High-resolution velocity models developed using full-waveform inversion (FWI) can image fine details of the nature and structure of the subsurface. Using a 3D FWI velocity model of hyper-thinned crust at the Deep Galicia Margin (DGM) west of Iberia, we constrain the nature of the crust at this margin by comparing its velocity structure with those in other similar tectonic settings. Velocities representative of both the upper and lower continental crust are present, but there is no clear evidence for distinct upper and lower crustal layers within the hyper-thinned crust. Our velocity model supports exhumation of the lower crust under the footwalls of fault blocks to accommodate the extension. We used our model to generate a serpentinization map for the uppermost mantle at the DGM, at a depth of 100 ms (~340m) below the S-reflector, a low-angle detachment that marks the base of the crust at this margin. We find a good alignment between serpentinized areas and the overlying major block bounding faults on our map, suggesting that those faults played an important role in transporting water to the upper mantle. Further, we observe a weak correlation between fault heaves and serpentinization beneath the hanging-wall blocks, indicating that serpentinization was controlled by a complex faulting during rifting. A good match between topographic highs of the S and local highly serpentinized areas of the mantle suggests that the morphology of the S was affected by the volume-increasing process of serpentinization and deformation of the overlying crust.

Acquiring quantitative metrics-based analysis regarding the performance of most first-principle space physics modeling approaches is key in understanding the solar and space weather. As established by the successive the Geospace Environment Modeling Challenges, quantification of performance help set a precedent in understanding the science behind the various phenomena observed naturally in addition to elucidating the merits and demerits of a space weather prediction method. In this study, the performance of three magnetohydrodynamic models (SWMF/BATS-R-US, LFM and OpenGGCM) in estimating the Earth’s magnetopause location and the ionospheric cross polar cap potential (CPCP) have been studied. Using the Community Coordinated Modeling Center’s Run-on-Request system and extensive database on results of various magnetospheric scenarios run during a variety of solar weather patterns, the aforementioned model predictions have been compared with magnetopause standoff distance estimations obtained from six empirical models, and with cross polar cap potential estimations obtained from AMIE and SuperDARN. The events considered in this study contain a spectrum of possibilities – solar storms, substorms, constant solar wind events, which have been categorized using the Kp index as high, moderate and low magnitude solar events. Several of these storms have been well documented as part of the Geospace Environment Modeling (GEM) Challenges and other studies. The root-mean-square difference (RMS), prediction efficiency (PE) and maximum amplitude (Max Amp) metrics are used to quantify the model performances for the solar events considered. A separate metric called Wrong Prediction (WP) has also been used to study the models’ hit and miss rates with the empirical data. While almost all the cases considered for the magnetopause standoff distances have a satisfactory performance, there is huge deviation for the CPCP data both in the physics based models and the empirical data. The metric data is therefore valid for the magnetopause location comparisons, while not being that thorough for the CPCP comparative study.

The Snow Water Equivalent (SWE) describes the amount of water stored in snow. The SWE is a key parameter for various applications including meteorological information systems, run-off predictions for hydro power plants, and roof load monitoring. The SWE as well as the snow height and liquid water content can be determined with Global Navigation Satellite System (GNSS) signals. The set-up consists of two GNSS antennas where as one antenna is placed on the ground below the snow and the second one is placed on a pole above the snow, and serves as reference antenna. The differential GNSS signals are affected by the relative position between the antennas, the snow and the GNSS carrier phase ambiguities. The GNSS signals are refracted at the air-snow interface, and attenuated and delayed in the snow pack. The contribution of this talk is three-fold: First, we have extended our snow parameter estimation [2,3] from a single-frequency, dual constellation (GPS + Galileo) solution to a multi-frequency, triple-constellation (GPS + Galileo + Beidou) solution [1]. Secondly, we have used a Kalman filter to continuously estimate the SWE and carrier phase ambiguities [1] instead of a least-squares estimation. Third, the float ambiguity estimates are now fixed to integer numbers with the Least-Squares Ambiguity Decorrelation Adjustment (LAMBDA) method. The first results are very promising and indicate that the measurement period for snow parameter estimation can be reduced from several hours to less than 30 minutes. References: [1] Julian Weiss: “Snow Parameter Estimation with Multi-Frequency and Multi-Constellation GNSS”, Master thesis, Techn. Univ. Muenchen, Germany, 2021. [2] Patrick Henkel, Franziska Koch, Florian Appel, Heike Bach, Monika Prasch, Lino Schmid, Juerg Schweizer, and Wolfram Mauser: “Snow Water Equivalent of Dry Snow Derived from GNSS Carrier Phases“, in: IEEE Transactions on Geoscience and Remote Sensing, vol. 56, issue 6, pp. 3561 – 3572, Jun. 2018. [3] Franziska Koch, Patrick Henkel, Florian Appel, Lino Schmid, Heike Bach, Markus Lamm, Monika Prasch, Juerg Schweizer, and Wolfram Mauser: “Retrieval of snow water equivalent, liquid water content, and snow height of dry and wet snow by combining GPS signal attenuation and time delay“, in Water Resources Research, vol. 55, issue 5, pp. 4465 – 4487, May 2019.

