Geology Research Works

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182W and HSE constraints from 2.7 Ga komatiites on the heterogeneous nature of the Archean mantle
(Elsevier - Geochimica et Cosmochimica Acta, 2018) Puchtel, Igor S; Blichert-Toft, Janne; Touboul, Mathieu; Walker, Richard J.
While the isotopically heterogeneous nature of the terrestrial mantle has long been established, the origin, scale, and longevity of the heterogeneities for different elements and isotopic systems are still debated. Here, we report Nd, Hf, W, and Os isotopic and highly siderophile element (HSE) abundance data for the Boston Creek komatiitic basalt lava flow (BCF) in the 2.7 Ga Abitibi greenstone belt, Canada. This lava flow is characterized by strong depletions in Al and heavy rare earth elements (REE), enrichments in light REE, and initial epsilon143Nd = +2.5 ± 0.2 and initial epsilon176Hf = +4.2 ± 0.9 indicative of derivation from a deep mantle source with time-integrated suprachondritic Sm/Nd and Lu/Hf ratios. The data plot on the terrestrial Nd-Hf array suggesting minimal involvement of early magma ocean processes in the fractionation of lithophile trace elements in the mantle source. This conclusion is supported by a mean mu142Nd = -3.8 ± 2.8 that is unresolvable from terrestrial standards. By contrast, the BCF exhibits a positive 182W anomaly (mu182W = +11.7 ± 4.5), yet is characterized by chondritic initial gamma187Os = +0.1 ± 0.3 and low inferred source HSE abundances (35 ± 5% of those estimated for the present-day Bulk Silicate Earth, BSE). Collectively, these characteristics are unique among Archean komatiite systems studied so far. The deficit in the HSE, coupled with the chondritic Os isotopic composition, but a positive 182W anomaly, are best explained by derivation of the parental BCF magma from a mantle domain characterized by a predominance of HSE-deficient, differentiated late accreted material. According to the model presented here, the mantle domain that gave rise to the BCF received only ~35% of the present-day HSE complement in the BSE before becoming isolated from the rest of the convecting mantle until the time of komatiite emplacement at 2.72 Ga. These new data provide strong evidence for a highly heterogeneous Archean mantle in terms of absolute HSE abundances and W isotopic composition, and also indicate slow mixing, on a timescale of at least 1.8 billion years. Additionally, the data are consistent with a stagnant-lid plate tectonic regime in the Hadean and Archean, prior to the onset of modern-style plate tectonics.
182W and HSE constraints from 2.7 Ga komatiites on the heterogeneous nature of the Archen mantle
(Elsevier, 2018-03-02) Puchtel, I.S.; Blichert-Toft, J.; Touboul, M.; Walker, Richard J.
While the isotopically heterogeneous nature of the terrestrial mantle has long been established, the origin, scale, and longevity of the heterogeneities for different elements and isotopic systems are still debated. Here, we report Nd, Hf, W, and Os isotopic and highly siderophile element (HSE) abundance data for the Boston Creek komatiitic basalt lava flow (BCF) in the 2.7 Ga Abitibi greenstone belt, Canada. This lava flow is characterized by strong depletions in Al and heavy rare earth elements (REE), enrichments in light REE, and initial e143Nd = +2.5 ± 0.2 and initial e176Hf = +4.2 ± 0.9 indicative of derivation from a deep mantle source with time-integrated suprachondritic Sm/Nd and Lu/Hf ratios. The data plot on the terrestrial Nd-Hf array suggesting minimal involvement of early magma ocean processes in the fractionation of lithophile trace elements in the mantle source. This conclusion is supported by a mean mu142Nd = -3.8 ± 2.8 that is unresolvable from terrestrial standards. By contrast, the BCF exhibits a positive 182W anomaly (mu182W = +11.7 ± 4.5), yet is characterized by chondritic initial g187Os = +0.1 ± 0.3 and low inferred source HSE abundances (35 ± 5% of those estimated for the present-day Bulk Silicate Earth, BSE). Collectively, these characteristics are unique among Archean komatiite systems studied so far. The deficit in the HSE, coupled with the chondritic Os isotopic composition, but a positive 182W anomaly, are best explained by derivation of the parental BCF magma from a mantle domain characterized by a predominance of HSE-deficient, differentiated late accreted material. According to the model presented here, the mantle domain that gave rise to the BCF received only ~35% of the present-day HSE complement in the BSE before becoming isolated from the rest of the convecting mantle until the time of komatiite emplacement at 2.72 Ga. These new data provide strong evidence for a highly heterogeneous Archean mantle in terms of absolute HSE abundances and W isotopic composition, and also indicate slow mixing, on a timescale of at least 1.8 billion years. Additionally, the data are consistent with a stagnant-lid plate tectonic regime in the Hadean and Archean, prior to the onset of modern-style plate tectonics.
