cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.o65ea1
title: Covariation of airborne biogenic tracers (CO2, COS, and CO) supports stronger than expected growing season photosynthetic uptake in the southeastern US

description: The ACT-America Earth Venture mission conducted five airborne campaigns across four seasons from 2016-2019, to study the transport and fluxes of Greenhouse gases across the eastern United States (US). Unprecedented spatial sampling of atmospheric tracers (CO2, CO, and COS) related to biospheric processes offers opportunities to improve our qualitative and quantitative understanding of seasonal and spatial patterns of biospheric carbon uptake.Here, we examine co-variation of boundary layer enhancements of CO2, CO, and COS across three diverse regions: the crop-dominated Midwest, evergreen-dominated South, and deciduous broadleaf-dominated Northeast. To understand the biogeochemical processes controlling these tracers, we compare the observed co-variation to simulated co-variation resulting from model- and satellite- constrained surface carbon fluxes. We found indication of a common terrestrial biogenic sink of CO2 and COS and secondary production of CO from biogenic sources in summer throughout the eastern US. Stomatal conductance likely drives fluxes through diffusion of CO2 and COS into leaves and emission of biogenic volatile organic compounds into the atmosphere. ACT-America airborne campaigns filled a critical sampling gap in the southern US, providing information about seasonal carbon uptake in southern temperate forests, and demanding a deeper investigation of underlying biological processes and climate sensitivities. Satellite- constrained carbon fluxes capture much of the observed seasonal and spatial variability, but underestimate the magnitude of net CO2 and COS depletion in the Southeast, indicating a stronger than expected net sink in late summer.
DOI: 10.48577/jpl.qssq8u
title: Interband cascade laser frequency combs

description: Interband cascade lasers (ICLs) have emerged as efficient, room-temperature semiconductor light sources with relatively highwallplug effiency and low power consumption in the 3–6 µm wavelength region. The recent discovery that ICLs can generateself-starting optical frequency combs has triggered a new avenue of research that ultimately promises to provide broadband,gap-free chemical sensing sources for the simultaneous detection of multiple species or rapid scanning of broad absorptionfeatures. Here we review ICL frequency combs for the first time, focusing on device topologies, spectral characteristics, andfrequency stabilization. Future perspectives such as the development of on-chip dual-comb spectrometers based on the ICLplatform, real-time probes of molecular dynamics, and combs that use harmonic comb states to generate millimeter waves arealso discussed.
DOI: 10.48577/jpl.tp0irr
title: An ALMA study of outflow parameters of protoclusters: outflow feedback to maintain the turbulence

description: With the aim of understanding the role of outflows in star formation, we performed a statistical study of the physical parameters of outflows in eleven massive protoclusters associated with ultra-compact Hii regions. A total of 106 outflow lobes are identified in these protoclusters using the ALMA CO (3–2), HCN (4–3) and HCO+ (4–3) line observations. Although the position angles of outflow lobes do not differ in these three tracers, HCN and HCO+ tend to detect lower terminal velocity of the identified outflows compared to CO. Majority of the outflows in our targets are young with a typical dynamical time-scale of 102−104 years, and are mostly composed of low-mass outflows along with at least one high-mass outflows in each target in general. An anti-correlation trend of the outflow rate with the dynamical time-scale indicates that the outflow rate possibly decreases with time. Also, an increasing trend of dynamical time-scale with the mass of the associated core hints that the massive cores might have longer accretion history than the low mass cores. Estimation of different energies in these protoclusters show that outflows observed here cannot account for the generation of the turbulence, but can sustain the turbulence at the current epoch as the energy injection rate from outflows is similar to the estimated dissipation rate.
DOI: 10.48577/jpl.ddl4mi
title: Effects of Amino Acids on Phosphate Adsorption onto Iron (Oxy)hydroxide Minerals under Early Earth Conditions

