bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymmetries in the ENSO phase space
Authors: Dommenget Dietmar , Al Ansari Maryam
Published: March 2022

El Niño Southern Oscillation (ENSO) dynamics are best described by the recharge oscillator model, in which the eastern tropical Pacific sea surface temperatures (T) and subsurface heat content (thermocline depth; h) have an out-of-phase relationship. This defines a 2-dimensional phase space diagram between T and h. In an idealized damped oscillator, the phase space diagram should be a perfectly symmetrical circle with a clockwise propagation over time. However, the observed phase space shows strong asymmetries in this diagram. In this study we will illustrate how the ENSO phase space can be used to discuss the phase-dependency of ENSO dynamics. The normalized spherical coordinate system allows to define a phase-depending ENSO growth rates and phase transition speeds. Based on these we discuss the implications of the observed asymmetries are for the dynamics and predictability of ENSO, with a particular focus on the variations in the growth rate and coupling of ENSO along the oscillation cycle.  Using linear and non-linear recharge oscillator models we will show how noise and internal dynamics are driving ENSO at different phases of the ENSO cycles. We will illustrate that a non-linear growth rate of T can explain most of the observed non-linear phase space characteristics.
The non-negligible contribution of shallow injection wells on the triggering of the Mw 5.0 Mentone earthquake via coupled poroelastic stress perturbations
Authors: Tan Xinyu , Lui Semechah K. Y.
Published: March 2022

Occurred in the Delaware Basin, western Texas, near the town of Mentone, the Mw 5.0 Mentone earthquake is one of the largest induced earthquakes in the central US. Within 25 km of the epicenter, there are a few deep injection wells to the northwest injecting in the high permeable limestone layer at about 22 km averagely, as well as a lot of shallow wells injecting in the upper high permeable sandstone layer at around 18 km averagely. Between the shallow sandstone and deep limestone layers is a thick shale layer with low permeability, which excludes the possibility of downward percolation of the injected fluid in the shallow injection layer. However, the cumulative injection volume of shallow injection wells is about five times as much as that of deep injection wells. Motivated by this, we investigate whether the shallow injection wells may play a role in triggering the Mw 5.0 Mentone earthquake through the injection-induced coupled poroelastic stress perturbations. We first perform focal mechanism inversion and earthquake relocation with the Cut and Paste (CAP) and hypoDD methods, respectively, to constrain the fault plane on which the Mw 5.0 event occurred. A south-facing fault plane with strike/dip of 81o/52o is successfully fitted. We then calculate the change of the Coulomb failure stress (ΔCFS) caused by the shallow injection wells at the mainshock location based on the linear fully coupled poroelastic stress model. The calculated ΔCFS of shallow injection wells is approximately 20 kPa and it is mostly contributed by the change in coupled poroelastic stress. Based on findings from other studies, this value of ΔCFS is sufficient in reactivating faults that are well aligned with the local stress field. Since we only account for about half of the total injection volume from the shallow wells in the calculation, we also hypothesize that the actual perturbations caused by shallow injection wells via the coupled poroelastic stress change would be more prominent. Our result reveals the vital role of injection-induced coupled poroelastic stress in triggering seismicity, especially in low permeable geologic settings.
The stress memory in rocks: insight from the deformation rate analysis (DRA) and acoustic emission (AE)
Authors: Ali Zulfiqar , Karakus Murat , Nguyen Giang D. , Amrouch Khalid
Published: March 2022

Deformation rate analysis (DRA) and Acoustic Emission (AE) are popular methods of in-situ stress measurements from oriented cored rocks which take advantage of the rock stress memory also known as the Kaiser effect. These methods rely on the accurate measurement of a point of inflection in the characteristic DRA and AE curves, however, due to the complex geological stress history in rocks, locating point of inflection can be problematic. In order to better understand the stress memory experiments were performed on a combination of six different types of soft, and hard crystalline rocks including concrete with no stress history. The effect of loading modes, strain rates, and time delay were studied on preloaded rock specimens to investigate their influence on the stress memory. A fading effect was observed when the number of the cycles in the test were increased which led to the development of a new method of quantifying the preloads. Results show that the type of loading and the loading rate has little to no influence on the Kaiser effect, however, under faster loading rates the Kaiser effect is more distinct. Likewise, no time dependency was observed for time delays up to seven months.
Full-Bayesian GNSS-A seafloor positioning solution derived by the Markov-Chain Monte Carlo method
Authors: Watanabe Shun-ichi , Ishikawa Tadashi , Nakamura Yuto , Yokota Yusuke
Published: March 2022

