cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.xhsecl
title: Model selection in atmospheric remote sensing with application to aerosol retrieval from DSCOVR/EPIC. Part 2: Numerical analysis

description: An algorithm for retrieving aerosol parameters by taking into account the uncertainty in 1 aerosol model selection is applied to the retrieval of aerosol optical thickness and aerosol layer height 2 from synthetic measurements from the EPIC sensor onboard the Deep Space Climate Observatory. The 3 synthetic measurements are generated using aerosol models derived from AERONET measurements 4 at different sites, while other commonly used aerosol models, such as OPAC, GOCART, OMI, and 5 MODIS databases are used in the retrieval. The numerical analysis is focused on the estimation of 6 retrieval errors when the true aerosol model is unknown. We found that the best aerosol model is the 7 one with a value of the asymmetry parameter and an angular variation of the phase function around 8 the viewing direction that are close to the values corresponding to the reference aerosol model.
DOI: 10.48577/jpl.yzelrb
title: Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Late infall causing disk warp and gravitational instability in SU Aur∗

description: SU Aur is one of the targets of the DESTINYS ESO large program, in which we study the evolution of gas-rich circumstellar disks within the first 10 Myr with near-infrared scattered light imaging. We are in particular interested in the presence of sub-structures in the disk, as well as the presence of forming planets and how the two may be linked. We used VLT/SPHERE in polarimetric imaging mode in the near infrared to spatially resolve the disk around SUAur down to scales of ∼ 7au. In addition to the new SPHERE observations we utilize VLT/NACO, HST/STIS and ALMA archival data. The new SPHERE data shows the disk around SU Aur as well as extended dust structures in unprece- dented detail. We resolve for the first time several dust tails connected to the Keplerian disk. By comparison with ALMA data we show that these dust tails are caused by material falling onto the disk. The disk itself shows an intricate spiral structure, consistent with gravitational instability, as well as a shadow lane, cast by an inner, misaligned component. Our observations suggest that SUAur is undergoing late infall of material, which can explain the observed disk structures. SU Aur, along with AB Aur are the clearest observational examples of this mechanism at work. The resulting warping of the disk may well explain the spin-orbit misalignment observed for many detected exoplanet systems.
DOI: 10.48577/jpl.zkhcbu
title: FUV Observations of the Inner Coma of 46P/Wirtanen

description: Far ultraviolet observations of comets yield information about the energetic processes that dissociate14 the sublimated gases from their primitive surfaces. Understanding which emission processes are dom15inant, their eects on the observed cometary spectrum, and how to properly invert the spectrum back16 to composition of the presumably pristine surface ices of a comet nuclei are all critical components for17 proper interpretation and analysis of comets. The close approach of comet 46P/Wirtanen in 2018-201918 provided a unique opportunity to study the inner most parts of a cometary coma with the Hubble19 Space Telescope Cosmic Origins Spectrograph, rarely accessible with remote observations, at lengthscales (100's of km) and wavelengths (900-1430 A~)20 previously probed only by the European Space21 Agency's Rosetta spacecraft. Our observations show a complex picture for the inner coma; atomic22 production rates for H and O that show water is the dominant source of both, an abundance of atomic23 sulfur that is dicult to explain with the lifetimes of common sulfur parent molecules, and a density24 distribution that is poorly t with both Haser and vectorial models.
DOI: 10.48577/jpl.wg0qa8
title: Hayabusa2 Extended Mission: New Voyage to Rendezvous with a Small Asteroid Rotating with a Short Period

