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At least 217 records · Page 12

On magnetodynamic effects initiated by a high-speed impact of a large cosmic body upon the Earth's surface

The impact of a large cosmic body with typical size R approximately = 1 km (mass M approximately = 4-10 Gt for a stony or icy body) moving with velocity V approximately = 50-70 km/s (kinetic energy of the order of 10 exp 21 J or 10 exp 6 Mt of TMT) on the Earth's surface leads to a full vaporization of a body and of a significant part of substance of the upper layers of the Earth and even to the ionization of this vapor cloud. As a result, a hypersonic jet of air and erosion plasma is formed. The kinetic energy E sub J is far above the total energy of the geomagnetic field of the Earth (approximately equivalent to the energy of 100 Mt) and the total mass of a fast-moving part of the jet M sub j approximately = 10 exp 12 kg is far above the mass of atmosphere in the jet expansion cone. Thus, the jet will propagate practically inertially with the constant mean velocity U approximately = 10-20 km/s and even higher. The interaction of this plasma jet with the Earth's magnetic field causes magnetodynamic effects similar to those which are produced by cosmic nuclear explosions but of a larger scale. The preliminary results of experimental and numerical modeling of the plasma jet-magnetosphere interaction are presented.

Nemchinov, I. V.↗

Taming the Wild West: Assessing Impacts-Relevant Climate Data Products (Abbreviated Report)

Impacts-relevant Earth system data refers to observational and ESM data that are downscaled, debiased, validated, and provisioned for use by decision-makers. Impacts-relevant Earth system data is essential for mitigation and adaptation planning across a variety of regions and sectors. A vast number of these data products have emerged in recent years, which has led to confusion among stakeholders and scientists as to the best product to use. With no standard evaluation protocol available for these products, the decision on which product to use was sometimes made because it was pragmatic rather than the best product to use. This project sought to develop foundational capabilities around impacts-relevant data products that would support more informed selection and application of these products. This work has been immensely successful, driving several academic publications and supported the development of a community of practice around impacts-relevant data products. Over the project’s three years we have addressed six tasks: First, the development of standard evaluation metrics for impacts-relevant climate data; second, the development of a novel suite of atmospheric river metrics; third, the development of novel metrics for precipitation feature analysis; fourth, the development of novel metrics for assessing co-variances between temperature and precipitation; fifth, the development of a dashboard for interactive examination of impacts-relevant climate data; and sixth, the establishment of a community of practice around impacts-relevant climate data that will continue beyond the conclusion of this project.

54 ENVIRONMENTAL SCIENCES↗

Taming the Wild West: Assessing Impacts-Relevant Climate Data Products (Final Report)

Impacts-relevant Earth system data refers to observational and ESM data that are downscaled, debiased, validated, and provisioned for use by decision-makers. Impacts-relevant Earth system data is essential for mitigation and adaptation planning across a variety of regions and sectors. A vast number of these data products have emerged in recent years, which has led to confusion among stakeholders and scientists as to the best product to use. With no standard evaluation protocol available for these products, the decision on which product to use was sometimes made because it was pragmatic rather than the best product to use. This project sought to develop foundational capabilities around impacts-relevant data products that would support more informed selection and application of these products. This work has been immensely successful, driving several academic publications and supported the development of a community of practice around impacts-relevant data products.

54 ENVIRONMENTAL SCIENCES↗

Using Information from Rendezvous Missions For Best-Case Appraisals of Impact Damage to Planet Earth Caused By Natural Objects

The Asteroid Threat Assessment Project (ATAP), a part of NASAs Planetary Defense Coordination Office (PDCO) has the responsibility to appraise the range of surface damage by potential asteroid impacts on land or water. If a threat is realized, the project will provide appraisals to officials empowered to make decisions on potential mitigation actions. This paper describes a scenario for assessment of surface damage when characterization of an asteroid had been accomplished by a rendezvous mission that would be conducted by the international planetary defense community. It is shown that the combination of data from ground and in-situ measurements on an asteroid provides knowledge that can be used to pin-point its impact location and predict the level of devastation it would cause. The hypothetical asteroid 2017 PDC with a size of 160 to 290 m in diameter to be discussed at the PDC 2017 meeting is used as an example. In order of importance for appraising potential damage, information required is: (1) where will the surface impact occur? (2) What is the mass, shape and size of the asteroid and what is its entry state (speed and entry angle) at the 100 km atmospheric pierce point? And (3) is the asteroid a monolith or a rubble pile? If it is a rubble pile, what is its sub and interior structure? Item (1) is of first order importance to determine levels of devastation (loss of life and infrastructure damage) because it varies strongly on the impact location. Items (2) and (3) are used as input for ATAPs simulations to define the level of surface hazards: winds, overpressure, thermal exposure; all created by the deposition of energy during the objects atmospheric flight, and/or cratering. Topics presented in this paper include: (i) The devastation predicted by 2017 PDCs impact based on initial observations using ATAPs risk assessment capability, (ii) How information corresponding to items (1) to (3) could be obtained from a rendezvous mission, and (iii) How information from a rendezvous mission could be used, along with that from ground observations and data from the literature, could provide input for an new risk analysis capability that is emerging from ATAPs research. It is concluded that this approach would result in appraisal with the least uncertainty possible (herein called the best-case) using simulation capabilities that are currently available or will be in the future.

