This document discusses changes in freshwater pathways in the Arctic Ocean from 2005-2008. Satellite and in situ observations show that freshwater content increased in the Canada basin over this period, balanced by a decrease in the Eurasian basin. This was due to a cyclonic shift in the ocean pathway of Eurasian runoff forced by a strengthening of the west-to-east atmospheric circulation in the Northern Hemisphere, characterized by an increased Arctic Oscillation index. Observations confirm that runoff is an important influence on the Arctic Ocean and that the spatial distribution of freshwater pathways is modulated by the Arctic Oscillation rather than local wind patterns.
This study uses basin modelling to analyze the hydrocarbon potential of two Neogene sedimentary sub-basins in southern Hungary. The modelling simulated the subsidence and thermal maturation histories. It determined that the southern sub-basin reached greater depths and temperatures, resulting in gas generation from source rocks beginning 11.6 million years ago. Oil generation in the northern sub-basin began more recently around 6.8 million years ago. While hydrocarbons migrated upward along faults, accumulations have only formed so far in the southern sub-basin within anticline structures in carbonate formations. The complex geological evolution and thermal anomalies revealed by the modelling provide new perspectives for hydrocarbon exploration in the area.
The document discusses environmental problems in the Ethiopian Rift region related to improper water resource utilization practices over the last few decades. Key issues include some lakes shrinking due to excessive water abstraction for irrigation and soda production, while others expanded due to increased surface runoff and groundwater from irrigated fields. Over-irrigation has led to salinization of soils and changed lake levels and hydrochemistry. The study analyzes changes in lake levels and hydrochemistry to understand the impacts of climate change and human activities on the fragile rift ecosystem. Urgent action is needed for integrated sustainable water management to address these problems.
Nuclear Magnetic Ressonance - Water content assessment in glacier ice and ben...Fundació Marcel Chevalier
Glaciers are widely spread on polar and sub-polar regions but also on middle latitude mountains, where cold-dry type glaciers, polythermal glaciers and temperate-wet glaciers are respectively present. Assess their water content is capital to understand the ice dynamics and how is related with the climate change.
Subglacial drainage in porous aquifer and sediment consolidation patterns in the glaciated valley of Andorra (Pyrenees). The poster was presented for the IAG/AIG (International Association of Geomorphologists) Regional Conference on Geomorphology Geodiversity of polar landforms which was held in Longyearbyen (Spitsbergen, Norway) on August 1-5, 2007. Conference was organised on the occasion of the International Polar Year 2007/2008 by the Association of Polish Geomorphologists.
The document examines the dynamics, extent, and timing of the British Ice Sheet during the Last Glacial Maximum through analysis of glacial landforms and dated sites in northern England. Key findings include:
1) The ice sheet was heterogeneous, reaching its maximum extent at different times in different areas. It advanced slowly from ice fields in upland areas before filling valleys.
2) Dynamics varied throughout growth and retreat. During growth, ice flowed radially from centers; during retreat, regional dispersal centers dominated.
3) Analysis of landforms showed complex and changing flow patterns, with ice reaching its maximum approximately 27,000 years ago before retreating rapidly across waterways by 15,000 years ago.
James Morison of the University of Washington has been studying Arctic sea ice for decades and runs an annual expedition to the North Pole to drop instruments through the ice into the ocean below. Here he lays out one scenario for the forces driving recent dramatic changes in summer sea ice on the Arctic Ocean.
Read more from Morison on Arctic change here: http://j.mp/dotmorison
And more on sea ice in a warming climate here: http://j.mp/DotArcIce
Here's the Web home for the North Pole Environmental Observatory: http://psc.apl.washington.edu/northpole/
This document describes a study that used audiomagnetotelluric data collected along two profiles in Cameroon to determine the dip of the contact between sedimentary and metamorphic formations. Geometric mean apparent resistivity values were calculated and used to create iso-resistivity contour maps. A resistivity discontinuity along contour lines indicated the contact between lithologically different blocks. By drawing tangents along a reference contour line, the dips of the contact under each station were calculated. The study found dip values ranging from 58-73 degrees for one profile and 21-60 degrees for the other, showing an abrupt, deep contact with little lateral spread at depth. The results confirmed the contact can be recognized through a
The Korayk Upland glaciers: new data after 60 years. Presented by Maria Ananicheva at the "Perth II: Global Change and the World's Mountains" conference in Perth, Scotland in September 2010.
