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Big Data Seismology

  •  23 April 2022

Key Points

  • Big Data Seismology is an emergent subdiscipline that uses “big data” inquiries to explore fundamental science questions in seismology

  • Three drivers of Big Data Seismology are the growth of large data volumes, the development of new algorithms, and advances in computing

  • Big Data Seismology is being applied to study earthquakes, to better resolve Earth structure, and to open new frontiers in seismology

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How Well Do We Understand the Land‐Ocean‐Atmosphere Carbon Cycle?

  •  8 April 2022

Key Points

  • Anthropogenic CO2 emissions would have produced larger atmospheric increases if ocean and land sinks had not removed over half of this CO2

  • Uptake by both ocean and land sinks increased in response to rising atmospheric CO2 levels, maintaining the airborne fraction near 45%

  • Improved and sustained measurements and models are needed to track changes in sinks and enhance the scientific basis for carbon management

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Issue Information

  •  29 March 2022
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The Role of Quartz Cementation in the Seismic Cycle: A Critical Review

  •  6 March 2022

Key Points

  • We critically review the potential role(s) of quartz cementation as a mechanism of fault “healing” on seismic cycle timescales

  • Our current understanding of silica kinetics cannot explain cementation of mesoscale fault-fracture networks within interseismic periods

  • Thin principal slip zones may be cemented interseismically but a complete understanding of fault-related quartz growth requires further work

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Surface Water and Groundwater Interactions in Salt Marshes and Their Impact on Plant Ecology and Coastal Biogeochemistry

  •  2 February 2022

Key Points

  • Tides play a primary role in salt marsh surface water and groundwater interactions

  • Surface water and groundwater interactions affect plant zonation, and carbon and nutrient outwelling

  • Future research needs to couple hydrological processes to ecological and geochemical processes

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From Fluid Flow to Coupled Processes in Fractured Rock: Recent Advances and New Frontiers

  •  1 February 2022

Key Points

  • Understanding and predicting fractured systems requires integrating field and lab experiments, simulation and uncertainty quantification

  • Densely monitored field sites and in situ lab experiments provide quantitative measures of flow and transport that can constrain models

  • Physics-based models with machine-learning emulators enable uncertainty quantification of flow and transport in complex fracture networks

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Radiocarbon as a Dating Tool and Tracer in Paleoceanography

  •  12 January 2022

Key Points

  • Radiocarbon is a powerful carbon cycle tracer and radiometric dating tool, that is widely used in paleoceanography

  • Marine radiocarbon activities, relative to the contemporary atmosphere, integrate three main effects: gas exchange, transport times, and the mixing of different water masses

  • Reconstructions attest to ocean ventilation's role in past CO2 change, but the long-term closure of the radiocarbon cycle remains unresolved

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Climate Changes and Their Elevational Patterns in the Mountains of the World

  •  11 January 2022

Key Points

  • Using station and gridded data sets, we compare global precipitation and temperature trends by elevation

  • Local comparisons of paired stations and regional comparisons using gridded data often show faster mountain than lowland warming

  • Precipitation differences between mountains and adjacent lowlands are reducing, often driven by stronger precipitation increase in lowlands

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Realistic Forests and the Modeling of Forest‐Atmosphere Exchange

  •  4 January 2022

Key Points

  • Most forests are naturally patchy. Many are being fragmented by humans. Studies of forest-air exchange rarely consider this heterogeneity

  • Gaps, edges, and patchy sources/sinks generate fluxes of momentum and scalars. Scalar quantities are rarely at equilibrium around forests

  • Better representations of forest structure, for example, from laser scans, should be included in models, along with more physics and chemistry

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Ice‐dynamical Glacier Evolution Modelling – A review

  •  23 April 2022

Key Point

  • We provide a review of glacier evolution studies in which mass transfer through ice flow is explicitly modelled (ice-dynamical modelling)

  • We highlight recent advances, including the incorporation of ice dynamics when modelling glaciers at regional to global scales

  • Recommendations are given concerning the steps to be considered when modelling the evolution of glaciers with an ice-dynamical setup

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Ice‐nucleating particles that impact clouds and climate: Observational and modeling research needs

  •  21 April 2022

Key Points

  • Atmospheric ice-nucleating particles (INPs) play a critical role in weather and climate by facilitating ice formation in clouds

  • This review summarizes current knowledge on observational constraints, modeling, and cloud impacts of INPs

  • Research priorities are identified to both advance fundamental understanding and bridge the observation-model gap for INPs

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Global and regional trends and drivers of fire under climate change

  •  11 April 2022

Key Points

  • The frequency and severity of fire weather has increased in recent decades and is projected to escalate with each added increment of warming

  • Fire weather is one of the major controls on fire activity, and is the dominant control on variability in BA in many mesic forest ecoregions

  • Various human and bioclimatic factors also control fire, modulating the relationship between burned area and fire weather in many regions

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A Review of Global Precipitation Data Sets: Data Sources, Estimation, and Intercomparisons