For the seafloor geodesy, the GNSS-A is an only tool to directly solve the global positions with the precision of centimeters. Different from the terrestrial GNSS observations, the GNSS-A has a lot of difficulties both in the observation operation and the error corrections. For the latter issue, the researchers should take care that the GNSS-A solutions strongly affected by the underwater sound speed perturbation because it uses acoustic waves for ranging between the sea-surface and seafloor instruments. To solve this issue, the authors had developed the GNSS-A analysis software named “GARPOS” (Watanabe et al., 2020, Front. Earth Sci.), which simultaneously solves the seafloor positions and the perturbation effects based on the empirical Bayes (EB) approach. It can search the appropriate strength of smoothness constraint to the temporal change of perturbation field using the statistical criterion, to avoid the overfitting of the travel-time residuals. This software provided the sufficiently stable solutions to discuss the time-dependent crustal deformation (e.g., Watanabe et al., 2021, Earth Planets Space). Meanwhile, to provide the information on the variance of estimated positions as the joint posterior probability, the probability distributions of hyperparameters should be accounted. Therefore, we developed the program for sampling from the full-Bayesian (FB) posterior probability, based on the Markov-Chain Monte Carlo (MCMC). In this presentation, we introduce the methodology of GARPOS and its expansion to the MCMC mode. We will also show the MCMC results for the GNSS-A data obtained at sites of the Seafloor Geodetic Observation Array (SGO-A) operated by the Japan Coast Guard, to discuss the difference between the EB-based and FB-based solutions.
Electron Injection via Stochastic Shock Drift Acceleration: Theory, Simulation, and Observation
Authors: Amano Takanobu
Published: March 2022

The acceleration of high-energy charged particles is common both in heliophysics and astrophysics. Although the diffusive shock acceleration (DSA) has been the well-accepted standard mechanism for particle acceleration at shocks, the fundamental issue is that DSA does not predict the number of accelerated particles. In other words, it relies on an unprescribed injection mechanism that provides a seed population from which the particle acceleration proceeds. Resolving the so-called injection problem is more challenging for electrons than ions because scattering low-energy electrons requires high-frequency waves, which are usually much lower in intensity than low-frequency fluctuations.

 

We have proposed stochastic shock drift acceleration (SSDA) as a plausible electron injection mechanism that can take place within the transition layer of quasi-perpendicular shocks [Katou & Amano, 2019]. The energy gain mechanism of SSDA is essentially the same as the conventional shock drift acceleration (SDA), but the presence of stochastic pitch-angle scattering makes the acceleration more efficient. We will show that the theoretical predictions nicely explain in-situ observations by Magnetospheric MultiScale (MMS) spacecraft [Amano et al. 2020]. Recent fully kinetic Particle-In-Cell (PIC) simulation results will also be shown, in which we found signatures of SSDA [Matsumoto et al. 2017, Kobzar et al. 2021]. We will also present an extended theoretical model that unifies SSDA and DSA. The model predicts a wide range of the energy spectrum from sub-relativistic and relativistic energies. The particle acceleration in the sub-relativistic energy will be dominated by SSDA, which has a spectral index steeper than the standard DSA. Under certain conditions, the particle acceleration mechanism may smoothly transition from SSDA to DSA, and the spectral index approaches the canonical DSA prediction. Therefore, the model can consistently describe the whole particle acceleration process, including the injection by SSDA and the main acceleration to cosmic-ray energies by DSA. We argue that the electron injection scheme through SSDA is realized preferentially at shocks with higher Alfven Mach numbers defined in the Hoffmann-Teller frame.
Reduced mass loss from the Greenland ice sheet under stratospheric aerosol injection
Authors: Greve Ralf , Moore John C. , Zwinger Thomas , Gillet-Chaulet Fabien , Yue Chao , Zhao Liyun , Goelzer Heiko
Published: March 2022

Stratospheric aerosol injection (SAI) has been proposed as a potential method of mitigating some of the adverse effects of anthropogenic climate change, including sea-level rise from the ice sheets. In this study, we use the SICOPOLIS (www.sicopolis.net) and Elmer/Ice (elmerice.elmerfem.org) dynamic models driven by changes in surface mass balance, surface temperature and ocean temperature (similar to ISMIP6-Greenland; Goelzer et al., 2020, doi: 10.5194/tc-14-3071-2020) to estimate the sea-level-rise contribution from the Greenland ice sheet under the IPCC RCP4.5, RCP8.5 and GeoMIP G4 (Kravitz et al., 2013, doi: 10.1002/2013JD020569) scenarios. The G4 scenario adds 5 Tg/yr sulfate aerosols to the equatorial lower stratosphere to the IPCC RCP4.5 scenario.

We simulate the mass loss of the Greenland ice sheet for the period 2015-2090 under the three scenarios with four earth system models, using SICOPOLIS with hybrid shallow-ice-shelfy stream dynamics and Elmer/Ice in the Elmer/Ice-sheet set-up with shelfy stream dynamics. For atmosphere-only forcing, the results from the two ice-sheet models are very similar. Relative to the constant-climate control simulations (CTRL), the losses from 2015 to 2090 are 64 [53, 80] mm SLE for RCP8.5, 46 [38, 53] mm SLE for RCP4.5 and 28 [18, 39] mm SLE for G4 (mean and full range). Thus, the mean mass loss under G4 is about 38% smaller than that under RCP4.5. For both models, the accumulated SMB is larger than the actual ice loss because, as the ice sheet recedes further from the coast, the mass loss due to calving is reduced. We　will also investigate the response of the ice sheet to ocean-only forcing and combined atmospheric and oceanic forcing.
First results of diurnal NO2 column variation over Asia from the Geostationary Environment Monitoring Spectrometer (GEMS) 
Authors: Park Junsung , Lee Hanlim , Hong Hyunkee , Yang Jiwon , van Roozendael Michel , Kim Siwan , Kim Jhoon , Lee Dong-won , Fayt Caroline , Ko Dai ho , Lee Seung-Hoon , A. Krotkov Nickolay , Wagner Thomas , Richter Andreas , N. Lamsal Lok
Published: March 2022

