cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.94qcna
title: Impact Probability Under Aleatory And Epistemic Uncertainties

description: We present an approach to estimate an upper bound for the impact probability of a potentially hazardous asteroid when part of the force model depends on unknown parameters whose statistical distribution needs to be assumed. As case study we consider Apophis' risk assessment for the 2036 and 2068 keyholes based on information available as of 2013. Within the framework of epistemic uncertainties, under the independence and non-correlation assumption, we assign parametric families of distributions to the physical properties of Apophis that define the Yarkovsky perturbation and in turn the future orbital evolution of the asteroid. We find ${\rm IP}\leq 5\times 10^{-5}$ for the 2036 keyhole and ${\rm IP}\leq 1.6\times 10^{-5}$ for the 2068 keyhole. These upper bounds are largely conservative choices due to the rather wide range of statistical distributions that we explored.
DOI: 10.48577/jpl.dka4qq
title: Comparison of Near-Fault Displacement Interpretations from Field and Aerial Data for the M 6.4 and M 7.1 Ridgecrest Earthquake Sequence Ruptures

description: Surface fault displacement presents a serious potential hazard for structures an infrastructure lifelines. Roads, shallowly buried pipelines and electrical transmission lines, due to their distributed nature, tend to cover large distances and are bound to go through several fault crossings, especially in active tectonic regions like California. The fault displacement causes strains that can cause important damage and even complete interruption of the system for long periods of time. This constitutes an important source of seismic hazard, yet fault displacement measurements for engineering applications are quite sparse, making the development of predictive models extremely difficult and fraught with large uncertainties. Detailed fault geological mapping exists for a few documented cases, but they may not capture the full width of deformations that are likely to impact distributed infrastructure. The 2019 Ridgecrest Earthquake Sequence presented an ideal case to collect data and evaluate the ability of different techniques to capture coseismic deformations on and near the fault ruptures. Both the M 6.4 and M 7.1 events ruptured the surface in sparsely populated areas and in the desert where little vegetation was present to obscure the surface features. We selected two relatively small study areas (~400 m x 500 m) around the two fault rupture traces for this purpose. We deployed teams and coordinated with data collection campaigns to gather field measurements and photographs as well as imagery from small uninhabited aerial systems and from airborne light detection and ranging.. Each of these techniques requires a different level of resources in terms of labor and time associated with the data collection, processing and interpretation efforts as well as deployment cost. In this paper, we present our methodology along with qualitive and quantitative assessments of the methods used in our two study areas. Our validation showed that 44 overall, the three techniques could capture the features that are important for displacement design of distributed infrastructure. We found that the use of remote sensing methods in combination with some field measurements for calibration presented a strong advantage over the use of a single technique, but that consideration must be made for the resolution of each approach.
DOI: 10.48577/jpl.d5pkv0
title: End-to-end ground calibration and in-flight performance of the FIREBall-2 instrument

description: The payload of the Faint Intergalactic Redshifted Emission Balloon (FIREBall-2), the second generation15 of the FIREBall instrument (PI: C. Martin, Caltech), has been calibrated and launched from the NASA Columbia Sci16entific Balloon Facility (CSBF) in Fort Sumner, NM. FIREBall-2 was launched for the first time on the 22nd September17 2018, and the payload performed the very first multi-object acquisition from space using a multi-object slit spectro18graph (MOS). This performance-oriented paper presents the calibration and last ground adjustments of FIREBall-2,19 the in-flight performance assessed based on the flight data, and the predicted instrument’s ultimate sensitivity. This20 analysis predicts that future flights of FIREBall-2 should be able to detect the HI Ly↵ resonance line in galaxies at21 z ⇠ 0.67, but will find it challenging to spatially resolve the circumgalactic medium (CGM).
DOI: 10.48577/jpl.ephihe
title: Impact-Driven Mobilization of Deep Crustal Brines on Dwarf Planet Ceres