A Better Understanding of Atmospheric Methane Sources Using 13CH3D and 12CH2D2 Clumped Isotopes
(2024-09) Haghnegahdar, Mojhgan A.
We evaluate the use of clumped isotopes of methane (CH4) to fingerprint local atmospheric sources of methane. We focus on a regenerative stormwater conveyance (RSC) stream wetland site running through the University of Maryland campus, which emits methane due to its engineering. Air samples in the RSC were collected at different heights above the surface and at different times of the day including both early in the morning, after methane accumulated below the nocturnal boundary layer, and late in the afternoon when convection mixed air to the cloud layer. Measured Δ12CH2D2 values of air samples record mixing between locally produced methane with low D/H and ambient air. The Δ12CH2D2 of the near surface air collected at the RSC during the early morning ranges from ~+23‰ to ~+35‰ which is lower than the ~+50‰ values of tropospheric air. Mixing between background air (with Δ12CH2D2 ~+50‰) and methane captured from chamber and bubble samples, as well as produced in incubation (all with negative Δ12CH2D2), explains the observed values of Δ12CH2D2 and Δ13CH3D of near surface RSC air samples. The effect of mixing with biogenic sources on Δ13CH3D is much smaller. The findings demonstrate how methane isotopologues can be used as a tool not only to fingerprint local contributions to these greenhouse gas emissions but also to identify sources of near-surface methane hot spots.
A New Method for Generating the SMOPS Blended Satellite Soil Moisture Data Product without Relying on a Model Climatology
(MDPI, 2022-03-31) Yin, Jifu; Zhan, Xiwu; Liu, Jicheng; Ferraro, Ralph R.
Soil moisture operational product system (SMOPS) is developed by National Oceanic and Atmospheric Administration (NOAA) to provide the real-time blended soil moisture (SM) for numeric weather prediction and national water model applications. However, all individual satellite SM data ingested into the current operational SMOPS are scaled to global land data assimilation system (GLDAS) 0–10 cm SM climatology before the combination. As a result, the useful information from the original microwave SM retrievals could be lost, and the GLDAS model errors could be brought into the final SMOPS blended product. In this paper, we propose to scale the individual SM retrievals to the soil moisture active passive (SMAP) data through building regression models. The rescaled individual SM data and the SMAP observations then have similar climatology and dynamics, which allows producing the SMOPScdr (distinguishing with the current operational SMOPSopr) data using an equal-weight averaging approach. With respect to the in situ SM measurements, the developed SMOPScdr is more successful tracking the surface SM status than the individual satellite SM products with significantly decreased errors. The proposed method also preserves the climatology of the reference SMAP data for the period when SMAP is not available, allowing us to produce a long-term SMOPScdr data product.
A Study of Lunar Microwave Radiation Based on Satellite Observations
(MDPI, 2020-04-02) Yang, Hu; Burgdorf, Martin
In recent years, the study of microwave radiation from the Moon’s surface has been of interest to the astronomy and remote sensing communities. Due to the stable geophysical properties of the Moon’s surface, microwave lunar radiation is highly predictable and can be accurately modeled, given sufficient observations from reliable instruments. Specifically, for microwave remote sensing study, if International System of Unit (SI) traceable observations of the Moon are available, the Moon can thus be used as an SI traceable calibration reference for microwave instruments to evaluate their calibration accuracies and assess their long-term calibration stabilities. Major challenges of using the Moon as a radiometric source standard for microwave sensors include the uncertainties in antenna pattern measurements, the reliability of measurements of brightness temperature (Tb) in the microwave spectrum of the lunar surface, and knowledge of the lunar phase lag because of penetration depths at different detection frequencies. Most microwave-sounding instruments can collect lunar radiation data from space-view observations during so-called lunar intrusion events that usually occur several days each month. Addressed in this work based on Moon observations from the Advanced Technology Microwave Sounder and the Advanced Microwave Sounding Unit/Microwave Humidity Sounder are two major issues in lunar calibration: the lunar surface microwave Tb spectrum and phase lag. The scientific objective of this study is to present our most recent progress on the study of lunar microwave radiation based on satellite observations. Reported here are the lunar microwave Tb spectrum and phase lag from 23 to 183 GHz based on observations of microwave-sounding instruments onboard different satellite platforms. For current Moon microwave radiation research, this study can help toward better understanding lunar microwave radiation features over a wide spectrum range, laying a solid foundation for future lunar microwave calibration efforts.
