scholarly journals Bedrock to soil: In-situ measurement and analytical techniques for initial weathering of proglacial environments

2021 ◽  
Author(s):  
◽  
Karsten Lorentz
Keyword(s):  
Polynomial Interpolation ◽  
Compositional Analysis ◽  
Age Dating ◽  
Average Error ◽  
Rock Surface ◽  
Earth System ◽  
The Earth ◽  
Electron Imaging ◽  
Exposure Ages

<p>Dirt. It is more important than one might think. Soil, along with its bedrock-derived components, provides a nexus in the earth system for energy, nutrient, and atmospheric control; yet it is a finite resource. Soils are consumed, transported, and replenished by natural and anthropogenic forces. Weathering—both physical and chemical—is the key process breaking down and regenerating the ions and mineral constituents of soils, facilitating the pathways from solid bedrock to soil to the rest of the global ecosystem. Yet our understanding of weathering is incomplete and the available methods to investigate these processes are limited. Here, the fundamental processes of weathering are questioned by studying them at their origins, the rock surface. New techniques were developed in pursuit of quantifying weathering at small scales in-situ, to obtain the highest resolution measurements possible. These were carried out in the proglacial regions of two New Zealand glaciers, Brewster Glacier and Franz Josef Glacier.  Proglacial bedrock environments provided a clean-slate model from which to measure incipient weathering at increasing exposure ages. To mitigate error, a holistic approach encompassing weathering signals from multiple angles was taken. Spatial characterisation was completed through the capture of structure-from-motion photogrammetry (SFM) at multiple scales of observation. The resultant three dimensional surface models had an average error of 1.06x10-1 mm. The models were characterised for weathering using roughness as a novel multi-point analysis of surface features, through two separate novel methods utilising global polynomial interpolation filtering and continuous wavelet transform analysis. Physical samples were collected from the field for cosmogenic radionuclide surface exposure age dating. Compositional analysis was performed through X-ray fluorescence, as well as electron microprobe analysis (EPMA). Nano-scale structural and compositional trends were investigated through optical analysis of backscatter electron imaging and secondary electron imaging.  Non-directional roughness and volumetric analysis patterns present compelling information to support negligible weathering occurring on bedrock surfaces in proglacial environments. Lithologic variation was identified as a strong influence on the results. Compositional analysis demonstrated insignificant levels of chemical alteration between sites, corroborating the spatial modelling results. The lack of surficial weathering in highly productive weathering environments necessitates the role of additional weathering factors. Deep subsurface weathering was investigated and presents the strongest case as a major contributor to chemical denudation. Validating the presence of deep weathering in many environments critically alters the knowledge required to evaluate and predict patterns of landscape evolution. By establishing a better understanding of how bedrock weathers in-situ, the groundwork is laid for making more accurate and educated forecasts on how the earth system will respond to changes in the future.</p>

scholarly journals Bedrock to soil: In-situ measurement and analytical techniques for initial weathering of proglacial environments

2021 ◽  
Author(s):  
◽  
Karsten Lorentz
Keyword(s):  
Polynomial Interpolation ◽  
Compositional Analysis ◽  
Age Dating ◽  
Average Error ◽  
Rock Surface ◽  
Earth System ◽  
The Earth ◽  
Electron Imaging ◽  
Exposure Ages

