Many countries around the world have carried out national-scale geochemical surveys,providing important information on the natural concentration of chemical elements and compounds in the near-surface regolith.Resultan...Many countries around the world have carried out national-scale geochemical surveys,providing important information on the natural concentration of chemical elements and compounds in the near-surface regolith.Resultant data and information layers have been put to a multitude of uses:identifying targets for mineral exploration;improving land-use management and environmental policy development;and展开更多
1.Introduction In 2018,the Australian Commonwealth Government committed 224.9 million AUD(160 million USD)to the Positioning Australia program in order to provide 10 cm accurate and reliable positioning to all Austral...1.Introduction In 2018,the Australian Commonwealth Government committed 224.9 million AUD(160 million USD)to the Positioning Australia program in order to provide 10 cm accurate and reliable positioning to all Australians and accelerate the adoption and development of positioning technology and applications.This is a significant improvement from the 5–10 m accuracy that can currently be achieved using consumer positioning devices.Geographically speaking,Australia is in the position to take advantage of highquality,accurate,and efficient space-based positioning constellations with view of all global and regional constellations,including those of the United States(Global Positioning System,GPS),Russia(Global Navigation Satellite System,GLONASS),the European Union(Galileo),China(BeiDou),Japan(Quasi-Zenith Satellite System,QZSS),and India(Indian Regional Navigation Satellite System,IRNSS).展开更多
We have examined the fluid inclusion data and fluid chemistry of Australian orogenic and intrusion-related gold deposits to determine if similar mineralization processes apply to both styles of deposits.The fluid incl...We have examined the fluid inclusion data and fluid chemistry of Australian orogenic and intrusion-related gold deposits to determine if similar mineralization processes apply to both styles of deposits.The fluid inclusion data from the Yilgarn craton,the western subprovince of the Lachlan orogen,the Tanami,Tennant Creek and Pine Creek regions,and the Telfer gold mine show that mineralization involved fluids with broadly similar major chemical components(i.e.H_2O+NaCl+CO_2±CH_4±N_2).These deposits formed over a wide range of temperature-pressure conditions(<200 to>500℃,<100~400MPa).Low salinity, CO_2-bearing inclusions and low salinity aqueous inclusions occur in both systems but the main difference between these two types of deposits is that most intrusion-related gold deposits also contain at least one population of high-salinity aqueous brine.Oxygen and hydrogen isotope data for both styles of deposit usually cannot distinguish between a magmatic or metamorphic source for the ore-bearing fluids.However,sulfur and lead isotope data for the intrusion-related gold deposits generally indicate either a magmatic source or mixing between magmatic and sedimentary sources of fluid.The metamorphic geothermal gradients associated with intrusion-related gold deposits are characterized by low pressure,high temperature metamorphism and high crustal geothermal gradients of>30/km.Where amphibole breakdown occurs in a granite source region,the spatially related deposits are more commonly associated with Cu-Au deposits rather than Au-only deposits that are associated with lower temperature granites.The dominant processes thought to cause gold precipitation in both types of deposits are fluid-rock interaction(e.g.desulfidation)or phase separation.Consideration of the physical and chemical properties of the H_2O-NaCl-CO_2 system on the nature of gold precipitation mechanisms at different crustal levels infers different roles of chemical(fluid-rock interaction)versus rheological(phase separation and/or fluid mixing)host-rock controls on gold deposition.This also implies that at the site of deposition,similar precipitation mechanisms operate at similar crustal levels for both orogenic and intrusion-related gold deposits.展开更多
Accurate estimation of clocks, for example for the Gravity Recovery And Climate Experiment(GRACE)twin-satellites, is a critical part of precise orbit determination(POD) that ensures temporal gravity inversion. Charact...Accurate estimation of clocks, for example for the Gravity Recovery And Climate Experiment(GRACE)twin-satellites, is a critical part of precise orbit determination(POD) that ensures temporal gravity inversion. Characterizing the periodic variations of the receiver clocks is critical for precise clock modeling and prediction. In this study, the receiver clock is estimated using two different POD procedure: kinematic and reduced-dynamic approaches. Choices and the number of orbital parameters estimated in POD process affect the clock