Nitrogen dioxide (NO2) is generally emitted from the anthropogenic source such as fossil fuel combustion and natural sources such as lightning, forest fires, and soil emission. These NO2 have adverse effects on human health and are known to affect regional climate as a short lived climate forcer. In addition, it is a precursor of aerosol nitrate and plays a key role the photochemistry of tropospheric Ozone. Up to date, NO2 observation has been possible only once a day using low earth orbit satellite sensors such as GOME, SCIAMACHY, GEMS-2, OMI, OMPS, and TROPOMI. However, hourly NO2 monitoring is expected to provide better understanding of atmospheric chemistries and climate effects related with NOx in regional and global scales. From February, 2020, it is possible, for the first time, to observe the diurnal NO2 variations using Geostationary Environment Monitoring Spectrometer (GEMS). Here, we present first results of diurnal changes in total and tropospheric NO2 columns observed over Asia with high temporal and spatial resolutions using the GEMS operational NO2 algorithm. NIER of Ministry of Environment in South Korea plans to release the GEMS NO2 data in real-time. The GEMS operational NO2 algorithm based on DOAS technique and LUT based NO2 AMF to retrieve the total NO2 columns. We, in addition, retrieve the GEMS tropospheric NO2 columns by subtracting stratospheric NO2 columns from the total NO2 columns. The stratospheric NO2 columns are calculated from scaling stratospheric NO2 from SLIMCAT model using the real GEMS observation data over Pacific ocean. In this present study, we introduce diurnal characteristics at various major cities including, ports, and industrial regions. We also evaluate the performance of the GEMS NO2 retrieval algorithm by comparing GEMS NO2 columns and those observed from ground based Pandora at Seosan in South Korea and MAX-DOAS at Xianghe in China. The comparisons also are made between the total and tropospheric GEMS NO2 data and that of TROPOMI. The validation results show good agreements of GEMS data against those from others.
Integration of Multiple Drought Indices for Agriculture Drought Categorization and Impact Assessment in Central India
Authors: Katneshwarkar Bageshree , Kinouchi Tsuyoshi
Published: March 2022

Drought is a complex and multidimensional phenomenon affecting the global population. The widespread impacts of drought propagate through the climatic and hydrological cycle and affect the socio-economic security of the related stakeholders, especially farmers. Countries like India use several indices to determine the severity of the drought for governmental relief and mitigation measures, which is crucial for farmers facing agricultural stress and failures. However, the use of single or several separate drought indices cannot capture the combined effect of principal drivers responsible for the drought, where the effect of groundwater availability for agriculture is often neglected despite its heavy use in irrigation through groundwater extraction. In this study, we focus on the multidimensional response of drought in a single joint index to better capture the spatiotemporal variability in drought severity. The semi-arid region of Marathwada from central India, which frequently faces drought and is infamous for farmer suicides due to agriculture failures is taken as the study area. The response of hydroclimatic variables viz. precipitation, evapotranspiration, soil moisture, surface runoff, and groundwater storage were captured in their respective standardized indices (SPEI, SSI, SRI, and SGI respectively) which were then used to construct the Joint Drought Index (JDI) using two principal methods: 1) Principal Component Analysis (PCA) and 2) Gaussian copula. Both the methods were found to be capable of identifying the severity of the drought along with its onset, duration, and termination. Although individual indices such as SPI can sometimes acknowledge the meteorological response better, the JDI has the potential of capturing the response of multiple hydrological variables together at once for drought monitoring and assessment. During the period between 2003 to 2020, the drought of 2015 was identified as exceptionally severe in both the methods, where copula could better accommodate the severity of every integrated index whereas PCA averages the response of the variables to drought by allocating the weights to each index for each month.
Asymmetry of Auroral Kilometric Radiation in the Northern and Southern hemispheres
Authors: Tang Jiawen , Xiao Fuliang , Liu Si , Zhang Sai
Published: March 2022

Auroral kilometric radiations (AKR) are existed by suprathermal (1-10keV) electrons, which are accelerated by parallel electric fields and pitch angle scattered by magnetic field gradients. Here, using observations of the Arase satellite and Van Allen Probes from 23 March 2017 to 31 July 2019, we present the first statistical study of AKR distribution characteristic in the region of λ = 0°−40°and L = 3.0−9.0. Results (totally 32,043 samples) show that southern AKR on the nightside (12,853 samples) are positioned to the east relative to their northern conjugates (13,630 samples), the wave frequencies and amplitudes of AKR in the southern hemisphere are greater than those in the northern hemisphere. Further studies suggest that SYM-H indexes and interplanetary magnetic field (IMF) have different distributions in the northern and southern hemispheres. The probable reason is that different IMF conditions cause asymmetric Field-aligned currents between the northern and southern hemispheres, then yield the asymmetry of AKR and auroras. This study helps to provide more information on the magnetosphere-ionosphere-atmosphere coupling.
Differences in Arctic sea ice simulations from various SODA3 data sets
Authors: Ge Zhicheng , Wang Xuezhu , Wang Xidong
Published: March 2022

