bluuebunny/crossref_metadata_2025 huggingface dataset:
Drought and food security in Senegal from the perspective of household access
Authors: Giannini Alessandra , Ilboudo-Nébié Elisabeth
Published: March 2021

In the Sahel food security has been a top development priority since the abrupt onset of persistent drought caught the region by surprise in the early 1970s, causing repeated recurrences of extreme food insecurity. Research ultimately demonstrated the global climate root of drought, going so far as to partially attributing persistence to anthropogenic emissions of aerosols and greenhouse gases. 

We exploit surveys collected in Senegal in the last 10 years to assess the year-to-year dynamics of household food security in relation to rainfall variability. We combine three variables from the household surveys, namely the Food Consumption Score, the Food Expenditure Share and the Reduced Coping Strategies Index, to explore the access dimension of food security. Cluster analysis on these three variables leads us to 1) classify households into categories of food security, and 2) discuss the response of each category of household to seasonality and year-to-year variability in climate. 

The UN World Food Programme and in-country partner institutions normally survey thousands of households every few years, in order to assess "baseline" (as opposed to "crisis") food security conditions. However, the years that Senegal households were surveyed in this most recent decade include 2014, a year of severe, national-scale drought. Comparison with the other, non-drought years allows to directly assess the shock from the perspective of the households themselves, and to describe coping mechanisms based on "baseline" food security category. We find that in the drought year (1) more of the “average rural” households that normally do not recur to coping strategies actually did, and (2) food expenditure share increases in all but one food security category.
Global soil erosion: Storm on the horizon 
Authors: Borrelli Pasquale , Robinson David A. , Panagos Panos , Lugato Emanuele , Yang Jae E. , Alewell Christine , Wuepper David , Montanarella Luca , Ballabio Cristiano
Published: March 2021

We use the latest projections of climate and land use change (year 2070) to assess potential global soil erosion rates by water erosion (interrill and rill processes) (Borrelli et al., 2020) using the RUSLE-based semiempirical modeling platform (GloSEM) (Borrelli et al., 2017). With some degree of uncertainty, GloSEM allows prediction of both state and change of soil erosion, identifying hotspots thanks to its high resolution (250 × 250 m) and predicting future variation based on projections of change in land use, soil conservation practices, and climate change.

Three alternative scenarios (2.6, 4.5, and 8.5) are tested using the Shared Socioeconomic Pathway and Representative Concentration Pathway (SSP-RCP) (LUH2 data) and 14 General Climate Models (GCMs) (WorldClim data), for a total of 42 modelling scenarios.

In the 2015 scenario, we estimate global soil erosion equal to 43 (+9.2/−7) Pg yr−1; with a study area covering ∼95.5% of the Earth’s land surface (in Borrelli et al. 2017 the study area was ~84.1% of the Earth’s land surface). The future scenarios suggest that socioeconomic developments impacting land use will either decrease (SSP1-RCP2.6–10%) or increase (SSP2-RCP4.5 +2%, SSP5-RCP8.5 +10%) water erosion by 2070. By contrast, climate projections, for all global dynamics scenarios, indicate a trend, moving toward a more vigorous hydrological cycle, which could increase global water erosion (+30 to +66%). Quantitatively, 56.1 (+20.6+ /- 16.4) Pg yr−1, 64.8 (+28.5/-21.4) Pg yr−1, and 71.6 (+32.5/-24.7) Pg yr−1 are predicted for the SSP1-RCP2.6, SSP2-RCP4.5, and SSP5-RCP8.5 scenarios, respectively.

The modeling framework presented in this study adopts standardized data in an adequate format to communicate with adjacent disciplines and moves us toward robust, reproducible, and open data science.

 

References

Borrelli, P., Robinson, D.A., Fleischer, L.R., Lugato, E., Ballabio, C., Alewell, C., Meusburger, K., Modugno, S., Schütt, B., Ferro, V. and Bagarello, V., 2017. An assessment of the global impact of 21st century land use change on soil erosion. Nature communications, 8(1), pp.1-13.

Borrelli, P., Robinson, D.A., Panagos, P., Lugato, E., Yang, J.E., Alewell, C., Wuepper, D., Montanarella, L. and Ballabio, C., 2020. Land use and climate change impacts on global soil erosion by water (2015-2070). Proceedings of the National Academy of Sciences, 117(36), pp.21994-22001.
Emissions from the Canadian oil sands:  Merging aircraft and satellite observations to derive emissions of pollutants co-emitted with NOx
Authors: Moser Sarah , Griffin Debora , Wren Sumi , McLinden Chris , Liggio John , Wheeler Michael , Wentzell Jeremy J.B. , Mittermeier Richard , Hayden Katherine , Darlington Andrea , Leithead Amy , Krotkov Nickolay
Published: March 2021

