Synoptic analysis of globally-distributed data sets of cosmogenic-nuclide exposure ages

2021 ◽  
Author(s):  
Greg Balco
Keyword(s):  
Global Analysis ◽  
Glacier Change ◽  
Data Sets ◽  
Distributed Data ◽  
Data Set ◽  
Cosmogenic Nuclide ◽  
Synoptic Analysis ◽  
Exposure Age ◽  
Exposure Ages ◽  
Globally Distributed

<p>This abstract describes a project to make large data sets of cosmogenic-nuclide measurements useable for synoptic global analysis of paleoclimate, glacier change, and landscape change. It is based on the 'ICE-D' (Informal Cosmogenic-nuclide Exposure-age Database), a transparent-middle-layer infrastructure for compiling and storing cosmogenic-nuclide measurements and generating internally consistent exposure-age data. The prototype implementation of this project focuses on a global data set of exposure ages from glacial deposits that are, potentially, useful for synoptic analysis of glacier change and paleoclimate. The aim is to address a number of messy data-management and analysis problems associated with cosmogenic-nuclide data, thus making it possible to apply unbiased, automated quantitative analysis to the entire globally-distributed data set. The presentation will highlight (i) examples of error-tolerant hypothesis testing using this approach; (ii) means of quantifying the importance of the details of cosmogenic-nuclide production-rate calculations to global paleoclimate inferences, and (iii) likewise, approaches to understanding the importance of geomorphic processes and landform evolution to global paleoclimate inferences drawn from exposure-dated landforms.</p>

Glacier Change and Paleoclimate Applications of Cosmogenic-Nuclide Exposure Dating

2020 ◽  
Vol 48 (1) ◽  
pp. 21-48 ◽  
Author(s):  
Greg Balco
Keyword(s):  
Climate Changes ◽  
Cosmic Ray ◽  
Glacier Change ◽  
Valuable Insight ◽  
Mountain Areas ◽  
Data Set ◽  
Mountain Glaciers ◽  
Exposure Dating ◽  
Geologic Record ◽  
Globally Distributed

Surface exposure dating using cosmic-ray-produced nuclides has been applied to determine the age of thousands of landforms produced by alpine glaciers in mountain areas worldwide. These data are potentially an extensive, easily accessible, and globally distributed paleoclimate record. In particular, exposure-dated glacier chronologies are commonly applied to study the dynamics of massive, abrupt climate changes characteristic of the transition between the Last Glacial Maximum and the present interglacial climate. This article reviews developments in exposure dating from the perspective of whether this goal is achievable and concludes that ( a) individual exposure-dated landforms cannot, in general, be associated with millennial-scale climate events at high confidence, but ( b) dating uncertainties appear to be geographically and temporally unbiased, so the data set as a whole can be used to gain valuable insight into regional and global paleoclimate dynamics. Future applications of exposure-age chronologies of glacier change should move away from reliance on individual dated landforms and toward synoptic analysis of the global data set. ▪  Mountain glaciers worldwide leave a geologic record of their past advances and retreats, which reflect past climate changes. ▪  Geochemical dating methods based on cosmic-ray-produced nuclides have been used to date these deposits at thousands of sites worldwide. ▪  This data set is potentially an extensive, accessible, and globally distributed paleoclimate record.

Cosmogenic nuclide age estimate for Laurentide Ice Sheet recession from the terminal moraine, New Jersey, USA, and constraints on latest Pleistocene ice sheet history

2017 ◽  
Vol 87 (3) ◽  
pp. 482-498 ◽  
Author(s):  
Lee B. Corbett ◽  
Paul R. Bierman ◽  
Byron D. Stone ◽  
Marc W. Caffee ◽  
Patrick L. Larsen
Keyword(s):  
New Jersey ◽  
Global Climate ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Data Set ◽  
Terminal Moraine ◽  
Cosmogenic Nuclide ◽  
Fluvial Incision ◽  
Exposure Ages