estimates, e.g., there are 8895 and 34,560 total parameters in the reduced-dynamic and kinematic approaches, respectively. In the both cases, the periodic variations of GRACE receiver clock are mainly dominated by the GPS orbit period, as well as once-(1-pr) and twiceper-revolution(2-pr) effects. Here the 1-pr effect is coupled with the relativistic effect, resulting in a difficulty to separate both signals. The clock amplitudes caused by the GPS orbit period, 1-pr and 2-pr are about 0.1, 0.03 and 0.01 ns, respectively. The GPS orbit period is almost one order magnitude larger than the 1-and 2-pr effect. The 0.1-ns amplitude of the 12-h periodic variation is equivalent to a 3-cm error in range. Such a systematic error should be considered in the receiver clock modeling for both the improvement of positioning accuracy and the reduction of number of unknown parameters, if the precise point positioning(PPP) technique is used for the orbit determination of the GRACE.展开更多
Anomalous topographic swells and Cenozoic volcanism in east Africa have been associated with mantle plumes.Several models involving one or more fixed plumes beneath the northeastward migrating African plate have been ...Anomalous topographic swells and Cenozoic volcanism in east Africa have been associated with mantle plumes.Several models involving one or more fixed plumes beneath the northeastward migrating African plate have been suggested to explain the space-time distribution of magmatism in east Africa.We devise paleogeographically constrained global models of mantle convection and,based on the evolution of flow in the deepest lower mantle,show that the Afar plume migrated southward throughout its lifetime.The models suggest that the mobile Afar plume provides a dynamically consistent explanation for the spatial extent of the southward propagation of the east African rift system(EARS),which is difficult to explain by the northeastward migration of Africa over one or more fixed plumes alone,over the last≈45 Myr.We further show that the age-progression of volcanism associated with the southward propagation of EARS is consistent with the apparent surface hotspot motion that results from southward motion of the modelled Afar plume beneath the northeastward migrating African plate.The models suggest that the Afar plume became weaker as it migrated southwards,consistent with trends observed in the geochemical record.展开更多
Petascale archives of Earth observations from space(EOS)have the potential to characterise water resources at continental scales.For this data to be useful,it needs to be organised,converted from individual scenes as ...Petascale archives of Earth observations from space(EOS)have the potential to characterise water resources at continental scales.For this data to be useful,it needs to be organised,converted from individual scenes as acquired by multiple sensors,converted into“analysis ready data”,and made available through high performance computing platforms.Moreover,converting this data into insights requires integration of non-EOS data-sets that can provide biophysical and climatic context for EOS.Digital Earth Australia has demonstrated its ability to link EOS to rainfall and stream gauge data to provide insight into surface water dynamics during the hydrological extremes of flood and drought.This information is supporting the characterisation of groundwater resources across Australia’s north and could potentially be used to gain an understanding of the vulnerability of transport infrastructure to floods in remote,sparsely gauged regions of northern and central Australia.展开更多
To comprehensively support national and international initiatives for sustainable development,land cover products need to be reliably and routinely generated within operational frameworks.Coupled with consistent seman...To comprehensively support national and international initiatives for sustainable development,land cover products need to be reliably and routinely generated within operational frameworks.Coupled with consistent semantics and taxonomies,ensuring confidence in mapping land cover for multiple time periods,facilitates informed decision-making at scales appropriate to multiple policy domains.The United Nations Food and Agriculture Organisation(FAO)Land Cover Classification System(LCCS)provides a taxonomy that comparable at different scales,level of detail and geographic location.The Open Data Cube(ODC)initiative offers a framework for operational continental-scale land cover mapping using analysis-ready Earth Observation data.This study utilised the FAO LCCS framework and the Landsat sensor data through Digital Earth Australia(DEA;Australia’s ODC instance)to generate consistent and continent-wide land cover mapping(DEA Land Cover)of the Australian continent.DEA Land Cover provides annual maps from 1988 to 2020 at 25 m resolution.Output maps were validated with∼12,000 independent validation points,giving an overall map accuracy of 80%.DEA Land Cover provides Australia with a nationally consistent picture of land cover,with an open-source software package using readily available global coverage data and demonstrates a pathway of adoption for national implementations across the world.展开更多