This study uses basin modelling to analyze the hydrocarbon potential of two Neogene sedimentary sub-basins in southern Hungary. The modelling simulated the subsidence and thermal maturation histories. It determined that the southern sub-basin reached greater depths and temperatures, resulting in gas generation from source rocks beginning 11.6 million years ago. Oil generation in the northern sub-basin began more recently around 6.8 million years ago. While hydrocarbons migrated upward along faults, accumulations have only formed so far in the southern sub-basin within anticline structures in carbonate formations. The complex geological evolution and thermal anomalies revealed by the modelling provide new perspectives for hydrocarbon exploration in the area.
The document discusses environmental problems in the Ethiopian Rift region related to improper water resource utilization practices over the last few decades. Key issues include some lakes shrinking due to excessive water abstraction for irrigation and soda production, while others expanded due to increased surface runoff and groundwater from irrigated fields. Over-irrigation has led to salinization of soils and changed lake levels and hydrochemistry. The study analyzes changes in lake levels and hydrochemistry to understand the impacts of climate change and human activities on the fragile rift ecosystem. Urgent action is needed for integrated sustainable water management to address these problems.
Nuclear Magnetic Ressonance - Water content assessment in glacier ice and ben...Fundació Marcel Chevalier
Glaciers are widely spread on polar and sub-polar regions but also on middle latitude mountains, where cold-dry type glaciers, polythermal glaciers and temperate-wet glaciers are respectively present. Assess their water content is capital to understand the ice dynamics and how is related with the climate change.
Subglacial drainage in porous aquifer and sediment consolidation patterns in the glaciated valley of Andorra (Pyrenees). The poster was presented for the IAG/AIG (International Association of Geomorphologists) Regional Conference on Geomorphology Geodiversity of polar landforms which was held in Longyearbyen (Spitsbergen, Norway) on August 1-5, 2007. Conference was organised on the occasion of the International Polar Year 2007/2008 by the Association of Polish Geomorphologists.
The document examines the dynamics, extent, and timing of the British Ice Sheet during the Last Glacial Maximum through analysis of glacial landforms and dated sites in northern England. Key findings include:
1) The ice sheet was heterogeneous, reaching its maximum extent at different times in different areas. It advanced slowly from ice fields in upland areas before filling valleys.
2) Dynamics varied throughout growth and retreat. During growth, ice flowed radially from centers; during retreat, regional dispersal centers dominated.
3) Analysis of landforms showed complex and changing flow patterns, with ice reaching its maximum approximately 27,000 years ago before retreating rapidly across waterways by 15,000 years ago.
James Morison of the University of Washington has been studying Arctic sea ice for decades and runs an annual expedition to the North Pole to drop instruments through the ice into the ocean below. Here he lays out one scenario for the forces driving recent dramatic changes in summer sea ice on the Arctic Ocean.
Read more from Morison on Arctic change here: http://j.mp/dotmorison
And more on sea ice in a warming climate here: http://j.mp/DotArcIce
Here's the Web home for the North Pole Environmental Observatory: http://psc.apl.washington.edu/northpole/
This document describes a study that used audiomagnetotelluric data collected along two profiles in Cameroon to determine the dip of the contact between sedimentary and metamorphic formations. Geometric mean apparent resistivity values were calculated and used to create iso-resistivity contour maps. A resistivity discontinuity along contour lines indicated the contact between lithologically different blocks. By drawing tangents along a reference contour line, the dips of the contact under each station were calculated. The study found dip values ranging from 58-73 degrees for one profile and 21-60 degrees for the other, showing an abrupt, deep contact with little lateral spread at depth. The results confirmed the contact can be recognized through a
The Korayk Upland glaciers: new data after 60 years. Presented by Maria Ananicheva at the "Perth II: Global Change and the World's Mountains" conference in Perth, Scotland in September 2010.
Analysis Of Core Samples And Stratigraphic Sections In Light Of The Glacial G...West Hollow MS Ms. Gill
The document analyzes stratigraphic sections and a core sample from Long Island in light of its glacial geology. Stratigraphic columns were created from exposed sections along a creek valley wall at Stony Brook University, showing layers of organic material, loess, clay, sand, gravel, and iron/manganese. A core sample was also taken and analyzed, showing alternating layers of gravelly sand and silty sand, indicative of glacial outwash stream channels. Sediments found in both the core and exposed sections are consistent with glacial depositional environments like tunnel valleys and outwash plains on Long Island.