The Athabasca Oil Sands Region (AOSR) in Alberta, Canada is one of the largest sources of extractable oil in the world. To better understand its impact, Environment and Climate Change Canada led two intensive measurement campaigns, in 2013 (August to September) and 2018 (April to July).  Each included airborne measurements in which dozens of species were measured using a variety of in situ instruments. In this presentation, a method is described in which these aircraft measurements were examined to find species that were well correlated with NOx (the sum of NO and NO2) in order to derive their annual emissions. The species found to have a good correlation with NOx were black carbon, CO, HCN, HONO, CH4, and SO2. The annual emissions were found by applying individual species to NOx ratios to the satellite-derived NOx emissions from the TROPOspheric Monitoring Instrument (TROPOMI). The emissions derived in this way were compared with emissions reported to the National Pollutant Release Inventory (NPRI), as well as emissions derived from the aircraft measurements using the Top-down Emission Rate Retrieval Algorithm (TERRA). Additionally, Ozone Monitoring Instrument (OMI) NOx emissions were used to estimate historical changes in species emissions over time, between 2005 and 2020.
Linkage between the absorbing aerosol snow darkening effects over the Himalayas-Tibetan Plateau and the pre-monsoon climate over northern India
Authors: Das Sushant , Coppola Erika , Panicker Abhilash Sukumara , Gautam Alok Sagar
Published: March 2021

A large uncertainty exists today in quantifying the absorbing aerosol snow darkening effects, especially at the regional scale. It is considered as one of the main factors contributing to snow melting and glacier retreat over the Himalayas-Tibetan Plateau (HTP). Using International Centre for Theoretical Physics (ICTP)’s regional climate model - RegCM4 coupled with SNow, ICe and Aerosol Radiation (SNICAR) embedded within Community Land Model (CLM4.5), we examine the possible changes induced by aerosol deposition over the HTP and its dynamical impacts over northern India during the pre-monsoon season, which is critical for the inception and development of the monsoon. Sensitivity experiments without (DRE) and with aerosol snow darkening effects (SDDRE) were carried out over the South Asia - Coordinated Regional Climate Downscaling Experiment (CORDEX) domain for the period 2005-2010. It is found that there is a significant reduction of snow fraction by 10 to 25 % and an increase in surface temperatures (> 4° C) in SDDRE, which improves the model performance when comparing against observations. This response is dominated by a larger portion of dust deposition compared to black carbon. The associated increase in the surface and tropospheric temperature over HTP draws in dry air from central and west Asia towards northern India leading to a decrease in the precipitation in SDDRE.  The increase in the northwesterly winds also modulates the dust cycle by enhancing dust emissions over the Thar Desert as well as the columnar burden and depositional fluxes over northern India. As a result of the decrease in precipitation, surface temperature increases and generates a low-pressure system over northern India, which further strengthens the dust transport and partially contributes to the occurrence of dust storms. We also find that the snow darkening effect induces an earlier monsoon onset due to larger temperature gradients initiated over the HTP. Some analysis of precipitation and temperature extremes as well as limitations will be presented. Our study provides evidence that the aerosol snow darkening effects could have substantial impacts over HTP as well as over northern India through feedbacks and hence needs to be considered in climate simulations.
Understanding the variability of the Eddy Kinetic Energy in the Arctic Ocean.
Authors: Lique Camille , Regan Heather , Meneghello Gianluca , Talandier Claude
Published: March 2021

Mesoscale activity in the Arctic Ocean remains largely unexplored, owing primarily to the challenges of i) observing eddies in this ice-covered region and ii) modelling at such small deformation radius. In this talk, we will use results from a simulation performed with a high-resolution, eddy resolving model to investigate the spatial and temporal variations of the eddy kinetic energy (EKE) in the Arctic Basin. On average and in contrast to the typical open ocean conditions, the levels of mean and eddy kinetic energy are of the same order of magnitude, and EKE is intensified along the boundary and in the subsurface. On long time scales (interannual to decadal), EKE levels do not respond as expected to changes in the large scale circulation. This can be exemplified when looking at the spin up of the gyre that occurred in response to a strong surface input of momentum in 2007-2008. On seasonal time scales, the estimation of a Lorenz energy cycle allows us to investigate the drivers behind the peculiarities of the EKE field, and to understand the relative roles played by the atmospheric forcing for them.

 
Atmospheric Turbulence and Clouds in the Tropics: Shipborne Lidar Measurements of Dynamics and Thermodynamics During EUREC4A
Authors: Lange Diego , Behrendt Andreas , Senff Christoph , Späth Florian , Wulfmeyer Volker
Published: March 2021

During the EUREC4A campaign (Bony et al., 2017, Stevens et al, 2020), a unique combination of lidar systems was operated to study ocean-atmosphere interaction on the German research vessel R/V Maria S Merian between 18 January and 18 February 2020. These systems observed the maritime boundary layer (MBL) and its relation to cloud development in the trade wind alley east of Barbados and in the "Boulevard des Tourbillons" east of Venezuela with turbulence resolving resolution.

For this purpose, for the first time, the Atmospheric Raman Temperature and Humidity Sounder (ARTHUS) (Lange et al. 2019; Lange et al. this conference) was operated on a shipborne platform in vertically staring mode. This system is capable of measuring water-vapor, temperature, and aerosol profiles with unprecedented resolution of 7.5 m and 10 s in the lower troposphere. ARTHUS was combined with one Doppler lidar in vertically staring mode and a second one in a 6-beam scanning mode.