SODA (Simple Ocean Data Assimilation) is one of the ocean reanalysis data widely used in oceanographic research. The SODA3 dataset provides multiple ocean reanalysis data sets driven by different atmospheric forcing fields. The differences between their arctic sea ice simulations are assessed and compared with observational data from different sources. We find that in the simulation of arctic sea ice concentration, the differences between SODA3 reanalysis data sets driven by different forcing fields are small, showing a low concentration of thick ice and a high concentration of thin ice. In terms of sea ice extent, different forced field model data can well simulate the decline trend of observed data, but the overall arctic sea ice extent is overestimated, which is related to more simulated sea ice in the sea ice margin. In terms of the simulation of arctic sea ice thickness, the results of different forcing fields show that the simulation of arctic sea ice thickness by SODA data set is relatively thin on the whole, especially in the thick ice region. The results of different models differ greatly in the Beaufort Sea, the Fram Strait, and the Central Arctic Sea. The above differences may be related to the differences between the model-driven field and the actual wind field, which leads to the inaccurate simulation of arctic sea ice transport and ultimately to the different thickness distribution simulation. In addition, differences in heat flux may also lead to differences in arctic sea ice between models and observations. In this paper, the differences between the results of arctic sea ice driven by different SODA3 forcing fields are studied, which provides a reference for the use of SODA3 data in the study of arctic sea ice and guidance for the selection of SODA data in the study of sea ice in different arctic seas.
Finding the Silver Lining: Benefits and lessons learned from pivot to virtual short courses for instructor professional development for classroom and field geoscience
Authors: Pratt-Sitaula Beth , Walker Becca , Douglas Bruce , Crosby Benjamin , Charlevoix Donna
Published: March 2022

GETSI (GEodesy Tools for Societal Issues) is a US National Science Foundation-funded program that develops, tests, and disseminates data-rich and societally relevant curriculum for undergraduate field and classroom teaching. GETSI has published 13 modules (~2-3 weeks of class time each) co-authored by faculty at varied colleges and universities (serc.carleton.edu/getsi). The dissemination plan for the 2020-21 academic year was originally entirely in-person workshops. When the COVID19 pandemic necessitated the postponement and/or cancellation of essentially all face-to-face activities, the project pivoted to an online dissemination model for the 2020-21 academic year and convened a GETSI Virtual Mini Short Course Series and a virtual short course: Teaching in the field with SfM and RTK GPS/GNSS.

The Virtual Mini Short Course Series was October 2020-April 2021 and included 9 mini-courses. Unlike a webinar, the majority of the mini-course consisted of time for participants to work individually and collaboratively through portions of the student exercises, discuss teaching ideas, and develop a plan for implementation. The series attracted a wider range of participants from a broader range of institutions than many in-person events. Participants could choose to attend one or more of the mini-courses, depending on their area(s) of interest. Each 2-hour mini-course, co-led by a GETSI PI and module co-author(s), highlighted a different GETSI module and offered participants a small stipend for completing an implementation plan for using GETSI materials in their classroom. We used a variety of active learning strategies during the mini courses, including think-pair-shares, polling, report-outs, gallery tours, and jigsaws.

The two virtual short courses "Teaching in the Field with SfM and GPS" brought together graduate students and college/university faculty into an online learning cohort. Each institutional team received an RTK GPS receiver pair to practice with for several weeks and the cohort worked through similar field tasks separately, while periodically reconvening online to share challenges and accomplishments.

The lessons learned from this unanticipated shift to virtual professional development have implications moving forward for designing high-quality, interactive professional development for the whole STEM community.
How important are annual tree stem methane emissions to the total wetland flux? A seasonal case study of subtropical lowland Melaleuca forest.
Authors: Jeffrey Luke , Moras Charly , Tait Douglas , Call Mitchell , Laicher Dylan , Sippo James , Johnston Scott , Maher Damien
Published: March 2022

Tree stem methane emissions are gaining rapid research momentum, with about one-third of all literature in this field published in 2021 alone. Long term and seasonal studies are currently rare, limiting our ability to constrain spatial and seasonal emissions variability, and to resolve the tree stem contribution to the total wetland methane flux i.e. soil, water and trees. Here we present preliminary methane flux data from a lowland Melaleuca quinquenervia forest. We measured emissions in situ along a ~3 m amplitude topo-gradient, encompassing forest in lower, transitional and upper elevation zones. Eight (ongoing) field campaigns at monthly intervals, captured flooded to dry to re-flooded site conditions. We measured the stem fluxes from 30 trees at four stem heights, along with 30 adjacent soil and water CH4 fluxes. Ancillary parameters such as pore water (CH4, DO%, pH, temp, redox, EC), water table depth, and soil moisture (VWC %) were also measured. Tree stem fluxes ranged several orders of magnitude between hydrological seasons and topo-gradient zones (ranging from negligible to 17, 426 mmol ha-1 d-1). Soil fluxes were similar in amplitude and shifted from maximal CH4 emissions during the wet conditions, to CH4 uptake in dry locations. The importance of tree stem flux to the net ecosystem flux (NEF) differed between campaigns and hydrological zones, but were most substantial during flooded conditions and ranged from 36-75% of the NEF in the lower and transitional zones during peak emissions respectively. In the upper zone, the tree stem emissions offset the soil sink capacity by ~50% when the water table was closest to the soil surface. This study shows the importance of quantifying lowland tree stem CH4 emissions to the total wetland flux. This data provides important baseline readings for southern hemisphere and Australian wetland forests, that generally experience dynamic rainfall and soil redox oscillations between flooding and droughts.
CT scan of a small-scale fault network: 3D fault geometries and their interpretation
Authors: Vaknin Inbar , Nicol Andy
Published: March 2022

