bluuebunny/crossref_metadata_2025 huggingface dataset:
Agricultural Management and Soil Carbon Sequestration: the potential of APSIM model to support climate change mitigation
Authors: S.S. Ferreira Carla , Kalantari Zahra , Martin Nicolas , Marcillo Guillermo , Zhao Pan , Wu Jing , Hovakimyan Naira
Published: March 2022

Leveraging soil carbon sequestration in croplands can support climate change mitigation; however, it is challenging to develop optimal management practices to maximize both sequestered carbon and crop yield. In intelligent agricultural management systems, large-scale crop models can provide an understanding of the complex soil-water-plant-atmosphere interactions and allow the evaluation of the effects of various management practices on carbon sequestration. This study aims to investigate soil carbon dynamics in maize cropland under different management practices, and discuss their potential to leverage the carbon sink capacity of agricultural soils. The Agricultural Production Systems sIMulator (APSIM) is used to investigate soil carbon dynamics in maize cropland of Baixo Mondego, an agricultural region in central mainland Portugal, under Mediterranean climate. The model was set up using soil properties retrieved from the INFOSOIL national database and run with daily climate data from 2001 to 2020 provided by local weather stations (i.e., solar radiation, maximum and minimum temperature, and rainfall). The maize yields’ records from an agricultural farm were used for model calibration (2017 - 2019) and validation (2020 - 2021). The model was then used to investigate the impact of different scenarios focusing on distinct fertilization management practices (i.e. fertilization rates, timing, and type of fertilizer) on soil carbon and crop yields. This study is part of a larger research project funded by C3.AI Digital Transformation Institute to develop an intelligent agricultural management system using deep reinforcement learning (RL) for agriculture sustainability and climate change mitigation. This project has great potential for impact on climate change and food security, two of the most significant challenges currently facing humanity.
Investigating INT2 and INT3 VLBI session performance for the determination of dUT1 
Authors: Schartner Matthias , Plötz Christian , Soja Benedikt
Published: March 2022

The rapid determination of the Earth's phase of rotation, expressed through the Earth rotation parameter dUT1, is one of the core tasks of geodetic Very Long Baseline Interferometry (VLBI). To ensure a low latency between observation and analysis results, dedicated 1-hour-long VLBI sessions, so-called Intensives, are regularly observed. Two of these Intensive programs, namely INT2 and INT3, are organized and monitored by the joint IVS operation center DACH. 

Within this study, a detailed overview over the last five years of the VLBI Intensive observing programs INT2 and INT3 is provided. INT2 sessions are typically observed on Saturdays and Sundays using a single baseline and a recording rate of 256 Mbps. INT3 sessions are multi-baseline Intensives with up to five stations, observed on Mondays with a recording rate of 1 Gbps. 

Starting in 2019, the scheduling strategy of the INT3 sessions was significantly changed, leading to a reduction of the estimated average dUT1 formal errors by 25% (from (6.1 ± 2.0) µs to (4.5 ± 1.0) µs) for the 4-station network. The improvement w.r.t. dUT1 mean formal errors for the 5-station network is 45% (from (6.3 ± 1.7) µs to (3.5 ± 0.5) µs). 

The best performing INT2 baseline is observed between station MK-VLBA (USA) and WETTZELL (Germany). Mid-2020, the same change was applied for these INT2 sessions, leading to a reduction in the average dUT1 mean formal error of 44% (from (11.7 ± 5.7) µs to (6.6± 4.7) µs). 

Furthermore, comparisons of dUT1 estimates from various analysis centers w.r.t. IERS EOP C04 and JPL EOP2 are conducted. It is revealed that the previously mentioned INT2 baseline shows a bias of only -2.5 µs and 1.9 µs based on the estimates provided by the analysis centers Goddard Space Flight Center (GSF) and Bundesamt für Karthographie und Geodäsie (BKG), respectively, when compared with JPL EOP2. In contrast, the bias is 10.4 µs and 14.9 µs w.r.t. IERS EOP C04. 

Besides analyzing dUT1 formal errors, the latency of the dUT1 results is compared. For INT3 sessions, results are typically available within 24 hours, while it takes two to three days for INT2 sessions, due to observations occurring on weekends. This reveals that the increased data volume recorded by the up to five stations with 1 Gbps does not increase the latency of the analysis results and dUT1 estimates can be obtained within 24-hours. 

Overall, this work provides a detailed insight into the INT2 and INT3 session performances, revealing a strong positive trend in the precision of dUT1 measurements over the last few years.
Normal Mode Constraints on Anelastic Structures in the Earth's Lower Mantle
Authors: Jagt Lisanne , Talavera-Soza Sujania , Deuss Arwen
Published: March 2022

Free oscillations, or normal modes, of the Earth provide important constraints on large-scale structures in the mantle, both elastic and anelastic. In addition to shear-wave (Vs), compressional-wave velocity (Vp) and density (ρ), normal modes are sensitive to perturbations in attenuation, or loss of energy. Attenuation is key in imaging partial melt, water, grain size differences and temperature. Surface waves have imaged the upper mantle attenuation, but lower mantle attenuation is still unknown. Normal mode observations of attenuation in the lower mantle provide constraints on the origin and nature of the two lower mantle Large Low Shear wave Velocity Provinces (LLSVPs). Scattering and focussing, which are hard to separate from intrinsic attenuation in the case of body waves, are included by cross-coupling between normal modes. 