For studying the above mentioned processes, a data set was collected, which includes profiles of water vapor mixing ratio, temperature, relative humidity, vertical and horizontal wind as well as the statistics of higher-order moments of these parameters. Synergetic parameters from the combination of the data are turbulent kinetic energy (TKE), momentum flux, dissipation rate, sensible and latent heat flux profiles (Behrendt et al. 2020). At the conference, highlights of the measurements will be presented which show the dependence of cloud evolution on sea surface temperature and MBL properties as well as the interaction with the trade wind layer.

 

References

 

Behrendt et al. 2020, https://doi.org/10.5194/amt-13-3221-2020

Bony et al. 2017, https://doi.org/10.1007/s10712-017-9428-0

Lange et al. 2019, https://doi.org/10.1029/2019GL085774

Stevens et al. 2020, submitted to ESSD
Spatial bootstrapping for model-free estimation of subcatchment parameter uncertainty for a semi-distributed rainfall runoff model
Authors: Snieder Everett , Khan Usman
Published: March 2021

Semi-distributed rainfall runoff models are widely used in hydrology, offering a compromise between the computational efficiency of lumped models and the representation of spatial heterogeneity offered by fully distributed models. In semi-distribute models, the catchment is divided into subcatchments, which are used as the basis for aggregating spatial characteristics. During model development, uncertainty is usually estimated from literature, however, subcatchment uncertainty is closely related to subcatchment size and level of spatial heterogeneity. Currently, there is no widely accepted systematic method for determining subcatchment size. Typically, subcatchment discretisation is a function of the spatiotemporal resolution of the available data. In our research, we evaluate the relationship between lumped parameter uncertainty and subcatchment size. Models with small subcatchments are expected to have low spatial uncertainty, as the spatial heterogeneity per subcatchment is also low. As subcatchment size increases, as does spatial uncertainty. Our objectives are to study the trade-off between subcatchment size, parameter uncertainty, and computational expense, to outline a systematic and precise framework for subcatchment discretisation. A proof of concept is presented using the Stormwater Management Model (EPA-SWMM) platform, to study a semi-urban catchment in Southwestern Ontario, Canada. Automated model creation is used to create catchment models with varying subcatchment sizes. For each model variation, uncertainty is estimated using spatial statistical bootstrapping. Applying bootstrapping to the spatial parameters directly provides a model free method for calculating the uncertainty of sample estimates. A Monte Carlo simulation is used to propagate uncertainty through the model and spatial resolution is assessed using performance criteria including the percentage of observations captured by the uncertainty envelope, the mean uncertainty envelope width, and rank histograms. The computational expense of simulations is tracked across the varying spatial resolution, achieved through subcatchment discretisation. Initial results suggest that uncertainty estimates often disagree with typical values listed in literature and vary significantly with respect to subcatchment size; this has significant implications on model calibration.
May macropores increase contaminant retention? 
Authors: Raimbault Jérôme , Lassabatere Laurent , Peyneau Pierre-Emmanuel , Courtier-Murias Denis , Béchet Béatrice
Published: March 2021

Preferential flow is quite usual in natural environments. Non-uniform and preferential flows co-exist or alternate, impacting water transport and contaminant transfer through the vadose zone. In this study, we investigated how macropore-induced flow affects manufactured nanoparticles, as emerging contaminants reactive transfer. Previous studies showed that the presence of a macropore into water-saturated soil columns can foster preferential water flow within the macropore. One could expect that this preferential flow may increase contaminant transfer and reduce retention by the matrix in the case of contaminant, as previously reported. In this study, we injected pulses of silver nanoparticles to assess their transfer through sand columns with and without a macropore. Both systems (with and without macropore) were studied under similar conditions. An unexpected result was obtained: more nanoparticles were retained in the system with a macropore, i.e., with a preferential flow. This result is quite counter-intuitive. It appears that the relation between flow homogeneity and contaminant retention is not straightforward. Some possible explanations, related to chemical and physical kinetics, are put forward to explain the experimental results.
GIS-based multicriteria decision analysis for the environmental assessment of the Pesqueria River in Northeast Mexico, using UAS and multi-spectral imagery 
Authors: Mireles Soria Diana Laura , Yépez Rincón Fabiola Doracely , Ramírez Serrato Nelly Lucero , Ortiz Martínez Maria Gabriela , Ferriño Fierro Adrián Leonardo , Guerra Cobián Victor Hugo
Published: March 2021

