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415 results on '"Tregoning, Paul"'

3. A statistical fracture model for Antarctic ice shelves and glaciers

Author

Emetc, Veronika, Tregoning, Paul, Morlighem, Mathieu, Borstad, Chris, and Sambridge, Malcolm

Subjects
Earth Sciences, Physical Geography and Environmental Geoscience, Climate Action, Oceanography, Meteorology & Atmospheric Sciences, Physical geography and environmental geoscience
Abstract

Antarctica and Greenland hold enough ice to raise sea level by more than 65 m if both ice sheets were to melt completely. Predicting future ice sheet mass balance depends on our ability to model these ice sheets, which is limited by our current understanding of several key physical processes, such as iceberg calving. Large-scale ice flow models either ignore this process or represent it crudely. To model fractured zones, an important component of many calving models, continuum damage mechanics as well as linear fracture mechanics are commonly used. However, these methods have a large number of uncertainties when applied across the entire Antarctic continent because the models were typically tuned to match processes seen on particular ice shelves. Here we present an alternative, statistics-based method to model the most probable zones of the location of fractures and demonstrate our approach on all main ice shelf regions in Antarctica, including the Antarctic Peninsula. We can predict the location of observed fractures with an average success rate of 84 % for grounded ice and 61 % for floating ice and a mean overestimation error rate of 26 % and 20 %, respectively. We found that Antarctic ice shelves can be classified into groups based on the factors that control fracture location.

Published
2018

10. Thank You to Our 2022 Peer Reviewers.

Author

Manighetti, Isabelle, Abercrombie, Rachel, Bernabé, Yves, Bostock, Michael, Dekkers, Mark J., Ide, Satoshi, Schmitt, Douglas R., Han, Shin‐Chan, and Tregoning, Paul

Subjects
EDITORIAL boards, PEERS
Abstract

Editors of JGR‐Solid Earth express their appreciation to those who served as peer reviewers for the journal in 2022. Plain Language Summary: The editorial board of JGR‐Solid Earth thanks those who served as peer reviewers for the journal in 2022. Key Points: Thank you to the reviewers of articles submitted to JGR‐Solid Earth [ABSTRACT FROM AUTHOR]

Published
2023
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16. Thank You to Our 2021 Peer Reviewers

Author

Manighetti, Isabelle, primary, Abercrombie, Rachel, additional, Ben‐Zion, Yehuda, additional, Bernabé, Yves, additional, Bostock, Michael, additional, Dekkers, Mark J., additional, Ide, Satoshi, additional, Parman, Stephen W., additional, Schmitt, Douglas R., additional, and Tregoning, Paul, additional

Published
2022
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21. Thank You to Our 2020 Peer Reviewers

Author

Manighetti, Isabelle, primary, Abercrombie, Rachel, additional, Ben‐Zion, Yehuda, additional, Bernabé, Yves, additional, Bostock, Michael, additional, Dekkers, Mark, additional, Parman, Stephen W., additional, Schmitt, Douglas, additional, and Tregoning, Paul, additional

Published
2021
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27. Thank You to Our 2019 Reviewers

Author

Manighetti, Isabelle, primary, Brink, Uri, additional, Abercrombie, Rachel, additional, Ben‐Zion, Yehuda, additional, Bernabé, Yves, additional, Bostock, Michael, additional, Parman, Stephen W., additional, Revil, André, additional, Savage, Martha, additional, Schmitt, Doug, additional, and Tregoning, Paul, additional

Published
2020
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29. Heavy water: how melting ice sheets and pumped groundwater can lower local sea levels - and boost them elsewhere.