Fault surfaces and networks have been shown to have complex geometries. Outcrop observations are typically two-dimensional and limited in size by the exposure dimensions, while three-dimensional (3D) seismic data lack the resolution to characterize and quantify fault complexities on length scales less than a decameter. Defining the geometries of faults and their networks (high-resolution in 3D) is critical for understanding the interactions between faults and fluids. This presentation will examine the geometries of a network of small-scale normal faults displacing (by <1 cm) well bedded sand and silt layers in the Mount Messenger and Mohakatino formations in Taranaki, New Zealand. A 3D model of faulting was produced from high-resolution multi-band CT scanner (MARS Bioimaging Ltd.) imagery of a 10x8x3 cm rock sample. The digitally sectioned rock contains calcified fault rock that is distinguishable from wall rock and mapped throughout the rock volume at sub-millimeter scale. Fault-rock thicknesses vary by in excess of an order of magnitude, with greatest thicknesses at fault steps and fault bends. Fault zones comprise a series of lenses that have strike lengths greater than dip lengths and lens shapes that are often elongate parallel to bedding. The fault network is highly connected with branch lines, fault steps and fault bends most often sub-parallel to bedding. These observations suggest that mechanical heterogeneity of beds may partly control the geometries of both fault zones and the fault network. At the time of formation, the interconnected fault network likely increased bedding-parallel permeability (at scales from sub-millimeter and above) along fault zones.
Moon Formation via Streaming Instability
Authors: Nakajima Miki , Atkins Jeremy , Simon Jacob B. , Quillen Alice C.
Published: March 2022

The Apollo lunar samples reveal that Earth and the Moon have strikingly similar isotopic ratios, suggesting that these bodies may share the same source materials. This leads to the "standard" giant impact hypothesis, suggesting the Moon formed from a partially vaporized disk that was generated by an impact between the proto-Earth and a Mars-sized impactor. This disk would have had high temperature (~ 4000 K) and vapor mass fraction of ~20 wt %. However, impact simulations indicate that this model does not mix the two bodies well, making it challenging to explain the isotopic similarity. In contrast, more energetic impacts, such as a collision between two half Earth-sized objects, could mix the two bodies well, naturally solving the problem. These impacts would produce much higher disk temperatures (6000-7000K) and higher vapor mass fractions (~80-90 wt%). These energetic models, however, may have a challenge during the Moon accretion phase. Our analyses suggest that km-sized moonlets, which are building blocks of the Moon, would experience strong gas drag from the vapor portion of the disk and fall onto Earth on a very short timescale. This problem could be avoided if large moonlets (>1000 km) form very quickly by the process called streaming instability, which is a large clump formation mechanism due to spontaneous concentration of dust particles followed by gravitational collapse. We investigate this possibility by conducting numerical simulations with the code called Athena. Our 2D and 3D hydrodynamic simulations show that moonlet formation by streaming instability is possible in the Moon-forming disk, but their maximum size is approximately 50 km, which is not large enough to avoid the strong gas drag. This result supports the Moon formation models that produce vapor-poor disks, such as the standard model. We will further discuss implications for moons in the solar system and extrasolar systems (exomoons). 
The geoid gravity potential inversion to dense anomalies and their comparison with the seismic tomography models
Authors: Greku Rudolf , Greku Dmitry
Published: March 2022

Greku R.Kh., Greku D.R.

Institute of Geological Sciences, Ukraine

SATMAR Laboratory, DDS Capital Investments, Australia

 

The geoid gravity potential inversion to dense anomalies and their comparison with the seismic tomography models

 

The results of using the gravitational tomography method is based on the use of algorithms for inverting the values ​​of the gravitational potential (geoid) for calculating the Earth's density anomalies in the entire range of depths up to 5300 km [H. Moritz. The Figure of the Earth's Interior, Wichmann / Karlsruhe, 1990]. The initial data are the anomalies of the geoid heights according to the EGM2008 model in the expansion in spherical functions to harmonics n, m = 2190. The spatial resolution of the data on the surface is 10 km. The depths of the disturbing masses are determined taking into account the harmonic number. The result is maps of density distribution at specified depths, vertical sections and 3D models.

Examples of the distribution of density anomalies for certain regions of Ukraine, Europe and Antarctica are given. Discrepancies with known works on seismotomography are mainly due to different physical properties of the studied medium: density and acoustic properties of rocks.

Density anomaly results are reported as the percent deviation from the Earth's PREM density model for a given location and depth. The entire range of density anomalies in the form of deviations from the PREM model does not exceed 12%. Complete coincidence of the results is observed, for example, at great depths of 2800 km throughout the Earth. The section through the continent of Antarctica with a complex relief and structure to a depth of 400 km also shows similar images from seismic and gravity tomography. The gravitomographic model of the tectonically active region of Vrancea confirms the delamination nature of the formation of the disturbing mass and the occurrence of earthquakes in Europe.

