ORCID Profile
0000-0002-8963-3044
Current Organisations
Taipei Medical University
,
University of Tasmania
,
Bureau of Meteorology
,
CSIRO
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Publisher: Copernicus GmbH
Date: 13-02-2023
Abstract: Abstract. Across the long-term (∼43-year) satellite record, Antarctic sea ice extent shows a small overall circumpolar increase, resulting from opposing regional sea ice concentration anomalies. Running short-term s les of the same sea ice concentration data, however, show that the long-term trend pattern is dominated by the earliest years of the satellite record. Compensating regional anomalies diminish over time, and in the most recent decade, these tend towards spatial homogeneity instead. Running 30-year trends show the regional pattern of sea ice behaviour reversing over time while in some regions, trend patterns abruptly shift in line with the record anomalous sea ice behaviour of recent years, in other regions a steady change predates these record anomalies. The shifting trend patterns in many regions are co-located with enhanced north–south flow due to an increasingly wave-3-like structure of the Southern Annular Mode. Sea surface temperature anomalies also shift from a circumpolar cooling to a regional pattern that resembles the increasingly asymmetric structure of the Southern Annular Mode, with warming in regions of previously increasing sea ice such as the Ross Sea.
Publisher: Elsevier BV
Date: 06-2014
Publisher: American Meteorological Society
Date: 22-03-2021
Abstract: The CSIRO Climate retrospective Analysis and Forecast Ensemble system: version 1 (CAFE60v1) provides a large (96 member) ensemble retrospective analysis of the global climate system from 1960 to present with sufficiently many realizations and at spatio-temporal resolutions suitable to enable probabilistic climate studies. Using a variant of the ensemble Kalman filter, 96 climate state estimates are generated over the most recent six decades. These state estimates are constrained by monthly mean ocean, atmosphere and sea ice observations such that their trajectories track the observed state while enabling estimation of the uncertainties in the approximations to the retrospective mean climate over recent decades. For the atmosphere, we evaluate CAFE60v1 in comparison to empirical indices of the major climate teleconnections and blocking with various reanalysis products. Estimates of the large scale ocean structure, transports and biogeochemistry are compared to those derived from gridded observational products and climate model projections (CMIP). Sea ice (extent, concentration and variability) and land surface (precipitation and surface air temperatures) are also compared to a variety of model and observational products. Our results show that CAFE60v1 is a useful, comprehensive and unique data resource for studying internal climate variability and predictability, including the recent climate response to anthropogenic forcing on multi-year to decadal time scales.
Publisher: American Geophysical Union (AGU)
Date: 11-2018
DOI: 10.1029/2018JC014177
Publisher: Elsevier BV
Date: 09-2022
Publisher: Copernicus GmbH
Date: 24-03-2017
Abstract: Abstract. The response of Antarctic sea ice to large-scale patterns of atmospheric variability varies according to sea ice sector and season. In this study, interannual atmosphere–sea ice interactions were explored using observations and reanalysis data, and compared with simulated interactions by models in the Coupled Model Intercomparison Project Phase 5 (CMIP5). Simulated relationships between atmospheric variability and sea ice variability generally reproduced the observed relationships, though more closely during the season of sea ice advance than the season of sea ice retreat. Atmospheric influence on sea ice is known to be strongest during advance, and it appears that models are able to capture the dominance of the atmosphere during advance. Simulations of ocean–atmosphere–sea ice interactions during retreat, however, require further investigation. A large proportion of model ensemble members overestimated the relative importance of the Southern Annular Mode (SAM) compared with other modes of high southern latitude climate, while the influence of tropical forcing was underestimated. This result emerged particularly strongly during the season of sea ice retreat. The zonal patterns of the SAM in many models and its exaggerated influence on sea ice overwhelm the comparatively underestimated meridional influence, suggesting that simulated sea ice variability would become more zonally symmetric as a result. Across the seasons of sea ice advance and retreat, three of the five sectors did not reveal a strong relationship with a pattern of large-scale atmospheric variability in one or both seasons, indicating that sea ice in these sectors may be influenced more strongly by atmospheric variability unexplained by the major atmospheric modes, or by heat exchange in the ocean.