 

Here, we will use normal mode spectra to make tomographic models of 3D variations in shear-wave velocity and shear attenuation qμ = 1/Qμ. Normal mode spectra can be inverted in two ways, using either 1) a direct spectrum one-step inversion or 2) a two-step inversion with splitting function measurements as intermediate step. We will image attenuation using the first method. In synthetic tests, we are able to recover Vs and Qμ structure very well. In our real data inversions, we find anti-correlation in the upper mante, i.e. strong attenuation in low-velocity zones, agreeing with the idea of ridges being hotter and containing melt. In the lower mantle, we find weak attenuation in the center of LLSVPs, and stronger attenuation in the ring around them, which is in agreement with results for the two-step splitting function inversion. 
Assessment of the sea aerosol production including the "bag breakup" effect in the spray generation function
Authors: Poplavsky Evgeny , Kuznetsova Alexandra , Dosaev Alexander , Troitskaya Yuliya
Published: March 2022

Marine aerosol has a large impact on the earth system, including the physics and chemistry of the atmosphere over the oceans. It is a suspension in the air, consisting mainly of droplets injected from the ocean surface as a result of wave breaking in the coastal zone or during strong winds. A marine aerosol production model is an element of great importance in climate change and forecasting models.

In this work, the calculation of the production of sea aerosol using the developed parameterization of the sea spray generation function is carried out taking into account the contribution of the «bags breakup» spume droplet generation mechanism. For example, the work [1] show the decisive contribution of this type of spray to the sea spray generation function. The calculation is carried out both on the basis of reanalysis data on the global distribution of wind speed (CFSv2 [2]) and wave parameters (WAVEWATCH III® Hindcast and Reanalysis Archives [3]), and on the basis of calculation data within the WRF atmospheric model and the WAVEWATCH III wave model. An assessment of the production of sea aerosol is carried out using the example of hurricane Irma. The wind data in the calculations in the WRF model is obtained using the Large Eddy Simulation (LES) technique of the planetary boundary layer (PBL) with the boundary conditions from the CFSv2 reanalysis. Wave parameters data is obtained from calculations within the WAVEWATCH III wave model. A comparison of the resulting sea spray generation function obtained using the WRF LES and WAVEWATCH III data and the distribution obtained using the reanalysis data is carried out. Conclusions are made about the advantages of using computational models of high spatial resolution.

The work is supported by President Grant for young scientists MK-2489.2022.1.5.

[1] Troitskaya, Y., Kandaurov, A., Ermakova, O., Kozlov, D., Sergeev, D., & Zilitinkevich, S. (2018). The “bag breakup” spume droplet generation mechanism at high winds. Part I: Spray generation function. Journal of physical oceanography, 48(9), 2167-2188.

[2] Saha, S., et al. 2011, updated monthly. NCEP Climate Forecast System Version 2 (CFSv2) Selected Hourly Time-Series Products. Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory. https://doi.org/10.5065/D6N877VB. Accessed 14 December 2021.

[3] https://polar.ncep.noaa.gov/waves/hindcasts/
Modelling the propagation of slow magnetoacoustic waves in a multi-stranded coronal loop
Authors: Sayamanthula Krishna Prasad , Van Doorsselaere Tom
Published: March 2022

The cross-field thermal structure of a coronal loop is one of the critical parameters useful to distinguish the major heating theories. In a recent study we are able to isolate two thermal components of a coronal loop using observations of propagating slow magnetoacoustic waves in two different temperature channels. In order to properly interpret these observations and identify the actual cross-field thermal structure, we develop multiple three-dimensional magnetohydrodynamic models of coronal loop. In each of these models slow magnetoacoustic waves are driven by perturbing the plasma at one end and the corresponding multi-wavelength propagation characteristics are studied by applying forward modelling techniques. We compare the wave propagation properties between different models including a monolithic and a multi-stranded model with those from observations to draw some important inferences which will be discussed in this talk.
Garnet petrochronology reveals the lifetime and dynamics of phonolitic magma chambers at Somma-Vesuvius
Authors: Wotzlaw Jörn-Frederik , Bastian Lena , Guillong Marcel , Forni Francesca , Laurent Oscar , Neukampf Julia , Sulpizio Roberto , Chelle-Michou Cyril , Bachmann Olivier
Published: March 2022