The original call to the present topic of the GD7.5 session (Prof. Saskia Goes) rightly notes the important role of rheological variability in the mantle layers on the deformation of the earth's crust and surface, which can cause catastrophic destruction of large-block structures. In this sense, the intensity of the inner layers according to the data of structural inhomogeneities becomes more and more urgent.
What kind of factors do give diversities of benthic foraminiferal fauna at hadal depths ?
Authors: Kitazato Hiroshi
Published: March 2022

Benthic foraminifers are one of major biota at marine environments. We have long been worked deep sea benthic foraminiferal communities at the Western Pacific since 1990th.  We analyzed more than ten localities of the western Pacific deep-sea, in particular to hadal depths. Hadal foraminiferal community consists of monothalamous soft-shelled forms, agglutinated forms, porcelaneous forms, hyaline forms and large xenophyophores.  In the shallower deep-sea such as abyssal depths, there are many environmental factors that are limiting distribution of species.  They are temperature, salinity, hydraulic pressures, oxygen concentrations and others.  Benthic foraminifers are so sensitively adapted to these environmental factors, benthic foraminifers are used as proxy organisms.  How about populations of hadal depth?

We compare populations between Challenger deep (10,899m) and Horizon deep (10,811m) of the western Pacific hadal trenches, where differences of the depth show less than 100m each other. Foraminiferal population at the Horizon Deep shows much higher concentrations of agglutinated forms. How can we explain populational differences between two deeps? What kind of factors show differences in hadal environments?  Sea water environments are mostly the same in hadal depths.

I propose sediment characters that give hidden diversities of bottom environments at hadal trenches.  There are two types of subduction tectonics at hadal trenches, both Mariana-type and Chilean-type.  Mariana-type is characterized by sedimentary rocks that are accreted  when oceanic plate subducted.  Mariana-type trenches are characterized by big earthquakes and tsunamis.  In contrast, Chilean-type is characterized by mantle peridotite and related rocks such as serpentinite.  There is few earthquakes at Chilean-type subduction area.  The differences of foraminiferal faunal composition between Marianas and Tonga Trenches should be related to the sediment characters that are reflecting trench geology.
Large biophysical impacts of forest fire size
Authors: Zhao Jie , Li Guangyao , Yue Chao
Published: March 2022

Future climate warming is projected to increase the occurrence of large or extreme forest fires, but how fire size impacts forest damage and forest biophysical processes remains unclear. Using multiple datasets including satellite observations, here we reported that the dominant fire size has almost doubled in northern temperate and boreal forest ecosystems over the period of 2003-2016, concomitant with significant surface air warming during the fire season. Increasing forest size is accompanied by enhanced fire behaviour, including faster rate of spread and elongated fire duration. Bigger fires drive enhanced forest mortality and fire intensity. Forest canopy damage measured by decrease in postfire leaf area index, changes in surface albedo and ecosystem evaporation all demonstrate strong linear relationship with the logarithm of fire size (R2>0.9), which collectively drive elevated postfire land surface warming with the increase of fire size. Thus, the temporal increase of fire size leads to significantly increasing postfire surface warming, which provides strong positive feedback for further warming. Such a scaling relationship between postfire warming with fire size is, however, strongly regulated by forest type, with surface warming with fire size being most sensitive in evergreen needleleaf forest, followed by deciduous needleleaf forest, and then by forest with deciduous broadleaf trees. Our study thus highlights that important feedbacks exist between fire regime and climate warming and demand the inclusion of explicit representation of fire size in Earth System Models on the one hand, and suggest that increasing broadleaf trees can mitigate such positive feedbacks on the other hand.
The Dispersive Nature of the Heliospheric Termination Shock
Authors: Zieger Bertalan , Giacalone Joe , Swisdak Marc , Zank Gary , Opher Merav
Published: March 2022

The Voyager spacecraft are the first man-made objects to cross the termination shock (TS), where the solar wind becomes sub-fast magnetosonic due to the interaction with the local interstellar medium. Voyager 2 observations revealed that classical single-fluid magnetohydrodynamic (MHD) or multispecies single-fluid MHD models are not sufficient to describe the microstructure of the TS and the observed nonlinear waves downstream the TS. Consequently, more sophisticated physical models, like multifluid, hybrid or fully kinetic solar wind models, are needed to capture nonlinear waves, dispersive shock waves, and ion-ion instabilities, where each ion species (and electrons) can move independently with their own bulk velocities, and the fluctuating parts of the ion velocities are often comparable to the mean velocity of the collective plasma fluid. The multifluid simulation of the TS by Zieger et al. [2015] shows a remarkable agreement with high-resolution Voyager 2 observations, reproducing not only the microstructure of the third TS crossing (TS3) but also the energy partitioning among thermal ions, pickup ions (PUI), and electrons across the shock. It was demonstrated that TS3 is a subcritical dispersive shock wave with low fast magnetosonic Mach number and high plasma ß. Here we present multifluid, hybrid, and particle-in-cell (PIC) simulations of the second TS crossing (TS2) by Voyager 2, which was somewhat stronger than TS3, with an observed compression ratio of 2.2. All three types of simulations confirm the dispersive nature of the TS in agreement with Voyager 2 observations. We conclude that TS2, just as TS3, is a subcritical dispersive shock wave with a soliton (overshoot) at the leading edge of the shock and a quasi-stationary nonlinear wave train downstream of the shock front. We compared the cross-shock electric field in the multifluid, hybrid, and PIC simulations and found a reasonable agreement. We show that the Hall electric field is dominating over the convective and ambipolar electric fields, which indicates that electrons play an important role in the shock transition. Finally, we demonstrate that the microstructure of the termination shock is controlled by dispersion rather than ion reflection, and only slightly affected by reflected solar wind ions in the hybrid and PIC simulations, which validates the multifluid model on fluid scale. The dispersive nature of the termination shock has important implications for the transition and acceleration of PUIs across the termination shock, which is revealed in the PUI distributions in our hybrid [Giacalone et al., 2021] and PIC simulations.
Tropical tropopause layer structure during QBO disruptions and the roles of waves
Authors: Luan Lan , Staten Paul , Randel William , Kuo Ying-Hwa
Published: March 2022