description: Hayabusa2 is the Japanese Asteroid Return Mission and targeted the carbonaceous asteroid Ryugu, conducted by the Japan Aerospace Exploration Agency (JAXA). The goal of this mission was to conduct proximity operations including remote sensing observations, material sampling, and a Small Carry-On Impact experiment, as well as sample analyses. As of September 2020, the spacecraft is on the way back to Earth with samples from Ryugu with no critical issues after the successful departure in November 2019. Here, we propose an extended mission in which the spacecraft will rendezvous with a small asteroid with ~30 m - ~40 m in diameter that is rotating at a spin period of ~10 min after an additional ~10-year cruise phase. We introduce that two scenarios are suitable for the extended mission. In the first scenario, the spacecraft will perform swingby maneuvers at Venus once and Earth twice to arrive at asteroid 2001 AV43. In the second scenario, it will perform swing-by maneuvers at Earth twice to reach asteroid 1998 KY26. In both scenarios, the mission will continue until the early 2030s. JAXA recently released the decision that the spacecraft will rendezvous with 1998 KY26. This paper focuses on our scientific assessments of the two scenarios but leaves the decision process to go to 1998 KY26 for future reports. Rendezvous operations will be planned to detail the physical properties and surrounding environments of the target, one of the smallest elements of small planetary bodies. By achieving the planned operations, the mission will provide critical hints on the violent histories of collisions and accumulations of small bodies in the solar system. Furthermore, the established scientific knowledge and techniques will advance key technologies for planetary defense.
DOI: 10.48577/jpl.ycvfoj
title: Laboratory predictions for the night-side surface ice glow of Europa

description: Europa’s surface continuously experiences high fluxes of charged particles due to the presence of Jupiter’s strong magnetic field. These high-energy charged particles, including electrons, interact with ice- and salt-rich surface, resulting in complex physical and chemical processes. Here we report that Europa ice analogs emit characteristic spectral signatures in the visible region when exposed to high-energy electron radiation. The strongest emission (ice glow) we observed was centered at ~525 nm. We found that the presence of sodium chloride and carbonate strongly quenched, while epsomite enhanced, the radiation-induced ice glow. These emission characteristics could be used to determine the chemical composition of Europa’s surface during night-time low-altitude flybys of spacecraft such as the Europa Clipper. We estimate that the Europa Clipper Wide Angle Camera could record between 500 and 280,000 counts per second through different color filters, depending on the chemical composition of Europa’s surface. Though we focus here on Europa, our study may be relevant to other bodies exposed to high doses of ionizing radiation, such as Io and Ganymede. With its extreme radiation environment, rich surface geology, and compositional diversity, the radiation-induced ice glow on Europa could enable more precise surface characterization and provide unique night-time views.
DOI: 10.48577/jpl.yxnqch
title: Intercomparison of remote sensing retrievals: an examination of prior-induced biases in averaging kernel corrections

description: Abstract: In remote sensing applications, Optimal Estimation (OE) retrievals are sometimes compared 2 to independent OE retrievals of the same process. This intercomparison is often done in instrument 3 validation, where retrievals are compared with data from a separate validation instrument, and it 4 is sometimes done in data assimilation, where data from multiple instruments need to be adjusted 5 to the ‘same footing.’ In these cases, the two different retrievals are compared using an adjustment 6 that is colloquially known as the averaging kernel correction. A general misconception in the 7 existing literature is that this averaging kernel correction removes any bias introduced by prior 8 misspecification by either (or both) of the two comparative OE retrievals. In this paper, we will 9 analytically show that this is not the case, and the averaging kernel correction process is implicitly 10 ‘shifting’ both OE retrievals to a common comparison prior. We will also show that there is generally 11 a non-zero bias that is proportional to the difference between this comparison prior mean and 12 the true (but unobserved) mean state, which has large implications for retrieval validation and 13 data assimilation in remote sensing. Finally, to better characterize OE retrievals and retrieval 14 intercomparisons, we will make some recommendations for mitigating this prior-induced bias 15 in intercomparison of OE retrievals.
DOI: 10.48577/jpl.3web0z
title: Emerging satellite observations for diurnal cycling of ecosystem processes

description: Diurnal cycling of plant carbon uptake and water use, and their responses to water and heat stresses, provide direct insight for assessing ecosystem productivity, agricultural production and management practices, water and carbon cycles, and feedbacks to the climate. Temperature, light, atmospheric water demand, soil moisture, and leaf water potential/storage vary over the course of the day, leading to diurnal variations in stomatal conductance and ecosystem processes. Earth observations from polar-orbiting satellites are incapable of studying these diurnal variations. We review the emerging satellite observations that have the potential for studying how ecosystem processes vary over the course of the diurnal cycle. The recently launched ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) and Orbiting Carbon Observatory-3 (OCO-3) provide land surface temperature (LST), evapotranspiration (ET), and solar-induced chlorophyll fluorescence (SIF) data at different times of day. New generation operational geostationary satellites such as Himawari-8 and GOES-R can provide continuous, high-frequency data of LST, solar radiation, and gross primary production (GPP). Future satellite missions such as GeoCarb, TEMPO, and Sentinel-4 will also have diurnal SIF sampling capability. We explore the unprecedented opportunities for characterizing and understanding how GPP, ET, and water use efficiency (WUE) vary over the course of the diurnal cycle in response to temperature and water stresses and management practices. We also offer visions that these emerging observations will revolutionize studies of ecosystem processes and these observations and findings can inform agricultural and forest management and improvement of Earth system models and climate projections.
DOI: 10.48577/jpl.f3mpya
title: Annual and Seasonal Mean Tropical and Subtropical Precipitation Bias in CMIP5 and CMIP6 Models