<p>Dirt. It is more important than one might think. Soil, along with its bedrock-derived components, provides a nexus in the earth system for energy, nutrient, and atmospheric control; yet it is a finite resource. Soils are consumed, transported, and replenished by natural and anthropogenic forces. Weathering—both physical and chemical—is the key process breaking down and regenerating the ions and mineral constituents of soils, facilitating the pathways from solid bedrock to soil to the rest of the global ecosystem. Yet our understanding of weathering is incomplete and the available methods to investigate these processes are limited. Here, the fundamental processes of weathering are questioned by studying them at their origins, the rock surface. New techniques were developed in pursuit of quantifying weathering at small scales in-situ, to obtain the highest resolution measurements possible. These were carried out in the proglacial regions of two New Zealand glaciers, Brewster Glacier and Franz Josef Glacier.  Proglacial bedrock environments provided a clean-slate model from which to measure incipient weathering at increasing exposure ages. To mitigate error, a holistic approach encompassing weathering signals from multiple angles was taken. Spatial characterisation was completed through the capture of structure-from-motion photogrammetry (SFM) at multiple scales of observation. The resultant three dimensional surface models had an average error of 1.06x10-1 mm. The models were characterised for weathering using roughness as a novel multi-point analysis of surface features, through two separate novel methods utilising global polynomial interpolation filtering and continuous wavelet transform analysis. Physical samples were collected from the field for cosmogenic radionuclide surface exposure age dating. Compositional analysis was performed through X-ray fluorescence, as well as electron microprobe analysis (EPMA). Nano-scale structural and compositional trends were investigated through optical analysis of backscatter electron imaging and secondary electron imaging.  Non-directional roughness and volumetric analysis patterns present compelling information to support negligible weathering occurring on bedrock surfaces in proglacial environments. Lithologic variation was identified as a strong influence on the results. Compositional analysis demonstrated insignificant levels of chemical alteration between sites, corroborating the spatial modelling results. The lack of surficial weathering in highly productive weathering environments necessitates the role of additional weathering factors. Deep subsurface weathering was investigated and presents the strongest case as a major contributor to chemical denudation. Validating the presence of deep weathering in many environments critically alters the knowledge required to evaluate and predict patterns of landscape evolution. By establishing a better understanding of how bedrock weathers in-situ, the groundwork is laid for making more accurate and educated forecasts on how the earth system will respond to changes in the future.</p>

scholarly journals Development of Observation-based Global Multi-layer Soil Moisture Products for 1970 to 2016

2021 ◽  
Author(s):  
Yaoping Wang ◽  
Jiafu Mao ◽  
Mingzhou Jin ◽  
Forrest M. Hoffman ◽  
Xiaoying Shi ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Earth System Model ◽  
System Model ◽  
Surface Model ◽  
Earth System ◽  
Model Simulations ◽  
The Earth ◽  
Wide Range ◽  
In Situ Observations

Abstract. Soil moisture (SM) datasets are critical to understanding the global water, energy, and biogeochemical cycles and benefit extensive societal applications. However, individual sources of SM data (e.g., in situ and satellite observations, reanalysis, offline land surface model simulations, Earth system model simulations) have source-specific limitations and biases related to the spatiotemporal continuity, resolutions, and modeling/retrieval assumptions. Here, we developed seven global, gap-free, long-term (1970–2016), multi-layer (0–10, 10–30, 30–50, and 50–100 cm) SM products at monthly 0.5° resolution (available at https://doi.org/10.6084/m9.figshare.13661312.v1) by synthesizing a wide range of SM datasets using three statistical methods (unweighted averaging, optimal linear combination, and emergent constraint). The merged products outperformed their source datasets when evaluated with in situ observations and the latest gridded datasets that did not enter merging because of insufficient spatial, temporal, or soil layer coverage. Assessed against in situ observations, the global mean bias of the synthesized SM data ranged from −0.044 to 0.033 m3/m3, root mean squared error from 0.076 to 0.104 m3/m3, and Pearson correlation from 0.35 to 0.67. The merged SM datasets also showed the ability to capture historical large-scale drought events and physically plausible global sensitivities to observed meteorological factors. Three of the new SM products, produced by applying any of the three merging methods onto the source datasets excluding the Earth system models, were finally recommended for future applications because of their better performances than the Earth system model–dependent merged estimates. Despite uncertainties in the raw SM datasets and fusion methods, these hybrid products create added value over existing SM datasets because of the performance improvement and harmonized spatial, temporal, and vertical coverages, and they provide a new foundation for scientific investigation and resource management.

scholarly journals Formation and loss of metastable brucite: does Fe(II)-bearing brucite support microbial activity in serpentinizing ecosystems?