The tropical tropopause layer (TTL) is an important region where air enters from the tropical troposphere to the stratosphere. The cold point tropopause (CPT) within the TTL determines how much water vapor can enter the tropical stratosphere. The water vapor will then be transported to higher latitudes via the Brewer-Dobson circulation and further influences the stratospheric chemistry and the radiation budget around the globe. 
A dominant mode of variability in the tropical stratosphere – the quasi-biennial oscillation (QBO) – can influence the TTL and related processes through thermal wind balance and secondary circulation. The QBO consists of downward propagating easterlies and westerlies, alternating with a period of about 27–28 months. But twice since its discovery – first in 2015/16 and then again in 2019/20 – the QBO was disrupted — both in the past decade. During these anomalous years, easterlies developed at around 40–50 hPa within the westerly regime, while the westerly regime ascended and halted for about 6 months. There was also stronger tropical upwelling during QBO disruptions that favored the development of anomalous easterly wind. 
Here we focus on how the QBO disruptions can influence the TTL structure and water vapor using GPS-RO data, MLS observations, and ERA-5 reanalysis. We analyze temperature, water vapor, and tropical upwelling fields between QBO disruptions and the westerly QBO composite. We find there tends to be a colder zonal mean CPT temperature but relatively more water vapor during QBO disruptions. The increased water vapor relates to the regional pattern of the CPT temperature. During QBO disruptions, CPT temperature tends to be warmer over the western Pacific and colder over the eastern Pacific where the western Pacific is usually called the “cold trap” region and the air gets final dehydrated. Since both tropical and extratropical waves can influence the QBO and the tropical upwelling, we also investigate the roles of waves during QBO disruptions by analyzing the EP flux and its divergence and the momentum equation. We find that tropical waves and midlatitude Rossby waves both influence the zonal wind in the tropical lower stratosphere, but the stronger tropical upwelling is mainly caused by the midlatitude Rossby waves. Studying the influences of QBO on the TTL structure and roles of waves during QBO disruptions sheds light on a better understanding of the mechanisms causing QBO disruptions and their potential influences on the climate.
Greenhouse gas emitted from vehicles in Seoul megacity, South Korea: Molar ratios (N2O:CO2, CH4:CO2) and stable isotopic compositions of N2O
Authors: Kim JeongEun , Ahn Jinho , Ghosh Sambit
Published: March 2022

 Quantifying greenhouse gas (GHG) emissions in the megacities is important to mitigating climate change. To characterize the vehicle emissions which is one of the largest contributors to anthropogenic greenhouse gas emissions, we collected air samples from the entry and exit points of the Sang-do Tunnel in Seoul, South Korea in 2021, and measured dry molar mixing ratios of major greenhouse gases spices emitted from vehicles (CO2, CH4, and N2O). The N2O:CO2 emission molar ratio from vehicles is 3.82 ± 0.39 × 10-5, being within a range of 1.8 – 18.7 × 10-5 previously reported in Germany, Switzerland, Sweden, and the USA. The CH4:CO2 emission molar ratio from the vehicles is 33.52 ± 0.43 × 10-5, which is significantly greater than those observed in Switzerland and the USA of 4.6 ± 0.2 × 10–5 and 15 ± 4 ×10–5, respectively. Compared with the calculated Further, we also analyzed δ15N and δ 18O values of N2O from the tunnel air. The δ15N and δ 18O values of N2O emitted from the vehicles are estimated as The newly measured data from Seoul may help us better understand greenhouse gas emissions from vehicles in megacities.
800 years of summer European-North Atlantic jet stream variability and its impact on climate extremes and human systems
Authors: Xu Guobao , Broadman Ellie , Meko Matthew , Klippel Lara , Ludlow Francis , Dorado-Liñan Isabel , Esper Jan , Trouet Valerie
Published: March 2022

Climate extremes over the mid-latitudes are driven by a combination of thermodynamical and dynamical factors. In Europe, the primary dynamical driver of summer climate extremes is the position of the jet stream over the Europe-North Atlantic (EU) region. In certain configurations, the EU jet creates a summer climate dipole between northwestern and southeastern Europe that can result in contrasting extreme weather conditions in the two regions. To study long-term variability in the EU jet configuration, as well as its potential impact on past climate extremes and human systems, we have reconstructed EU jet variability over the past 800+ years (1200-2005 CE). To accomplish this, we have combined five European tree-ring chronologies to reconstruct the July-August jet stream latitude for the EU domain (30°W - 40°E; EU JSL). Our reconstruction explains 40% of summer EU JSL variability over the instrumental period (1948-2005 CE) with strong skill.