Vesuvius is one of the most iconic active volcanoes on Earth. Historic and archaeological records document numerous hazardous eruptions with thousands of fatalities. Today, more than one-million people live around Vesuvius and are threatened by future volcanic activity. Petrologic and geochemical studies of eruptive products provide important insights into the evolution of the eruption-feeding magma reservoir prior to eruption. Here we quantify the duration of shallow crustal storage and track the evolution of phonolitic magmas prior to major explosive eruptions of Vesuvius employing in-situ uranium-thorium dating of garnet phenocrysts in tandem with detailed geochemical and textural characterization. Garnet uranium-thorium dates provide evidence for progressively shorter pre-eruption storage times throughout the lifetime of the volcano, decreasing from ~5,000 years for the pre-historic Mercato and Avellino eruptions to approximately 1,000 years for the historic AD 79 Pompeii and AD 472 Pollena eruptions. These decreasing residence times mirror the progressively shorter repose intervals between eruptions implying that distinct phonolite magma batches were present throughout most of the volcano’s evolution thereby controlling the eruption dynamics by preventing the ascent of mafic magmas from longerlived and deeper reservoirs. Frequent lower-energy eruptions during the recent history sample this deeper reservoir and suggest that future Plinian eruptions are unlikely without centuries of volcanic quiescence. Crystal residence times from other volcanoes reveal that discrete long-lived deep-seated reservoirs and transient upper-crustal magma chambers are common features of sub-volcanic plumbing systems.
North Water Polynya Sensitivity to Arctic Warming
Authors: Patel Rajan , Ugrinow Patrick , Jahn Alexandra , Wyburn-Powell Chris
Published: March 2022

The North Water Polynya (NOW) in northern Baffin Bay contains nutrient-rich waters which are essential to the biodiversity of the region and the native Inuit people. Over the observational period the size and duration of the NOW in spring has varied considerably, and recent studies suggest the NOW may fail to form in the future. Even small changes to the polynya have the potential to impact local ocean circulation and nutrient cycling. 

To assess the projected changes to the NOW, we look at CMIP5 large ensembles under multiple forcing scenarios. Initial results from CESM1 LE suggest that global temperatures greater than 2.5ºC above pre-industrial levels shift the peak polynya area from June to May. Work is ongoing to assess biogenic and physical impacts of such changes. Implications for climate change are that to avoid large changes to the NOW, warming should be limited.

Additionally, the Polynya area fluctuates with time but decreases as a whole throughout the 21st century.
Quality Control of Radio Frequency Interference in UHF Wind Profiler Radar Data
Authors: Lee KyungHun , Kwon ByungHyuk , Kim SangJin , Kim Min Seong , Kim YuJin
Published: March 2022

The test operation of UHF wind profiler developed for 4 years from 2017 was carried out from March to September 2021. During the test operation, radio frequency interference (RFI) contamination was investigated in the spectrum data. We found discontinuous and overlapping RFI as well as the general form of RFI on continuous altitudes as the same magnitude. An algorithm was developed to remove them and to retrieve meteorological signal. Multi-interference refers to RFI that overlaps several times, such as discontinuous peaks by altitude or reappearing even after the first RFI is removed, unlike external RFI. After threshold filtering, a continuity check is checked on the gates that are identified as non-meteorological signals to determine the contamination by RFI. The contaminated spectrum is made noise to remove RFI and a new peak is derived. 5 points (±2 points) at the corresponding peak become noises by means of the noise-ization method. In addition, in a meteorological signal, 5 points are linearly interpolated on the gate identified as a meteorological signal after the continuity check. In order to prevent the actual meteorological signal from being removed, the continuity criterion was set to 15 gates or more for the vertical beam and 8 or more gates for the tilted beam (about 1/2, 1/4 based on the number of gates in low mode). In order to remove double and triple overlapping RFI, filtering and continuity are repeatedly tested until the peak is found below the reference point. For the newly derived peak in the iterative process, the spectral width was calculated using the single peak moment method and this is used as the threshold value.
A Test of Energetic Particle Precipitation Models Using Simultaneous Incoherent Scatter Radar and Van Allen Probes Observations
Authors: Sanchez Ennio , Ma Qianli , Xu Wei , Marshall Robert , Bortnik Jacob , Reyes Pablo , Varney Roger , Kaeppler Stephen
Published: March 2022

Quantification of energetic electron precipitation caused by wave-particle interactions is fundamentally important to understand the cycle of particle energization and loss of the radiation belts. One important way to determine how well the wave-particle interaction models predict losses through pitch-angle scattering into the atmospheric loss cone is the direct comparison between the ionization altitude profiles expected in the atmosphere due to the precipitating fluxes and the ionization profiles actually measured with incoherent scatter radars. This paper reports such a comparison using a forward propagation of loss-cone electron fluxes, calculated with the electron pitch angle diffusion model applied to Van Allen Probes measurements, coupled with the Boulder Electron Radiation to Ionization (BERI) model, which propagates the fluxes into the atmosphere. The density profiles measured with the Poker Flat Incoherent Scatter Radar operating in modes especially designed to optimize measurements in the D-region, show multiple instances of quantitative agreement with predicted density profiles from precipitation of electrons caused by wave-particle interactions in the inner magnetosphere. There are two several-minute long intervals of close prediction-observation approximation in the 65-93 km altitude range. These results indicate that the whistler wave-electron interactions models are realistic and produce precipitation fluxes of electrons with energies between 10 keV to >100 keV that are consistent with observations.
Effects of Warming, Wildfire, and Permafrost Thaw on Carbon Dioxide Fluxes from Boreal Peat Landscapes in northwestern Canada
Authors: Schulze Christopher , Olefeldt David , Emmerton Craig , Harris Lorna , Kljun Natascha , Chasmer Laura , Hopkinson Chris , Detto Matteo , Helbig Manuel , Gosselin Gabriel Hould , Sonnentag Oliver
Published: March 2022