Global Positioning System(GPS)position verification and legal traceability in Australia supports industry,trade,science and innovation and is trusted and recognized domestically and internationally.At the end of 2017,...Global Positioning System(GPS)position verification and legal traceability in Australia supports industry,trade,science and innovation and is trusted and recognized domestically and internationally.At the end of 2017,the Australia’s national datum was transitioned from the Geocentric Datum of Australia 1994(GDA94)to the Geocentric Datum of Australia 2020(GDA2020).As such,the datum for the legal traceability of GPS positions in Australia has also moved to GDA2020.This paper highlights the importance of legal metrology and measurement in terms of GPS positions in accordance with the National Measurement Act 1960(Commonwealth of Australia).Here we provide an overview of the process of issuing the so-called‘Regulation 13 Certificates’for Continuously Operating Reference Stations(CORS)across Australia.The position verification methodology is detailed,including the quality control,metadata assurance,and dynamic management of the certificates as well as positional uncertainty determination of CORS with varying quality.A quality monitoring system of positions is also discussed along with how measurement traceability is ensured including short-term and long-term position monitoring schemes.展开更多
The FAIR principles of Wilkinson et al.[1]are finding their way from research into application domains,one of which is the precise positioning with global satellite navigation systems(GNSS).Current GNSS users demand t...The FAIR principles of Wilkinson et al.[1]are finding their way from research into application domains,one of which is the precise positioning with global satellite navigation systems(GNSS).Current GNSS users demand that data and services are findable online,accessible via open protocols(by both,machines and humans),interoperable with their legacy systems and reusable in various settings.Comprehensive metadata are essential in seamless communication between GNSS data and service providers and their users,and,for decades,geodetic and geospatial standards are efficiently implemented to support this.However,GNSS user community is transforming from precise positioning by highly specialised use by geodetic professionals to every-day precise positioning by autonomous vehicles or wellness obsessed citizens.Moreover,rapid technological developments allow alternative ways of offering data and services to their users.These transforming circumstances warrant a review whether metadata defined in generic geospatial and geodetic standards in use still support FAIR use of modern GNSS data and services across its novel user spectrum.This paper reports the results of current GNSS users'requirements in various application sectors on the way data,metadata and services are provided.We engaged with GNSS stakeholders to validate our findings and to gain understanding on their perception of the FAIR principles.Our results confirm that offering FAIR GNSS data and services is fundamental,but for a confident use of these,there is a need to review the way metadata are offered to the community.Defining standard compliant GNSS community metadata profile and providing relevant metadata with data on-demand,the approach outlined in this paper,is a way to manage current GNSS users'expectations and the way to improve FAIR GNSS data and service delivery for both humans and the machines.展开更多
The technological landscape for managing big Earth observation(EO)data ranges from global solutions on large cloud infrastructures with web-based access to self-hosted implementations.EO data cubes are a leading techn...The technological landscape for managing big Earth observation(EO)data ranges from global solutions on large cloud infrastructures with web-based access to self-hosted implementations.EO data cubes are a leading technology for facilitating big EO data analysis and can be deployed on different spatial scales:local,national,regional,or global.Several EO data cubes with a geographic focus(“local EO data cubes”)have been implemented.However,their alignment with the Digital Earth(DE)vision and the benefits and trade-offs in creating and maintaining them ought to be further examined.We investigate local EO data cubes from five perspectives(science,business and industry,government and policy,education,communities and citizens)and illustrate four examples covering three continents at different geographic scales(Swiss Data Cube,semantic EO data cube for Austria,DE Africa,Virginia Data Cube).A local EO data cube can benefit many stakeholders and players but requires several technical developments.These developments include enabling local EO data cubes based on public,global,and cloud-native EO data streaming and interoperability between local EO data cubes.We argue that blurring the dichotomy between global and local aligns with the DE vision to access the world’s knowledge and explore information about the planet.展开更多