This study reconstructs stable nitrogen isotopic ratios from sediment core samples at Ocean Drilling Program Site 1010 along the California margin from the past 5 million years. The results show relatively stable and enriched δ15N values, which can be interpreted in two ways. First, near complete nutrient utilization at coastal sites led to Rayleigh distillation effects transporting nitrate to Site 1010 through surface currents. Second, Site 1010 itself experiences complete nitrate utilization with no changes in denitrification, unlike sites 1012 and 1242 which do show changes. The aim is to expand reconstructions of oxygen minimum zone conditions to this site further offshore to help understand global changes in the fixed nitrogen inventory and atmospheric CO2 during the Pli
The document discusses how climate change is reducing Arctic sea ice, opening up new shipping routes like the Northern Sea Route. It analyzes projections from a high-resolution ocean model that show sea ice declining rapidly after 2030, allowing shipping in summer without icebreakers after 2050. Shorter Arctic routes could cut shipping times and emissions, but also impact the Arctic environment if accidents occurred. Improved forecasts will help shipping assess risks and benefits of Arctic operations.
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
Impacts of Hydrology and Habitat Changes on the Primary Production of the Ton...tacochrane
Arias, M.E., Cochrane, T.A., Piman, T. and Kummu M. (2012) Impacts of hydrology and habitat changes on the primary production of Southeast Asia's largest lake. IWA (International Water Association) World Congress on Water, Climate and Energy. Dublin, Ireland, 13-18 May 2012.
This study focuses on determining rock properties, trap integrity, and fluid presence in the Hammerfest Basin to lower exploration risk. Seven different play models in the basin were evaluated using well log analysis, AVI seismic inversion, and lithology/fluid prediction from a regional seismic dataset. The plays include Permian, Triassic, Jurassic, and Cretaceous reservoirs, with the main risks being adequate source and migration, and intact traps. Absolute acoustic impedance and Poisson's ratio were mapped throughout the basin to better understand the rock properties of different plays and aid future exploration.
This study presents a comprehensive digital mosaic of ice motion across Antarctica assembled from satellite radar data. The data reveal widespread, patterned, enhanced flow of tributary glaciers reaching hundreds to thousands of kilometers inland over the entire continent. This emphasizes the importance of basal-slip dominated tributary flow over deformation-dominated ice sheet flow, redefining our understanding of ice sheet dynamics. The extensive network of fast-flowing tributaries challenges prior views of ice sheet flow and implies a tighter connection between coastal and interior ice flow than previously thought.
Conclusions
• Studyingthecurrentstateofsub-seapermafrost is of critical importance in order to elucidate the time scale of the ongoing process;
• Giventhatspatialandtemporalvariabilityof methane releases is very high, this underscores importance of establishing monitoring network over the ESAS;
• ConsideringthesignificanceoftheESAS methane reservoir and enhancing mechanism of its destabilization, this region should be considered the most potential in terms of possible climate change caused by abrupt release of methane.
1) The study modifies the geometry of the Fraser River in a numerical ocean model to improve simulations of tides and the Fraser River plume.
2) Extending and deepening the river channel generated stronger cross-strait surface currents that better matched observations, and tidal amplitudes in the estuary corresponded well with measurements.
3) Reducing vertical mixing parameters, such as eddy viscosity and diffusivity, produced weaker along-strait flow and surface current patterns closer to drifter data, further improving the model results.
Delineation of Hydrocarbon Bearing Reservoirs from Surface Seismic and Well L...IOSR Journals
Hydrocarbon reservoir has been delineated and their boundaries mapped using direct indicators from 3-D seismic and well log data from an oil field in Nembe creek, Niger Delta region. Well log signatures were employed to identify hydrocarbon bearing sands. Well to seismic correlation revealed that these reservoirs tied with direct hydrocarbon indicators on the seismic section. The results of the interpreted well logs revealed that the hydrocarbon interval in the area occurs between 6450ft to 6533ft for well A, 6449ft to 6537ft for well B and 6629ft to 6704ft for well C; which were delineated using the resistivity, water saturation and gamma ray logs. Cross plot analysis was carried out to validate the sensitivity of the rock attributes to reservoir saturation condition. Analysis of the extracted seismic attribute slices revealed HD5000 as hydrocarbon bearing reservoir.