AbstractThe time at which the Laurentide Ice Sheet reached its maximum extent and subsequently retreated from its terminal moraine in New Jersey has been constrained by bracketing radiocarbon ages on preglacial and postglacial sediments. Here, we present measurements of in situ produced 10Be and 26Al in 16 quartz-bearing samples collected from bedrock outcrops and glacial erratics just north of the terminal moraine in north-central New Jersey; as such, our ages represent a minimum limit on the timing of ice recession from the moraine. The data set includes field and laboratory replicates, as well as replication of the entire data set five years after initial measurement. We find that recession of the Laurentide Ice Sheet from the terminal moraine in New Jersey began before 25.2±2.1 ka (10Be, n=16, average, 1 standard deviation). This cosmogenic nuclide exposure age is consistent with existing limiting radiocarbon ages in the study area and cosmogenic nuclide exposure ages from the terminal moraine on Martha’s Vineyard ~300 km to the northeast. The age we propose for Laurentide Ice Sheet retreat from the New Jersey terminal position is broadly consistent with regional and global climate records of the last glacial maximum termination and records of fluvial incision.

scholarly journals Very low inheritance in cosmogenic surface exposure ages of glacial deposits: A field experiment from two Norwegian glacier forelands

The Holocene ◽  
2017 ◽  
Vol 27 (9) ◽  
pp. 1406-1414 ◽  
Author(s):  
John A Matthews ◽  
Richard A Shakesby ◽  
Derek Fabel
Keyword(s):  
Field Experiment ◽  
Ice Sheets ◽  
Viable Alternative ◽  
Rock Fragments ◽  
Perceived Need ◽  
Cosmogenic Nuclide ◽  
Exposure Age ◽  
Cosmogenic Nuclide Dating ◽  
Southern Norway ◽  
Exposure Ages

Terrestrial cosmogenic nuclide dating has been widely used to estimate the surface exposure age of bedrock and boulder surfaces associated with deglaciation and Holocene glacier variations, but the effect of inherited age has been rarely directly addressed. In this study, small clasts, embedded in flute surfaces on two cirque glacier forelands in Jotunheimen, southern Norway and deposited within the last ~60 years, were used to test whether such clasts have the modern surface exposure age expected in the absence of inheritance. Two different approaches were taken involving dating of (1) a single clast of cobble size from the proglacial area of Austanbotnbreen, and (2) 75 clasts mostly of pebble size from the proglacial area of Storbreen crushed and treated as a single sample. 10Be surface exposure ages were 99 ± 98 and 368 ± 90 years, respectively, with 95% confidence (±2σ). It is concluded that (1) these small glaciers have eroded and deposited rock fragments with a cosmogenic zero or near-zero concentration, (2) the likelihood of inherited cosmogenic nuclide concentrations in similar rock fragments deposited by larger warm-based glaciers and ice sheets should be small, and (3) combining a large number of small rock particles into one sample rather than using single large clasts of boulder size may provide a viable alternative to the commonly perceived need for five or more independent estimates of exposure age per site.

scholarly journals Performance evaluation of various deployment scenarios of the 3-replicated Cassandra NoSQL cluster on AWS

2021 ◽  
pp. 157-165
Author(s):  
Anatoliy Gorbenko ◽  
Andrii Karpenko ◽  
Olga Tarasyuk
Keyword(s):  
Data Consistency ◽  
Distributed Data ◽  
Data Set ◽  
Nosql Database ◽  
Report Analysis ◽  
Quantitative Results ◽  
Primary Focus ◽  
And Performance ◽  
Relational Database Management ◽  
Globally Distributed

A concept of distributed replicated NoSQL data storages Cassandra-like, HBase, MongoDB has been proposed to effectively manage Big Data set whose volume, velocity and variability are difficult to deal with by using the traditional Relational Database Management Systems. Tradeoffs between consistency, availability, partition tolerance and latency is intrinsic to such systems. Although relations between these properties have been previously identified by the well-known CAP and PACELC theorems in qualitative terms, it is still necessary to quantify how different consistency settings, deployment patterns and other properties affect system performance.This experience report analysis performance of the Cassandra NoSQL database cluster and studies the tradeoff between data consistency guaranties and performance in distributed data storages. The primary focus is on investigating the quantitative interplay between Cassandra response time, throughput and its consistency settings considering different single- and multi-region deployment scenarios. The study uses the YCSB benchmarking framework and reports the results of the read and write performance tests of the three-replicated Cassandra cluster deployed in the Amazon AWS. In this paper, we also put forward a notation which can be used to formally describe distributed deployment of Cassandra cluster and its nodes relative to each other and to a client application. We present quantitative results showing how different consistency settings and deployment patterns affect Cassandra performance under different workloads. In particular, our experiments show that strong consistency costs up to 22 % of performance in case of the centralized Cassandra cluster deployment and can cause a 600 % increase in the read/write requests if Cassandra replicas and its clients are globally distributed across different AWS Regions.