description: Ceres, the only dwarf planet in the inner solar system, appears to be a relict ocean world. Data collected by NASA’s Dawn spacecraft provided evidence that global aqueous alteration within Ceres resulted in a chemically evolved body that remains volatile-rich [1]. Recent emplacement of bright deposits sourced from brines attests to Ceres being a persistently geologically-active world [2, 3], but the surprising longevity of this activity at the 92-km Occator crater has yet to be explained. Here we use new high-resolution Dawn gravity data to study the subsurface architecture of the region surrounding Occator crater, which hosts extensive young bright carbonate deposits (faculae). Gravity data and thermal modeling imply an extensive deep brine reservoir beneath Occator, which we argue could have been mobilized by the heating and deep fracturing associated with the Occator impact, leading to long-lived extrusion of brines and formation of the faculae. Moreover, we find that pre-existing tectonic cracks may provide pathways for deep brines to migrate within the crust, extending the regions affected by impacts and creating compositional heterogeneity. The long-lived hydrological system resulting from the impact might also occur for large impacts in icy moons, with implications for creation of transient habitable niches over time.
DOI: 10.48577/jpl.yqtxqc
title: Tracking the Atmospheric Pulse of a North American Megacity from a Mountaintop Remote Sensing Observatory

description: Atmospheric carbon monoxide (CO) is an effective tracer for monitoring atmospheric transport processes and for detecting pollution sources of anthropogenic origin. However, very few observation systems exist that are capable of providing measurements with high spatial and temporal resolution to identify hotspots for emission control purposes. Here we introduce a mountain-top remote sensing observatory, the California Laboratory for Atmospheric Remote Sensing (CLARS), for mapping the enhancement of CO column-averaged mixing ratio (XCO) over the Los Angeles (LA) megacity. Compared to conventional observation networks, CLARS is unique in the following ways: (1) it mimics a geostationary satellite observatory for LA with hourly- and kilometer-scale mapping capability; (2) the free tropospheric background atmosphere is simultaneously measured; and (3) the measurements are highly sensitive to anthropogenic emissions due to the long light path along the planetary boundary layer (PBL). The CO slant column density and XCO are retrieved from reflected sunlight measurements in the 2.3 m CO band and the 1.27 m oxygen (O2) band. Data filtering and corrections for aerosol scattering and geometric effects are then implemented to derive the XCO enhancement, which is the XCO excess in the PBL compared to the background value. In the LA megacity, the XCO enhancement shows a distinctive diurnal cycle primarily driven by changes in anthropogenic emissions and sea-breeze circulation. Such diurnal patterns can be reproduced by the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). The enhancement also shows a significant weekly cycle resulting from the weekly pattern in anthropogenic CO emissions. On average, the XCO enhancements on Sunday and Saturday are 16.1% and 4.4%, respectively, lower than weekday values. The weekly XCO enhancement patterns also show high correlation with traffic counts. A seasonal pattern of XCO enhancement with high (low) spatial contrast in Summer (Winter), resulting from changing sea-breeze circulation, can be observed. These diurnal, weekly, and seasonal patterns of XCO enhancement serve as tracers of the atmospheric pulse of the LA megacity. The CLARS observatory can serve as a testbed for future geostationary missions to track anthropogenic emissions in cities.
DOI: 10.48577/jpl.ed46bs
title: Insights into the planetary dynamics of HD 206893 with ALMA

description: Radial substructure in the form of rings and gaps has been shown to be ubiquitous among protoplanetary discs. This could be the case in exoKuiper belts as well, and evidence for this is emerging. In this paper we present ALMA observations of the debris/planetesimal disc surrounding HD 206893, a system that also hosts two massive companions at 2 and 11 au. Our observations reveal a disc extending from 30 to 180 au, split by a 27 au wide gap centred at 74 au, and no dust surrounding the reddened brown dwarf (BD) at 11 au. The gap width suggests the presence of a 0.9 MJup planet at 74 au, which would be the third companion in this system. Using previous astrometry of the BD, combined with our derived disc orientation as a prior, we were able to better constrain its orbit finding it is likely eccentric (0:14+0:05 􀀀0:04). For the innermost companion, we used RV, proper motion anomaly and stability considerations to show its mass and semi-major axis are likely in the range 10–100 MJup and 1.4–2.7 au. These three companions will interact on secular timescales and perturb the orbits of planetesimals, stirring the disc and potentially truncating it to its current extent via secular resonances. Finally, the presence of a gap in this system adds to the growing evidence that gaps could be common in wide exoKuiper belts. Out of 6 wide debris discs observed with ALMA with enough resolution, 4–5 show radial substructure in the form of gaps.
DOI: 10.48577/jpl.esw3wt
title: Future Missions to the Giant Planets that can Advance Atmospheric Science Objectives