The Taiga Plains ecozone in northwestern Canada is characterized by vast peat landscapes consisting of both mostly tree-less, permafrost-free and forested, permafrost-affected peat landscapes. In response to warming due to ongoing climate change, more frequent and severe wildfires and rapid permafrost thaw affect landscape composition, structure and functioning, whereas more and more ice-rich permafrost peat plateaus transform into water-saturated thermokarst wetlands or lakes. Collectively, these three agents of change, namely warming, wildfire, and thermokarst, could turn these boreal peat landscape from atmospheric carbon and nitrogen sinks into sources with potentially positive climate system feedbacks. We studied net ecosystem exchange (NEE) and its two component fluxes, i.e., gross primary productivity (GPP) and ecosystem respiration (ER), from three sites with five eddy covariance towers near the southern limit of permafrost in western Canada. Around the southernmost site Lutose, both footprint areas around the two towers have completely burned in wildfires in 2007 and 2019, respectively. We hypothesized that these two subsites would act as net CO2 sources, because of the recent disturbance history. This has been confirmed by preliminary results. The two other sites mainly differed in permafrost extent, ranging from sporadic (Scotty Creek) to discontinuous (Smith Creek), and in peat plateau-to-wetland ratio and corresponding forest cover (Scotty Creek < Smith Creek). Between the two sites Scotty Creek and Smith Creek, we hypothesized that the overall landscape GPP and ER will be higher at Scotty Creek compared to the northernmost site Smith Creek, due to both more abundant thermokarst wetlands and higher GPP and ER of the peat plateau areas at this more southern site. We further hypothesized that the effects of warming on GPP are greater than on ER and thus that the warmer Scotty Creek site is a greater net CO2 sink. Contrary to expectations, preliminary results have shown that there is no difference in NEE between Scotty Creek and Smith Creek, whereas both, the overall landscape GPP and ER, are actually higher at Smith Creek. To identify differences in the NEE, GPP, and ER between their peat plateaus and thermokarst wetlands, respectively, we move forward by applying footprint analyses for Smith Creek and Scotty Creek. Through these analyses we will be able to shed light on how each of the drivers, i.e., warming, wildfire, and thermokarst, alters magnitude and direction in greenhouse gas fluxes from rapidly thawing boreal peat landscapes.
Windows of opportunity for Anticipatory Action along the crisis timeline for slow-onset hazards: a phased approach
Authors: Ngaina Joshua , Lombardi Niccolo , Dujanovic Dunja , Guerten Nora , Jones Catherine , Parodi Luca , Innocente Sergio , Lazarus Brenda , Merzouk Quraishia , Moloinyane Siphokazi
Published: March 2022

Slow-onset disasters build up gradually over time, often at the confluence of different hazards, and progressively erode livelihoods, especially among most vulnerable people. The aim of the paper is to summarize FAO’s conceptual and programmatic approach for anticipating and mitigating the impact of slow-onset hazards on the most vulnerable people depending on agriculture for their livelihoods and food security. In order to protect diverse livelihood groups at the right time before such sequenced impacts materialize, the phased approach to Anticipatory Action (AA) seeks to facilitate the identification of multiple windows of opportunity for anticipatory action along the crisis timeline of the slow-onset hazards. The five steps process include (1) determining who is at risk and when, (ii) which actions can be taken to mitigate hazard impacts, and when, (iii) how much time is needed to implement the actions selected, (iv) what kind of early warning information is available at the critical points in time identified and (v) bringing all the information together to define the action phases and the cut-off points beyond which an intervention cannot be considered ‘anticipatory’ anymore.  Since 2016, FAO has supported extensive country-level work on AA against several slow-onset hazards such as drought (e.g. in Kenya, Madagascar, Afghanistan, Philippines, Pakistan, and Sudan, among others), cold waves dzud (Mongolia), pests and diseases (e.g. desert locusts in the Greater Horn of Africa Region and Yemen), Rift valley fever in Kenya and the secondary consequences of COVID-19 (e.g. in Afghanistan, Bangladesh, the Democratic Republic of the Congo, Haiti, Kenya, Senegal, Sierra Leone, the Syrian Arab Republic, and Zimbabwe). Drawing on FAO’s experiences gathered in implementing AA and the technical expertise built over decades of supporting agriculture-based livelihoods, this paper recommends a phased approach to AA for slow-onset hazards as it reduces uncertainties associated with early warning information, improves the targeting of AA interventions, and helps adapt the selection of AA options to the evolving hazard context.
Inland lake temperature initialization via cycling with atmospheric data assimilation
Authors: Benjamin Stan , Smirnova Tatiana , James Eric , Anderson Eric , Fujisaki-Manome Ayumi , Kelley John
Published: March 2022