Active Seismic Exploration of Planetary Subsurfaces via Compressive Sensing
(2025) Wang, Jingchuan; Schmerr, Nicholas; Lekic, Vedran
The software supports the following study: We present a method for improving seismic data collection on planetary surfaces such as the Moon and Mars. This approach is based on recent advances in compressive sensing technology to reduce the number of data collection points required compared to conventional methods without sacrificing the quality of the resulting subsurface images. We demonstrate its effectiveness using both synthetic and field data from locations with similarities to planetary surface environments. The method is then applied to reanalyze seismic data collected by the crew of the Apollo 14 and 16 missions. Our study has implications for mission planning, as this method can make space missions more efficient by reducing the equipment and time to collect geophysical data on planetary surfaces. It also makes it possible to reconstruct missing or damaged data, improving the quality of imagery and enhancing our understanding of the interior of other worlds.
Age, genetics, and crystallization sequence of the group IIIE iron meteorites
(Elsevier, 2023-06-14) Chiappe, Emily M.; Ash, Richard; Walker, Richard J.
Chemical and isotopic data were obtained for ten iron meteorites classified as members of the IIIE group. Nine of the IIIE irons exhibit broadly similar bulk siderophile element characteristics. Modeling of highly siderophile element abundances suggests that they can be related to one another through simple crystal-liquid fractionation of a parent melt. Our preferred model suggests initial S, P, and C concentrations of approximately 12 wt%, 0.8 wt %, and 0.08 wt%, respectively. The modeled IIIE parent melt composition is ~4 times more enriched in highly siderophile elements than a non-carbonaceous (NC) chondrite-like parent body, suggesting a core comprising ~22% of the mass of the parent body. Although chemically distinct from the other IIIE irons, formation of the anomalous IIIE iron Aletai can potentially be accounted for under the conditions of this model through the nonequilibrium mixing of an evolved liquid and early formed solid. Cosmic ray exposure-corrected nucleosynthetic Mo, Ru, and W isotopic compositions of four of the bona fide IIIE irons and Aletai indicate that they originated from the non-carbonaceous (NC) isotopic domain. Tungsten-182 isotopic data for the IIIE irons and Aletai yield similar model metal-silicate segregation ages of 1.6 ± 0.8 Myr and 1.2 ± 0.8 Myr, respectively, after calcium aluminum-rich inclusion (CAI) formation. These ages are consistent with those reported for other NC-type iron meteorite parent bodies. The IIIE irons are chemically and isotopically similar to the much larger IIIAB group. Despite some textural, mineralogical, and chemical differences, such as higher C content, the new results suggest they may have originated from a different crystallization sequence on the same or closely-related parent body.
Anomalous 33S in the Lunar Mantle
(Wiley, 2023-02-02) Dottin, J. W. III; Kim, S.-T.; Wing, B.; Farquhar, J.; Shearer, C.
The origin, evolution, and cycling of volatiles on the Moon are established by processes such as the giant moon forming impact, degassing of the lunar magma ocean, degassing during surface eruptions, and lunar surface gardening events. These processes typically induce mass-dependent stable isotope fractionations. Mass-independent fractionation of stable isotopes has yet to be demonstrated during events that release large volumes of gas on the moon and establish transient lunar atmospheres. We present quadruple sulfur isotope compositions of orange and black glass beads from drive tube 74002/1. The sulfur isotope and concentration data collected on the orange and black glasses confirm a role for magmatic sulfur loss during eruption. The Δ33S value of the orange glasses is homogenous (Δ33S = −0.029‰ ± 0.004‰, 2SE) and different from the isotopic composition of lunar basalts (Δ33S = 0.002‰ ± 0.004‰, 2SE). We link the negative Δ33S composition of the orange glasses to an anomalous sulfur source in the lunar mantle. The nature of this anomalous sulfur source remains unknown and is either linked to (a) an impactor that delivered anomalous sulfur after late accretion, (b) sulfur that was photochemically processed early during lunar evolution and was transported to the lunar mantle, or (c) a primitive sulfur component that survived mantle mixing. The examined black glass preserves a mass-dependent Δ33S composition (−0.008‰ ± 0.006‰, 2SE). The orange and black glasses are considered genetically related, but the discrepancy in Δ33S composition among the two samples calls their relationship into question.