Key Points

  • We conduct a comprehensive review of precipitation data sets
  • We evaluate the differences between data sets at different spatial and temporal scales
  • We explore the opportunities and challenges in generating reliable precipitation estimates

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Vertical land motion as a key to understanding sea level change and variability

Key Points

  • Vertical land motion: a key element to understanding sea level change along the coasts
  • Updated results on vertical land motion from the primary space geodetic methods
  • Discussion on the predominance of subsidence or uplift along the world coasts

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An Assessment of Earth's Climate Sensitivity Using Multiple Lines of Evidence

Key Points

  • We assess evidence relevant to Earth's climate sensitivity S: feedback process understanding and the historical and paleoclimate records
  • All three lines of evidence are difficult to reconcile with S < 2 K, while paleo evidence provides the strongest case against S > 4.5 K
  • A Bayesian calculation finds a 66% range of 2.6–3.9 K, which remains within the bounds 2.3–4.5 K under plausible robustness tests

Plain Language Summary

Earth's global “climate sensitivity” is a fundamental quantitative measure of the susceptibility of Earth's climate to human influence. A landmark report in 1979 concluded that it probably lies between 1.5°C and 4.5°C per doubling of atmospheric carbon dioxide, assuming that other influences on climate remain unchanged. In the 40 years since, it has appeared difficult to reduce this uncertainty range. In this report we thoroughly assess all lines of evidence including some new developments. We find that a large volume of consistent evidence now points to a more confident view of a climate sensitivity near the middle or upper part of this range. In particular, it now appears extremely unlikely that the climate sensitivity could be low enough to avoid substantial climate change (well in excess of 2°C warming) under a high-emission future scenario. We remain unable to rule out that the sensitivity could be above 4.5°C per doubling of carbon dioxide levels, although this is not likely. Continued research is needed to further reduce the uncertainty, and we identify some of the more promising possibilities in this regard.

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A Review of Global Precipitation Data Sets: Data Sources, Estimation, and Intercomparisons

Key Points

  • We conduct a comprehensive review of precipitation data sets
  • We evaluate the differences between data sets at different spatial and temporal scales
  • We explore the opportunities and challenges in generating reliable precipitation estimates

Open access

Large earthquakes and creeping faults

Key Points

  • Plate tectonic strain is accumulated and released in a variety of ways including both locked and unlocked (creeping) fault behavior
  • Deep fault creep occurs for all tectonic plate-bounding faults whereas only some faults creep at shallower depths over long time periods
  • The existence of fault creep illuminates faults but may not reduce ground shaking during large earthquakes

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Deep Learning for Geophysics: Current and Future Trends

Key Points

  • The concept of deep learning (DL) and classical architectures of deep neural networks are introduced

  • A review of state-of-the-art DL methods in geophysical applications is provided

  • The future directions for developing new DL methods in geophysics are discussed

Plain Language Summary

With the rapid development of artificial intelligence (AI), students and researchers in the geophysical community would like to know what AI can bring to geophysical discoveries. We present a review of deep learning (DL), a popular AI technique, for geophysical readers to understand recent advances, open problems, and future trends. This review aims to pave the way for more geophysical researchers, students, and teachers to understand and use DL techniques.

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Detecting, Extracting, and Monitoring Surface Water From Space Using Optical Sensors: A Review

Key Points

  • Satellite-based optical sensors are an efficient means for observing surface water regionally and globally
  • Pixel unmixing and reconstruction, and spatio-temporal fusion are two common and low-cost approaches to enhance surface water monitoring
  • The potential to estimate flow using only optical remote sensing has greatly enriched the data source of hydrological studies

Plain Language Summary

Observing surface water is essential for ecological and hydrological studies. This paper reviews the current status of detecting, extracting, and monitoring surface water using optical remote sensing, especially progress in the last decade. It also discusses the current status and challenges in this field. For example, it was found that pixel unmixing and reconstruction, and spatio-temporal fusion are two common and low-cost approaches to enhance surface water monitoring. Remote sensing data have been integrated with in situ river flow to model spatio-temporal dynamics of surface water. Recent studies have also proved that the river discharge can be estimated using only optical remote sensing imagery. This will be a breakthrough for hydrological studies in ungauged areas. Optical sensors are also easily obscured by clouds and vegetation. This limitation can be reduced by integrating optical data with synthetic aperture radar data and digital elevation model data. There is increasing demand of monitoring global water dynamics at high resolutions. It is now easy to achieve with the development of big data and cloud computation techniques. Enhanced global or regional water monitoring in the future requires integrated use of multiple sources of remote sensing data.

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Where glaciers meet water: Subaqueous melt and its relevance to glaciers in various settings

Key Points

  • Glaciers entering water display a great variety of shapes and behaviors
  • This variety can be explained by different rates of subaqueous melt
  • Subaqueous melt can trigger shifts in glacier dynamics

Open access

Interglacials of the last 800,000 years

Key Points

  • We have reviewed the occurrence, strength, shape, and timing of interglacials
  • Despite spatial variability, MIS 5 and 11 stand out as strong/warm
  • The current interglacial is expected to be longer than any of those reviewed

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