description: Phosphate, an essential molecule in biochemistry, is not abundant in modern oceans and would have been even less abundant in early Earth’s oceans. One possible mechanism for concentrating phosphate for prebiotic reactions is adsorption onto iron (oxy)hydroxide minerals, which would have precipitated from interactions between iron-rich oceans of the early Earth and near neutral-alkaline hydrothermal fluids. In this work, we synthesized ferrous and ferric (oxy)hydroxides to test their adsorptivity toward phosphate under early Earth oceanic conditions (anoxic, dissolved Fe2+, pH 6 – 9, low phosphate levels). Prebiotically relevant amino acids (cysteine, histidine, and arginine) were added to test their effect on phosphate adsorption. Colorimetry techniques coupled with NMR and statistical analysis were utilized to determine how experimental conditions influenced the adsorption reaction. We observed an 80-90% reduction of ferric to ferrous iron minerals in the presence of cysteine; we hypothesize that iron and cysteine underwent a redox reaction to produce cystine. In addition, phosphate was readily adsorbed onto iron (oxy)hydroxide minerals but their efficacy depended on the iron redox state and pH at which the minerals were precipitated. Phosphate adsorption was greatest with ferrous (oxy)hydroxide minerals precipitated at pH 9, reaching a maximum average adsorption of 45%. Under these conditions, the addition of organics significantly enhanced phosphate adsorption by an additional ~30%; differences due to the amino acid side chain were not statistically significant. This work shows how environmental conditions (redox state, pH, presence of organics) influenced adsorption in a simulated mineral system; such systems merit further study in increasingly complex conditions in order to better understand phosphate dynamics on wet-rocky worlds such as early Earth or Mars.
DOI: 10.48577/jpl.gymwvl
title: Carbon Monitoring System Flux Net Biosphere Exchange 2020 (CMS-Flux NBE 2020)

description: Here we present a global and regionally-resolved terrestrial net biosphere exchange30 (NBE) dataset with corresponding uncertainties between 2010–2018: CMS-Flux NBE 2020. It is31 estimated using the NASA Carbon Monitoring System Flux (CMS-Flux) top-down flux32 inversion system that assimilates column CO2 observations from the Greenhouse gases33 Observing SATellite (GOSAT) and NASA’s Observing Carbon Observatory -2 (OCO-2). The34 regional monthly fluxes are readily accessible as tabular files, and the gridded fluxes are35 available in NetCDF format. The fluxes and their uncertainties are evaluated by extensively36 comparing the posterior CO2 mole fractions with CO2 observations from aircraft and the NOAA37 marine boundary layer reference sites. We describe the characteristics of the dataset as global38 total, regional climatological mean, and regional annual fluxes and seasonal cycles. We find that39 the global total fluxes of the dataset agree with atmospheric CO2 growth observed by the surface40observation network within uncertainty. Averaged between 2010 and 2018, the tropical regions41 range from close-to neutral in tropical South America to a net source in Africa; these contrast42 with the extra-tropics, which are a net sink of 2.5 ± 0.3 gigaton carbon per year. The regional43 satellite-constrained NBE estimates provide a unique perspective for understanding the terrestrial44 biosphere carbon dynamics and monitoring changes in regional contributions to the changes of45 atmospheric CO2 growth rate. The gridded and regional aggregated dataset can be accessed at:46 https://doi.org/10.25966/4v02-c391 (Liu et al., 2020).
DOI: 10.48577/jpl.vgjnli
title: Science Objectives for Flagship-class mission concepts for the search for evidence of life at Enceladus

description: Cassini revealed that Saturn’s moon Enceladus hosts a subsurface ocean that meets the accepted criteria for habitability with bio-essential elements and compounds, liquid water, and energy sources available in the environment. Whether these conditions are sufficiently abundant and collocated to support life remains unknown and cannot be determined from Cassini data. But, thanks to the plume of oceanic material emanating from Enceladus’s south pole, a new mission to Enceladus could search for evidence of life without having to descend through kilometers of ice. In this paper, we outline the science motivations for such a successor to Cassini, choosing determining whether Enceladus is inhabited as the primary science goal and assuming a resource level equivalent to NASA’s Flagship-class missions. We selected a set of potential biosignature measurements that are complementary and orthogonal to build a robust case for any life detection result. This result would be further informed by quantifications of the habitability of the environment through geochemical and geophysical investigations into the ocean and crust. This study demonstrates that Enceladus’ plume offers an unparalleled opportunity for in situ exploration of an Ocean World and that the planetary science and astrobiology community is well equipped to take full advantage of it in the coming decades.
DOI: 10.48577/jpl.nfewel
title: Classication of High Density Regions in Global Ionospheric Maps with Neural Networks