Assessment of Himawari-8 AHI Aerosol Optical Depth Over Land
(MDPI, 2019-05-09) Zhang, Wenhao; Xu, Hui; Zhang, Lili
This study conducted the first comprehensive assessment of the aerosol optical depth (AOD) product retrieved from the observations by the Advanced Himawari Imager (AHI) onboard the Himawari-8 satellite. The AHI Level 3 AOD (Version 3.0) was evaluated using the collocated Aerosol Robotic Network (AERONET) level 2.0 direct sun AOD measurements over the last three years (May 2016–December 2018) at 58 selected AERONET sites. A comprehensive comparison between AHI and AERONET AOD was carried out, which yielded a correlation coefficient (R) of 0.82, a slope of 0.69, and a root mean square error (RMSE) of 0.16. The results indicate a good agreement between AHI and AERONET AOD, while revealing that the AHI aerosol retrieval algorithm tends to underestimate the atmospheric aerosol load. In addition, the expected uncertainty of AHI Level 3 AOD (Version 3.0) is ± (0.1 + 0.3 × AOD). Furthermore, the performance of the AHI aerosol retrieval algorithm exhibits regional variation. The best performance is reported over East Asia (R 0.86), followed by Southeast Asia (R 0.79) and Australia (R 0.35). The monthly and seasonal comparisons between AHI and AERONET show that the best performance is found in summer (R 0.93), followed by autumn (R 0.84), winter (R 0.82), and spring (R 0.76). The worst performance was observed in March (R 0.75), while the best performance appeared in June (R 0.94). The variation in the annual mean AHI AOD on the scale of hours demonstrates that AHI can perform continuous (no less than ten hours) aerosol monitoring.
Assessment of the Reprocessed Suomi NPP VIIRS Enterprise Cloud Mask Product
(MDPI, 2021-06-26) Lin, Lin; Hao, Xianjun; Zhang, Bin; Zou, Cheng-Zhi; Cao, Changyong
The Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (S-NPP) satellite continually provides global observations used to retrieve over 20 VIIRS Environmental Data Record (EDR) products. Among them, the cloud mask product is essential for many other VIIRS EDR products such as aerosols, ocean color, and active fire. The reprocessed S-NPP VIIRS Sensor Data Record (SDR) data produced by NOAA/Center for Satellite Applications and Research (STAR) have shown improved stability and consistency. Recently, the VIIRS Enterprise Cloud Mask (ECM) has been reprocessed using the reprocessed VIIRS SDR data. This study assesses the reprocessed ECM product by comparing the reprocessed cloud mask types and cloud probability with those from the operational VIIRS ECM product. It found that the overall differences are small. Most of the discrepancies occur between neighboring types at the cloud edge. These findings help lay the foundation for the user community to understand the reprocessed ECM product. In addition, due to the better quality of the reprocessed VIIRS SDR data that are utilized to generate the reprocessed ECM product, it is expected that the reprocessed ECM product will have better stability and consistency compared to the operational ECM products. Therefore, the reprocessed ECM product is a useful benchmark for the user community.
Can Managed Aquifer Recharge Overcome Multiple Droughts?
(MDPI, 2021-08-20) Zhao, Mengqi; Boll, Jan; Adam, Jennifer C.; Beall King, Allyson
Frequent droughts, seasonal precipitation, and growing agricultural water demand in the Yakima River Basin (YRB), located in Washington State, increase the challenges of optimizing water provision for agricultural producers. Increasing water storage through managed aquifer recharge (MAR) can potentially relief water stress from single and multi-year droughts. In this study, we developed an aggregated water resources management tool using a System Dynamics (SD) framework for the YRB and evaluated the MAR implementation strategy and the effectiveness of MAR in alleviating drought impacts on irrigation reliability. The SD model allocates available water resources to meet instream target flows, hydropower demands, and irrigation demand, based on system operation rules, irrigation scheduling, water rights, and MAR adoption. Our findings suggest that the adopted infiltration area for MAR is one of the main factors that determines the amount of water withdrawn and infiltrated to the groundwater system. The implementation time frame is also critical in accumulating MAR entitlements for single-year and multi-year droughts mitigation. In addition, adoption behaviors drive a positive feedback that MAR effectiveness on drought mitigation will encourage more MAR adoptions in the long run. MAR serves as a promising option for water storage management and a long-term strategy for MAR implementation can improve system resilience to unexpected droughts.