In this paper,we summarizefindings from the Tenth International Workshop on Tropical Cyclones(IWTC-10)subgroup on forecasting wind hazards and impacts.We found that new approaches to TC wind hazard forecasts continue t...In this paper,we summarizefindings from the Tenth International Workshop on Tropical Cyclones(IWTC-10)subgroup on forecasting wind hazards and impacts.We found that new approaches to TC wind hazard forecasts continue to be developed and are becoming an increasingly common product offered by operational centres.To add greater context to wind risk information for users,many operational and research centres are also working to develop impact-based forecasts that incorporate hazard,vulnerability,and exposure data.Efforts to develop tropical cyclone wind impact forecasts present resourcing challenges,and when compared to wind hazard forecasting,are generally still in their infancy.Overall,both operational and research centres are extending significant efforts to meet the strong public need for accurate predictions of TC wind hazards and impacts around the world.展开更多
Earth Observation(EO)has been recognised as a key data source for supporting the United Nations Sustainable Development Goals(SDGs).Advances in data availability and analytical capabilities have provided a wide range ...Earth Observation(EO)has been recognised as a key data source for supporting the United Nations Sustainable Development Goals(SDGs).Advances in data availability and analytical capabilities have provided a wide range of users access to global coverage analysis-ready data(ARD).However,ARD does not provide the information required by national agencies tasked with coordinating the implementation of SDGs.Reliable,standardised,scalable mapping of land cover and its change over time and space facilitates informed deci-sion making,providing cohesive methods for target setting and reporting of SDGs.The aim of this study was to implement a global framework for classifying land cover.The Food and Agriculture Organisation’s Land Cover Classification System(FAO LCCS)provides a global land cover taxonomy suitable to comprehensively support SDG target setting and reporting.We present a fully implemented FAO LCCS optimised for EO data;Living Earth,an open-source software package that can be readily applied using existing national EO infrastructure and satellite data.We resolve several semantic challenges of LCCS for consistent EO implementation,including modifications to environmental descriptors,inter-dependency within the mod-ular-hierarchical framework,and increased flexibility associated with limited data availability.To ensure easy adoption of Living Earth for SDG reporting,we identified key environmental descriptors to provide resource allocation recommendations for generating routinely retrieved input parameters.Living Earth provides an optimal platform for global adoption of EO4SDGs ensuring a transparent methodology that allows monitoring to be standardised for all countries.展开更多
The effort and cost required to convert satellite Earth Observation(EO)data into meaningful geophysical variables has prevented the systematic analysis of all available observations.To overcome these problems,we utili...The effort and cost required to convert satellite Earth Observation(EO)data into meaningful geophysical variables has prevented the systematic analysis of all available observations.To overcome these problems,we utilise an integrated High Performance Computing and Data environment to rapidly process,restructure and analyse the Australian Landsat data archive.In this approach,the EO data are assigned to a common grid framework that spans the full geospatial and temporal extent of the observations–the EO Data Cube.This approach is pixel-based and incorporates geometric and spectral calibration and quality assurance of each Earth surface reflectance measurement.We demonstrate the utility of the approach with rapid time-series mapping of surface water across the entire Australian continent using 27 years of continuous,25 m resolution observations.Our preliminary analysis of the Landsat archive shows how the EO Data Cube can effectively liberate high-resolution EO data from their complex sensor-specific data structures and revolutionise our ability to measure environmental change.展开更多