2020 ◽  
Vol 378 (2165) ◽  
pp. 20180423 ◽  
Author(s):  
A. S. Templeton ◽  
E. T. Ellison
Keyword(s):  
Ultramafic Rocks ◽  
Earth System ◽  
Aqueous Alteration ◽  
Rock Interaction ◽  
Secondary Minerals ◽  
Dissolved Carbon ◽  
The Earth ◽  
Reaction Zones ◽  
Water Rock Interaction

Ultramafic rocks undergo successive stages of hydration and oxidation during water/rock interaction, giving rise to secondary minerals such as brucite, serpentine, magnetite and the production of H 2(g) . Ferroan brucite ( M g x Fe ( 1 − x ) 2 + ( OH ) 2 ) often forms under low water/rock ratios early during the ‘serpentinization’ process. The formation of ferroan brucite sequesters Fe(II) and suppresses the production of H 2 , thereby limiting the flux of reductants suitable for sustaining microbial metabolism. Yet ferroan brucite is a relatively soluble mineral ‘reservoir’ for reactive Fe(II). Brucite is often metastable and can be lost at later stages of peridotite hydration when there is a significant increase in the water/rock ratio or the activity of SiO 2 or CO 2 . The Fe(OH) 2 component of brucite has the thermodynamic potential to reduce most aqueous oxidants. Therefore, ferroan brucite may reduce water and/or dissolved carbon, nitrogen and sulfur species, while the Fe(II) is converted into more stable secondary minerals such as Fe(II/III)-oxides and hydroxides (e.g. green-rust, magnetite, iowaite and pyroaurite) and ferric serpentine. The reactivity of ferroan brucite, and the associated rate of Fe solubilization and oxidation in subsurface fluids, could be a key regulator on the rate of electron transfer from serpentinites to the rock-hosted biosphere. Aqueous alteration of ferroan brucite may significantly modulate the H 2 activity in fluids circulating within partially serpentinized rocks, and buffer H 2 as it is lost by advection or in situ consumption by a hydrogenotrophic microbial community. Moreover, there may be microbial organisms that specifically colonize and use ferroan brucite as an electron donor for their metabolism. The energy fluxes sustained by localized brucite oxidation may often be sufficiently large to sustain abundant microbial communities; water/rock reaction zones where brucite is consumed could serve as environments to search for extant or fossil serpentinite-hosted life. This article is part of a discussion meeting issue ‘Serpentinite in the Earth System’.

scholarly journals An Evaluation of Antarctic Sea Ice Thickness from the Global Ice-Ocean Modeling and Assimilation System based on In-situ and Satellite Observations

2021 ◽  
Author(s):  
Sutao Liao ◽  
Hao Luo ◽  
Jinfei Wang ◽  
Qian Shi ◽  
Jinlun Zhang ◽  
...  
Keyword(s):  
Sea Ice ◽  
Satellite Observations ◽  
Ocean Modeling ◽  
Ice Thickness ◽  
Earth System ◽  
Sea Ice Thickness ◽  
Antarctic Sea Ice ◽  
The Earth ◽  
Assimilation System

Abstract. Antarctic sea ice is an important component of the Earth system. However, its role in the Earth system is still not very clear due to limited Antarctic sea ice thickness (SIT) data. A reliable sea ice reanalysis can be useful to study Antarctic SIT and its role in the Earth system. Among various Antarctic sea ice reanalysis products, the Global Ice-Ocean Modeling and Assimilation System (GIOMAS) output is widely used in the research of Antarctic sea ice. As more Antarctic SIT observations with quality control are released, a further evaluation of Antarctic SIT from GIOMAS is conducted in this study based on in-situ and satellite observations. Generally, though only sea ice concentration is assimilated, GIOMAS can basically reproduce the observed variability of sea ice volume and its changes in the trend before and after 2013, indicating that GIOMAS is a good option to study the long-term variation of Antarctic sea ice. However, due to deficiencies in model and asymmetric changes in SIT caused by assimilation, GIOMAS underestimates Antarctic SIT especially in deformed ice regions, which has an impact on not only the mean state of SIT but also the variability. Thus, besides the further development of model, assimilating additional sea ice observations (e.g., SIT and sea ice drift) with advanced assimilation methods may be conducive to a more accurate estimation of Antarctic SIT.

scholarly journals Observation Impact Assessment on the Prediction of the Earth System Dynamics Using the Adjoint-Based Method

2018 ◽  
Vol 6 (61) ◽  
pp. 5-28
Author(s):  
Peter Steinle ◽  
Chris Tingwell ◽  
Sergei Soldatenko
Keyword(s):  
Earth System ◽  
Initial State ◽  
Future State ◽  
The Earth ◽  
Observation Network ◽  
Australian Community ◽  
Accuracy Of Prediction ◽  
The Impact