Application of lake models coupled within earth-system prediction models, especially for short-term predictions from days to weeks, requires accurate initialization of lake temperatures.   Here, we describe a lake initialization method by cycling within an hourly updated weather prediction model to constrain lake temperature evolution.   We compare these simulated lake temperature values with other estimates from satellite and in situ and interpolated-SST data sets for a multi-month period in 2021.   The lake cycling initialization, now applied to two operational US NOAA weather models, was found to decrease errors in lake temperature from as much as 5-10K (using interpolated-SST data) to about 1-2 K (comparing with available in situ and satellite observations. 
Multi-year drought impacts on streamflow regimes 
Authors: Azarnivand Ali , Bende-Michl Ulrike , Sharples Wendy , Bahramian Katayoon
Published: March 2022

Abstract:       With its highly variable climate, Australia is naturally susceptible to multi-year droughts. Previous studies have shown that Australia will, in future, experience longer and more severe droughts, especially across southern Australia. Extended periods of drought have been associated with hydrological changes, in particular streamflow  regimes including changes to the magnitude, frequency, duration, predictability or flashiness of streamflow (Kiem et al. 2016). Despite significantly impacting water availability across the world, links between multi-year drought effects on the hydrological responses of catchments and changing flow regimes are not well understood. This is an important issue since regime shifts from e.g., perennial to non-perennial, could be correlated to the variability in rainfall intensity and frequency, leading to changes in infiltration, excess overland flow and surface-subsurface connectivity.

Our study aims to assess the effect of multi-year droughts on the streamflow regimes to inform future water resource management. We classify historical and current dominant streamflow regimes across Australia and explore whether the susceptibility of stream networks to perennialism under multi-year drought periods is likely to increase in the future. We first use Victoria as a case study region to improve collective knowledge on non-perennial rivers; their drivers, flow regime patterns and frequency of occurrence using the Australian Bureau of Meteorology (BoM)'s long-term hydrologic reference stations and a range of streamflow-based indicators. We analyse pre-drought states of streamflow regimes and explore whether they have shifted after the Millennium multi-year drought. We also investigate the major climatological and hydrological drivers that affect streamflow regime shifts, with a particular focus on those catchments which have shown to have shifted rainfall-runoff relationships resulting from the Millennium drought.

References

Kiem, A. S., and Coauthors, 2016: Natural hazards in Australia: droughts. Clim. Change, 139, 37–54.
The impact of Southern Ocean bathymetry on the ocean circulation and the overlying atmosphere
Authors: De Boer Agatha , Hutchinson David , Roquet Fabien , Sime Louise , Burls Natalie
Published: March 2022

Southern Ocean bathymetry constrains the path of the Antarctic Circumpolar Current (ACC), but the bathymetric influence on the coupled ocean-atmosphere system is poorly understood. Here, we investigate this impact by respectively flattening large topographic barriers around the Kerguelen Plateau, Campbell Plateau, Mid-Atlantic Ridge, and Drake Passage in four simulations in a coupled climate model. The barriers impact both the barotropic and baroclinic forcing of the ACC, which increases by between 3% and 14% when barriers are removed individually and by 56% when all barriers are removed simultaneously. The removal of Kerguelen Plateau bathymetry increases convection south of the plateau and the removal of Drake Passage bathymetry reduces convection upstream in the Ross Sea, affecting the deep overturning cell. When the barriers are removed, zonal flattening of the currents leads to SST anomalies upstream and downstream of their locations. These SST anomalies strongly correlate to precipitation in the overlying atmosphere, with correlation coefficients ranging between r=0.92 and r=0.97 in the four experiments. Windspeed anomalies are also positively correlated to SST anomalies in some locations but other forcing factors obscure this correlation in general. The meridional variability in the wind stress curl contours over the Mid-Atlantic Ridge, the Kerguelen Plateau and the Campbell Plateau disappears when these barriers are removed, confirming the impact of bathymetry on overlying winds. However, bathymetry-induced wind changes are too small to affect the overall wave-3 asymmetry in the Southern Hemisphere Westerlies. Removal of Southern Hemisphere orography is also inconsequential to the wave-3 pattern, suggestion a remote control.
Likely ring-fault activation at Askja caldera (Iceland) during the 2021 unrest
Authors: Nobile Adriano , Vasyura-Bathke Hannes , Viltres Reier , Trippanera Daniele , Gunnar Ófeigsson Benedikt , Ruch Joël , Jónsson Sigurjón
Published: March 2022