To obtain an optimum irrigation management strategy, reaching lower water applications as well as highest possible yields, can be complex regarding various plant and environmental parameters along with various dominancy of each parameter. For this purpose, the relationship among the input irrigation factors (irrigation interval, water salinity, environment), moderate factors (evapotranspiration, soil salinity, plant parameters, fruit parameters, crop yield) and a response (WUE: water use efficiency) were carefully determined using a structural equation modeling according to the first year of experiments. The relations were improved using the dataset of the second year of experiments. The improved models were then used in two optimization methods, water cycle algorithm (WCA) and genetic algorithm (GA), to determine the best combination of irrigation factors and optimize eggplant cultivation. The structural equation modeling indicated that the irrigation interval negatively impacted WUE with a more dominant effect on plant parameters, while water salinity negatively impacted the WUE with a more dominant effect on soil salinity, crop yield and fruit parameters. Further, a low salinity level will be more important than full irrigation to optimize WUE. WCA appeared that the optimal ranges of irrigation interval and water salinity were 2.13‒5.23 day and 0.8‒2.21 ds/m cultivated in outdoor cultivation, resulting to optimize evapotranspiration, soil salinity, fruit parameters and crop yield in the ranges of 346.23‒738.19 mm, 4.16‒9.45 ds/m, 33.81‒35.12 cm and 1715.7‒2190.8 g/plant, respectively; and thus, increase WUE in the range of 3.08‒4.89 g/(plant-mm). WCA and GA presented very close optimal values.

Most efforts to characterize the size and composition of the mantle that complements the continental crust have assumed that the mid-ocean ridge basalt (MORB) source is the incompatible-element depleted residue of continental crust extraction. The use of Nd isotopes to model this process led to the conclusion that the “depleted MORB reservoir” is confined to the upper ~30% of the mantle, leaving the lower mantle in a more “primitive” state. Here we use Nb/U and Ta/U to evaluate mass and composition of the mantle reservoir residual to continent extraction and find that it exceeds 67% of the total mantle. Thus the (Nb,Ta)/U-based mass balance conflicts with the ε(Nd)-based mass balance, and this invalidates the classical 3-reservoir silicate Earth model (continental crust, depleted mantle, primitive mantle). Including the combined MORB + ocean island basalt (OIB) sources in the ε(Nd)-based mass balance does not reconcile the conflict as it would require their average ε(Nd) to be ≤3.0, much lower than observed MORB+OIB ε(Nd) averages. We resolve this conflict by invoking an additional, “early-enriched reservoir” (EER), formed prior to extraction of significant continental crust, but now hidden or lost. This EER differs from EERs previously invoked by having no Nb-Ta anomaly. We suggest that it originated as an early mafic crust, which had unfractionated (Nb,Ta)/U but fractionated Sm/Nd ratios. The corresponding “early-depleted” reservoir (EDR) generated the present-day continental crust and the “residual mantle” MORB-OIB reservoir, which occupies at least 70% of the present-day mantle and is only moderately depleted in incompatible trace elements.

A document by Jerome Pinti. Click on the document to view its contents.