Arnold, James O.↗

Using Information from Rendezvous Missions For Best-Case Appraisals of Impact Damage to Planet Earth Caused By Natural Objects

The Asteroid Threat Assessment Project (ATAP), a part of NASAs Planetary Defense Coordination Office (PDCO) has the responsibility to appraise the range of surface damage by potential asteroid impacts on land or water. If a threat is realized, the project will provide appraisals to officials empowered to make decisions on potential mitigation actions. This paper describes a scenario for assessment of surface damage when characterization of an asteroid had been accomplished by a rendezvous mission that would be conducted by the international planetary defense community. It is shown that the combination of data from ground and in-situ measurements on an asteroid provides knowledge that can be used to pin-point its impact location and predict the level of devastation it would cause. The hypothetical asteroid 2017 PDC with a size of 160 to 290 m in diameter to be discussed at the PDC 2017 meeting is used as an example. In order of importance for appraising potential damage, information required is: (1) where will the surface impact occur? (2) What is the mass, shape and size of the asteroid and what is its entry state (speed and entry angle) at the 100 km atmospheric pierce point? And (3) is the asteroid a monolith or a rubble pile? If it is a rubble pile, what is its sub and interior structure? Item (1) is of first order importance to determine levels of devastation (loss of life and infrastructure damage) because it varies strongly on the impact location. Items (2) and (3) are used as input for ATAPs simulations to define the level of surface hazards: winds, overpressure, thermal exposure; all created by the deposition of energy during the objects atmospheric flight, andor cratering. Topics presented in this paper include: (i) The devastation predicted by 2017 PDCs impact based on initial observations using ATAPs risk assessment capability, (ii) How information corresponding to items (1) to (3) could be obtained from a rendezvous mission, and (iii) How information from a rendezvous mission could be used, along with that from ground observations and data from the literature, could provide input for an new risk analysis capability that is emerging from ATAPs research. It is concluded that this approach would result in appraisal with the least uncertainty possible (herein called the best-case) using simulation capabilities that are currently available or will be in the future.

Arnold, J. O.↗

Using Information from Rendezvous Missions for Best-Case Appraisals of Impact Damage to Planet Earth Caused by Natural Objects

The Asteroid Threat Assessment Project (ATAP), a part of NASAs Planetary Defense Coordination Office (PDCO) has the responsibility to appraise the range of surface damage by potential asteroid impacts on land or water. If a threat is realized, the project will provide appraisals to officials empowered to make decisions about potential mitigation actions. This paper describes a scenario for assessment of surface damage when characterization of an asteroid had been accomplished by a rendezvous mission that would be conducted by the international planetary defense community. It is shown that the combination of data from ground and in-situ measurements on an asteroid provides knowledge that can be used to pin-point its impact location and predict the level of devastation it would cause. The hypothetical asteroid 2017 PDC with a size range of 160 to 290 m in diameter to be discussed at the PDC 2017 is used as an example. In order of importance for appraising potential damage, information required is: (1) where will the surface impact occur? (2) what is the mass, shape and size of the asteroid and what is its entry state (speed and entry angle) at the 100 km atmospheric pierce point? And (3) is the asteroid a monolith or a rubble pile? If it is a rubble pile, what is its structure and heterogeneity from the surface and throughout its interior? Item (1) is of first order importance to determine levels of devastation (loss of life and infrastructure damage) because it varies strongly on the impact location. Items (2) and (3) are used as inputs for ATAPs simulations to define the level of surface hazards: winds, overpressure, thermal exposure; all created by the deposition of energy during the objects atmospheric flight, andor cratering. Topics presented in this paper include: (i) the devastation predicted by 2017 PDCs impact on land based on initial observations using ATAPs risk assessment capability, (ii) how information corresponding to items (1) to (3) could be obtained from a rendezvous mission, and (iii) how information from a rendezvous mission could be used, along with that from ground observations and data from the literature to provide input for a new risk analysis capability that is emerging from ATAPs research. It is concluded that this approach would result in the creation of an appraisal of the threat from 2017 PDC with the least uncertainty possible, herein called the best-case.