Urbanization is the dominant force shaping social, economic, and environmental life in the 21 century. Urban areas will become essential to achieve the Sustainable Development Goals (SDGs) established by the United Nations in their 2030 Agenda. Local governments must identify the vulnerable ecosystems to make cities inclusive, safe, and resilient (SDG 11). In Latin America, urban rivers are vulnerable ecosystems, negatively impacted by rapid urbanization. Furthermore, detailed geospatial information of urban rivers is not updated frequently, therefore available data doesn’t reflect changes occurring due to rapid urban development processes affecting the quality of water, sediments, or vegetation health. This research uses a GIS-based multicriteria decision analysis (GIS-MCDA) for the environmental assessment of the Pesqueria River as a decision tool to facilitate mitigation focused strategies. The developed method has used the pixel to pixel data from socio-economical, environmental, topographical, geological, and hydrological factors affecting the environmental health of urban rivers. Census data, geological formation or soil type were obtained from official information; reflectance indices and vegetation height were obtained using aerial photogrammetry with near-infrared and red bands; terrain and hydrological analysis used digital elevation models derived from LIDAR; land cover was created using a SENTINEL 2 image; and water quality data was obtained from field sampled raised and analyzed with traditional laboratory analysis of Chemical Oxygen Demand and validated also with official data. Results implied the generation of the thematic maps with ranges from 1 (very low quality) to 5 (very high quality) according to the environmental quality assessment. For the GIS-MCDA, the values of each map were converted to the same scale, each criterion was weighted in function of its importance according to the literature review and the objective of this research, and there were aggregated by the way of a lineal combination. The result is a map that shows the level of mitigation or conservation priority along the river. This map can offer information to the stakeholders in a relatively short time and accelerate the actions aimed to protect the quality of this important urban ecosystem. 
Summer Heatwaves in Present and Future Climate simulated with global models participating in CMIP6
Authors: Zhao Yanfeng , Cheruy Frederique
Published: March 2021

Heat waves lead to major impacts on human health, food production and ecosystems, and are projected to increase with climate change. This study evaluates global climate models participating in the Coupled Model Intercomparison Project phase 6 (CMIP6) for their performance in simulating the present climate characteristics of summer heat waves. The analysis exploits the available global datasets (reanalyses, satellite products, gridded in-situ observations) to assess the realism of variables impacting the energy and water balance at the surface during heatwave events.The role of the underlying processes affecting the occurrence and intensity of the heat waves characteristics in present and future climate is also investigated based on the multi-model analysis.  A sensitivity study performed with the coupled atmospheric and land-surface modules of the IPSL climate model helps to support the multi-model analysis. A robust impact of the soil moisture on the dispersion of the heat-wave characteristics is diagnosed.  For 2 models it is possible to analyse the moist heat waves whose intensity and frequency is dramatically increased with respect to the dry heat waves at the end of the 21th century.
Root exudates compounds and microbial community composition regulates CH4 dynamics in fire degraded tropical peatland
Authors: Lupascu Massimo , Akhtar Hasan , Bandla Aditya , Sukri Rahayu S , Swarup Sanjay
Published: March 2021

Fires and drainage are common disturbance factors in tropical peatlands (TP) in Southeast Asia. These disturbances alter the hydrology, vegetation composition, and peat biogeochemistry; thereby affecting the microbiome where microbial communities reside. Studies from northern peatlands have well established the role of vegetation composition in regulating the labile C, in the form of plant root exudates, and microbial community composition affecting the peat decomposition; however, for tropics, it remains unexplored. Recent studies have also established how these fire-degraded TP areas become a hot spot of sedge-mediated CH4 emission. To further our understanding of control mechanisms regulating CH4 dynamics, we investigated the composition of plant root exudates (n=3 per plant species) from sedges (Scleria sumatrensis) and ferns (Blechnum indicum, Nephrolepis hirsutula), the most commonly occurring plant species at our fire-degraded tropical peatland site in Brunei, Northwest Borneo, as well as microbial community composition in plant (n=9 for S. sumatrensis, and B. indicum, and n=5 for N. hirsutula) rhizo-compartments (rhizosphere, rhizoplane, endosphere).

         Using a targeted analysis, we found that the root exudates compounds secreted from sedge (Scleria sumatrensis) and one species of fern (Blechnum indicum) were significantly different (p<0.05) and showed a similar ratio of 2:1 for sugars (glucose, fructose) and organic acids (acetate, formate, lactate, malate, oxalate, succinate, tartrate), which is in contrast to that secreted from trees in intact tropical peatlands (1:2). Further, using 16S rRNA gene amplicon sequencing, we found that the microbial community composition in rhizo-compartments of plant species showed significant differences (p<0.001). Interestingly, the sedge species harboured a relatively higher abundance of methanogens (Thermoplasmata) and lesser methanotrophs (Alphaproteobacteria, Gammaproteobacteria) across all three compartments compared to fern species, which further supports the higher sedge-mediated CH4 emissions from fire-degraded TP.