We find that, over the past 800 years, opposite phases of EU JSL variability have consistently resulted in contrasting climate extremes, including heatwaves, droughts, floods, and wildfires, between northwestern Europe, specifically the British Isles, and southeastern Europe, specifically the Balkans and Italy. This EU JSL-driven summer climate dipole is captured in a network of historical documentary data that further document the societal impacts of EU JSL-related climate extremes on both sides of the dipole.

Our summer EU JSL reconstruction shows a century-long negative phase from ca. 1355-1450 CE, corresponding to anomalously wet and cool summers over the British Isles and dry and hot conditions over the Balkans. This negative phase is comparable to the recent (1970-present) EU JSL configuration. We also found a positive phase, with opposite summer climate dipole conditions, from ca. 1812-1861 CE. Our results thus suggest that the EU JSL has been a long-term primary driver of the European summer climate dipole, as well as of the associated climate extremes and societal impacts.
Land Surface Temperature/ Vegetation Index Space for Soil Moisture Assessment over Ganga Basin
Authors: Krishnan Sooraj , Jayaluxmi Indu
Published: March 2022

Soil Moisture (SM) remains one of the inevitable geophysical land surface variables, influencing climatological and hydrological fluxes that can control the interaction between Earth's surface and atmosphere. It is also a crucial land surface parameter indicating drought conditions in agricultural areas, significantly impacting agricultural production. The temperature vegetation dryness index (TVDI), a simplified surface dryness index based on vegetation index (VI) - land surface temperature (LST) triangle/trapezoidal spectral space, can monitor SM conditions in vegetation-covered areas.

The present study estimated a high-resolution temperature vegetation dryness index (TVDI) for assessing SM over the largest river basin in India, Ganga Basin. Triangular feature space between LST and VI is generated to obtain the dry and wet edges to calculate TVDI over the Ganga basin for three years (2017, 2018, and 2019). Two different TVDI were developed using two vegetation indices, normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI). Estimated TVDI is evaluated using ESA CCI SM product. The relation of subsurface SM with TVDI is investigated using GLDAS Noah LSM SM available at four different layer depths (0–10, 10–40, 40–100, and 100–200 cm).

The result shows that TVDI generated using EVI correlates better with SM than NDVI generated TVDI. The relationship between TVDI and SM was found to be closer in Summer (-0.49–0.62) than in post monsoon season. The applicability of TVDI in investigating SM at soil layer depth at 10-40 cm (r close to -0.6) was found to be better than that at depth 0-10 cm, especially during the summer season. The results reveal relevance of generated TVDI with satellite-derived information only, in SM monitoring and assessment, especially in the summer season, over the area of sparse in-situ SM network.
Application of Simulation-Optimization modeling to suggest optimal hybrid in-situ flushing for nitrate attenuation
Authors: Lee Suh-Ho , Park In-Woo , Lee Seong-Sun , Lee Kang-Kun
Published: March 2022

Uncertainties in efficiently managing contaminated groundwater still pertains. Several in-situ remediation technologies can be applied to treat nitrate contamination; however, those cannot be applied at aquifer which has high hydraulic conductivity. In this study, we apply Simulation-Optimization modeling (S-O modeling) to suggest optimal in-situ flushing integrated to pump-and-treat design that can reduce and manage nitrate contamination of groundwater. MODFLOW-2005 and MT3D-USGS are used to simulate groundwater flow and nitrate transport. Genetic Algorithm(GA) is used to suggest proper well location and pumping rate for reducing nitrate contamination. Our optimization modeling based on the field tests conducted on a multi-layered aquifer. There is an uncontaminated lower aquifer and an upper aquifer contaminated with nitrate. At the first stage, we generated hydraulic gradient for collecting pre-existed contamination with installing pumping well at the lower aquifer and injection well at the upper aquifer contaminated with nitrate. In the second stage, 1 moving well of variable location and pumping rate was used for pump-and treat well. Cost function satisfies minimizing the total expenses of drilling, pumping, injection, water treatment, and penalty for violating nitrate concentration. The early stage result of S-O modeling shows nitrate moves along the groundwater flow and is captured at the moving well that is located in the center of nitrate plume.

 

Keyword: Simulation-Optimization modeling (S-O modeling) ∙ Remediation ∙ On-site flushing ∙ Groundwater modeling

Acknowledgement: This work was supported by Korea Environment Industry & Technology Institute(KEITI) through "Activation of remediation technologies by application of multiple tracing techniques for remediation of groundwater in fractured rocks" funded by Korea Ministry of Environment (MOE) (Grant number:20210024800002/1485017890), Korea Environment Industry & Technology Institute(KEITI) through the Demand Responsive Water Supply Service Program (RE20191097) funded by the Korea Ministry of Environment (MOE) and Korea Ministry of Environment as "The SEM projects; RE2020002470001/1485017133".