Asteroid Impact Appraisals↗

Biospheric traumas caused by large impacts and predicted relics in the sedimentary record

When a large asteroid or comet impacts the Earth the supersonic plume ejected on impact causes severe shock heating and chemical reprocessing of the proximal atmosphere. The resultant NO is converted rapidly to NO2, foliage damage due to exposure to NO2 and HNO3, toxicosis resulting from massive mobilization of soil trace metals, and faunal asphyxiation due to exposure to NO2. One class of relic evidence for the above effects arises because extinction of species caused by these chemically induced traumas would be selective. A second class of relic evidence arises because the acid rain will cause massive weathering of continental rocks and soils characterized by large ratios of the relatively insoluble metals, to the more soluble metals. This weathering would be best recorded in fossils in unperturbed deltaic, neritic, or limnetic sediments and for metals with very long oceanic residence times in deep ocean sediments as well. This evidence is discussed.

Prinn, R. G.↗

Big Science in Small Packages: a Constellation of Cubesats to Search for Near Earth Asteroids

Astronomers for many decades have been searching for Near Earth Asteroids (NEA) that could potentially impact the Earth in the future. Large Synoptic Survey Telescope (LSST), when completed, would be by far the most powerful tool for a ground-based search for NEAs. In space, IR telescopes are undergoing detailed design studies. These facilities are projected to find 90% of potentially hazardous NEAs in about a dozen years. We introduce a different approach to search for these objects by using multiple micro- and nano-spacecraft distributed in orbit around the Sun. Their ability to faint moving objects with small telescopes is based on a new generation of low noise, fast-frame cameras combined with processors that can execute 100’s of gigaflops in a low power space environment.

Shao, Michael↗

The Impact Hazard

The Earth has been subject to hypervelocity impacts from comets and asteroids since its formation, and such impacts have played an important role in the evolution of life on our planet. We now recognize not only the historical role of impacts, but the contemporary hazard posed by such events. In the absence of a complete census of potentially threatening Earth-crossing asteroids or comets (called collectively Near Earth Objects, or NEOs), or even of a comprehensive cur-rent search program to identify NEOs, we can consider the hazard only from a probabilistic perspective. We know the steep power-law relationship between NEO numbers and size, with many more small bodies than large ones. We also know that few objects less than about 50 m in diameter (with kinetic energy near 10 megatons) penetrate the atmosphere and are capable of doing surface damage. But there is a spectrum of possible impact hazards associated with objects from this 10-megaton threshold all the way up to NEOs 5 km or larger in diameter, which are capable of inflicting severe damage on the environment, leading to mass extinction's of species. Detailed analysis has shown that, in general, the larger the object the greater the hazard, even when allowance is made for the infrequency of large impacts. Most of the danger to human life is associated with impacts by objects roughly 2 km or larger (energy greater than 1 million megatons), which can inject sufficient submicrometer dust into the atmosphere to produce a severe short-term global cooling with subsequent loss of crops, leading to starvation. Hazard estimates suggest that the chance of such an event occurring during a human lifetime is about 1:5000, and the global probability of death from such impacts is of the order of 1:20000, values that can be compared with risks associated with other natural hazards such as earthquakes, volcanic eruptions, and severe storms. However, the impact hazard differs from the others in that it can be largely prevented by a comprehensive survey for threatening objects and the application of technological solutions to deflect or destroy objects that are found to have orbits that will lead to collision with the Earth.

Morrison, David↗

Impact-induced atmospheres and oceans on earth and Venus

The effects of planetesimal-impact induced atmosphere formation on the earth and Venus are modeled to gain an indication why the two planets, at relatively equal distances from the sun, evolved so differently. Both planets gained approximately 10 to the 21 kg of water from the impacts. The water mass of the accreting planetesimals would have remained, initially, as a hot atmosphere. A two-stream approximation is defined for the temperature profile of a plane parallel atmosphere in radiative equilibrium. It is shown that the Venus atmosphere did not, as happened on earth, condense into a hot ocean after the impact epoch. Instead, the greenhouse effect caused the Venus equilibrium thermal structure to remain higher than the vapor pressure, keepinig the atmosphere in a vapor phase until the vapor dissociated and H2 atoms eventually escaped into space.