The Askja volcanic system, located in the North Volcanic Zone of Iceland, consists of a central volcano with three nested calderas (Kollur, Askja, and Öskjuvatn) and a 20 km wide and ~190 km long fissure swarm with a NNE-SSW trend. Kollur caldera is ~5 km wide and formed in the Pleistocene while the younger 8-km wide Askja caldera, the largest among the three, formed in the Holocene. The smaller (~4 km) and lake-filled Öskjuvatn caldera is located within the Askja caldera and formed following the 1875 Plinian eruption. This event was followed by several localized eruptions along the Öskjuvatn ring fault system (1921, 1922, and 1929) and the last eruption occurred in 1961 in correspondence with the Askja northern caldera border. After this eruption, the Askja caldera first underwent inflation for several years followed by slow (< 1 cm/yr) subsidence over decades. In early August 2021, the volcano entered a period of unrest with new earthquake activity located below the central volcano, and the GNSS station OLAC, located near the center of Askja caldera, started to uplift at a high rate (~3 cm/week). The uplift continued until the end of November 2021. Here we use SAR images acquired from four different orbits (two ascending and two descending) by the Sentinel-1 satellites to study the ground deformation during this unrest period. Only data from the first half of the unrest period could be used (until the end of September). Later, heavy snow resulted in the loss of interferometric coherence within the caldera, preventing retrieval of the deformation signal. The maximum ground displacement of ~10 cm (from the end of July to the end of September) was found at the center of the Askja caldera, near the western shore of Öskjuvatn Lake. Interestingly, the interferograms show an asymmetric deformation pattern that follows the ring faults in the northwestern part of Askja caldera. Analytical models suggest that a roughly 7 x 3 km2 NW-SE elongated sill inflated at a shallow depth of ~2 km below the Askja caldera. However, simple sill models cannot explain the asymmetrical deformation pattern observed in the InSAR data. Therefore, using boundary element modeling, we find that while the magmatic intrusion accounts for the broad uplift, possible ring-fault activity would localize the deformation close to the caldera rim. Furthermore, an elongated sill, like the one obtained from the first source estimation, would probably activate only a part of the ring-fault system, leading to an asymmetric deformation pattern.
A fuzzy multi-criteria decision tree model for flood hazard assessment in the Dhemaji district of the state of Assam in India
Authors: barman Diganta , baruah Anupal , bm Arjun , aggarwal Shiv prasad
Published: March 2022

Flood in the North-Eastern part of India is a chronic event occurring from the River Brahmaputra and its tributaries and causes immense loss to the human life and property. Particularly, during the monsoon period, the north bank tributaries cause havoc on the nearby regions especially in the Dhemaji District. These tributaries mainly originate from the glacier fed regions and inundate the different locations of the Dhemaji district. In this work a fuzzy multi-criteria decision analysis model is developed to prepare the flood hazard map of the Dhemaji district. Six different layers are considered in the analysis such as elevation profile, Flood occurrence period, River confluence points of the second order tributaries, historical embankment breach locations, normalized difference vegetation index and normalized difference moisture index. The outputs from the model are categorized into very low to high hazard zone. The consistency ratio calculated from the assigned weights is found as 0.092. The computed flood hazard map from the present model is compared with the observed flood occurrence events and found to be realistic and satisfactory.

Keywords: Fuzzy AHP, Multi criteria decision analysis, Flood occurrence, Embankment breach, River confluence points
Projected Climate Change Impact Assessment on Drought Characteristics Over a Humid Tropical Region in India
Authors: Sadhwani Kashish , Eldho T. I. , Karmakar Subhankar
Published: March 2022

Droughts are the major natural disasters affecting water availability leading to social, economic, and environmental challenges. Due to climate variability, investigation of climate change impact on droughts is of vital importance for sustainable societal and ecosystem functioning.  Western Ghats, a humid tropical region of India is selected as a case study to investigate the change in drought characteristics subjected to future climate change. In the last few decades, due to monsoon failure, the intensity of droughts has been identified to increase in this region making this study important. For future climatic variables, the ensemble of five Global Climate Models (GCMs) in the Coupled Model Intercomparison Project (CMIP5) are considered for the Representative Concentration Pathways (RCPs) 4.5 and 8.5. Standardized Precipitation-Evapotranspiration Index (SPEI) for the 12-month accumulated period is considered to assess the change in the drought characteristics during near (2011–2040), mid (2041–2070), and far future (2071–2100). The results indicate an increase in drought events in the future with maximum change during the far future for both RCP 4.5 and 8.5 scenarios. The major areas affected are in the southern part of Kerala and Karnataka. The change in total severity and duration of these drought events are high during the near future, moderate during the mid-future, and very high during the far future in both scenarios with RCP 8.5 being more severe. The findings show the variability in drought characteristics both spatially and temporally across the study area. The results will be helpful in identifying the hotspots prone to drought risk. This will serve as important guidance in improving the identification of causes, minimizing impacts, and enhancing the resilience to droughts in the study area. Further, the important implication of the study will be for water resource planning and management to strategize policies that emphasize on providing water in water-scarce regions during extreme drought situations.
The Spatiotemporal Variations of Provenance in the Chinese Loess Plateau by the Sensitivity of Quartz Optical Stimulated Luminescence
Authors: Li Jiao
Published: March 2022

The Spatiotemporal Variations of Provenance in the Chinese Loess Plateau by the Sensitivity of Quartz Optical Stimulated Luminescence

Jiao Li1,*

1,*Department of Geology, Northwest University, Xi’an710069, China

E-mail: 1,*nwu_lijiao@163.com

Loess contains a lot of quartz, which is stable in nature and is not easy to be weathered and transformed. It can retain the original rock information, and the response of quartz crystals to radiation energy is obvious. Thus, optical stimulated luminescence (OSL) sensitivity can identify provenance. The magnetic susceptibility reflects the strength of the summer monsoon, and the grain size is a proxy for the winter monsoon. The magnetic susceptibility and grain size have been widely used in the study of Chinese loess as proxy indicators of the East Asian monsoon.