            Our results provide fresh insights into the effects of post-fire vegetation composition in regulating the labile C and microbial community composition, and hence affecting CH4 emissions from fire-degraded TP. Further, our results can form an important basis for future CH4 dynamics studies as the emissions might increase with the expansion of degraded TPs as a consequence of frequent fire episodes and flooding
Europe-Atlantic jet caused dipole mode of European climate and increased climatic extremes
Authors: Xu Guobao , Matthew Meko , Klippel Lara , Dorado-Liñán Isabel , Trouet Valerie
Published: March 2021

The jet stream configuration over the Atlantic Ocean and the European continent substantially affects climatic extremes in Western Eurasia by transporting heat and vorticity. However, how the Europe-Atlantic jet configuration varies and how it affects European climate on the long time-scales are still unclear. We compiled a network of tree-ring width, blue intensity, and maximum density chronologies from Europe to explore past variability in the summer Europe-Atlantic Jet stream and its influence on regional climate. By combining five regional chronologies, we were able to reconstruct July-August jet stream latitude (JSL) PC2 variability over the past millennium (978-2010 CE) for the Europe-Atlantic domain (30°W to 40°E). Our reconstruction explains 40% of summer JSL PC2 variability over the instrumental period (1948-2010 CE) with strong skill. Our millennial-long reconstruction shows that summer JSL is a relevant driver of the temperature, precipitation, and drought dipoles observed between Northwestern and Southern Europe. Positive summer JSL PC2 values (northward jet position) generally lead to a strengthening of the European summer climate dipole, while negative values (southward jet position) lead to a weak or insignificant dipole mode. Our summer JSL reconstruction shows large variability and a high occurrence rate of extremes over the 20th century, as well as 1200-1350 CE Medieval Climate Anomaly (MCA). The high occurrence rate of summer JSL extremes corresponds to periods with increased number of climatic extremes. Our results suggest that the summer JSL contributes to the European climate dipole both in a long-term context and in its extremes. We also reveal that the occurrence rate of summer JSL extremes is double during the 20th century compared to other periods, especially for the negative extremes, which might be related to anthropogenic warming. Our results suggest a high occurrence rate of summer JSL extremes during the 20th century, leading to more climatic extremes in Europe, as well as a prevailing northward summer JSL position resulting in a weakening climatic dipole.
Is silicon a double-edged sword against insect herbivores? 
Authors: Islam Tarikul , Moore Ben D. , Johnson Scott N.
Published: March 2021

In recent years, silicon (Si) has been increasingly linked to biotic stress management in plants including insect herbivory. The effectiveness of Si against chewing insects is now well recognized. Silicification of plant tissues makes them abrasive and tougher, reducing their masticability and digestibility to insect herbivores. This can cause mandibular wearing of chewers and affect their growth and feeding. Although there has been extensive research on the effects of Si on plant defences (i.e. antixenosis and antibiosis), it remains unclear how feeding on silicified plants affects insect defences to their natural enemies. Insect herbivores show morphological and behavioural defences when encountering predators and parasitoids. For example, lepidopteran larvae can regurgitate, twist the body, or even drop off the plants when attacked by natural enemies. Moreover, insects possess innate immunity (physiological defence) against the attackers, demonstrating cellular and humoral responses upon attack. Notably, there could be potential trade-offs between different defence and immunity traits. Given that feeding on Si-rich plants affects insect growth rates, this could impact their relative investment in different defences, thereby making insects more susceptible to their enemies. We are investigating the effects of Si on plant resistance and tolerance to herbivory and its cascading effects on insect defences to their enemies. We have been growing the model grass, Brachypodium distachyon, a high Si-accumulator, hydroponically with or without Si and examining the effects of Si against the global insect herbivore, Helicoverpa armigera. Our preliminary results suggest that Si supplementation enhances plant antixenotic and antibiotic traits and increases plant tolerance to herbivory. We are currently exploring insect defence and immunity traits when fed on silicified versus non-silicified plants. Our study would shed light on the impacts of Si on insects’ susceptibility to biocontrol agents and provide a better understanding of the effects of Si on insect-plant-natural enemy interactions.
Multiple debris flow surges monitored directly by DFLP system at Kamikamihori Creek
Authors: Itoh Takahiro , Nagayama Takahiko , Matsuda Satoru , Mizuyama Takahisa
Published: March 2021

The monitoring method for direct debris flow measurements using loadcells and so on, that were preliminary developed by WSL in Switzerland (McArdell et al., 2007), was firstly installed in Sakura-jima Island in Japan, where volcanic activity was severe, and many debris flows took place due to deposition of falling ash after eruptions. Debris Flow measurements with Loadcells and Pressure sensors (DFLP) system was installed referring to the method by WSL, and debris flow characteristics such as specific weight and volumetric sediment concentration have been obtained (e.g., Osaka et al., 2014).

 In Japan, as well as in Sakura-jima island, attempts for debris flow monitoring were also carried out at KamiKamihori Creek since 1970s (e.g., Okuda et al., 1980), and there were a lot of debris flow events due to heavy rainfall. KamiKamihori Creek is at western side of Mt. Yake, where volcanic activity was severe at those time. The DFLP system was modified and installed there in November in 2014, because there were a lot of sediment deposition and debris flows took place though volcanic activity has been inactive. Present research could report the following results.  

(1) Multiple debris floe over five surges were monitored using DFLP system installed in 2014 during 15 minutes in debris flow events on August 29th, 2019. Rainfall intensity for 10 minutes was 12 mm and accumulated depth was 56 mm just before those events. Antecedent time before those events was 4.5 hours.