description: Other papers in this special issue have discussed the diversity of planetary atmospheres andsome of the key science questions for giant planet atmospheres to be addressed in thefuture. There are crucial measurements that can only be made by orbiters of giant planetsand probes dropped into their atmospheres. To help the community be more effectivedevelopers of missions and users of data products, we summarize how NASA and ESAcategorize their planetary space missions, and the restrictions and requirements placed oneach category. We then discuss the atmospheric goals to be addressed by currentlyapproved giant-planet missions as well as missions likely to be considered in the next fewyears, such as a joint NASA/ESA Ice Giant orbiter with atmospheric probe. Our focus is oninterplanetary spacecraft, but we acknowledge the crucial role to be played by ground-basedand near-Earth telescopes, as well as theoretical and laboratory work.
DOI: 10.48577/jpl.8xxtkq
title: Standing on Apollo’s Shoulders: a Microseismometer for the Moon

description: Seismometers deployed on the Moon by the Apollo astronauts from 1969 to 1972 detected moonquakes and impacts and added to our understanding of the lunar interior. Several lunar missions are currently being planned, including the Commercial Lunar Payload Services (CLPS), the Lunar Geophysical Network (LGN) and the astronaut program Artemis. We propose a microseismometer for the Moon: the Silicon Seismic Package (SSP). The SSP’s sensors are etched in silicon, and will have a noise floor below 2x10−10m/s2/√Hz between 0.03 and 3 Hz (similar to the Apollo instruments). The SSP will measure horizontal and vertical motion with the three sensors in a triaxial configuration and is robust to high shock (&gt;1000g) and vibration (&gt;30grms) with an operational range from -196Cto +60C, allowing deployment under harsh conditions. The first-generation version of this sensor, the SEIS-SP, was deployed on Mars in 2018 as part of the InSight mission’s seismic package. We will reconfigure the seismometer for the lower gravity of the Moon. At this level of performance, the limiting factor for detecting smaller moonquakes is the noise environment of the Moon. Using the Apollo seismic data, we estimate that a single SSP instrument operating for one year would detect around 74 events above a signal-to-noise ratio of 2.5, as well as an additional 500+ above the noise floor.A mission lasting from lunar dawn until dusk, carried on a CLPS lander, could test the instrument in-situ, and provide invaluable information for an extensive future network.
DOI: 10.48577/jpl.j8egng
title: Tidally-induced magmatic pulses on the oceanic floor of Jupiter’s moon Europa

description: Jupiter’s icy moon Europa harbours underneath a tectonically active ice shell, a salty ocean interacting with a possibly still active rocky interior. Such an oceanic environment makes Europa a primary target for the search of a habitable world outside the Earth5. The habitability of Europa’s ocean is conditioned by the heat released from the deep interior to the seafloor, and hence by the intensity of magmatic activity. Similarly to the volcanic moon, Io, tidal energy dissipated in its interior is expected to influence its thermal state. However, its impact on magmatic activity is still poorly constrained. Here we investigate the melting of the silicate mantle through time and the consequences for seafloor magmatism by modelling the heat production and transfer using a three-dimensional numerical model. Even though silicate volcanism is strongly reduced compared to Io, we show that a significant amount of silicate melts can be produced during most of Europa’s history due to the limited efficiency of internal cooling by thermal convection. The melting rate is amplified by tidal friction, possibly leading to magmatic pulses during periods of enhanced eccentricity. The volume of generated melts during magmatic episodes are comparable to those involved in Large Igneous Provinces (LIPs), commonly observed on Earth, and may have an impact on the oceanic chemistry. Tidal dissipation also leads to a concentration of magmatic activity at high latitudes, which signatures may be revealed by future exploration missions.
DOI: 10.48577/jpl.zeglq4
title: Acetonyl Peroxy and Hydro Peroxy Self- and Cross-Reactions: Kinetics, Mechanism, and Chaperone Enhancement from the Perspective of the Hydroxyl Radical Product