Eddy activities are particularly prominent in the Southern Ocean due to the instabilities of the Antarctic Circumpolar Current (ACC), which plays a critical role in energy transport of the global ocean. The Indian sector of the Southern Ocean is not only a typical eddy-rich region with strong Eddy Kinetic Energy (EKE) and associated energy conversions among different energy reservoirs (kinetic energy and potential energy of the eddy and mean flow), but also events of extreme EKE. In this study, a systematic energetics analysis framework is employed to examine the notable anomalies of an intensified EKE event observed in the southwest region of the Kerguelen Plateau in 2017 based on a reanalysis product. The EKE anomaly existing at all depths emerges in April, reaches its peak during the austral winter, and persists into the following summer. Energetics analysis indicates that the strong anomalous EKE is primarily determined by baroclinic instability, with distinct governing mechanisms at the surface and in the internal ocean. The anomalous intrusion of warm Circumpolar Deep Water intensifies the baroclinic energy conversion in the subsurface, which contributes to the observed EKE anomalies. Moreover, the anomalous strong wind-induced Ekman pumping serves to amplify the lifting of isopycnals, which enhances the baroclinic instability and subsequently intensifies the EKE anomalies. This study sheds new light on underlying mechanisms governing local polar dynamics and provides insights into the intricate interaction between ocean dynamics and energy distribution in the Antarctic.

A document by Eva E. Stüeken. Click on the document to view its contents.

Many global climate models underestimate the cloud cover and overestimate the cloud albedo, especially for low-level clouds. We determine how a correct representation of the vertical structure of clouds can fix part of this bias. We use the 1D McICA framework and focus on low-level clouds. Using LES results as reference, we propose a method based on exponential-random overlap (ERO) that represents the cloud overlap between layers and the subgrid cloud properties over several vertical scales, with a single value of the overlap parameter. Starting from a coarse vertical grid, representative of atmospheric models, this algorithm is used to generate the vertical profile of the cloud fraction with a finer vertical resolution, or to generate it on the coarse grid but with subgrid heterogeneity and cloud overlap that ensures a correct cloud cover. Doing so we find decorrelation lengths are dependent on the vertical resolution, except if the vertical subgrid heterogeneity and interlayer overlap are taken into account coherently. We confirm that the frequently used maximum-random overlap leads to a significant error by underestimating the low-level cloud cover with a relative error of about 50%, that can lead to an error of SW cloud albedo as big as 70%. Not taking into account the subgrid vertical heterogeneity of clouds can cause an additional relative error of 20% in brightness, assuming the cloud cover is correct.

Extreme heat events are one of the most dangerous climate hazards and they are projected to increase in frequency, intensity and duration as this century progresses. Change in future exposure to extreme heat events depends not only on climate change, but also on changes to future population size and the areas this population inhabits. This study explores exposure to the heat event known as a tropical night. Using a CMIP6 multi-model ensemble, coupled with population projections, this study projects exposure for the four alternative futures described by SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5. Exposure is quantified annually at both the global and regional scale, relative to a preindustrial baseline. By the end of the twenty-first century global annual exposure to tropical nights will total 1338-2674 billion person-days depending on the pathway followed. Of the four pathways, globally change in exposure from the pre-industrial is avoided most under SSP1-2.6, which, when compared to SSP3-7.0 which projects the greatest change, is a reduction of 1336 billion person-days annually. Exposure reduction varies at the regional level, yet in the majority of cases, SSP1-2.6 remains the more desirable future in terms of minimising future exposure. Moreover, this study finds that changes in climate versus changes in population do not equally influence changes in exposure, and their contributions vary regionally. Irrespective of the future pathway followed, human exposure is set to increase at the global scale and for the vast majority of regions.

Climate change is an important issue that affects all aspects of human life and the environment. Through this project, we wrote an original pop song about the local impacts and solutions to climate change in the Northeast. We used a mixed-methods evaluation to test the effectiveness of musical science communication in relation to traditional methods, to change the mindsets of college students and encourage them to take political action. Marist students responded to surveys asking about their sustainability and lifestyle choices, as well as their opinions on climate change. After watching either the traditional presentation or listening to the song, participants answered whether their stance toward climate change had changed, whether they had learned more, and whether they plan to take specific steps to make their lifestyles more sustainable. Through a Fisher Chi-Square analysis, we determined that the change in stances between the two treatments was not significant (p-value = 0.33). However, to an 84% confidence level, there were differences between the two treatments in whether students learned about climate change, and whether they were more likely to change their lifestyle. We found that the traditional science presentation was better at teaching new information (p-value = 0.08), while the song was better at convincing students to act in the future (p-value = 0.16). In summary, we found that traditional science communication is better at teaching someone about climate change, but if the goal is to convince someone to take action to do something about it, then communicating that message through music is the better option. Examples of these types of communication can be found on YouTube, https://youtu.be/gXedvKkpLGs for the song, and https://youtu.be/gbf6cTDNp18 for the traditional presentation.

