225 research outputs found
Morphological traits can track coral reef responses to the Anthropocene
MD was supported by the John Templeton Foundation (60501) and JM was supported by the Australian Research Council (FT110100609) during the period this research was undertaken.1. Susceptibility to human-driven environmental changes is mediated by species traits. Therefore, identifying traits that predict organism performance, ecosystem function and response to changes in environmental conditions can help forecast how ecosystems are responding to the Anthropocene. 2. Morphology dictates how organisms interact with their environment and other organisms, partially determining the environmental and biological contexts in which they are successful. Morphology is important for autogenic ecosystem engineering organisms, such as reef-building corals, because it determines the shape of the structures they create and by extension the communities they support. 3. Here, we present six morphological traits that capture variation in volume compactness, surface complexity and top-heaviness. With support from the literature, we propose causal links between morphology and a performanceâfunctionâresponse framework. 4. To illustrate these concepts, we combine 3D scanning and coral survey data to predict morphological traits from in situ colonies. We present a case study that examines how assemblage-scale morphological traits have responded to two cyclones and the 2016 mass bleaching eventâtwo phenomena predicted to increase in severity in the Anthropoceneâand discuss how these changes may impact ecosystem function. 5. The morphological traits outlined here offer a generalised and hypothesis-driven approach to tracking how reefs respond to the Anthropocene. The ability to predict these traits from field data and the increasing use of photogrammetry makes them readily applicable across broad spatiotemporal scales.PostprintPeer reviewe
Fibre-optic delivery of time and frequency to VLBI station
The quality of Very Long Baseline Interferometry (VLBI) radio observations
predominantly relies on precise and ultra-stable time and frequency (T&F)
standards, usually hydrogen masers (HM), maintained locally at each VLBI
station. Here, we present an operational solution in which the VLBI
observations are routinely carried out without use of a local HM, but using
remote synchronization via a stabilized, long-distance fibre-optic link. The
T&F reference signals, traceable to international atomic timescale (TAI), are
delivered to the VLBI station from a dedicated timekeeping laboratory.
Moreover, we describe a proof-of-concept experiment where the VLBI station is
synchronized to a remote strontium optical lattice clock during the
observation.Comment: 8 pages, 8 figures, matches the version published in A&A, section
Astronomical instrumentatio
Thermomechanical Fatigue Behavior of a Silicon Carbide Fiber-Reinforced Calcium Aluminosilicate Composite
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65874/1/j.1151-2916.1993.tb04022.x.pd
Strontium optical lattice clocks for practical realization of the metre and secondary representation of the second
We present a system of two independent strontium optical lattice standards
probed with a single shared ultra-narrow laser. The absolute frequency of the
clocks can be verified by the use of Er:fiber optical frequency comb with the
GPS-disciplined Rb frequency standard. We report hertz-level spectroscopy of
the clock line and measurements of frequency stability of the two strontium
optical lattice clocks.Comment: This is an author-created, un-copyedited version of an article
accepted for publication in Meas. Sci. Technol. The publisher is not
responsible for any errors or omissions in this version of the manuscript or
any version derived from it. The Version of Record is available online at
doi:10.1088/0957-0233/26/7/07520
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Inconsistent coral bleaching risk indicators between temperature data sources
Coral reefs are facing severe threats and are at risk of accelerated decline due to climate change-induced changes in their environment. Ongoing efforts to understand the mechanisms of coral response to warming rely on multiple sources of temperature data. Yet, it remains uncertain whether the Sea Surface Temperature (SST) data used for coral reef studies are consistent among different data products, despite potential implications for conservation. A better understanding of the consistency among the different SST data applied to coral reefs may facilitate the fusion of data into a standard product. This will improve monitoring and understanding of the impact of global warming on coral reefs. Four types of SST data across North-Western and South-Western Australia are compared to assess their differences and ability to observe high thermal stress during historical coral bleaching events. The four SST data sources included those derived from Global Circulation Models, NOAA CoralTemp SST product, ESA CCI SST product, and coral core derived SST. Coral bleaching risk indicators, Degree Heating Week (DHW), and Degree Heating Month (DHM) were calculated using these sources and compared for consistency. DHW and DHM were inconsistent among data sets and did not accurately reflect high thermal stress metrics during moderate and severe bleaching events. Some reefs did not experience bleaching in spite of high DHWs and DHMs, suggesting a mismatch in data scales, or perhaps other oceanographic factors and coral adaptation. By exploring the differences and similarities among these four data sources, this study highlights the need to compare existing indicators of thermal stress from different data sets
Observation of Coherent Elastic Neutrino-Nucleus Scattering
The coherent elastic scattering of neutrinos off nuclei has eluded detection
for four decades, even though its predicted cross-section is the largest by far
of all low-energy neutrino couplings. This mode of interaction provides new
opportunities to study neutrino properties, and leads to a miniaturization of
detector size, with potential technological applications. We observe this
process at a 6.7-sigma confidence level, using a low-background, 14.6-kg
CsI[Na] scintillator exposed to the neutrino emissions from the Spallation
Neutron Source (SNS) at Oak Ridge National Laboratory. Characteristic
signatures in energy and time, predicted by the Standard Model for this
process, are observed in high signal-to-background conditions. Improved
constraints on non-standard neutrino interactions with quarks are derived from
this initial dataset
Merged SAGEÂ II, Ozone_cci and OMPS ozone profile dataset and evaluation of ozone trends in the stratosphere
In this paper, we present a merged dataset of ozone profiles from
several satellite instruments: SAGEÂ II on ERBS, GOMOS, SCIAMACHY and
MIPAS on Envisat, OSIRIS on Odin, ACE-FTS on SCISAT, and OMPS on
Suomi-NPP. The merged dataset is created in the framework of the
European Space Agency Climate Change Initiative (Ozone_cci) with
the aim of analyzing stratospheric ozone trends. For the merged
dataset, we used the latest versions of the original ozone
datasets. The datasets from the individual instruments have been
extensively validated and intercompared; only those datasets which
are in good agreement, and do not exhibit significant drifts with
respect to collocated ground-based observations and with respect to
each other, are used for merging. The long-term SAGEâCCIâOMPS
dataset is created by computation and merging of deseasonalized
anomalies from individual instruments.