The accuracy of topographic correction of Landsat data based on a Digital Surface Model(DSM)depends on the quality,scale and spatial resolution of the DSM data used and the co-registration between the DSM and the sate...The accuracy of topographic correction of Landsat data based on a Digital Surface Model(DSM)depends on the quality,scale and spatial resolution of the DSM data used and the co-registration between the DSM and the satellite image.A physics-based bidirectional reflectance distribution function(BRDF)and atmospheric correction model in conjunction with a 1-second DSM was used to conduct the analysis in this paper.The results show that for the examples used from Australia,the 1-second DSM,can provide an effective product for this task.However,it was found that some remaining artefacts in the DSM data,originally due to radar shadow,can still cause significant local errors in the correction.Where they occur,false shadows and over-corrected surface reflectance factors can be observed.More generally,accurate co-registration between satellite images and DSM data was found to be critical for effective correction.Mis-registration by one or two pixels could lead to large errors of retrieved surface reflectance factors in gully and ridge areas.Using low-resolution DSM data in conjunction with high-resolution satellite images will also fail to correct significant terrain components where they occur at the finer scales of the satellite images.DSM resolution appropriate to the resolution of satellite image and the roughness of the terrain is needed for effective results,and the rougher the terrain,the more critical will be the accurate registration.展开更多
文摘Many countries around the world have carried out national-scale geochemical surveys,providing important information on the natural concentration of chemical elements and compounds in the near-surface regolith.Resultant data and information layers have been put to a multitude of uses:identifying targets for mineral exploration;improving land-use management and environmental policy development;and
文摘1.Introduction In 2018,the Australian Commonwealth Government committed 224.9 million AUD(160 million USD)to the Positioning Australia program in order to provide 10 cm accurate and reliable positioning to all Australians and accelerate the adoption and development of positioning technology and applications.This is a significant improvement from the 5–10 m accuracy that can currently be achieved using consumer positioning devices.Geographically speaking,Australia is in the position to take advantage of highquality,accurate,and efficient space-based positioning constellations with view of all global and regional constellations,including those of the United States(Global Positioning System,GPS),Russia(Global Navigation Satellite System,GLONASS),the European Union(Galileo),China(BeiDou),Japan(Quasi-Zenith Satellite System,QZSS),and India(Indian Regional Navigation Satellite System,IRNSS).
文摘We have examined the fluid inclusion data and fluid chemistry of Australian orogenic and intrusion-related gold deposits to determine if similar mineralization processes apply to both styles of deposits.The fluid inclusion data from the Yilgarn craton,the western subprovince of the Lachlan orogen,the Tanami,Tennant Creek and Pine Creek regions,and the Telfer gold mine show that mineralization involved fluids with broadly similar major chemical components(i.e.H_2O+NaCl+CO_2±CH_4±N_2).These deposits formed over a wide range of temperature-pressure conditions(<200 to>500℃,<100~400MPa).Low salinity, CO_2-bearing inclusions and low salinity aqueous inclusions occur in both systems but the main difference between these two types of deposits is that most intrusion-related gold deposits also contain at least one population of high-salinity aqueous brine.Oxygen and hydrogen isotope data for both styles of deposit usually cannot distinguish between a magmatic or metamorphic source for the ore-bearing fluids.However,sulfur and lead isotope data for the intrusion-related gold deposits generally indicate either a magmatic source or mixing between magmatic and sedimentary sources of fluid.The metamorphic geothermal gradients associated with intrusion-related gold deposits are characterized by low pressure,high temperature metamorphism and high crustal geothermal gradients of>30/km.Where amphibole breakdown occurs in a granite source region,the spatially related deposits are more commonly associated with Cu-Au deposits rather than Au-only deposits that are associated with lower temperature granites.The dominant processes thought to cause gold precipitation in both types of deposits are fluid-rock interaction(e.g.desulfidation)or phase separation.Consideration of the physical and chemical properties of the H_2O-NaCl-CO_2 system on the nature of gold precipitation mechanisms at different crustal levels infers different roles of chemical(fluid-rock interaction)versus rheological(phase separation and/or fluid mixing)host-rock controls on gold deposition.This also implies that at the site of deposition,similar precipitation mechanisms operate at similar crustal levels for both orogenic and intrusion-related gold deposits.