Publisher: Copernicus GmbH
Date: 04-10-2016
Publisher: Copernicus GmbH
Date: 04-10-2016
DOI: 10.5194/TC-2016-200
Abstract: Abstract. The response of Antarctic sea ice to large-scale patterns of atmospheric variability varies according to sea ice sector and season. In this study, interannual atmosphere-sea ice interactions were explored using observation-based data and compared with simulated interactions by models in the Coupled Model Intercomparison Project Phase 5. Simulated relationships between atmospheric variability and sea ice variability generally reproduced the observed relationships, though more closely during the season of sea ice advance than the season of sea ice retreat. Atmospheric influence on sea ice is known to be strongest during its advance, with the ocean emerging as a dominant driver of sea ice retreat therefore, while it appears that models are able to capture the dominance of the atmosphere during advance, simulations of ocean-atmosphere-sea ice interactions during retreat require further investigation. A large proportion of model ensemble members overestimated the relative importance of the Southern Annular Mode compared with other modes on high southern latitude climate, while the influence of tropical forcing was underestimated. This result emerged particularly strongly during the season of sea ice retreat. The lified zonal patterns of the Southern Annular Mode in many models and its exaggerated influence on sea ice overwhelm the comparatively underestimated meridional influence, suggesting that simulated sea ice variability would become more zonally symmetric as a result. Across the seasons of sea ice advance and retreat, 3 of the 5 sectors did not reveal a strong relationship with a pattern of large-scale atmospheric variability in one or both seasons, indicating that sea ice in these sectors may be influenced more strongly by atmospheric variability unexplained by the major atmospheric modes, or by heat exchange in the ocean.
Publisher: American Geophysical Union (AGU)
Date: 29-05-2021
DOI: 10.1029/2020GL091835
Abstract: The Southern Ocean plays an important role in the uptake of atmospheric CO 2 . In seasonally ice‐covered regions, estimates of air‐sea exchange remain uncertain in part because of a lack of observations outside the summer season. Here we present new estimates of air‐sea CO 2 flux in the West Antarctic Peninsula (WAP) from an autonomous mooring on the continental shelf. In summer, the WAP is a sink for atmospheric CO 2 followed by a slow return to atmospheric equilibrium in autumn and winter. Outgassing is almost entirely suppressed by ice cover from June through October, resulting in a modest net annual CO 2 sink. Model projections indicate sea ice formation will occur later in the season in the coming decades potentially weakening the net oceanic CO 2 sink. Interannual variability in the WAP is significant, highlighting the importance of sustained observations of air‐sea exchange in this rapidly changing region of the Southern Ocean.
Publisher: Society for Neuroscience
Date: 23-01-2018
DOI: 10.1523/JNEUROSCI.2257-17.2018
Abstract: The precise assembly of a functional nervous system relies on the guided migration of axonal growth cones, which is made possible by signals transmitted to the cytoskeleton by cell surface-expressed guidance receptors. We investigated the function of ephexin1, a Rho guanine nucleotide exchange factor, as an essential growth-cone guidance intermediary in the context of spinal lateral motor column (LMC) motor axon trajectory selection in the limb mesenchyme. Using in situ mRNA detection, we first show that ephexin1 is expressed in LMC neurons of chick and mouse embryos at the time of spinal motor axon extension into the limb. Ephexin1 loss of function and gain of function using in ovo electroporation in chick LMC neurons, of either sex, perturbed LMC axon trajectory selection, demonstrating an essential role of ephexin1 in motor axon guidance. In addition, ephexin1 loss in mice of either sex led to LMC axon trajectory selection errors. We also show that ephexin1 knockdown attenuates the growth preference of LMC neurites against ephrins in vitro and Eph receptor-mediated retargeting of LMC axons in vivo , suggesting that ephexin1 is required in Eph-mediated LMC motor axon guidance. Finally, both ephexin1 knockdown and ectopic expression of nonphosphorylatable ephexin1 mutant attenuated the retargeting of LMC axons caused by Src overexpression, implicating ephexin1 as an Src target in Eph signal relay in this context. In summary, our findings demonstrate that ephexin1 is essential for motor axon guidance and suggest an important role in relaying ephrin:Eph signals that mediate motor axon trajectory selection. SIGNIFICANCE STATEMENT The proper development of functioning neural circuits requires precise nerve connections among neurons or between neurons and their muscle targets. The Eph tyrosine kinase receptors expressed in neurons are important in many contexts during neural-circuit formation, such as axon outgrowth, axon guidance, and synaptic formation, and have been suggested to be involved in neurodegenerative disorders, including amyotrophic lateral sclerosis and Alzheimer's disease. To dissect the mechanism of Eph signal relay, we studied ephexin1 gain of function and loss of function and found ephexin1 essential for the development of limb nerves toward their muscle targets, concluding that it functions as an intermediary to relay Eph signaling in this context. Our work could thus shed new light on the molecular mechanisms controlling neuromuscular connectivity during embryonic development.
Publisher: Copernicus GmbH
Date: 30-01-2017
Publisher: Informa UK Limited
Date: 02-01-2015
Location: Australia
No related grants have been discovered for Serena Schroeter.