The merged SAGEâCCIâOMPS dataset consists of deseasonalized
anomalies of ozone in 10° latitude bands from 90°âŻS
to 90°âŻN and from 10 to 50âŻkm in steps of
1âŻkm covering the period from October 1984 to
July 2016. This newly created dataset is used for evaluating ozone
trends in the stratosphere through multiple linear
regression. Negative ozone trends in the upper stratosphere are
observed before 1997 and positive trends are found after 1997. The
upper stratospheric trends are statistically significant at
midlatitudes and indicate ozone recovery, as expected from the
decrease of stratospheric halogens that started in the middle of the
1990s and stratospheric cooling
Chapter 4: The LOTUS regression model
One of the primary motivations of the LOTUS effort is to attempt to reconcile the discrepancies in ozone trend results from the wealth of literature on the subject. Doing so requires investigating the various methodologies employed to derive long-term trends in ozone as well as to examine the large array of possible variables that feed into those methodologies and analyse their impacts on potential trend results. Given the limited amount of time, the LOTUS group focused on the most common methodology of multiple linear regression and performed a number of sensitivity tests with the goal of trying to establish best practices and come to a consensus on a single regression model to use for this study. This chapter discusses the details and results of the sensitivity tests before describing the components of the final single model that was chosen and the reasons for that choice
Frequency Dependence of Fatigue Life and Internal Heating of a Fiber-Reinforced/Ceramic-Matrix Composite
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65943/1/j.1151-2916.1994.tb04587.x.pd
Updated merged SAGE-CCI-OMPS+ dataset for the evaluation of ozone trends in the stratosphere
In this paper, we present the updated SAGE-CCI-OMPS+ climate data record of monthly zonal mean ozone profiles. This dataset covers the stratosphere and combines measurements by nine limb and occultation satellite instruments â SAGE II (Stratospheric Aerosol and Gases Experiment II), OSIRIS (Optical Spectrograph and InfraRed Imaging System), MIPAS (Michelson Interferometer for Passive Atmospheric Sounding), SCIAMACHY (SCanning Imaging Spectrometer for Atmospheric CHartographY), GOMOS (Global Ozone Monitoring by Occultation of Stars), ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer), OMPS-LP (Ozone Monitor Profiling Suite Limb Profiler), POAM (Polar Ozone and Aerosol Measurement) III, and SAGE III/ISS (Stratospheric Aerosol and Gases Experiment III on the International Space Station). Compared to the original version of the SAGE-CCI-OMPS dataset (Sofieva et al., 2017b), the update includes new versions of MIPAS, ACE-FTS, and OSIRIS datasets and introduces data from additional sensors (POAM III and SAGE III/ISS) and retrieval processors (OMPS-LP).
In this paper, we show detailed intercomparisons of ozone profiles from
different instruments and data versions, with a focus on the detection of
possible drifts in the datasets. The SAGE-CCI-OMPS+ dataset has a better
coverage of polar regions and of the upper troposphere and the lower
stratosphere (UTLS) than the previous dataset.
We also studied the influence of including new datasets on ozone trends,
which are estimated using multiple linear regression. The changes in the
merged dataset do not change the overall morphology of post-1997 ozone
trends; statistically significant trends are observed in the upper
stratosphere. The largest changes in ozone trends are observed in polar
regions, especially in the Southern Hemisphere.
The updated SAGE-CCI-OMPS+ dataset contains profiles of deseasonalized
anomalies and ozone concentrations from 1984 to 2021, in 10â
latitude bins from 90ââS to 90ââN and in the altitude
range from 10 to 50âkm. The dataset is open access and available at https://climate.esa.int/en/projects/ozone/data/ (last access: 9Â March 2023) and at ftp://[email protected]/esacci (ESA Climate Office; last access: 9 March 2023).</p
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