基金funded by the Ministry of Science and Technology of Taiwan, under grant numbers 103-2116-M-008-014
文摘Accurate estimation of clocks, for example for the Gravity Recovery And Climate Experiment(GRACE)twin-satellites, is a critical part of precise orbit determination(POD) that ensures temporal gravity inversion. Characterizing the periodic variations of the receiver clocks is critical for precise clock modeling and prediction. In this study, the receiver clock is estimated using two different POD procedure: kinematic and reduced-dynamic approaches. Choices and the number of orbital parameters estimated in POD process affect the clock estimates, e.g., there are 8895 and 34,560 total parameters in the reduced-dynamic and kinematic approaches, respectively. In the both cases, the periodic variations of GRACE receiver clock are mainly dominated by the GPS orbit period, as well as once-(1-pr) and twiceper-revolution(2-pr) effects. Here the 1-pr effect is coupled with the relativistic effect, resulting in a difficulty to separate both signals. The clock amplitudes caused by the GPS orbit period, 1-pr and 2-pr are about 0.1, 0.03 and 0.01 ns, respectively. The GPS orbit period is almost one order magnitude larger than the 1-and 2-pr effect. The 0.1-ns amplitude of the 12-h periodic variation is equivalent to a 3-cm error in range. Such a systematic error should be considered in the receiver clock modeling for both the improvement of positioning accuracy and the reduction of number of unknown parameters, if the precise point positioning(PPP) technique is used for the orbit determination of the GRACE.
基金supported by ARC grants IH130200012 and DP130101946supported by the National Science Foundation under award EAR-1645775undertaken with the assistance of resources from the National Computational Infrastructure(NCI),which is supported by the Australian Government。
文摘Anomalous topographic swells and Cenozoic volcanism in east Africa have been associated with mantle plumes.Several models involving one or more fixed plumes beneath the northeastward migrating African plate have been suggested to explain the space-time distribution of magmatism in east Africa.We devise paleogeographically constrained global models of mantle convection and,based on the evolution of flow in the deepest lower mantle,show that the Afar plume migrated southward throughout its lifetime.The models suggest that the mobile Afar plume provides a dynamically consistent explanation for the spatial extent of the southward propagation of the east African rift system(EARS),which is difficult to explain by the northeastward migration of Africa over one or more fixed plumes alone,over the last≈45 Myr.We further show that the age-progression of volcanism associated with the southward propagation of EARS is consistent with the apparent surface hotspot motion that results from southward motion of the modelled Afar plume beneath the northeastward migrating African plate.The models suggest that the Afar plume became weaker as it migrated southwards,consistent with trends observed in the geochemical record.
文摘Petascale archives of Earth observations from space(EOS)have the potential to characterise water resources at continental scales.For this data to be useful,it needs to be organised,converted from individual scenes as acquired by multiple sensors,converted into“analysis ready data”,and made available through high performance computing platforms.Moreover,converting this data into insights requires integration of non-EOS data-sets that can provide biophysical and climatic context for EOS.Digital Earth Australia has demonstrated its ability to link EOS to rainfall and stream gauge data to provide insight into surface water dynamics during the hydrological extremes of flood and drought.This information is supporting the characterisation of groundwater resources across Australia’s north and could potentially be used to gain an understanding of the vulnerability of transport infrastructure to floods in remote,sparsely gauged regions of northern and central Australia.
基金support of Geoscience Australia,through the DEA Land Cover project,and the European Regional Development Fund(ERDF)Sêr Cymru II programme award[grant number 80761-AU-108,Living Wales].
文摘To comprehensively support national and international initiatives for sustainable development,land cover products need to be reliably and routinely generated within operational frameworks.Coupled with consistent semantics and taxonomies,ensuring confidence in mapping land cover for multiple time periods,facilitates informed decision-making at scales appropriate to multiple policy domains.The United Nations Food and Agriculture Organisation(FAO)Land Cover Classification System(LCCS)provides a taxonomy that comparable at different scales,level of detail and geographic location.The Open Data Cube(ODC)initiative offers a framework for operational continental-scale land cover mapping using analysis-ready Earth Observation data.This study utilised the FAO LCCS framework and the Landsat sensor data through Digital Earth Australia(DEA;Australia’s ODC instance)to generate consistent and continent-wide land cover mapping(DEA Land Cover)of the Australian continent.DEA Land Cover provides annual maps from 1988 to 2020 at 25 m resolution.Output maps were validated with∼12,000 independent validation points,giving an overall map accuracy of 80%.DEA Land Cover provides Australia with a nationally consistent picture of land cover,with an open-source software package using readily available global coverage data and demonstrates a pathway of adoption for national implementations across the world.