Characterization of Regolith And Trace Economic Resources (CRATER): An Orbitrap-based laser desorption mass spectrometry instrument for in situ exploration of the Moon
(Wiley, 2024-02-11) Ray, Soumya; Arevalo, Ricardo Jr.; Southard, Adrian; Willhite, Lori; Bardyn, Anais; Ni, Ziqin; Danell, Ryan; Grubisic, Andrej; Gundersen, Cynthia; Llano, Julie; Yu, Anthony; Fahey, Molly; Hernandez, Emanuel; Graham, Jacob; Lee, Jane; Ersahin, Akif; Briois, Christelle; Thirkell, Laurent; Colin, Fabrice; Makarov, Alexander
Rationale Characterization of Regolith And Trace Economic Resources (CRATER), an Orbitrap™-based laser desorption mass spectrometry instrument designed to conduct high-precision, spatially resolved analyses of planetary materials, is capable of answering outstanding science questions about the Moon's formation and the subsequent processes that have modified its (sub)surface. Methods Here, we describe the baseline design of the CRATER flight model, which requires <20 000 cm3 volume, <10 kg mass, and <60 W peak power. The analytical capabilities and performance metrics of a prototype that meets the full functionality of the flight model are demonstrated. Results The instrument comprises a high-power, solid-state, pulsed ultraviolet (213 nm) laser source to ablate the surface of the lunar sample, a custom ion optical interface to accelerate and collimate the ions produced at the ablation site, and an Orbitrap mass analyzer capable of discriminating competing isobars via ultrahigh mass resolution and high mass accuracy. The CRATER instrument can measure elemental and isotopic abundances and characterize the organic content of lunar surface samples, as well as identify economically valuable resources for future exploration. Conclusion An engineering test unit of the flight model is currently in development to serve as a pathfinder for near-term mission opportunities.
Chemical and genetic characterization of the ungrouped pallasite Lieksa
(Wiley, 2023-11-03) Chiappe, Emily M.; Ash, Richard D.; Luttinen, Arto; Lukkari, Sari; Kuva, Jukka; Hilton, Connor D.; Walker, Richard J.
The meteorite Lieksa was found in 2017 in Löpönvaara, Finland, and later donated to the Finnish Museum of Natural History. Here, we report siderophile element concentrations, genetic isotopic data, and a metal–silicate segregation age for the meteorite. The ~280 g Lieksa is ~80% metal and ~20% silicate and oxide inclusions by volume, with the inclusions consisting primarily of Fe-rich olivine. Due to Lieksa's silicate content, coupled with a texture characterized by metal enclosing the silicates, it has been classified as a pallasite. Lieksa's olivine and bulk chemical characteristics are distinct from those of the known pallasite and iron meteorite groups, consistent with its classification as ungrouped. The meteorite exhibits a flat, chondrite-normalized highly siderophile element pattern, consistent with an origin as an early crystallization product from a metallic melt with chondritic relative abundances. Molybdenum, Ru, and 183W isotopic data indicate that Lieksa formed in the non-carbonaceous (NC) domain of the solar nebula. Radiogenic 182W abundances for Lieksa yield a model metal–silicate segregation age of 1.5 ± 0.8 Myr after calcium-aluminum-rich inclusion formation, which is within the range established for other NC-type pallasite and iron meteorite parent bodies.