By studying the change of quartz optical stimulated luminescence sensitivity of loess-paleosol in the Xifeng section of the Chinese Loess Plateau, combined with the related work from others in the Chinese Loess Plateau, the provenance changes of the Chinese Loess Plateau in the time-space sequence were analyzed. In the time series, the sensitivity of quartz OSL showed a high value in paleosol, and the highest value was about 2700 counts/Gy/mg. Meanwhile, it exhibited a low value in loess, and the lowest value was about 200 counts/Gy/mg, which is different from paleosol. In the spatial sequence, the OSL sensitivity of quartz from west to east in the Chinese Loess Plateau has a large difference (8-10 times) in the interglacial (paleosol), and a small difference (1-2 times) in the glacial (loess). The sensitivity of quartz OSL preliminarily indicates that the provenance of the Chinese Loess Plateau has changed in time series (loess-paleosol). Moreover, in space sequence (among different profiles), the sensitivity of quartz OSL has changed in paleosol during the interglacial, but has a minor difference in the loess during glacial.

At the same time, combined with the study of magnetic susceptibility and grain size, the quartz OSL sensitivity corresponds well to the fluctuation of the climate proxy index, which shows that the quartz OSL sensitivity is positively correlated with the magnetic susceptibility and negatively correlated with the particle size. The OSL sensitivity and magnetic susceptibility of quartz were higher in the paleosol and lower in the loess; the variation of grain size was the opposite.

 

Keywords: quartz, optically stimulated luminescence sensitivity, loess provenance, glacial-interglacial, Chinese Loess Plateau

 
Experimental Investigation of Glaucophane Rheology Through General Shear Deformation Experiments
Authors: Hufford Lonnie , Tokle Leif , Madonna Claudio , Behr Whitney
Published: March 2022

Glaucophane is a major constituent mineral associated with subducted mafic oceanic crust at blueschist facies conditions. Viscous deformation of glaucophane has been documented in natural blueschists; however, no experimental study has characterized the specific deformation mechanisms that occur in glaucophane nor the flow law parameters. We are conducting a suite of general shear deformation experiments in a Griggs apparatus to investigate crystal-plastic deformation mechanisms and microstructures of deformed glaucophane over a range of experimental conditions. Experimental samples consist of glaucophane powder separated from natural MORB blueschists  from Syros Island, Greece. Our experimental suite thus far includes temperatures and pressures ranging from 650° to 750°C and 1.0 to 1.5 GPa, strain rates ranging from ~3x10-6/s to ~8x10-5/s (both constant-rate and strain-rate stepping), and different grain size populations from 75-90 µm, 63-125 µm , and 63-355 µm. The lowest temperature and the strain-rate-stepping experiments exhibit evidence for combined frictional-viscous deformation and provide constraints on the brittle-ductile transition in glaucophane at laboratory conditions. The constant-rate experiments conducted at higher temperatures show greater evidence for viscous deformation by dislocation creep, including kinked grains, deformation lamellae, undulose extinction, and bulging via bulge recrystallisation. Mechanical data from the strain-rate stepping experiments allow us to interpret what parameters have the largest effect on peak stress. When comparing experiments conducted at 1 GPa and initial powder grain sizes of 63-355 µm, we find temperature having the largest effect on peak stresses. The 700°C experiment with an initial deformation speed 5 times faster (LH038) than another 700°C strain-rate stepping experiment (LH042) has a ~90 MPa higher peak shear stress, whereas the 750°C strain-rate stepping experiment with an initial deformation speed 4 times faster than LH042 has a ~115 MPa lower peak shear stress. At the time of abstract submission, further constant-rate experiments are planned at slower strain-rates to continue exploring the laboratory conditions necessary to activate glaucophane crystal-plastic deformation mechanisms. These data will be used with further strain-rate stepping experiments to develop flow law parameters from mechanical data.
WOAST : an Xarray package applying Wavelet Scattering Transform to geophysical data
Authors: Gauvrit Edouard , Delouis Jean-Marc , Bouin Marie-Noëlle , Boulanger François
Published: March 2022

Ocean plays a key role in regulating climate through the dynamical coupling between sea surface and the atmosphere. Understanding this coupling is a key issue in climate change modeling, but an adapted statistical representation is still lacking. A strong limitation comes from the non-Gaussianities existing inside a wind over waves surface layer, where wind flows are constrained by the sea state and the swell. We seek an approach to describe statistically the couplings across scales, which is poorly measured by the power spectrum. Recent developments in data science provide new tools as the Wavelet Scattering Transform (WST), which gives a low-variance statistical description of non-Gaussian processes and offers to go beyond the power spectrum representation. The latter is blind to position consistency between scales. To find the methodology, we applied the WST on 1D anemometer time series and 2D atmospheric simulations (LES) and compared them with well known statistical information. These analyses were made possible thanks to the development of WOAST (Wavelet Ocean-Atmosphere Scattering Transform) software. Computation of WST is mathematically embarrassingly parallel and the time consumption is mainly dominated by data access and memory management. Our preliminary geophysical analysis using WOAST and its efficiency of extracting unknown properties of intermittent processes will be shown through a jupyter notebook example. This work is part of the Astrocean project supported by 80Prime grants (CNRS).
Drag-based deformation of a multi-point CME event
Authors: Amerstorfer Tanja , Bauer Maike , Möstl Christian , Barnard Luke , Riley Pete , Weiss Andreas J. , Reiss Martin A.
Published: March 2022