CLIMATE CHANGE, SEA-LEVEL RISE and COASTAL GEOLOGIC HAZARDSriseagrant
CLIMATE CHANGE, SEA-LEVEL RISE
and
COASTAL GEOLOGIC HAZARDS
URI Climate Change Symposium
5 May 2011
Jon C. Boothroyd
Rhode Island State Geologist,
Research Professor Emeritus – Quaternary Geology
-------------
Rhode Island Geological Survey and Department of Geosciences
College of the Environment and Life Sciences
University of Rhode Island
jon_boothroyd@uri.edu
The paper describes efforts to better understand an oil field in Oman through integrated interpretation of pressure, temperature, seismic and other data from a trial steam injection pattern, which showed a non-homogeneous response. Multiple geological models were built calibrated to production and surveillance data, finding that no single concept fully explains observations. A combination of fluvial facies distributions and internal reservoir structure with baffles and structural dip is likely needed to understand steam flood performance.
Stepped Pilo-Pleistocene climate variablity at Lake EUmassGeo
This document summarizes research from a team studying the 3.58 million year climate record from Lake El'gygytgyn in Arctic Russia. The record shows stepped Plio-Pleistocene climate variability with a transition from a warm and wet Pliocene to cooler and more variable glacial/interglacial conditions in the Pleistocene. Significant findings include evidence of forested conditions in the Arctic prior to 3 million years ago, a complex transition to tundra vegetation by 2.3 million years ago, and periods of extreme warmth called "super interglacials" that may have been linked to Antarctic ice sheet disintegration events. The cause of these super interglacials remains unclear but does not appear
This document discusses climate change, coastal hazards, and sea level rise in Rhode Island. It provides background on past glaciation and ice sheets in the region. It then examines current coastal hazards from storms and erosion exacerbated by sea level rise. Projections show global sea level rising significantly by 2100 due to climate change, threatening Rhode Island's coasts with flooding and barrier migration. Adaptation strategies may be needed to address these coastal impacts of climate change.
Anisotropic Avo Analysis for Reservoir Characterization in Derby Field Southe...IOSRJAP
Anisotropic AVO analysis for reservoir characterization in Derby field southeastern Niger delta has been investigated. The objective of this study was to investigate the AVO response of shale over gas sandsonisotropic and anisotropic synthetic models and the real CDP gathers. This was done by plotting amplitude of reflections versus offsets and carrying out AVO intercept-gradient analysison HD1horizon. The results of the models were compared with the real CDP gather to deduce the robust synthetic model for efficient AVO analysis in the field. Well, CDP processed gathers and Hampson-Russell GEOVIEW and AVO module were used for the analysis. Results revealed that the plots of amplitude versus offset of the isotropic and anisotropic synthetic models agree at near offset but show opposite AVO response due to increasing contributions of seismic anisotropy at far offsets. The results of the anisotropic synthetic model correlates well with the CDP gathers indicating that seismic anisotropy is an important factor in AVO analysis. Results also show that a bright spot indicative of gas charged sands was delineated for the isotropic and anisotropic models but with different classes of AVO anomalies andproducts. The isotropic synthetic model show a class II AVO anomaly with a positive AVO product, while the anisotropic model show a class IV AVO anomaly with a negative AVO product comparable to the real CDP gather.These analysesclearly show that description of rock without anisotropy especially, seismic anisotropy is incomplete since most rocks are not completely isotropic. Therefore, accounting for seismic anisotropy in AVO synthetic modelling will ensure that the correct earth model is predicted and the reservoir is adequately characterized.
This document summarizes a hydrogeophysical investigation using self-potential and resistivity surveys at Hidden Dam in California to better understand seepage patterns and subsurface geology. 512 self-potential measurements identified known seepage areas and a potential new area, while two 2,500 foot resistivity profiles indicated a sediment channel that may be a significant seepage pathway. Numerical modeling of subsurface flow correlated with geophysical data and confirmed a focusing of seepage in low-lying areas downstream, consistent with past observations. The integrated approach provides a framework for improved understanding of seepage conditions at the site.