Children’s Perspectives on Fairness and Inclusivity in the Classroom
(Cambridge University Press, 2022-11-02) Kaufman, Elisa Marie; Killen, Melanie
School represents an important context for children’s social, moral, and identity development. Research indicates that supportive teacher-student relationships are significantly related to positive student academic achievement. Unfortunately, teacher bias as well as peer exclusion based on group identity (gender, race, ethnicity, and nationality) pervade many school contexts. The presence of these biases in the classroom is negatively related to students’ academic development, especially for children who are minoritized and marginalized. Very little research has connected teacher bias and children’s reasoning about bias and inequalities in the classroom context. The classroom is a complex environment in which to examine children’s social and moral reasoning about bias, given teachers’ position of authority which often includes power, status, and prestige. We propose that understanding both teacher bias and peer intergroup exclusion are essential for promoting more fair classrooms. This paper reviews foundational theory as well as the social reasoning developmental model as a framework for studying how children think about fairness and bias in the classroom context. We then discuss current research on children’s social-cognitive and moral capacities, particularly in the contexts of societal inequality and social inclusion or exclusion. Finally, this article proposes new directions for research to promote fairness and inclusivity in schools and suggests how these new lines of research might inform school-based interventions.
Collective phenomena in granular and atmospheric electrification
(2015-07-29) Nordsiek, Freja; Lathrop, Daniel
This repository contains data from the Granular Electrification Experiment in the University of Maryland Nonlinear Dynamics Lab. The experiment consists of a cylindrical cell with aluminum plates on the top and bottom. The cell is filled with granular particles and shaken vertically for several cycles. The vertical position of the cell and the electric potential between the top and bottom endplates of the cell are acquired. The data in this repository is from experiments in which the cylindrical cell is filled with only one type of particle. One exception uses two types of particles, pointed out below. A particle type is comprised of its material, form (spheres or powder), and size range. The acceleration timeseries of the shaking is approximately a square wave with amplitude a, meaning that the vertical position is approximately a sequence of parabolas of alternating concavity. The stroke-length of the oscillation is 10.0 cm. The shaking strength is quantified as a/g where g is the free fall acceleration due to gravity on Earth. The amount of particles is quantified by the dimensionless parameter lambda = 2 N_p d^2 / (3 D^2) where N_p is the number of particles, d is the particle diameter (or effective diameter), and D is the diameter of the cell.
Combined Lithophile-Siderophile Isotopic Constraints on Hadean Processes Preserved in Ocean Island Basalt Sources
(American Geophysical Union - Geochemistry, Geophysics, Geosystems, 2021) Peters, Bradley; Mundl-Petermeier, Andrea; Carlson, Richard; Walker, Richard; Day, James
Detection of Hadean isotopic signatures within modern ocean island basalts (OIB) has greatly influenced understanding of Earth's earliest history and long-term dynamics. However, a relationship between two isotopic tools for studying early Earth processes, the short-lived 146Sm-142Nd and 182Hf-182W systems, has not been established in this context. The differing chemical behavior of these two isotopic systems means that they are complementary tracers of a range of proposed early Earth events, including core formation, magma ocean processes, and late accretion. There is a negative trend between 142Nd/144Nd and 182W/184W ratios among Réunion OIB that is extended by Deccan continental flood basalts. This finding is contrary to expectations if both systems were affected by silicate differentiation during the lifetime of 182Hf. The observed isotopic compositions are attributed to interaction between magma ocean remnants and Earth's core, coupled with later assimilation of recycled Hadean mafic crust. The effects of this scenario on the long-lived 143Nd-176Hf isotopic systematics mirror classical models invoking mixing of recycled trace-element enriched (sedimentary) and depleted (igneous) domains in OIB mantle sources. If the core provides a detectible contribution to the tungsten element budget of the silicate Earth, this represents a critical component to planetary-scale tungsten mass balance. A basic model is explored that reconciles the W abundance and isotopic composition of the bulk silicate Earth resulting from both late accretion and core-mantle interaction. The veracity of core-mantle interaction as proposed here would have many implications for long-term thermochemical cycling.
Comment on: Aquatic adaptation in the skull of carnivorous dinosaurs (Theropoda: Spinosauridae) and the evolution of aquatic habits in spinosaurids. 93: 275–284
(2022-06) Hone, David William Elliot; Holtz, Thomas Richard Jr
In a recent paper, the contention that spinosaurine theropods were semi-aquatic was supported by Arden et al., (2019) and they provided a hypothetical sequence of acquisition of traits that had evolved in line with this lifestyle. However, we find that the presented traits were either loosely defined and/or are clearly distinct from those traits seen in extant animals with adaptations to life in water. Some spinosaurs may have spent extensive time in water, but the data to support this is currently insufficient and other hypotheses for their behaviour also fit the available data.