Slow regolith degradation without creep determined by cosmogenic nuclide measurements in Arena Valley, Antarctica

2008 ◽  
Vol 69 (2) ◽  
pp. 242-249 ◽  
Author(s):  
Jaakko Putkonen ◽  
Greg Balco ◽  
Daniel Morgan
Keyword(s):  
Indirect Evidence ◽  
Soil Surface ◽  
Ice Cover ◽  
Surface Erosion ◽  
Dry Valleys ◽  
Cosmogenic Nuclide ◽  
Exposure Age ◽  
Excellent Preservation ◽  
Exposure Ages ◽  
Landslide Deposit

Estimates of regolith degradation in the McMurdo Dry Valleys of Antarctica are currently based on indirect evidence and ancient ashes at or near the soil surface that suggest excellent preservation of surfaces. On the other hand, the existing cosmogenic-nuclide surface exposure ages from many parts of the Dry Valleys are younger than the age of surface deposits inferred from stratigraphic relations. This suggests some combination of surface erosion or past ice cover, both of which would reduce the apparent exposure age. This paper quantifies the regolith degradation and/or past ice cover by measuring10Be and26Al from a landslide deposit that contains 11.3 Ma volcanic ash. The surface sample yields an apparent exposure age of only 0.4 Ma. However, measurements of the subsurface nuclide concentrations show that the deposit has not been shielded by ice, and that the age of the ash does not conflict with the apparent exposure age when slow degradation of the deposit (2 m Ma−1) is taken into account. Soil creep, which is a common degradational process in a wide variety of environments, is non-existent at this field site, which likely reflects the persistent lack of bio- and cryoturbation.

scholarly journals Technical note: A prototype transparent-middle-layer data management and analysis infrastructure for cosmogenic-nuclide exposure dating

Geochronology ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 169-175 ◽  
Author(s):  
Greg Balco
Keyword(s):  
Observational Data ◽  
Middle Layer ◽  
Technical Note ◽  
Data Sets ◽  
Time Data ◽  
Data Set ◽  
Exposure Dating ◽  
Cosmogenic Nuclide ◽  
Analysis Application ◽  
Active Research

Abstract. Geologic dating methods for the most part do not directly measure ages. Instead, interpreting a geochemical observation as a geologically useful parameter – an age or a rate – requires an interpretive middle layer of calculations and supporting data sets. These are the subject of active research and evolve rapidly, so any synoptic analysis requires repeated recalculation of large numbers of ages from a growing data set of raw observations, using a constantly improving calculation method. Many important applications of geochronology involve regional or global analyses of large and growing data sets, so this characteristic is an obstacle to progress in these applications. This paper describes the ICE-D (Informal Cosmogenic-Nuclide Exposure-age Database) database project, a prototype computational infrastructure for dealing with this obstacle in one geochronological application – cosmogenic-nuclide exposure dating – that aims to enable visualization or analysis of diverse data sets by making middle-layer calculations dynamic and transparent to the user. An important aspect of this concept is that it is designed as a forward-looking research tool rather than a backward-looking archive: only observational data (which do not become obsolete) are stored, and derived data (which become obsolete as soon as the middle-layer calculations are improved) are not stored but instead calculated dynamically at the time data are needed by an analysis application. This minimizes “lock-in” effects associated with archiving derived results subject to rapid obsolescence and allows assimilation of both new observational data and improvements to middle-layer calculations without creating additional overhead at the level of the analysis application.