description: Pulsed laser photolysis coupled with infrared (IR) wavelength modulation spectroscopy and ultraviolet (UV) absorption spectroscopy was used to study the kinetics and branching fractions for the acetonyl peroxy (CH3C(O)CH2O2) self-reaction and the reaction with hydro peroxy (HO2) at a temperature and pressure of 298 K and 100 Torr, respectively. Near-IR and mid-IR lasers simultaneously monitored HO2 and hydroxyl, OH, respectively, while UV absorption measurements monitored the CH3C(O)CH2O2 concentrations. The overall rate constant for the reaction between CH3C(O)CH2O2 and HO2 was found to be (5.5 ± 0.5) × 10-12 cm3 molecule-1 s-1 and the branching fraction for OH yield from this reaction was directly measured as 0.30 ± 0.04. The CH3C(O)CH2O2 self-reaction rate constant was measured to be (4.8 ± 0.8) × 10-12 cm3 molecule-1 s-1 and the branching fraction for alkoxy formation was inferred from secondary chemistry as 0.33 ± 0.13. An increase in the rate of the HO2 self-reaction was also observed as a function of acetone (CH3C(O)CH3) concentration which suggests a chaperone effect resulting from hydrogen-bond complexation between HO2 and CH3C(O)CH3. The chaperone enhancement factor for CH3C(O)CH3 was determined to be kA = (4.0 ± 0.2)  10-29 cm6 molecule¬-2 s-1 and the equilibrium constant for HO2• CH3C(O)CH3 complex formation was found to be Kc(R15) = (2.0 ± 0.89) × 10-18 cm3 molecule-1; from these values the rate constant for the HO2 + HO2• CH3C(O)CH3 reaction was estimated to be (2 ± 1) × 10-11 cm3 molecule-1 s-1. Results from UV cross-section measurements of CH3C(O)CH2O2 and prompt OH radical yields arising from possible oxidation of the CH3C(O)CH3-derived alkyl radical are also discussed. Using theoretical methods, no likely pathways for the observed prompt OH radical formation have been found and this remains unexplained.
DOI: 10.48577/jpl.rwbjvo
title: Spectroscopic Imaging of Sub-Kilometer Spatial Structure in Lower Tropospheric Water Vapor

description: This study maps the sub-kilometer spatial structure in total column water vapor with Visible to Shortwave Infrared (VSWIR) imaging spectroscopy. We describe our inversion approach and validate its accuracy with coincident measurements by airborne imaging spectrometers and the AERONET ground-based observation network. Next we analyze data from NASA’s AVIRIS-NG airborne campaign in India where favorable solar angles enable a uniquely high-resolution measurement of water vapor’s spatial variability and scaling properties. We find second order structure function scaling exponents consistent with convective and non-convective atmospheres. Finally, we conclude by discussing the implications of these measurements and paths toward future campaigns to build upon these results.
DOI: 10.48577/jpl.tbm6wv
title: Multi-orbital-phase and multi-band characterization of exoplanetary atmospheres with reflected light spectra

description: Direct imaging of widely separated exoplanets from space will obtain their reflected light spectra and measure atmospheric properties. Previous calculations have shown that a change in the orbital phase would cause a spectral signal, but whether this signal may be used to characterize the atmosphere has not been shown. We simulate starshade-enabled observations of the planet \umab, using the to-date most realistic simulator SISTER to estimate the uncertainties due to residual starlight, solar glint, and exozodiacal light. We then use the Bayesian retrieval algorithm \exorelr\ to determine the constraints on the atmospheric properties from observations using a WFIRST- or HabEx-like telescope, comparing the strategies to observe at multiple orbital phases or in multiple wavelength bands. With a $\sim20\%$ bandwidth in 600 -- 800 nm on a WFIRST-like telescope, the retrieval finds a degenerate scenario with a lower gas abundance and a deeper or absent cloud than the truth. Repeating the observation at a different orbital phase or at a second 20\% wavelength band in 800 -- 1000 nm, with the same integration time and thus degraded S/N, would effectively eliminate this degenerate solution. Single observation with a HabEx-like telescope would yield high-precision constraints on the gas abundances and cloud properties, without the degenerate scenario. These results are also generally applicable to high-contrast spectroscopy with a coronagraph with a similar wavelength coverage and S/N, and can help design the wavelength bandwidth and the observation plan of exoplanet direct imaging experiments in the future.
DOI: 10.48577/jpl.cflilz
title: ISSM-SLPS: geodetically compliant Sea-Level Projection System for the Ice-sheet and Sea-level System Model v4.17