description: Annual and seasonal mean tropical and subtropical precipitation biases in present-day climate simulations by CMIP6 models are evaluated. We analyze twenty-three CMIP6 models, which are grouped into those without (NOS) and with (SON) falling ice (snow) radiative effects (FIREs). The SON group is further divided according to treatments of ice-cloud radiative properties with separate (SON2) and combined cloud ice and snow contents (SON1). SON2 mitigates precipitation bias drastically relative to NOS, but SON1 overestimates precipitation in the subtropics, which deteriorates its performance relative to SON2 and NOS. Large offsets between SON2 and SON1 and between SON and NOS contribute to the slight improvement of CMIP6 relative to CMIP5, largely due to the contribution of SON2. The different treatments of ice-cloud radiative properties between SON2 and SON1 seem to be potentially linked to differences in precipitation biases. Results suggest that further in-depth investigation of cloud ice-radiation-circulation interactions is required.
DOI: 10.48577/jpl.hlb4sf
title: GAIA GRAL: GAIA DR2 GRAVITATIONAL LENS SYSTEMS. VI. SPECTROSCOPIC CONFIRMATION AND MODELING OF QUADRUPLY-IMAGED LENSED QUASARS

description: Combining the exquisite angular resolution of Gaia with optical light curves and WISE photometry, the Gaia Gravitational Lenses working group (GraL) uses machine learning techniques to identify candidate strongly lensed quasars, and has confirmed over two dozen new strongly lensed quasars since 2018. This paper reports on the 12 quadruply-imaged quasars identified by this effort to date, which is a ∼ 20% increase in the number of confirmed quadruply-imaged quasars. We discuss the candidate selection, spectroscopic follow-up, and lens modeling. We also report the spectroscopic failures as an aid for future investigations.
DOI: 10.48577/jpl.hwz6mn
title: An overview of the ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) project: aerosol-cloud-radiation interactions in the Southeast Atlantic basin

description: Southern Africa produces almost a third of the Earth’s biomass burning (BB) aerosol particles, yet the fate of these particles and their influence on regional and global climate is poorly understood. ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) is a five-year NASA EVS-2 (Earth Venture Suborbital-2) investigation with three Intensive Observation Periods designed to study key atmospheric processes that determine the climate impacts of these aerosols. During the Southern Hemisphere winter and spring (June-October), aerosol particles reaching 3-5 km in altitude are transported westward over the South-East Atlantic, where they interact with one of the largest subtropical stratocumulus subtropical stratocumulus (Sc) cloud decks in the world. The representation of these interactions in climate models remains highly uncertain in part due to a scarcity of observational constraints on aerosol and cloud properties, and due to the parameterized treatment of physical processes. Three ORACLES deployments by the NASA P-3 aircraft in September 2016, August 2017 and October 2018 (totaling ~350 science flight hours), augmented by the deployment of the NASA ER-2 aircraft for remote sensing in September 2016 (totaling ~100 science flight hours), were intended to help fill this observational gap. ORACLES focuses on three fundamental science themes centered on the climate effects of African BB aerosols: (a) direct aerosol radiative effects; (b) effects of aerosol absorption on atmospheric circulation and clouds; (c) aerosol-cloud microphysical interactions. This paper summarizes the ORACLES science objectives, describes the project implementation, provides an overview of the flights and measurements in each deployment, and highlights the integrative modeling efforts from cloud to global scales to address science objectives. Significant new findings on the vertical structure of BB aerosol physical and chemical properties, chemical aging, cloud condensation nuclei, rain and precipitation statistics, and aerosol indirect effects are emphasized, but their detailed descriptions are the subject of separate publications. The main purpose of this paper is to familiarize the broader scientific community with the ORACLES project and the data set it produced.
DOI: 10.48577/jpl.x0gzhi
title: Lagged effects regulate the inter-annual variability of the tropical carbon balance