(2) The DFLP system measured multiple debris flow surges in events on August 29th, 2019, and sediment concentration was calculated temporary and continuously. Time-averaged sediment concentration and relative mass density are calculated as 0.470 and 1.73, respectively, under flow discharge obtained by images analysis of CCTV video camera. Equilibrium sediment concentration of coarse sediment particles is estimated 0.160 for bed slope of 0.141 (8 degrees) and calculated value using the DFLP system is over than the equilibrium value because of mud phase due to fine sediment particles.

 

References

McArdell B.W., Bartelt P., Kowalski J. (2007). Field observations of basal forces and fluid pore pressure in a debris flow, Geophysical Research Letters, Vo. 34, L07406.

Okuda, S., Suwa, H., Okunishi, K., Yokoyama, K., and Nakano, M. (1980). Observation of the motion of debris flow and its geomorphological effects, Zeitschrift fur Geomorphology, Suppl.-Bd.35, pp. 142–163.

Osaka T., Utsunomiya R., Tagata S., Itoh T., Mizuyama T. (2014). Debris Flow Monitoring using Load Cells in Sakurajima Island, Proceedings of the Interpraevent 2014 in the Pacific Rim (edited by Fujita, M. et al.), Nov. 25-28, Nara, Japan, 2014, O-14.pdf in DVD.
Impact of Urban Land Cover Types on Surface Temperature
Authors: Naserikia Marzie , Hart Melissa , Nazarian Negin
Published: March 2021

The conversion of natural land to built-up surfaces has been widely documented as the main determinant of warming across urban areas. However, uncertainties remain regarding which primary land cover variables control urban heat in different climatic conditions at a global scale. While there is a very little understanding of how the cooling effects of vegetation cover vary over different cities, there is a deep knowledge gap in realizing how other land covers (such as soil, water, and built-up areas) are associated with urban warming and how this relationship is varied in different background climates. Accordingly, using a high spatial resolution dataset, a global synthetic investigation is needed to find the underlying factors influencing intra-urban temperature variability in various climates. To address this shortcoming, this study focuses on exploring the relationship between land surface temperature and land cover in different cities (using Landsat 8 imagery) and aims to investigate the effects of these land cover types on thermal environments in different climatic backgrounds. Preliminary analysis shows that different land cover types have different roles in different climate classes due to their various surface characteristics and in particular, the performance of green spaces to reduce LST is highly dependent on its background climate. For example, the efficiency of vegetation cover to reduce urban surface warming in temperate and tropical climates is more than that in arid and semi-arid areas. In this climate class, since baren soil is the main contributor to the intensity of LST, increasing the area of a green space presents an effective method to mitigate the adverse effects of local warming. Our findings provide helpful information for future urban climate-sensitive planning oriented at mitigating local climate warming in cities.
Guessing the missing half of a geophysical field with blunt extension of discrete Universal Multifractal cascades
Authors: Gires Auguste , Tchiguirinskaia Ioulia , Schertzer Daniel
Published: March 2021

Universal Multifractals have been widely used to characterize and simulate geophysical fields extremely variable over a wide range of scales such as rainfall. Despite strong limitations, notably its non-stationnarity, discrete cascades are often used to simulate such fields. Recently, blunt cascades have been introduced in 1D and 2D to cope with this issue while remaining in the simple framework of discrete cascades. It basically consists in geometrically interpolating over moving windows the multiplicative increments at each cascade steps.

 

In this paper, we first suggest an extension of this blunt cascades to space-time processes. Multifractal expected behaviour is theoretically established and numerically confirmed. In a second step, a methodology to address the common issue of guessing the missing half of a field is developed using this framework. It basically consists in reconstructing the increments of the known portion of the field, and then stochastically simulating the ones for the new portion, while ensuring the blunting the increments on the portion joining the two parts of the fields. The approach is tested with time series, maps and in a space-time framework. Initial tests with rainfall data are presented.

 

Authors acknowledge the RW-Turb project (supported by the French National Research Agency - ANR-19-CE05-0022), for partial financial support.
Analysis between ancient human settlements and volcanic landscapes using earth observation and archaeological data
Authors: Alexandrakis George , Nomi Federico , Speciale Claudia , De Vita Sandro , Di Vito Mauro Antonio
Published: March 2021

Geological and environmental conditions that influence local topography also affect indirectly the location of human settlement dynamics. Understanding those relationships plays an important role in archaeological research related to the evolution of settlement dynamics. In the lower Tyrrhenian Islands, an important parameter is also the volcanic landscape evolution. This work aims to study the patterns of Neolithic, Cooper and Bronze Age settlements, based on known archaeological sites at the Low Tyrrhenian Islands, and to generate hypotheses about the relations of settlement patterns with the volcanic landscape. To that end, a Web-GIS database was created, which was fed with topographic, geological, geomorphological data and Earth Observation data. Geomorphological analysis, derived from digital elevation models, and earth observation products such as the SENTINEL missions, can provide useful estimations into the processes shaping landscapes and insight into the location and evolution of settlements. The analysis includes a series of different data correlation, from geomorphologic to socioeconomic, integrated by an indicator analysis. A series of thematic maps were developed to interpret why areas were selected to host settlements. Through the use of the database that was developed during the project, a set of indexes have been applied. Those included exposure and vulnerability indices for the inland and coastal areas, but also location and defensibility indices for the archaeological sites. Moreover, baseline maps for future risk estimations through a Multi-Criteria Decision Analysis System (MCDA), have been produced. The Volcanic Islands of the lower Tyrrhenian coast have a volcanic origin and were influenced, and partly still are, by explosive and effusive eruptions of various energy and types, by more or less intense deformational events, often connected with the dynamics of the volcano, and quiescent periods of varying duration. The areas under investigation present different characteristics in their geomorphological but also their societal evolution. Geomorphological data further analyzed in a ternary diagram that indicated the relative influence of each of the parameters in each area. From the diagram, it can be seen that the locations of human activities are strongly affected by past and recent volcanic activity.