文摘Global Positioning System(GPS)position verification and legal traceability in Australia supports industry,trade,science and innovation and is trusted and recognized domestically and internationally.At the end of 2017,the Australia’s national datum was transitioned from the Geocentric Datum of Australia 1994(GDA94)to the Geocentric Datum of Australia 2020(GDA2020).As such,the datum for the legal traceability of GPS positions in Australia has also moved to GDA2020.This paper highlights the importance of legal metrology and measurement in terms of GPS positions in accordance with the National Measurement Act 1960(Commonwealth of Australia).Here we provide an overview of the process of issuing the so-called‘Regulation 13 Certificates’for Continuously Operating Reference Stations(CORS)across Australia.The position verification methodology is detailed,including the quality control,metadata assurance,and dynamic management of the certificates as well as positional uncertainty determination of CORS with varying quality.A quality monitoring system of positions is also discussed along with how measurement traceability is ensured including short-term and long-term position monitoring schemes.
基金the P1008-Positioning Australia:Accelerating Industry Adoption project supported by Geoscience Australia,Frontiersl,Curtin University and Positioning Insights。
文摘The FAIR principles of Wilkinson et al.[1]are finding their way from research into application domains,one of which is the precise positioning with global satellite navigation systems(GNSS).Current GNSS users demand that data and services are findable online,accessible via open protocols(by both,machines and humans),interoperable with their legacy systems and reusable in various settings.Comprehensive metadata are essential in seamless communication between GNSS data and service providers and their users,and,for decades,geodetic and geospatial standards are efficiently implemented to support this.However,GNSS user community is transforming from precise positioning by highly specialised use by geodetic professionals to every-day precise positioning by autonomous vehicles or wellness obsessed citizens.Moreover,rapid technological developments allow alternative ways of offering data and services to their users.These transforming circumstances warrant a review whether metadata defined in generic geospatial and geodetic standards in use still support FAIR use of modern GNSS data and services across its novel user spectrum.This paper reports the results of current GNSS users'requirements in various application sectors on the way data,metadata and services are provided.We engaged with GNSS stakeholders to validate our findings and to gain understanding on their perception of the FAIR principles.Our results confirm that offering FAIR GNSS data and services is fundamental,but for a confident use of these,there is a need to review the way metadata are offered to the community.Defining standard compliant GNSS community metadata profile and providing relevant metadata with data on-demand,the approach outlined in this paper,is a way to manage current GNSS users'expectations and the way to improve FAIR GNSS data and service delivery for both humans and the machines.
基金the Austrian Research Promotion Agency(FFG)under the Austrian Space Application Programme(ASAP)within the projects Sen2Cube.at(project no.:866016)SemantiX(project no.:878939)SIMS(project no.:885365).
文摘The technological landscape for managing big Earth observation(EO)data ranges from global solutions on large cloud infrastructures with web-based access to self-hosted implementations.EO data cubes are a leading technology for facilitating big EO data analysis and can be deployed on different spatial scales:local,national,regional,or global.Several EO data cubes with a geographic focus(“local EO data cubes”)have been implemented.However,their alignment with the Digital Earth(DE)vision and the benefits and trade-offs in creating and maintaining them ought to be further examined.We investigate local EO data cubes from five perspectives(science,business and industry,government and policy,education,communities and citizens)and illustrate four examples covering three continents at different geographic scales(Swiss Data Cube,semantic EO data cube for Austria,DE Africa,Virginia Data Cube).A local EO data cube can benefit many stakeholders and players but requires several technical developments.These developments include enabling local EO data cubes based on public,global,and cloud-native EO data streaming and interoperability between local EO data cubes.We argue that blurring the dichotomy between global and local aligns with the DE vision to access the world’s knowledge and explore information about the planet.