Matsui, T.↗

Hestia SW-IFL Onroad Fossil Fuel Carbon Dioxide (FFCO2) product: Road segment-level annual FFCO2 emissions across Arizona (2017-2022), version 1.1

The SW-IFL onroad fossil fuel carbon dioxide (FFCO2) emissions data product represents CO2 emissions from the combustion of fossil fuels by motor vehicles (e.g., passenger cars, trucks, buses, motorcycles) traveling on designated roadways. The emissions are represented geographically on each road segment within the state of Arizona spanning the 2017 to 2022 time period. This data product was developed as part of the Southwest Urban Corridor Integrated Field Laboratory (SW-IFL) project, which aims to provide new knowledge and tools that address urban environmental issues by integrating high-resolution observations, modeling, and civic engagement. The emissions data are provided in CSV (input data, ONR_FFCO2_AZ_county.csv) and GeoPackage form (output polyline objects - about 786,000 road segments, XXXX_AZ_v1.1.gpkg) designated by road class (interstates, arterials, collectors, local). The metadata file (Metadata_SW-IFL_Onroad_annualFFCO2_v1.1.docx) provides details about attributes and data formats. The GeoPackage emissions data are provided separately for local roads and nonlocal roads (interstates, arterials, collectors). The method file (Methods_SW-IFL_Onroad_annualFFCO2_v1.1.docx) describes the data processing flow and data sources. Update on 2024-04-17: Updates were made to both the input emission data file (.csv) and output segment-level emission file (.gpkg). There was an update in county-level emission input data (ONR_FFCO2_AZ_county.csv) and the entire road segments were reprocessed to reflect this update.Update on 2024-04-29: Update was made to one output segment-level emission file (Nonlocal_AZ_v1.0.gpkg). There was an error in the AADT values and the data were reprocessed to reflect this update.Update on 2024-10-22: Temporal coverage was extended to include 2022. VMT values were recalculated using new AADT data and the entire road segments were reprocessed to reflect these updates.

54 ENVIRONMENTAL SCIENCES↗

Thermal equilibration of the earth following a giant impact

A thermal evolution model for the cooling of a terrestrial planet, a prescribed fraction of which is melted during a giant impact, is described. Two model geometries are considered, one having a laterally inhomogeneous distribution of melt and solid through a mega-crater geometry and the other having a global magma ocean. It is found that almost the whole planet may melt if the impact originally melted half of the planet and if the first melt temperature was double a typical planet melting temperature. For reasonable choices of parameter values it is determined that thermal equilibration of the earth occurs on a time-scale of 1 to ten million years.

Spohn, Tilman↗

Impacts and tectonism in Earth and moon history of the past 3800 million years

The moon's surface, unlike the Earth's, displays a comparatively clear record of its past bombardment history for the last 3800 Myr, the time since active lunar tectonism under the massive premare bombardment ended. From Baldwin's (1987) tabulation of estimated ages for a representative sample of large lunar craters younger than 3800 Ma, six major cratering episodes can be discerned. These six bombardment episodes, which must have affected the Earth too, appear to match in time the six major episodes of orogenic tectonism on Earth, despite typical resolution errors of +/- 100 Myr and the great uncertainties of the two chronologies. Since more highly resolved events during the Cenozoic and Mesozoic Eras suggest the same correlation, it is possible that large impacts have influenced plate tectonics and other aspects of geologic history, perhaps by triggering flood basalt eruptions.

Stothers, Richard B.↗

Invited review: gravitational biology of the neuromotor systems: a perspective to the next era

Earth's gravity has had a significant impact on the designs of the neuromotor systems that have evolved. Early indications are that gravity also plays a key role in the ontogenesis of some of these design features. The purpose of the present review is not to assess and interpret a body of knowledge in the usual sense of a review but to look ahead, given some of the general concepts that have evolved and observations made to date, which can guide our future approach to gravitational biology. We are now approaching an era in gravitational biology during which well-controlled experiments can be conducted for sustained periods in a microgravity environment. Thus it is now possible to study in greater detail the role of gravity in phylogenesis and ontogenesis. Experiments can range from those conducted on the simplest levels of organization of the components that comprise the neuromotor system to those conducted on the whole organism. Generally, the impact of Earth's gravitational environment on living systems becomes more complex as the level of integration of the biological phenomenon of interest increases. Studies of the effects of gravitational vectors on neuromotor systems have and should continue to provide unique insight into these mechanisms that control and maintain neural control systems designed to function in Earth's gravitational environment. A number of examples are given of how a gravitational biology perspective can lead to a clearer understanding of neuromotor disorders. Furthermore, the technologies developed for spaceflight studies have contributed and should continue to contribute to studies of motor dysfunctions, such as spinal cord injury and stroke. Disorders associated with energy support and delivery systems and how these functions are altered by sedentary life styles at 1 G and by space travel in a microgravity environment are also discussed.