description: Inter-annual variations in the tropical land carbon (C) balance are a dominant component of the global atmospheric CO2 growthrate. Currently, the lack of quantitative knowledge on processes controlling net tropical ecosystems C balance on inter-annual20 timescales inhibits accurate understanding and projections of land-atmosphere C exchanges. In particular, uncertainty on therelative contribution of ecosystem C fluxes attributable to concurrent forcing anomalies (concurrent effects) and thoseattributable to the continuing influence of past phenomena (lagged effects) stifles efforts to explicitly understand the integratedsensitivity of tropical ecosystem to climatic variability. Here we present a conceptual framework—applicable in principle toany land biosphere model—to explicitly quantify net biospheric exchange (NBE) as the sum of anomaly-induced concurrentchanges and climatology-induced lagged changes to terrestrial ecosystem C states (NBE = NBECON + NBELAG 25 ). We apply thisframework to an observation-constrained analysis of the 2001-2015 tropical C balance: we use a data-model integrationapproach (CARDAMOM) to merge satellite-retrieved land-surface C observations (leaf area, biomass, solar-inducedfluorescence), soil C inventory data and satellite-based atmospheric inversion estimates of CO2 and CO fluxes to produce adata-constrained analysis of the 2001-2015 tropical C cycle. We find that the inter-annual variability of both concurrent and30 lagged effects substantially contribute to the 2001-2015 NBE inter-annual variability throughout 2001-2015 across the tropics(NBECON IAV = 80% of total NBE IAV, r = 0.76; NBELAG IAV = 64% of NBE IAV, r = 0.61) and the prominence of NBELAGIAV persists across both wet and dry tropical ecosystems. The magnitude of lagged effect variations on NBE across the tropicsis largely attributable to lagged effects on net primary productivity (NPP; NPPLAG IAV 113% of NBELAG IAV, r = -0.93, pvalue&lt;0.05), which emerge due to the dependence of NPP on inter-annual variations in foliar C and plant-available H2O states. 2We conclude that concurrent and lagged effects need to be explicitly and jointly resolved to retrieve an accurate understandingthe processes regulating the present-day and future trajectory of the terrestrial land C sink.
DOI: 10.48577/jpl.1ygxkp
title: The Interplanetary and Magnetospheric Causes of Geomagnetically Induced Currents (GICs) &gt; 10 A in the Mäntsälä Finland Pipeline: 1999 through 2019

description: The interplanetary and magnetospheric causes of intense geomagnetically induced current (GIC) &gt; 10 A (and &gt; 30 A) events during 21 years (1999 through 2019) at the Mäntsälä, Finland (57.9° magnetic latitude) gas pipeline have been studied. Although shocks and substorms are predominant causes of intense GICs, some newly discovered geoeffective interplanetary features are: solar wind plasma parcel impingements, interplanetary magnetic field (IMF) northward (Bn) and southward (Bs) turnings, interplanetary coronal mass ejection (ICME) filaments and reverse shocks. From a study of &gt; 30 A GIC events, it is found that supersubstorm (SML &lt; -2500 nT) and intense substorm (-2500 nT &lt; SML &lt; -2000 nT) auroral electrojet intensifications are the most frequent (76%) cause of all of these GIC events. These events occur most often (76%) in superstorm (SYM-H ≤ -250 nT) main phases, but they can occur in other storm phases and lesser intensity storms as well. All of the &gt; 30 A GICs were complex events involving a combination of two or more of shock, substorm, pressure pulse, and IMF Bs and Bn turnings. Shock-related GICs are observed to occur at all local times. The first and second “Halloween” superstorms (29-30 and 30-31 October 2003) combined, produced by far the greatest number of GICs in the interval of study (9 &gt; 30 A GICs and 168 &gt; 10 A GICs). In the first Halloween superstorm, a shock- triggered supersubstorm (SML &lt; -3548 nT) caused 33, 57, 51 and 52 A GICs. The 57 A GIC was the most intense event of the superstorm and of this study. Equally intense magnetic storms were also studied but their related GICs were far less numerous.
DOI: 10.48577/jpl.c8pcs8
title: Range-Visual-Inertial Odometry: No Need To Be Excited