The document summarizes a study on the physico-chemical characterization of water quality in Dayet Aoua lake in Morocco. Key findings from the study include:
1) The lake water is transparent with a maximum depth of 5.3 meters. Temperatures ranged from 7.1°C to 25.6°C depending on the season.
2) pH levels remained alkaline between 7.77 and 11.45. Dissolved oxygen levels indicated the lake is well oxygenated.
3) Nutrient levels of nitrogen, phosphorus and chlorophyll-a were low, indicating an absence of organic pollution and classifying the lake as mesotrophic.
The document summarizes a study on the physico-chemical characterization of water quality in Dayet Aoua lake in Morocco. Key findings from the study include:
1) The lake water is transparent with a maximum depth of 5.3 meters. Temperatures ranged from 7.1°C to 25.6°C depending on the season.
2) pH levels remained alkaline between 7.77 and 11.45. Dissolved oxygen levels indicated the lake is well oxygenated.
3) Nutrient levels of nitrogen, phosphorus and chlorophyll-a were low, indicating an absence of organic pollution and classifying the lake as mesotrophic.
The document summarizes a study on the physico-chemical characterization of water quality in Dayet Aoua lake in Morocco. Key findings from the study include:
1) The lake water is transparent with a maximum depth of 5.3 meters. Temperatures ranged from 7.1°C to 25.6°C depending on the season.
2) pH levels remained alkaline between 7.77 and 11.45. Dissolved oxygen levels indicated the lake is well oxygenated.
3) Nutrient levels of nitrogen, phosphorus and chlorophyll-a were low, indicating an absence of organic pollution and classifying the lake as mesotrophic.
This document summarizes a study of the physico-chemical characteristics of Lake Dayet Aoua in Morocco between March 2015 and February 2016. Key findings include:
- The lake water is transparent with a maximum depth of 5.3 meters. Dissolved oxygen levels were high, indicating the lake is well-oxygenated throughout.
- Temperature varied seasonally from 7.1°C in winter to 25.6°C in summer. The water remained well-mixed with no temperature variation between surface and bottom.
- pH was alkaline, ranging from 7.77 to 11.45. Conductivity varied from 362 to 520 μs/cm depending on inflow from a tributary river
Analysis Of Core Samples And Stratigraphic Sections In Light Of The Glacial G...West Hollow MS Ms. Gill
The document analyzes stratigraphic sections and a core sample from Long Island in light of its glacial geology. Stratigraphic columns were created from exposed sections along a creek valley wall at Stony Brook University, showing layers of organic material, loess, clay, sand, gravel, and iron/manganese. A core sample was also taken and analyzed, showing alternating layers of gravelly sand and silty sand, indicative of glacial outwash stream channels. Sediments found in both the core and exposed sections are consistent with glacial depositional environments like tunnel valleys and outwash plains on Long Island.
This study reconstructs stable nitrogen isotopic ratios from sediment core samples at Ocean Drilling Program Site 1010 along the California margin from the past 5 million years. The results show relatively stable and enriched δ15N values, which can be interpreted in two ways. First, near complete nutrient utilization at coastal sites led to Rayleigh distillation effects transporting nitrate to Site 1010 through surface currents. Second, Site 1010 itself experiences complete nitrate utilization with no changes in denitrification, unlike sites 1012 and 1242 which do show changes. The aim is to expand reconstructions of oxygen minimum zone conditions to this site further offshore to help understand global changes in the fixed nitrogen inventory and atmospheric CO2 during the Pli
The document discusses how climate change is reducing Arctic sea ice, opening up new shipping routes like the Northern Sea Route. It analyzes projections from a high-resolution ocean model that show sea ice declining rapidly after 2030, allowing shipping in summer without icebreakers after 2050. Shorter Arctic routes could cut shipping times and emissions, but also impact the Arctic environment if accidents occurred. Improved forecasts will help shipping assess risks and benefits of Arctic operations.
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
Impacts of Hydrology and Habitat Changes on the Primary Production of the Ton...tacochrane
Arias, M.E., Cochrane, T.A., Piman, T. and Kummu M. (2012) Impacts of hydrology and habitat changes on the primary production of Southeast Asia's largest lake. IWA (International Water Association) World Congress on Water, Climate and Energy. Dublin, Ireland, 13-18 May 2012.