Acknowledgement: This work is part of the Brains2Islands “INDAGINE MULTIDISCIPLINARE NEI CONTESTI INSULARI BASSO TIRRENICI” project Funded by FONDAZIONE CON IL SUD project number 2015-0296
Modelling Sediment Transport in the disastrous Flash Flood of November 2017 in Mandra (Attica, Greece)  
Authors: Sant Vasiliki , Mitsopoulos George , Bloutsos Aristides , Stamou Anastasios
Published: March 2021

 

Abstract

The flash flood in Mandra on the 15th of November 2017 was the third most disastrous “November” flood in Attica; it was characterized by heavy sediment and debris transport that can be easily observed in Figure 1.

We applied the Hydrologic Engineering Center's-River Analysis System (HEC-RAS) to model sediment transport using the Ackers-White sediment transport equation that is engraved in HEC-RAS to analyze sediment transport characteristics. The required input data were based on a limited number of available studies, which mainly include a survey performed by the Hellenic Centre for Marine Research in the coastal area of the Elefsis Bay where sediments were deposited after the catastrophic event. We compared the results of the model with calculations performed within a previous Thesis in 2018 using TELEMAC-2D and SISYPHE.

The present paper is based on the Diploma Thesis of the first author; it was performed within the project “National Network on Climate Change and its Impacts (CLIMPACT)” of the General Secretariat of Research and Technology.

 

Figure 1. The greater area of Mandra (a) before and (b) after the flood event
Global patterns of oceanic dust deposition during Pliocene-Pleistocene transitions
Authors: Teruel Oriol , Rosell-Melè Antoni , Penalva-Arias Nuria
Published: March 2021

The is a mounting evidence that global emissions of dust were significantly higher during glacial than interglacial periods of the Pleistocene, and probably the Pliocene epochs. this pattern is observed in records from the low and mid latitudes, albeit with a varying degree of amplitude. During these time periods spanning 4 million years, the Earth climate underwent major transitions, such as the initiation of the Northern Hemisphere Glaciations and the Mid Pleistocene Transition. In parallel, dust transport and deposition on the oceans might have underwent stepwise increases, mainly during glacials. However, it is not clear yet if such changes are representative of global or regional climate response. Thus, dust records in marine sediments reflect changes in the different processes that drive the emission, transport, and deposition of dust on the oceans. In here, we report a compilation of marine dust records spanning the Pliocene-Pleistocene from all the major ocean basins. The synthesis of dust records on a global scale allows the identification of common patterns of variability and drivers. We analyse the data to infer changes in the global atmospheric circulation on orbital time scale, and to assess its meridional and zonal response during major climate transitions since the Pliocene.
Boundary current heat loss and mixing processes at the Arctic Ocean continental margin
Authors: Schulz Kirstin , Janout Markus , Lenn Yueng-Djern , Ruiz-Castillo Eugenio , Polyakov Igor , Mohrholz Volker , Tippenhauer Sandra , Reeve Krissy Anne , Hölemann Jens , Rabe Benjamin , Vredenborg Myriel
Published: March 2021

Inflowing Atlantic Water forms a significant heat reservoir in the Arctic Ocean. In the Barents Sea, where the Atlantic Water layer resides close to the surface, strong upward heat fluxes reduce the sea ice cover. Along with a warming climate, an eastward progression of these conditions typical for the Barents Sea is anticipated. These new conditions have the potential to cause dramatic regime shifts in the Laptev Sea region, where the sea ice and the oceanic surface layer are currently sheltered from the warm Atlantic Water by a permanent halocline. Understanding and quantifying the dominant mixing processes in the Siberian Seas is hence crucial to predict how mixing and sea ice conditions, as well as particle and nutrient transport pathways will evolve in the future.

Based on recent temperature and current velocity profiles from this region, we quantify the Atlantic Water heat loss along its pathway around the Arctic basin margins. Contemporaneous turbulent microstructure measurement reveal that only 20% of this heat loss takes place in the deep basin, emphasizing the important role of stronger mixing in the continental slope region. Observed boundary mixing processes include:

Mixing in the frictional near bottom layer, strongly enhanced at the lee side of a topographic features and where large temperature gradients associated with the upper bound of the Atlantic Water layer are present in the turbulent near bottom layer.

Spatially confined but energetic mixing events over the whole water column. These events are ephemeral but re-occurring and can homogenize the intermediate water column down to a depth of over 300m, with substantial implications for heat transport, the vertical distribution of nutrients and cross-slope particle transport.