description: Understanding future impacts of sea-level rise at the local level is important for mitigating its effects. In particular, quantifying the range of sea-level rise outcomes in a probabilistic way enables coastal planners to better adapt strategies, depending on cost, timing and risk tolerance. For a time horizon of 100 years, frameworks have been developed that provide such projections by relying on 5 sea-level fingerprints where contributions from different processes are sampled at each individual time step and summed up to create probability distributions of sea-level rise for each desired location. While advantageous, this method does not readily allow for including new physics developed in forward models of each component. For example, couplings and feedbacks between ice sheets, ocean circulation, and solid-Earth uplift cannot easily be represented in such frameworks. Indeed, the main impediment to inclusion of more forward model physics in probabilistic sea-level frameworks is the avail10 ability of dynamically computed sea-level fingerprints that can be directly linked to local mass changes. Here, we demonstrate such an approach within the Ice-Sheet and Sea-level System Model (ISSM), where we develop a probabilistic framework that can readily be coupled to forward process models such as those for ice sheets, glacial-isostatic adjustment , hydrology and ocean circulation, among others. Through large scale uncertainty quantification, we demonstrate how this approach enables inclusion of incremental improvements in all forward models and provides fidelity to time-correlated processes. The projection 15 system may readily process input and output quantities that are geodetically consistent with space and terrestrial measurement systems. The approach can also account for numerous improvements in our understanding of sea-level processes.
DOI: 10.48577/jpl.qqo1v7
title: Statistical Relationship between Atmospheric Rivers and Extratropical Cyclones

description: In this study, some general relationships between atmospheric rivers (ARs) and extratropical cyclones (ECs) have been revealed for the first time based on analysis of 36-year global AR and EC datasets. Composites of atmospheric variables around mid-latitude ARs show that a strong cyclone is located poleward and westward of the AR centroid, which confirms the close link between the AR and EC. In addition to the cyclone, a pronounced anticyclone is located equatorward and eastward of the AR, which has not been emphasized before. This anticyclone is an essential component in the AR-EC system, whose presence leads to stronger horizontal pressure gradient that forces moisture to be transported along a narrow corridor within the warm sector of the cyclone. It is further found that the strength of ARs is better correlated with the pressure gradient between the cyclone and anticyclone than with the cyclone intensity.
DOI: 10.48577/jpl.sbvzik
title: Over a century of sinking in Mexico City: no hope for elevation, water levels, and water quality recovery

description: Many areas worldwide are known to experience land subsidence due to groundwater extraction. It is traditionally assumed that subsidence extent and rates are controlled by groundwater extraction location and volumes. Here, we reevaluate this assumption by combining over a century of data in Mexico City crossing the fields of stratigraphy, hydrology, and geodesy. Integration of 115 years of leveling, with 24 years of InSAR, and 14 years of GPS data reveals that subsidence rates have been constant in Mexico City since at least 1950 and reach 50 cm/yr. An independent component analysis shows that no elastic deformation exists, demonstrating that the subsidence is fully irreversible. In Mexico City, no relationship exists between water level changes and subsidence rates or between pumping rates and subsidence rates. In contrast, a strong positive correlation is isolated between subsidence rates and the thickness of the upper aquitard. Through integration of these long-term datasets, we forecast that it will take ~140 years to reach total compaction of the upper aquitard, which may lead to total subsidence up to 60 m. With the potentiometric surface now deeper than the aquitard, aquitard porewater rich in salts and other chemical constituents and pollutants is now flowing downward into the aquifer, hence decreasing water quality. Finally, our work shows that low- and very-low-income inhabitants of Mexico City are disproportionally affected by the consequences of land subsidence in the form of greater exposure to high deformation gradients and the associated fractures and decreased access to drinking water.