description: Traveling straight at constant speed is the most efficient trajectory for most robotics applications. Unfortunately without accelerometer excitation, monocular Visual-Inertial Odometry (VIO) cannot observe scale and suffers severe error drift. This is why NASA’s Ingenuity Mars Helicopter added a 1Dlaser range finder, but it is limited to flat terrains. Our novel range-VIO approach uses facet constraints, which efficiently leverage VIO feature depths to adapt to any scene structure.Due to the small range finder footprint, range-VIO also retains the minimal size, weight, power and real-time attributes of VIO.The facet scene model can scale from a flat world assumption,to virtually no structure assumption at all based on visual feature density. An important theoretical result shows that scale, with range-VIO, is no longer in the right nullspace of the observability matrix for constant acceleration motion.The benefits are evaluated on real flight data representative of common aerial robotics scenarios. Robustness is demonstrated using indoor stress data with full-state ground truth.
DOI: 10.48577/jpl.e4kjo0
title: The Salty Secrets of Icy Ocean Worlds

description: As new insights have emerged in recent decades about the dynamics of sea ice, researchers have sought to extend these insights to ice covered oceans in the solar system, where non-icy materials preserved in icy lithospheres may hold clues to solid-state convection and the possible presence of life. The recent study by Buffo et al. (2020) considers the salt content of the ice covering Jupiter’s moon Europa in the context of gravity drainage and mushy layer theory, and makes provocative predictions about the amounts of salts retained in the ice. A major question in such studies is how well the preservation and transport of salts in ice translates to the length and time scales of an ocean world.
DOI: 10.48577/jpl.phjtpz
title: Aluminum precursor interactions with alkali compounds in thermal atomic layer etching and deposition processes

description: Surface fluorination and volatilization using hydrogen fluoride and trimethyaluminum (TMA) is a useful approach to the thermal atomic layer etching of Al2O3. We have previously shown that significant enhancement of the TMA etching effect occurs when performed in the presence of lithium fluoride chamber-conditioning films. In this work, we extend this enhanced approach to other alkali halide compounds including NaCl, KBr, and CsI. These materials are shown to have varying capacities for the efficient removal of AlF3, and ultimately lead to larger effective Al2O3 etch rates at a given substrate temperature. The most effective compounds allow for continuous etching of Al2O3 at substrate temperatures lower than 150 °C, which can be a valuable route for processing temperature-sensitive substrates, and for improving the selectivity of the etch over other materials. The strong interaction between TMA and alkali halide materials also results in materials-selective thin film deposition at these reduced substrate temperatures. We discuss the possible mechanisms of the etching enhancement, along with prospects for extending this approach to other material systems.
DOI: 10.48577/jpl.cpxcdw
title: Towards Robust State Estimation by Boosting the Maximum Correntropy Criterion Kalman Filter with Adaptive Behaviors

description: Robust state estimation remains as an open prob- lem in robotics, specially when the robot is meant to navigate in perception degraded environments. As a step towards this robustness, in this paper we propose a new sensor fusion approach that extends the Maximum Correntropy Criterion Kalman Filter (MCCKF) by incorporating adaptive behaviors. The MCCKF outperforms traditional Kalman filters in the presence of large outliers or sensor failures. However, MCCKFs have a clear dependency on the size of their Kernel Bandwith (KB), which is a user-selected parameter and has a big impact on the resulting filter estimation. Further, MCCKFs have fixed system and observation noise covariance matrices, which usually require tedious tuning efforts and is a common source of divergence. To overcome these issues, we transform the MCCKF to an adaptive-MCCKF (AMCCKF) that dynamically modifies the KB size and both system and observation noise covariance matrices. The validation of the fusion algorithm is shown through real experiments using a small aerial platform and a ground robot in a loosely-coupled sensor fusion architecture. The presented approach is part of the solution used by the COSTAR team participating at the DARPA Subterranean Challenge.