Slab subduction imaged by seismic tomography implies extensive mantle convection and circulation in the Earth’s interior. Widespread subduction of the western Pacific plate beneath the eastern Eurasian plate has left peculiar geochemical and geophysical signatures in the upper mantle of East Asia, which allow to investigate the extent of thermochemical interactions between the subducting plates and the surrounding mantle. Here we provide refined images of the stagnant Pacific slab and the mantle transition zone beneath northeast Asia. We applied teleseismic traveltime tomography and 3-D body-wave waveform modeling by using high-quality datasets from dense seismic arrays including in the Korean Peninsula and southwestern Japan, and found a clear signature of fragmentation of the stagnant Pacific slab. We imaged a localized low-velocity anomaly with high Vp/Vs ratio at 410-km depth above the slab gap, which was interpreted to be partial melting. The segmented Pacific slab reflects a rapid change in boundaries between the Pacific plate, Eurasian plate, and Philippine Sea plate during the Early to mid-Miocene. The slab fragmentation likely has facilitated localized mantle convection in the upper mantle and the mantle transition zone around the slab segments. Our images provide evidence of dynamic interplay between the evolving plate configurations, subducting slabs, and the surrounding mantle.

Parameter estimation is one of the most challenging tasks in large-scale distributed modeling, because of the high dimensionality of the parameter space. Relating model parameters to catchment/landscape characteristics reduces the number of parameters, enhances physical realism, and allows the transfer of hydrological model parameters in time and space. This study presents the first large-scale application of automatic parameter transfer function (TF) estimation for a complex hydrological model. The Function Space Optimization (FSO) method can automatically estimate TF structures and coefficients for distributed models. We apply FSO to the mesoscale Hydrologic Model (mHM, mhm-ufz.org), which is the only available distributed model that includes a priori defined TFs for all its parameters. FSO is used to estimate new TFs for the parameters “saturated hydraulic conductivity” and “field capacity”, which both influence a range of hydrological processes. The setup of mHM from a previous study serves as a benchmark. The estimated TFs resulted in predictions in 222 validation basins with a median NSE of 0.68, showing that even with 5 years of calibration data, high performance in ungauged basins can be achieved. The performance is similar to the benchmark results, showing that the automatic TFs can achieve comparable results to TFs that were developed over years using expert knowledge. In summary, the findings present a step towards automatic TF estimation of model parameters for distributed models.

Sedimentary basins strongly affect earthquake ground motions of both body and surface waves that propagate through them. Yet to characterize seismic hazards at a specific site, it is common practice to consider only the effects of near-surface geology on vertically propagating body waves despite surface waves often causing strong damage. Recently, Bowden & Tsai (2017) proposed an semi-analytical method to predict surface-wave basin amplification and noticed that certain large regional earthquake ground motions are under-predicted if surface waves are not properly accounted for. Since the theory is based on a 1-D approximation of the near-surface geologic structure and does not account for path effects, it is of interest to know how significantly such additional complexity affects the 1-D predictions. When considering deep basins, several other basin parameters play a role in the amplification of surface waves: transmission and conversion at the basin edge, basin shape, lateral resonance and focusing effects. As surface waves propagate back and forth in a highly dispersive medium, the amplification also varies strongly from the edge to the center of the basin. These effects are not always accounted for because of the cost of geophysical surveys that would accurately constrain the structure, the lack of earthquake data for empirical predictions, the poor understanding of what main factors are responsible for basin amplification, and the absence of quantitative estimates of their contribution to the overall amplification. The current study aims to provide quantitative estimates of the importance of these various path effects on surface waves amplification and also extend the current 1-D theory to more complex multi-dimensional basin structures.

This research aims to identify several decision-making gaps which seem to be existed around Food-Energy-Water Nexus through local case study in the Kyoto city, Japan. Our research methodologies include calculating food self-sufficiency ratio at local level using national statistics, production area proportion of each food categories using local market reports, and conducting impact assessment for Water-Energy Nexus based on several scenarios of food policy. Based on the above calculation and scenario analysis on several food policies, decision-making gaps regarding Food-Energy-Water Nexus is abstracted. During the scenario analysis, decision-making gaps regarding Food-Energy-Water Nexus are found. In other words, while a watershed is decided automatically by natural and geographical conditions, energy-shed usually depend on big electricity companies and food-shed consists of consumers’ preferences, retailers’ procurement policy, farmers’ tendency to change (or not change) their production style and so on.