This study focuses on determining rock properties, trap integrity, and fluid presence in the Hammerfest Basin to lower exploration risk. Seven different play models in the basin were evaluated using well log analysis, AVI seismic inversion, and lithology/fluid prediction from a regional seismic dataset. The plays include Permian, Triassic, Jurassic, and Cretaceous reservoirs, with the main risks being adequate source and migration, and intact traps. Absolute acoustic impedance and Poisson's ratio were mapped throughout the basin to better understand the rock properties of different plays and aid future exploration.
This study presents a comprehensive digital mosaic of ice motion across Antarctica assembled from satellite radar data. The data reveal widespread, patterned, enhanced flow of tributary glaciers reaching hundreds to thousands of kilometers inland over the entire continent. This emphasizes the importance of basal-slip dominated tributary flow over deformation-dominated ice sheet flow, redefining our understanding of ice sheet dynamics. The extensive network of fast-flowing tributaries challenges prior views of ice sheet flow and implies a tighter connection between coastal and interior ice flow than previously thought.
Conclusions
• Studyingthecurrentstateofsub-seapermafrost is of critical importance in order to elucidate the time scale of the ongoing process;
• Giventhatspatialandtemporalvariabilityof methane releases is very high, this underscores importance of establishing monitoring network over the ESAS;
• ConsideringthesignificanceoftheESAS methane reservoir and enhancing mechanism of its destabilization, this region should be considered the most potential in terms of possible climate change caused by abrupt release of methane.
1) The study modifies the geometry of the Fraser River in a numerical ocean model to improve simulations of tides and the Fraser River plume.
2) Extending and deepening the river channel generated stronger cross-strait surface currents that better matched observations, and tidal amplitudes in the estuary corresponded well with measurements.
3) Reducing vertical mixing parameters, such as eddy viscosity and diffusivity, produced weaker along-strait flow and surface current patterns closer to drifter data, further improving the model results.
Delineation of Hydrocarbon Bearing Reservoirs from Surface Seismic and Well L...IOSR Journals
Hydrocarbon reservoir has been delineated and their boundaries mapped using direct indicators from 3-D seismic and well log data from an oil field in Nembe creek, Niger Delta region. Well log signatures were employed to identify hydrocarbon bearing sands. Well to seismic correlation revealed that these reservoirs tied with direct hydrocarbon indicators on the seismic section. The results of the interpreted well logs revealed that the hydrocarbon interval in the area occurs between 6450ft to 6533ft for well A, 6449ft to 6537ft for well B and 6629ft to 6704ft for well C; which were delineated using the resistivity, water saturation and gamma ray logs. Cross plot analysis was carried out to validate the sensitivity of the rock attributes to reservoir saturation condition. Analysis of the extracted seismic attribute slices revealed HD5000 as hydrocarbon bearing reservoir.
CLIMATE CHANGE, SEA-LEVEL RISE and COASTAL GEOLOGIC HAZARDSriseagrant
CLIMATE CHANGE, SEA-LEVEL RISE
and
COASTAL GEOLOGIC HAZARDS
URI Climate Change Symposium
5 May 2011
Jon C. Boothroyd
Rhode Island State Geologist,
Research Professor Emeritus – Quaternary Geology
-------------
Rhode Island Geological Survey and Department of Geosciences
College of the Environment and Life Sciences
University of Rhode Island
jon_boothroyd@uri.edu
The paper describes efforts to better understand an oil field in Oman through integrated interpretation of pressure, temperature, seismic and other data from a trial steam injection pattern, which showed a non-homogeneous response. Multiple geological models were built calibrated to production and surveillance data, finding that no single concept fully explains observations. A combination of fluvial facies distributions and internal reservoir structure with baffles and structural dip is likely needed to understand steam flood performance.