Comparison of GRUAN RS92 and RS41 Radiosonde Temperature Biases
(MDPI, 2021-06-30) Jing, Xin; Shao, Xi; Liu, Tung-Chang; Zhang, Bin
In this study, we validated the consistency of the GRUAN RS92 and RS41 datasets, versions EDT.1 and GDP.2, in the upper troposphere and lower stratosphere (200–20 hPa), through dual launch campaigns at the GRUAN site and using the radio occultation (RO) product and the ERA5 reanalysis from ECMWF as standards for double difference comparison. Separate comparisons with the references were also performed in order to trace the origin of the bias between the two instruments. Then, the performance of the GRUAN raw temperature correction algorithm was evaluated, from the aspects of day–night, the solar zenith angle, and the pressure level, for GDP.2 version products. The results show that RS92.EDT.1 has a warm bias of 0.355 K, compared to RS41.EDT.1, at 20 hPa, during daytime. This bias was found to mainly originate from RS92.EDT.1, based on the separate comparison with RO or ECMWF ERA5 data. RS92.GDP.2 is consistent with RS41.GDP.2, but a separate comparison indicated that the two original GDP.2 products have a ~1 K warm bias at 20 hPa during daytime, compared with RO or ECMWF ERA5 data. The GRUAN correction method can reduce the warm bias up to 0.5 K at 20 hPa during daytime. As a result, this GRUAN correction method is efficient, and it is dependent on the solar zenith angle and pressure level.
Comparison of the Remapping Algorithms for the Advanced Technology Microwave Sounder (ATMS)
(MDPI, 2020-02-18) Zhou, Jun; Yang, Hu
One of the limitations in using spaceborne, microwave radiometer data for atmospheric remote sensing is the nonuniform spatial resolution. Remapping algorithms can be applied to the data to ameliorate this limitation. In this paper, two remapping algorithms, the Backus–Gilbert inversion (BGI) technique and the filter algorithm (AFA), widely used in the operational data preprocessing of the Advanced Technology Microwave Sounder (ATMS), are investigated. The algorithms are compared using simulations and actual ATMS data. Results show that both algorithms can effectively enhance or degrade the resolution of the data. The BGI has a higher remapping accuracy than the AFA. It outperforms the AFA by producing less bias around coastlines and hurricane centers where the signal changes sharply. It shows no obvious bias around the scan ends where the AFA has a noticeable positive bias in the resolution-enhanced image. However, the BGI achieves the resolution enhancement at the expense of increasing the noise by 0.5 K. The use of the antenna pattern instead of the point spread function in the algorithm causes the persistent bias found in the AFA-remapped image, leading not only to an inaccurate antenna temperature expression but also to the neglect of the geometric deformation of the along-scan field-of-views.
Compositional Attributes of the Deep Continental Crust Inferred From Geochemical and Geophysical Data
(Wiley, 2022-08-03) Sammon, Laura G.; McDonough, William F.; Mooney, Walter D.
This study provides a global assessment of the abundance of the major oxides in the deep continental crust. The combination of geochemistry and seismology better constrains the composition of the middle and lower continental crust better than either discipline can achieve alone. The inaccessible nature of the deep crust (typically >15 km) forces reliance on analog samples and modeling results to interpret its bulk composition, evolution, and physical properties. A common practice relates major oxide compositions of small- to medium-scale samples (e.g., medium to high metamorphic grade terrains and xenoliths) to large scale measurements of seismic velocities (Vp, Vs, Vp/Vs) to determine the composition of the deep crust. We provide a framework for building crustal models with multidisciplinary constraints on composition. We present a global deep crustal model that documents compositional changes with depth and accounts for uncertainties in Moho depth, temperature, and physical and chemical properties. Our 3D compositional model of the deep crust uses the USGS Global Seismic Structure Catalog (Mooney, 2015) and a compilation of geochemical analyses on amphibolite and granulite facies lithologies (Sammon & McDonough, 2021, https://doi.org/10.1029/2021JB022791). We find a SiO2 gradient from 61.2 ± 7.3 to 53.3 ± 4.8 wt.% from the middle to the base of the crust, with the equivalent lithological gradient ranging from quartz monzonite to gabbronorite. In addition, we calculate trace element abundances as a function of depth from their correlations with major oxides. From here, other lithospheric properties, such as Moho heat flux (urn:x-wiley:21699313:media:jgrb55765:jgrb55765-math-0001 mW/m2), are derived.