文摘In this paper,we summarizefindings from the Tenth International Workshop on Tropical Cyclones(IWTC-10)subgroup on forecasting wind hazards and impacts.We found that new approaches to TC wind hazard forecasts continue to be developed and are becoming an increasingly common product offered by operational centres.To add greater context to wind risk information for users,many operational and research centres are also working to develop impact-based forecasts that incorporate hazard,vulnerability,and exposure data.Efforts to develop tropical cyclone wind impact forecasts present resourcing challenges,and when compared to wind hazard forecasting,are generally still in their infancy.Overall,both operational and research centres are extending significant efforts to meet the strong public need for accurate predictions of TC wind hazards and impacts around the world.
基金This research has been conducted with the support of Geoscience Australia,through the DEA Land Cover project,and the European Research Development Fund(ERDF)Sêr Cymru II program award(80761-AU-108,Living Wales).
文摘Earth Observation(EO)has been recognised as a key data source for supporting the United Nations Sustainable Development Goals(SDGs).Advances in data availability and analytical capabilities have provided a wide range of users access to global coverage analysis-ready data(ARD).However,ARD does not provide the information required by national agencies tasked with coordinating the implementation of SDGs.Reliable,standardised,scalable mapping of land cover and its change over time and space facilitates informed deci-sion making,providing cohesive methods for target setting and reporting of SDGs.The aim of this study was to implement a global framework for classifying land cover.The Food and Agriculture Organisation’s Land Cover Classification System(FAO LCCS)provides a global land cover taxonomy suitable to comprehensively support SDG target setting and reporting.We present a fully implemented FAO LCCS optimised for EO data;Living Earth,an open-source software package that can be readily applied using existing national EO infrastructure and satellite data.We resolve several semantic challenges of LCCS for consistent EO implementation,including modifications to environmental descriptors,inter-dependency within the mod-ular-hierarchical framework,and increased flexibility associated with limited data availability.To ensure easy adoption of Living Earth for SDG reporting,we identified key environmental descriptors to provide resource allocation recommendations for generating routinely retrieved input parameters.Living Earth provides an optimal platform for global adoption of EO4SDGs ensuring a transparent methodology that allows monitoring to be standardised for all countries.
文摘The effort and cost required to convert satellite Earth Observation(EO)data into meaningful geophysical variables has prevented the systematic analysis of all available observations.To overcome these problems,we utilise an integrated High Performance Computing and Data environment to rapidly process,restructure and analyse the Australian Landsat data archive.In this approach,the EO data are assigned to a common grid framework that spans the full geospatial and temporal extent of the observations–the EO Data Cube.This approach is pixel-based and incorporates geometric and spectral calibration and quality assurance of each Earth surface reflectance measurement.We demonstrate the utility of the approach with rapid time-series mapping of surface water across the entire Australian continent using 27 years of continuous,25 m resolution observations.Our preliminary analysis of the Landsat archive shows how the EO Data Cube can effectively liberate high-resolution EO data from their complex sensor-specific data structures and revolutionise our ability to measure environmental change.
文摘The accuracy of topographic correction of Landsat data based on a Digital Surface Model(DSM)depends on the quality,scale and spatial resolution of the DSM data used and the co-registration between the DSM and the satellite image.A physics-based bidirectional reflectance distribution function(BRDF)and atmospheric correction model in conjunction with a 1-second DSM was used to conduct the analysis in this paper.The results show that for the examples used from Australia,the 1-second DSM,can provide an effective product for this task.However,it was found that some remaining artefacts in the DSM data,originally due to radar shadow,can still cause significant local errors in the correction.Where they occur,false shadows and over-corrected surface reflectance factors can be observed.More generally,accurate co-registration between satellite images and DSM data was found to be critical for effective correction.Mis-registration by one or two pixels could lead to large errors of retrieved surface reflectance factors in gully and ridge areas.Using low-resolution DSM data in conjunction with high-resolution satellite images will also fail to correct significant terrain components where they occur at the finer scales of the satellite images.DSM resolution appropriate to the resolution of satellite image and the roughness of the terrain is needed for effective results,and the rougher the terrain,the more critical will be the accurate registration.