We present first results of a case study on a CME from October 2021 that was in situ detected by BepiColombo, Solar Orbiter, DSCOVR and STEREO-A, whose Heliospheric Imagers (HI) additionally observed the event remotely. The latter observations are used to model the evolution of the CME through the inner heliosphere using the CME propagation model ELlipse Evolution based on HI (ELEvoHI). ELEvoHI assumes a drag-based interaction of the CME-sheath with the solar wind and allows it to deform according to local drag regimes. The ambient solar wind is provided by the time-dependent HelioMAS/HUXt model. Using the arrivals at the four different spacecraft we are able to assess the ability of ELEvoHI to model the evolution of the shape of this CME.
Studying the stress field variations in the Vrancea-zone using clustering-based stress inversions
Authors: Czirok Lili , Kuslits Lukács , Bozsó István , Gribovszki Katalin
Published: March 2022

The SE-Carpathians indicate significant geodynamic activity, especially in the external part due to the current subduction processes. This part is the so-called Vrancea-zone where the distribution of the seismic events is quite dense considering the relatively small area (around 30*70 km).

The authors have carried out cluster analyses of the focal mechanism solutions and their inversions to support the recent and previously published studies in this region. They have applied different pre-existing clustering methods – e.g. HDBSCAN (hierarchical density-based clustering for applications with noise) and agglomerative hierarchical analysis – considering the geographical coordinates, focal depths and parameters of the focal mechanism solutions of the used seismic events, as well. Moreover, they have attempted to improve a fully-automated algorithm for the clustering of the earthquakes for the estimations. This algorithm has only one optional hyper-parameter which is eligible to detect the outliers from the input dataset. Due to this, it is possible to reduce the running time and subjectivity. In all cases, the calculated stress tensors are in close agreement with the previously published results.
Impact of urban heat island on inorganic aerosol in the lower free troposphere: a case study in Hangzhou, China
Authors: Kang Hanqing , Zhu Bin , Leeuw Gerrit de , van der A Ronald J.
Published: March 2022

Urban heat island (UHI) and urban air pollution are two major environmental problems faced by many metropolises. The UHI affects air pollution by changing the local circulation and the chemical reaction environment, e.g., air temperature and relative humidity. In this study, the WRF-CMAQ model was deployed to investigated the impact of UHI on the vertical distribution of aerosols, especially secondary inorganic aerosols (SIA), in a strong UHI case in Hangzhou. Results show that due to the UHI effect, PM2.5 concentrations over Hangzhou decreased by about 26% in the boundary layer (BL) but increased by about 21% in lower free troposphere (LFT). This is mostly attributed to the UHI circulation (~90%) rather than the changed air temperature (~5%) and humidity (~4%). The UHI circulation not only directly transports aerosols from ground level to LFT, but also redistributes aerosol precursors. In the LFT, the directly transported aerosol accounted for 80% of the UHI circulation effect and the secondary formed aerosol due to the transport of aerosol precursors accounted for 20%. The secondary formation of inorganic aerosols, especially nitrate and ammonium aerosols, contributed 91% of the secondary formed aerosol in the LFT over the urban area. The UHI circulation transported ammonia and nitric acid, the precursors of ammonium nitrate aerosol, from the lower BL to the LFT, where ammonium nitrate aerosol is formed. The ammonium nitrate is dissociated at the higher temperature in the lower part of the BL and in the LFT the lower temperature results in a shift of the equilibrium between the gases and ammonium nitrate aerosols toward the aerosol phase. The UHI circulation changed the vertical distribution of SIA, which may have potential implications on radiation budget, cloud formation, and precipitation in the urban and surrounding areas.
Implications of a 30-second Update Cycle for a Convective-Scale Ensemble Radar Data Assimilation System
Authors: taylor james , Honda Takumi , Amemiya Arata , otsuka shigenori , Miyoshi Takemasa
Published: March 2022

As we enter the era of post peta-scale computing, convective-scale NWP will be performed at increasingly higher model resolutions, using more sophisticated data assimilation (DA) schemes and advanced observational datasets. Here we explore the implications for a regional-scale numerical weather prediction system that uses a unique 30-second update for a 500-m grid, using observations from an advanced multi-parameter phased array weather radar (MP-PAWR), on forecasts of convective weather systems. Experiments showed a rapid buildup in the level of atmospheric dynamical activity in the analyses from the start of cycling that promoted the initialization of spurious and often overly-strong convection in forecasts. This was found to be the consequence of substantial differences between the initial conditions and observations and the rapid updating process, which together introduced large perturbations to the analyses during early cycling, leading to the generation of an atmospheric state that was characterized by strong low-level winds and regions of high convective instability. These conditions would remain at a near constant level well after the period of initial cycling, continuing to be a strongly determining factor on the level of development of convection in the forecasts. It was subsequently demonstrated that we could reduce the level of convective activity in forecasts and so improve forecast skill by reducing the localization scale parameter to near model grid resolution, which acted to force initial conditions closer to the initial set of observations following the first update and reduce the large pertubations that caused these conditions to develop.