The presented results provide new insights into the complex mixing and transport patterns at the Arctic basin margins, and further emphasize the importance of boundary mixing across disciplines.
Drivers of spatio-temporal salinity distribution in a hypersaline lake
Authors: Chamanmotlagh Fatemeh , Safaie Ammar
Published: March 2021

Increased salinisation of surface waters poses growing threats to agro- and aquatic ecosystems around the world. One extreme example is Lake Urmia, in northwestern Iran, which is one of the largest hypersaline lakes. Due to anthropogenic and climate-induced changes, the salinity of Lake Urmia has reached a maximum level of 420 PSU in recent years. This high salinity has endangered the food web and biodiversity in the regional ecosystem and caused an ecological regime shift. However, salinisation processes in the lake have not been well-explored yet. To address this, a combination of in-situ and remote sensing observations along with a numerical hydrodynamic model was used to study the salinity dynamics of the lake. To simulate the water salinity distribution, a three-dimensional hydrodynamic model of the lake was developed based on Finite Volume Community Ocean Model (FVCOM) and validated using field data. Wind field, heat flux, precipitation, and surface water evaporation were constructed based on meteorological data. The PHREEQC inverse modeling was then applied to obtain the precipitation and dissolution rates of minerals species. Simulated results indicate that the sedimentation and dissolution of minerals have a significant effect on the salinity levels of the lake. Although brine discharges of rivers to the lake increase the salinity of the lake, the elevated salinity of the lake is dominantly caused by the salt precipitation/dissolution processes. The results of this study provide a better understanding of the impact of precipitation and dissolution mechanisms on salinity dynamics in saltwater bodies.
Implementation of a new real time seismicity detector for the Mayotte crisis
Authors: Saurel Jean-Marie , Retailleau Lise , Zhu Weiqiang , Issartel Simon , Satriano Claudio , Beroza Gregory C.
Published: March 2021

Seismology is one of the main techniques used to monitor volcanic activity worldwide. Seismicity analysis through several seismic sensor deployments has been used to monitor Mayotte volcano crisis since its beginning in May 2018. Because volcanic activity can evolve rapidly, efficient and accurate seismicity detectors are crucial to assess in real-time the activity level of the volcano and, if needed, to issue timely warnings.

 

Traditional real-time seismic processing software, such as EarthWorm or SeisComP, use phase onset pickers followed by a phase association algorithm to declare an event and proceed with its location. Real-time phase pickers usually cannot identify whether the detected phase is a P or S arrival and this decision or assumption is made by the associator. The lack of S arrival has an obvious impact on the hypocentral location quality. S-phases can also help detection on small earthquakes where weak P-phases can be missed.

 

We implemented the deep neural network-based method PhaseNet to identify in real-time seismic P and S waves on 3-component seismometers deployed on Mayotte island. We also built an interface to subsequently process PhaseNet results and send pick objects to EarthWorm. We use EarthWorm binder_ew associator module specifically tuned for PhaseNet a priori phase identification to detect and locate the events, which are finally archived in a SeisComP database. We implemented this innovative real-time processing system for the REVOSIMA (Reseau de surveillance Volcanologique et Sismologique de Mayotte) hosted at OVPF (Observatoire Volcanologique du Piton de la Fournaise). We assess the robustness of the algorithm by comparing the results to existing automatic and manually detected seismicity catalogs.

 

We show that the existing SeisComP automatic system is outperformed by our new algorithm, both in number of earthquake detections and location reliability. Our implementation also detects more events than the daily manual data screening. While this promising new processing system was first applied to study the Mayotte seismicity, it can be used in any seismic active zone, of volcanic or tectonic origin. Indeed, it will be installed at Martinique volcanic and seismic observatory later this year.
Modulation of the snow cover changes in the French Alps and the Pyrenees by the deposition of light absorbing particles over the last 40 years 
Authors: Réveillet Marion , Dumont Marie , Gascoin Simon , Lafaysse Matthieu , Nabat Pierre , Ribes Aurelien , Nheili Rafife , Tuzet Francois , Menegoz Martin , Ginoux Paul
Published: March 2021

By darkening the snow surface, mineral dust and black carbon (BC) deposition accelerate snowmelt and triggers numerous feedbacks. Assessments of their long-term impact at the regional scale are still largely missing despite the environmental and socio-economic implications of snow cover changes. Using detailed snowpack simulations, we show that dust and BC deposition advance snowmelt by 17 days on average in the French Alps and the Pyrenees over the 1979-2018 period, with major implications for water availability and ground temperature. The effect of BC compared to dust is generally prevailing except in the Southern Pyrenees more exposed to Saharan dust events. We also quantify a contribution of BC and dust deposition up to 30% to the variance of the snow melt-out date. Lastly, we demonstrate that the decrease in BC deposition since the 80's alleviated the impact of current warming on snow cover decline. Therefore, this study highlights the importance of accounting for the inter-annual fluctuations in light absorbing particles deposition to improve the accuracy of snow cover reanalyses and climate projections.