Stepped Pilo-Pleistocene climate variablity at Lake EUmassGeo
This document summarizes research from a team studying the 3.58 million year climate record from Lake El'gygytgyn in Arctic Russia. The record shows stepped Plio-Pleistocene climate variability with a transition from a warm and wet Pliocene to cooler and more variable glacial/interglacial conditions in the Pleistocene. Significant findings include evidence of forested conditions in the Arctic prior to 3 million years ago, a complex transition to tundra vegetation by 2.3 million years ago, and periods of extreme warmth called "super interglacials" that may have been linked to Antarctic ice sheet disintegration events. The cause of these super interglacials remains unclear but does not appear
This document discusses climate change, coastal hazards, and sea level rise in Rhode Island. It provides background on past glaciation and ice sheets in the region. It then examines current coastal hazards from storms and erosion exacerbated by sea level rise. Projections show global sea level rising significantly by 2100 due to climate change, threatening Rhode Island's coasts with flooding and barrier migration. Adaptation strategies may be needed to address these coastal impacts of climate change.
Anisotropic Avo Analysis for Reservoir Characterization in Derby Field Southe...IOSRJAP
Anisotropic AVO analysis for reservoir characterization in Derby field southeastern Niger delta has been investigated. The objective of this study was to investigate the AVO response of shale over gas sandsonisotropic and anisotropic synthetic models and the real CDP gathers. This was done by plotting amplitude of reflections versus offsets and carrying out AVO intercept-gradient analysison HD1horizon. The results of the models were compared with the real CDP gather to deduce the robust synthetic model for efficient AVO analysis in the field. Well, CDP processed gathers and Hampson-Russell GEOVIEW and AVO module were used for the analysis. Results revealed that the plots of amplitude versus offset of the isotropic and anisotropic synthetic models agree at near offset but show opposite AVO response due to increasing contributions of seismic anisotropy at far offsets. The results of the anisotropic synthetic model correlates well with the CDP gathers indicating that seismic anisotropy is an important factor in AVO analysis. Results also show that a bright spot indicative of gas charged sands was delineated for the isotropic and anisotropic models but with different classes of AVO anomalies andproducts. The isotropic synthetic model show a class II AVO anomaly with a positive AVO product, while the anisotropic model show a class IV AVO anomaly with a negative AVO product comparable to the real CDP gather.These analysesclearly show that description of rock without anisotropy especially, seismic anisotropy is incomplete since most rocks are not completely isotropic. Therefore, accounting for seismic anisotropy in AVO synthetic modelling will ensure that the correct earth model is predicted and the reservoir is adequately characterized.
This document summarizes a hydrogeophysical investigation using self-potential and resistivity surveys at Hidden Dam in California to better understand seepage patterns and subsurface geology. 512 self-potential measurements identified known seepage areas and a potential new area, while two 2,500 foot resistivity profiles indicated a sediment channel that may be a significant seepage pathway. Numerical modeling of subsurface flow correlated with geophysical data and confirmed a focusing of seepage in low-lying areas downstream, consistent with past observations. The integrated approach provides a framework for improved understanding of seepage conditions at the site.
The document summarizes a study on the physico-chemical characterization of water quality in Dayet Aoua lake in Morocco. Key findings from the study include:
1) The lake water is transparent with a maximum depth of 5.3 meters. Temperatures ranged from 7.1°C to 25.6°C depending on the season.
2) pH levels remained alkaline between 7.77 and 11.45. Dissolved oxygen levels indicated the lake is well oxygenated.
3) Nutrient levels of nitrogen, phosphorus and chlorophyll-a were low, indicating an absence of organic pollution and classifying the lake as mesotrophic.
The document summarizes a study on the physico-chemical characterization of water quality in Dayet Aoua lake in Morocco. Key findings from the study include:
1) The lake water is transparent with a maximum depth of 5.3 meters. Temperatures ranged from 7.1°C to 25.6°C depending on the season.
2) pH levels remained alkaline between 7.77 and 11.45. Dissolved oxygen levels indicated the lake is well oxygenated.
3) Nutrient levels of nitrogen, phosphorus and chlorophyll-a were low, indicating an absence of organic pollution and classifying the lake as mesotrophic.
The document summarizes a study on the physico-chemical characterization of water quality in Dayet Aoua lake in Morocco. Key findings from the study include:
1) The lake water is transparent with a maximum depth of 5.3 meters. Temperatures ranged from 7.1°C to 25.6°C depending on the season.
2) pH levels remained alkaline between 7.77 and 11.45. Dissolved oxygen levels indicated the lake is well oxygenated.
3) Nutrient levels of nitrogen, phosphorus and chlorophyll-a were low, indicating an absence of organic pollution and classifying the lake as mesotrophic.