Improved moraine age interpretations through explicit matching of geomorphic process models to cosmogenic nuclide measurements from single landforms

2012 ◽  
Vol 77 (2) ◽  
pp. 293-304 ◽  
Author(s):  
Patrick J. Applegate ◽  
Nathan M. Urban ◽  
Klaus Keller ◽  
Thomas V. Lowell ◽  
Benjamin J.C. Laabs ◽  
...  
Keyword(s):  
Scattered Data ◽  
Process Models ◽  
Model Fit ◽  
Statistical Distributions ◽  
Data Set ◽  
Exposure Dating ◽  
Cosmogenic Nuclide ◽  
Geomorphic Process ◽  
Exposure Ages ◽  
Fitting Model

The statistical distributions of cosmogenic nuclide measurements from moraine boulders contain previously unused information on moraine ages, and they help determine whether moraine degradation or inheritance is more important on individual moraines. Here, we present a method for extracting this information by fitting geomorphic process models to observed exposure ages from single moraines. We also apply this method to 94 10Be apparent exposure ages from 11 moraines reported in four published studies. Our models represent 10Be accumulation in boulders that are exhumed over time by slope processes (moraine degradation), and the delivery of boulders with preexisting 10Be inventories to moraines (inheritance). For now, we neglect boulder erosion and snow cover, which are likely second-order processes. Given a highly scattered data set, we establish which model yields the better fit to the data, and estimate the age of the moraine from the better model fit. The process represented by the better-fitting model is probably responsible for most of the scatter among the apparent ages. Our methods should help resolve controversies in exposure dating; we reexamine the conclusions from two published studies based on our model fits.

A global analysis of spatial correlation lengths of water storage anomalies 

2021 ◽  
Author(s):  
Ehsan Sharifi ◽  
Julian Haas ◽  
Eva Boergens ◽  
Henryk Dobslaw ◽  
Andreas Güntner
Keyword(s):  
European Union ◽  
Spatial Correlation ◽  
Global Analysis ◽  
Water Storage ◽  
Seasonal Effects ◽  
Data Sets ◽  
Gaussian Filter ◽  
The European Union ◽  
Data Set ◽  
Correlation Lengths

<p>This study has been run in the context of the European Union research project G3P (Global Gravity-based Groundwater Product) on developing Groundwater storage (GW) as a new product for the EU Copernicus Services. GW variations can be derived on a global scale by subtracting from total water storage (TWS) variations based on the GRACE/GRACE-FO satellite missions variations in other water storage compartments such as soil moisture, snow, surface water bodies, and glaciers. Due to the nature of data acquisition by GRACE and GRACE-FO, the data need filtering in order to reduce North-South-oriented striping errors. However, this also leads to a spatially smoothed TWS signal. For a consistent subtraction of all individual storage compartments from GRACE-based TWS, the individual data sets for all other hydrological compartments need to be filtered in a similar way as GRACE-based TWS.</p><p>In order to test different filter methods, we used compartmental water storage data of the global hydrological model WGHM. The decorrelation filter known as DDK filter that is routinely used for GRACE and GRACE-FO data introduced striping artifacts in the smoothed model data. Thus, we can conclude that the DDK filter is not suitable for filtering water storage data sets that do not exhibit GRACE-like correlated error patterns. Alternatively, an isotropic Gaussian filter might be used. The best filter width of the Gaussian filter is determined by minimizing the differences between the empirical spatial correlation functions of each water storage and the spatial correlation function of GRACE-based TWS. We also analyzed time variations of correlation lengths such as seasonal effects. Finally, the selected filter widths are applied to each compartmental storage data set to remove them from TWS and to obtain the GW variations. </p><p> </p><p>Acknowledgement :</p><p>This study received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement nº 870353.</p>

scholarly journals Exposure-age data from across Antarctica reveal mid-Miocene establishment of polar desert climate

Geology ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 91-95
Author(s):  
Perry Spector ◽  
Greg Balco
Keyword(s):  
Liquid Water ◽  
High Elevation ◽  
Polar Desert ◽  
Cosmogenic Nuclide ◽  
Erosion Processes ◽  
Exposure Age ◽  
Antarctic Continent ◽  
The Antarctic ◽  
Exposure Ages ◽  
Desert Climate

Abstract High-elevation rock surfaces in Antarctica have some of the oldest cosmogenic-nuclide exposure ages on Earth, dating back to the Miocene. A compilation of all available 3He, 10Be, and 21Ne exposure-age data from the Antarctic continent shows that exposure histories recorded by these surfaces extend back to, but not before, the mid-Miocene cooling at 14–15 Ma. At high elevation, this cooling entailed a transition between a climate in which liquid water and biota were present and could contribute to surface weathering and erosion, and a polar desert climate in which virtually all weathering and erosion processes had been shut off. This climate appears to have continued uninterrupted between the mid-Miocene and the present.

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