Pockmarks are morphological depressions commonly observed in ocean and lake floors. Pockmarks form by fluid (typically gas) seepage thorough a sealing sedimentary layer, deforming and breaching the layer. The seepage-induced sediment deformation mechanisms, and their links to the resulting pockmarks morphology, are not well understood. To bridge this gap, we conduct laboratory experiments in which gas seeps through a granular (sand) reservoir, overlaid by a (clay) seal, both submerged under water. We find that gas rises through the reservoir and accumulates at the seal base. Once sufficient gas over-pressure is achieved, gas deforms the seal, and finally escapes via either: (i) doming of the seal followed by dome breaching via fracturing; (ii) brittle faulting, delineating a plug. The gas lifts the plug and seeps through the bounding faults; or (iii) plastic deformation by bubbles ascending through the seal. The preferred mechanism is found to depend on the seal thickness and stiffness: in stiff seals, a transition from doming and fracturing to brittle faulting occurs as the thickness increases, whereas bubbles rise is preferred in the most compliant, thickest seals. Seepage can also occur by mixed modes, such as bubbles rising in faults. Repeated seepage events suspend the sediment at the surface and create pockmarks. We present a quantitative analysis that explains the tendency for the various modes of deformation observed experimentally. Finally, we connect simple theoretical arguments with field observations, highlighting similarities and differences that bound the applicability of laboratory experiments to natural pockmarks.

Modeling studies have predicted that the acoustic resonance of the atmosphere during geophysical events such as earthquakes and volcanos can lead to an oscillation of the geomagnetic field with a frequency of about 4 mHz. However, observational evidence is still limited due to scarcity of suitable events. On January 15, 2022, the submarine volcano Hunga Tonga-Hunga Ha’apai (20.5˚S, 175.4˚W, Tonga) erupted in the Pacific Ocean and caused severe atmospheric disturbance, providing an opportunity to investigate geomagnetic effects associated with acoustic resonance. Following the eruption, geomagnetic oscillation is observed at Apia, approximately 835 km from Hunga Tonga, mainly in the Pc 5 band (150-600 s, or 1.7-6.7 mHz) lasting for about 2 hours. The dominant frequency of the oscillation is 3.8 mHz, which is consistent with the frequency of the atmospheric oscillation due to acoustic resonance. The oscillation is most prominent in the eastward (Y) component, with an amplitude of ~3 nT, which is much larger than those previously reported for other events (<1 nT). Comparably large oscillation is not found at other stations located further away (>2700 km). However, geomagnetic oscillation with a much smaller amplitude (~0.3 nT) is observed at Honolulu, which is located near the magnetic conjugate point of Hunga Tonga, in a similar wave form as at Apia, indicating interhemispheric coupling. This is the first time that geomagnetic oscillations due to the atmospheric acoustic resonance are simultaneously detected at magnetic conjugate points.

Rapid changes of magnetic fields associated with nighttime magnetic perturbation events (MPEs) with amplitudes |ΔB| of hundreds of nT and 5-10 min periods can induce geomagnetically-induced currents (GICs) that can harm technological systems. In this study we compare the occurrence and amplitude of nighttime MPEs with |dB/dt| ≥ 6 nT/s observed during 2015 and 2017 at five stations in Arctic Canada ranging from 75.2° to 64.7° in corrected geomagnetic latitude (MLAT) as functions of magnetic local time (MLT), the SME and SYM/H magnetic indices, and time delay after substorm onsets. Although most MPEs occurred within 30 minutes after a substorm onset, ~10% of those observed at the four lower latitude stations occurred over two hours after the most recent onset. A broad distribution in local time appeared at all 5 stations between 1700 and 0100 MLT, and a narrower distribution appeared at the lower latitude stations between 0200 and 0700 MLT. There was little or no correlation between MPE amplitude and the SYM/H index; most MPEs at all stations occurred for SYM/H values between -40 and 0 nT. SME index values for MPEs observed more than 1 hour after the most recent substorm onset fell in the lower half of the range of SME values for events during substorms, and dipolarizations in synchronous orbit at GOES 13 during these events were weaker or more often nonexistent. These observations suggest that substorms are neither necessary nor sufficient to cause MPEs, and hence predictions of GICs cannot focus solely on substorms.