Review, Tutorial↗

Impacts of NASA's Earth Observations on Subseasonal and Seasonal Forecasts

NASA's suite of Earth-observing satellites provides a unique view of many processes on Earth, with relevance on timescales ranging from hours to weeks and even years. NASA's observations span all parts of the Earth system: atmospheric, ocean, land and cryosphere, and include physical, chemical and biological components. This presentation explores use of NASA observations in extended-range prediction, from many days to months, using the Goddard Earth Observing System (GEOS) assimilation and predictive modeling capabilities. The skill of a weather forecast is linked to the fidelity of the initialization process (data assimilation) and the realistic representation of "fast" physical processes in the model. At longer time horizons, the slower "feedback" processes in the Earth System begin to take a more prominent role in the accuracy of the forecast. Simultaneously, forecast-skill attribution transitions away from feature-based metrics that emphasize smaller scales (e.g., representations of fronts and vortices) to metrics that emphasize the statistical distributions of large-scale features (e.g., ENSO diagnostics and teleconnections). This presentation will summarize studies performed using the GEOS-S2S (subseasonal to seasonal) system that explore the impacts of NASA observations on the fidelity of the forecasts. The GEOS-S2S system is configured for the atmosphere-ocean-land-ice model and is initialized using in-situ and space-based observations, including atmospheric aerosols and ozone which are not typically analyzed in such systems. The GEOS-S2S model routinely includes aerosol feedbacks, which systematically impact the realism of the forecasts, providing a first example of how suitable NASA observations impact the performance of the GEOS-S2S system. Studies in which a stratospheric chemistry module is activated in the GEOS-S2S system allow the impacts of ozone radiative feedbacks to be isolated. Space-based observations of sea-surface temperature and altimetry are routinely analyzed for the initialization of the GEOS-S2S system; recent advances allow the use of NASA's sea-surface salinity data, which are shown to impact the long-range skill of the forecasts.

Pawson, Steven↗

Cloudy with a Chance of Solar Flares: The Sun as a Natural Hazard

Space weather is a naturally occurring phenomenon that represents a quantifiable risk to space- and ground-based infrastructure as well as society at large. Space weather hazards include permanent and correctable faults in computer systems, Global Positioning System (GPS) and high-frequency communication disturbances, increased airline passenger and astronaut radiation exposure, and electric grid disruption. From the National Space Weather Strategy, published by the Office of Science and Technology Policy in October 2015, space weather refers to the dynamic conditions of the space environment that arise from emissions from the Sun, which include solar flares, solar energetic particles, and coronal mass ejections. These emissions can interact with Earth and its surrounding space, including the Earth's magnetic field, potentially disrupting technologies and infrastructures. Space weather is measured using a range of space- and ground-based platforms that directly monitor the Sun, the Earth's magnetic field, the conditions in interplanetary space and impacts at Earth's surface, like neutron ground-level enhancement. The NASA Goddard Space Flight Center's Space Weather Research Center and their international collaborators in government, industry, and academia are working towards improved techniques for predicting space weather as part of the strategy and action plan to better quantify and mitigate space weather hazards. In addition to accurately measuring and predicting space weather, we also need to continue developing more advanced techniques for evaluating space weather impacts on space- and ground-based infrastructure. Within the Earth's atmosphere, elevated neutron flux driven by atmosphere-particle interactions from space weather is a primary risk source. Ground-based neutron sources form an essential foundation for quantifying space weather impacts in a variety of systems.

neutron flux↗

Spatio-temporal multivariate cluster evolution analysis for detecting and tracking climate impacts

Recent years have seen a growing concern about climate change and its impacts. While Earth System Models (ESMs) can be invaluable tools for studying the impacts of climate change, the complex coupling processes encoded in ESMs and the large amounts of data produced by these models, together with the high internal variability of the Earth system, can obscure important source-to-impact relationships. Here, this paper presents a novel and efficient unsupervised data-driven approach for detecting statistically-significant impacts and tracing spatio-temporal source-impact pathways in the climate through a unique combination of ideas from anomaly detection, clustering and Natural Language Processing (NLP). Using as an exemplar the 1991 eruption of Mount Pinatubo in the Philippines, we demonstrate that the proposed approach is capable of detecting known post-eruption impacts/events. We additionally describe a methodology for extracting meaningful sequences of post-eruption impacts/events by using NLP to efficiently mine frequent multivariate cluster evolutions, which can be used to confirm or discover the chain of physical processes between a climate source and its impact(s).

Anomaly detection↗