Author

McGirr, Rebecca, Purcell, Anthony, McQueen, Herbert, and Tregoning, Paul

Subjects
ICE sheet thawing, SEA level, DEUTERIUM oxide, GROUNDWATER, FLOODS, DROUGHTS, EARTH sciences
Abstract

This article discusses how changes in water storage on land can affect sea levels. The melting of ice sheets and glaciers has contributed to a rise in global sea levels, but changes in water storage on ice-free land areas also play a role. The exchange of water between land and sea, through rainfall, rivers, and groundwater, can cause fluctuations in sea levels. The article highlights the influence of gravity on sea levels and explains how changes in water mass on land can lead to temporary local sea level rises or falls. The research suggests that groundwater extraction and climate cycles can mask the full effects of global warming on sea level rise, but the melting of ice sheets remains the primary driver of rising sea levels. [Extracted from the article]

Published
2024

30. Thank You to Our 2018 Peer Reviewers

Author

Brink, Uri, primary, Bernabe, Yves, additional, Ben‐Zion, Yehuda, additional, Parman, Stephen W., additional, Savage, Martha, additional, Schmitt, Doug, additional, and Tregoning, Paul, additional

Published
2019
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43. Improved star camera attitude data and their effect on the gravity field

Author

Bandikova, Tamara, Meyer, Ulrich, Klinger, Beate, Tregoning, Paul, Flury, Jakob, and Mayer-Gürr, Torsten

Subjects
520 Astronomy
Abstract

Efforts are ongoing to decrease the noise of the GRACE gravity field models and hence to arrive closer to the GRACE baseline. The most significant error sources belong the untreated errors in the observation data and the imperfections in the background models. The recent study (Bandikova&Flury,2014) revealed that the current release of the star camera attitude data (SCA1B RL02) contain noise systematically higher than expected by about a factor 3-4. This is due to an incorrect implementation of the algorithms for quaternion combination in the JPL processing routines. Generating improved SCA data requires that valid data from both star camera heads are available which is not always the case because the Sun and Moon at times blind one camera. In the gravity field modeling, the attitude data are needed for the KBR antenna offset correction and to orient the non-gravitational linear accelerations sensed by the accelerometer. Hence any improvement in the SCA data is expected to be reflected in the gravity field models. In order to quantify the effect on the gravity field, we processed one month of observation data using two different approaches: the celestial mechanics approach (AIUB) and the variational equations approach (ITSG). We show that the noise in the KBR observations and the linear accelerations has effectively decreased. However, the effect on the gravity field on a global scale is hardly evident. We conclude that, at the current level of accuracy, the errors seen in the temporal gravity fields are dominated by errors coming from sources other than the attitude data.

Published
2014
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45. Global joint assimilation of GRACE and SMOS for improved estimation of root-zone soil moisture and vegetation response.

Author

Siyuan Tian, Renzullo, Luigi J., Van Dijk, Albert I. J. M., Tregoning, Paul, and Walker, Jeffrey P.

Abstract

The lack of direct measurement of root-zone soil moisture poses a challenge to the large-scale prediction of ecosystem response to variation in soil water. Microwave remote sensing capability is limited to measuring moisture content in the uppermost few centimetres of soil. In contrast, GRACE (Gravity Recovery and Climate Experiment) mission detected the variability in storage within the total water column, which is often dominated by groundwater variation. However, not all vegetation communities can access groundwater. In this study, satellite-derived water content from GRACE and SMOS were jointly assimilated into an ecohydrological model to better predict the impact of changes in root-zone soil moisture on vegetation vigour. Overall, the accuracy of root-zone soil moisture prediction though the joint assimilation of surface soil moisture and total water storage retrievals showed improved consistency with ground-based soil moisture measurements and satellite-observed greenness when compared to open-loop estimates (i.e. without assimilation). For example, the correlation between modelled and in-situ measurements of root-zone moisture increased by 0.1 on average over grasslands and croplands. Improved correlations were found between vegetation greenness and soil water storage derived from the joint assimilation with an increase up to 0.47 over grassland compared to open-loop estimates. Joint assimilation results show a more severe deficit in soil water in eastern Australia, western North America and eastern Brazil over the period of 2010 to 2015 than the open-loop, consistent with the satellite-observed vegetation greenness. The assimilation of satellite-observed water content contributes to more accurate knowledge of soil water availability, providing new insights for monitoring hidden water stress and vegetation response. [ABSTRACT FROM AUTHOR]

Published
2018
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