flooding implies a dynamic representation of the risk, exposure, and danger, in a situation where parameters (roughness, infiltration, drainage network etc.), and input (bathymetry and rainfall) can be both uncertain and volatile. Ensemble strategy simulation appears as a good approach to deal with these issues.
Fast-flood event are also typically events where meteorological predictions can underestimate the actual rainfalls until very late. Urban microcharacteristics can also make models sensitive to spatial resolution, and « events » such as log jam can even modify DEM. 
At Strane Innovation, we develop a decision-support tool called BlueMapping. To be operational, that is, fast to deploy and reliable, we use this ensemble strategy together with the fastests simulation models deployed on powerful computers. It also requires quick and robust routines for the setup of the model, with proxies when data is not available at the moment, and inputs that are easy to modify if necessary.
We will ilustrate this discussion through the test case of the Alex storm that hit la Vésubie and la Roya valleys. After a quick benchmark with a standard model, we will compare the outcome between the flooding predicted by different models and the actual outcome. 
Since BlueMapping can be integrated in an alarm system, it is important to assess the values of the confusion matrix, in particular the false alarm ratio, to make sure our tool keeps its value over time.
Alternative livelihood programs to promote sustainable resources use in Afi, Mbe and Okwango Forests in Cross River State, Nigeria
Authors: Ologeh Idowu , Farinloye Kolawole
Published: March 2022

Poor people in rural areas of developing countries are often highly dependent on forest biodiversity to meet their day-to-day livelihood needs because protein from forest wildlife is crucial to rural food security and livelihoods across the tropics. The harvest of animals and reliance of poor, rural communities on forest resources has resulted in destructive gathering practices that directly degrade forest ecosystems; a practice which is largely unsustainable, hence there is a need for alternative livelihoods program in such communities. Several efforts in the past have applied alternative livelihoods programs with little or no success. The study aims to investigate the contributions of the Wildlife Conservation Society (WCS); a nongovernmental organization with the mission to save wildlife and wild places across the globe, in engendering alternative livelihoods program in selected communities in the forested zone in Cross River State, Nigeria. The study design is observational and socio-economic in nature. The sample frame for the study entails detailed appraisal of the success of the WCS alternative livelihoods program in Afi, Mbe and Okwango. Non-probabilistic Snowball sampling is being used; this method will help to identify trained and untrained hunters. The sample size for the study comprises one hundred and seventy four (174) respondents derived from four (4) groups of actors of the target population: Hunters trained by WCS (57), Project Managers (3), Rangers and Eco guards (15) and Hunters not trained by WCS (102). We compare the differences and associations between respondent categories in terms of livelihood strategies and outcomes using T-test statistics and qualitative methods.
Investigating Vrancea intermediate depth seismic activity in Romania using automatic waveform processing methods
Authors: Poiata Natalia , Grecu Bogdan , Dinescu Raluca , Borleanu Felix , Tataru Dragos
Published: March 2022

Seismic activity in Romania is dominated by the intermediate-depth earthquakes generated inside the seismogenic body of the Vrancea seismic zone extending to the depth of 180 km. This earthquakes represent the main source of seismic hazard for Romania and neighbouring countries, with the most recent largest events of M 7.7 and 7.4 in 1940 and 1977 that caused significant and widespread destruction. Space distribution of the intermediate-depth earthquakes from Vrancea is constrained to a compact volume (60-180 km in depth and 20x50 km areal extent) falling into the category of, so called, “seismic nests”, which have peculiar and not well understood seismogenic mechanisms.

We present first results obtained by applying the automated waveform analysis schemes to the detection, location and characterization of seismicity from the Vrancea zone to the continuous data recorded at seismic stations of the Romanian seismic network. We evaluate the performance of the methods like network-based full-waveform coherency earthquake detection and location and the template-based waveform similarity analysis for building a detailed view of seismic activity in space and time and to provide a fully automated workflow for continuous seismic data analysis. We use case-specific, for Vrancea seismic region, synthetic example to test the detection and location scheme setup and resolution. The real dataset of continuous seismic data focuses on the two month time period around the recent, moderate (M 5.6) December 27, 2016 earthquake.

The preliminary results of the automated detection and location analysis indicate reduced foreshock and aftershock activity for this event. According to the Romanian earthquake catalog, this appears to be a common pattern for moderate (M ~5.0-6.0) magnitude events. We also discuss the results of the template-based waveform similarity analysis for the detected and located events, as well as how the combination of the two methods can contribute to the enhanced seismic monitoring and hazard assessment.
CalxPy: a software for the calibration of geophysical systems against a reference 
Authors: Doury Benoît , Ketata Ichrak
Published: March 2022

The International Monitoring Systems (IMS) operational manuals for waveform stations require that IMS stations be calibrated regularly. Since 2012, the Provisional Technical Secretariat (PTS) had relied mostly on electrical calibration to meet that requirement. However electrical calibration has inherent challenges (no traceability, integration and sustainment issues, high operating costs…).

A part of the geophysical community, including Station Operators, has started performing regular calibrations by comparison against a co-located reference. This method allows a more systematic and centralized approach to calibration. Over the past few years, it has been increasingly used at IMS stations, particularly infrasound ones. In this context, the PTS is developing tools to support this alternative approach.

We present CalxPy, a web-application developed at the PTS for the calibration of geophysical systems by comparison. With CalxPy, one can calculate, store, and display the response of a system for a given period, or track the evolution of the response against time or environmental variables. CalxPy also allows the refinement and evaluation of the measured response against a baseline, and the reporting of calibration results.

CalxPy supports the Initial calibration and on-site yearly calibration processes, as well as data quality control. CalxPy can be deployed in the IDC pipeline and in NDC-in-a-box.
Surrogate model for seepage analysis of a dike using generative adversarial networks
Authors: Homma Yusuke , Kuroda Seiichiro , Makino Nobuo
Published: March 2022

In recent years, the risk of sediment-related disasters has increased due to the increase in heavy rain disasters. Therefore, a technique for more easily diagnosing the internal structure of dikes such as fill dams is desired. We applied machine learning to this task.
In this study, we estimated the correspondence between the hydraulic conductivity distribution and the pressure head distribution of the zoned dike using machine learning. The machine learning method is pix2pix which is derived from generative adversarial networks (GAN). Pix2pix learns the relationship between input and output image. Training datasets were generated by using HYDRUS-2D In the HYDRUS-2D simulation, the dike was divided into three zones, and the seepage analysis was performed by changing the hydraulic conductivity of each zone to various values, and the pressure head distribution in the steady state was obtained.
In the forward problem, most of the results could be estimated accurately. On the hand, it was difficult to estimate the inverse problem because of the ill-posed problem. In the inverse problem, we were able to improve the results by giving the training data a priori information about the hydraulic conductivity.
This approach can be used as a surrogate model for the forward problem and the inverse problem in seepage analysis.