This document summarizes a study of the physico-chemical characteristics of Lake Dayet Aoua in Morocco between March 2015 and February 2016. Key findings include:
- The lake water is transparent with a maximum depth of 5.3 meters. Dissolved oxygen levels were high, indicating the lake is well-oxygenated throughout.
- Temperature varied seasonally from 7.1°C in winter to 25.6°C in summer. The water remained well-mixed with no temperature variation between surface and bottom.
- pH was alkaline, ranging from 7.77 to 11.45. Conductivity varied from 362 to 520 μs/cm depending on inflow from a tributary river
The document analyzes coastal processes at Southern Palm Beach on the Gold Coast of Australia. Fieldwork and analysis found the beach is wave-dominated and highly dynamic, changing morphology frequently. Seasonal storms and tropical cyclones increase risks like beach erosion and flooding during peak tourism season. Due to unpredictable beach conditions, erosion hazards, and high maintenance costs, the document recommends against constructing a resort at the proposed site. A location further south near Currumbin Creek may be more suitable due to higher elevation and sediment accumulation.
The document discusses satellite radar altimeter measurements of elevation changes in the Larsen Ice Shelf between 1992 and 2001. It finds that the ice shelf lowered by up to 0.27 meters per year on average. This thinning is explained by increased summer meltwater and loss of basal ice through melting. Enhanced ocean-driven melting may provide a link between regional climate warming and the successive breakup of sections of the Larsen Ice Shelf. Testing rules out other potential causes of thinning like changes in sea level, ocean density, or surface accumulation. The long-term thinning observed suggests meltwater production alone does not account for the lowering, indicating additional thinning mechanisms are also involved.
Climate change is unbalancing the hydrological cycle in Latin America, causing more extreme floods and droughts. This is shifting hydroelectric power capacity and changing river flows. The Earth Simulator model projects further intensification of rainfall and longer dry periods under climate change. This will compromise the ability of mountain basins to regulate water flows as glaciers recede and fires reduce vegetation. To adapt, impacts must be assessed at the basin level to strengthen systems' resiliency and minimize reliability impacts.
The document summarizes the ocean's global conveyor belt circulation system. It describes how cold, dense water sinks near Iceland and flows south as the lower limb of the conveyor belt through the deep Atlantic. As it circulates around Antarctica, it mixes with other deep waters and loses its identity. About one part of the northern Atlantic deep water mixes with two parts of southern-sourced deep water to form the global deep water circulation. The upper limb returns water to the surface in the Pacific and Indian Oceans through upwelling that is more widespread than depicted by the iconic conveyor belt diagram.
Sea levels have changed dynamically throughout the Holocene epoch due to the interplay between absolute sea level changes and vertical land movement. As ice sheets melted after the last glacial period, sea levels rose globally from -130m to current levels through a combination of glacio-eustatic sea level rise and local glacio-isostatic land rebound and subsidence. Records of past sea level changes are reconstructed from dated geological indicators to develop sea level curves. Interpreting these indicators requires understanding their relationship to contemporaneous tide levels.
Hydrodynamic Factors Affecting The Persistence Of The Exxon Valdez Oil In A S...Jamie Boyd
This document summarizes a field study and numerical modeling of flow in a tidal gravel beach in Knight Island, Alaska where oil from the 1989 Exxon Valdez spill persisted. Measurements found the beach has a two-layer structure with a high permeability surface layer underlain by a low permeability lower layer. Simulations accurately reproduced observed water levels, salinity, and tracer concentrations. Small inland flow and tidal influence caused exchange between the beach and sea, explaining oil persistence. Nutrient addition simulations showed bioremediation could work if nutrients were not limiting.
Reservoir Characterization from Abnormal Pressure in Parts of Eleme, Southea...Scientific Review SR
This document analyzes well log data from two wells, Wells A and B, in Eleme, Nigeria to characterize abnormal reservoir pressures. Well logs including density, sonic, and acoustic impedance were interpreted to determine zones of abnormal pressure. For Well A, abnormal pressure was found between 2185-2785m, and for Well B between 1805-2525m. These zones had densities greater than 1.07kg/cm3 and pressure gradients exceeding normal hydrostatic gradients for the area. Accurately determining abnormal pressure zones is important for safely drilling wells in the region.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.