Mathematical models of the Earth system and its components represent one of the most powerful and effective instruments applied to explore the Earth system's behaviour in the past and present, and to predict its future state considering external influence. These models are critically reliant on a large number of various observations (in situ and remotely sensed) since the prediction accuracy is determined by, amongst other things, the accuracy of the initial state of the system in question, which, in turn, is defined by observational data provided by many different instrument types. The development of an observing network is very costly, hence the estimation of the effectiveness of existing observation network and the design of a prospective one, is very important. The objectives of this paper are (1) to present the adjoint-based approach that allows us to estimate the impact of various observations on the accuracy of prediction of the Earth system and its components, and (2) to illustrate the application of this approach to two coupled low-order chaotic dynamical systems and to the ACCESS (Australian Community Climate and Earth System Simulator) global model used operationally in the Australian Bureau of Meteorology. The results of numerical experiments show that by using the adjoint-based method it is possible to rank the observations by the degree of their importance and also to estimate the influence of target observations on the quality of predictions.

scholarly journals In Pursuit

2020 ◽  
Vol 48 (1) ◽  
pp. 1-20
Author(s):  
Inez Fung
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Fossil Fuels ◽  
Earth Science ◽  
Formal Training ◽  
Earth System ◽  
Cement Production ◽  
The Earth ◽  
Global Carbon

The atmosphere is the synthesizer, transformer, and communicator of exchanges at its boundaries with the land and oceans. These exchanges depend on and, in turn, alter the states of the atmosphere, land, and oceans themselves. To a large extent, the interactions between the carbon cycle and climate have mapped, and will map, the trajectory of the Earth system. My quest to understand climate dynamics and the global carbon cycle has been propelled by new puzzles that emerge from each of the investigations and has led me to study subdisciplines of Earth science beyond my formal training. This article sketches my trek and the lessons I have learned. ▪  About half the CO2 emitted from combustion of fossil fuels and from cement production has remained airborne. Where are the contemporary carbon sinks? To what degree will these sinks evolve with, and in turn accelerate, climate change itself? ▪  The pursuit of these questions has been propelled by the integration of in situ and satellite observations of the atmosphere, land, and oceans, as well as by advances in theory and coupled climate–carbon cycle modeling. ▪  The urgency of climate change demands new approaches to cross-check national emission statistics.

scholarly journals Observations for Reanalyses

2018 ◽  
Vol 99 (9) ◽  
pp. 1851-1866 ◽  
Author(s):  
Stefan Brönnimann ◽  
Rob Allan ◽  
Christopher Atkinson ◽  
Roberto Buizza ◽  
Olga Bulygina ◽  
...  
Keyword(s):  
Earth System ◽  
Production Chain ◽  
Research Activities ◽  
The Earth ◽  
Generation Cycle ◽  
Definition Of ◽  
Data Collections ◽  
Evaluation Of Data

AbstractGlobal dynamical reanalyses of the atmosphere and ocean fundamentally rely on observations, not just for the assimilation (i.e., for the definition of the state of the Earth system components) but also in many other steps along the production chain. Observations are used to constrain the model boundary conditions, for the calibration or uncertainty determination of other observations, and for the evaluation of data products. This requires major efforts, including data rescue (for historical observations), data management (including metadatabases), compilation and quality control, and error estimation. The work on observations ideally occurs one cycle ahead of the generation cycle of reanalyses, allowing the reanalyses to make full use of it. In this paper we describe the activities within ERA-CLIM2, which range from surface, upper-air, and Southern Ocean data rescue to satellite data recalibration and from the generation of snow-cover products to the development of a global station data metadatabase. The project has not produced new data collections. Rather, the data generated has fed into global repositories and will serve future reanalysis projects. The continuation of this effort is first contingent upon the organization of data rescue and also upon a series of targeted research activities to address newly identified in situ and satellite records.

Rendez vous with Saturn's rings

1984 ◽  
Vol 75 ◽  
pp. 743-759 ◽  
Author(s):  
Kerry T. Nock
Keyword(s):  
Solar Energy ◽  
Electric Propulsion ◽  
Power Source ◽  
Propulsion System ◽  
Low Thrust ◽  
Ring Plane ◽  
The Earth ◽  
Total Impulse ◽  
Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

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