description: The database of Global Ionospheric Maps (GIMs) produced at Jet Propulsion Laboratory is analyzed. We define high density Total Electron Content (TEC) regions (HDRs) in a map, following certain selection criteria. For the first time, we use convolutional neural network (CNN) approach to analyze a diachronic sequence of GIMs by treating these HDRs as objects to be identified in the GIMs. We trained four CNNs corresponding to four phases of a solar cycle to classify the GIMs by the number of HDRs in each map with 76% accuracy. We compared HDR counts for GIMs across ten years to draw conclusions on how the number of HDRs in the GIMs changes throughout the solar cycle. Occurrence of HDRs during different geomagnetic activity conditions is discussed. Catalogue of selected HDRs for ten years and four CNN-based models that can be used to extend classification to other years are provided for the community to use.
DOI: 10.48577/jpl.nwhqks
title: Revisiting the Entrainment Relationship in Convective Cloud Modeling: A CloudSat Perspective

description: Entrainment is an important process affecting convective transport and is a key parameter in convection modeling. For over half a century, an inverse relationship between entrainment rate (𝜆) and convective core size (R) has been used in modeling convective clouds. This short letter revisits the 𝜆 − 𝑅 relation using multiple years of CloudSat observations. Results show that the inverse relationship between 𝜆 and R is robust. However, they are not scaled by a simple constant. Global satellite observations provide some guidance for choosing the range of the scaling parameter. Further, our analysis shows that continental convective clouds tend to have smaller λ and larger 𝑅 compared to oceanic convective clouds, suggesting that vertical mass transport by continental convection is more efficient. The satellite-based study of the 𝜆 − 𝑅 relation has the potential to become a new diagnostic metric for assessing the representation of convection in weather and climate models.
DOI: 10.48577/jpl.wqhv6w
title: Spatial retrievals of atmospheric carbon dioxide from satellite observations

description: Abstract: Modern remote-sensing retrievals often invoke a Bayesian approach to infer atmospheric properties from observed radiances. In this approach, plausible mean states and variability for the quantities of interest are encoded in a prior distribution. Recent developments have devised prior assumptions for the correlation among atmospheric constituents and across observing locations. This work formulates a spatial statistical framework for simultaneous multi-footprint retrievals of carbon dioxide (CO2) with application to the Orbiting Carbon Observatory-2/3 (OCO-2/3). Formally, the retrieval state vector is extended to include atmospheric and surface conditions at many footprints in a small region, and a prior distribution that assumes spatial correlation across these locations is assumed. This spatial prior allows the length-scale, or range, of spatial correlation to vary between different elements of the state vector. Various single- and multi-footprint retrievals are compared in a simulation study. A spatial prior that also includes relatively large prior variances for CO2 results in posterior inferences that most accurately represent the true state and that reduce the correlation in retrieval error across locations.
DOI: 10.48577/jpl.myxmir
title: Evidence for widespread glaciation in Arcadia Planitia, Mars

description: Viscous flow features, including lobate debris aprons and lineated valley fill, are common ice-related features found across the mid-latitudes of Mars. These features are commonly found along the dichotomy boundary and around massifs where snow and ice can accumulate and flow to topographic lows during periods of higher obliquity. We have identified and mapped glacial-related features reminiscent of lineated valley fill and lobate debris aprons in the lower mid-latitudes of Arcadia Planitia based on morphology, thermal infrared reflectance, thermal inertia, and subsurface radar reflections. Three sinuous features show surface morphologies and supporting spectral properties indicative of massive buried ice, including distinct boundaries, arcuate and linear banding, deep radar reflections, dielectric constants similar to water-ice, expanded secondary craters, and proximity to lobate debris aprons. We interpret the sinuous and lobate features of Arcadia Planitia to be buried debris-covered glaciers formed during higher obliquity periods in Mars’ recent past. These sinuous features appear to be channelized ice that once flowed but currently reside in a flat-lying region. Although their origin is unclear, we consider an ice stream or subglacial history due to a lack of obvious topographic dependence. The abundant evidence of widespread near-surface ice in a flat-lying lower mid-latitude region of Mars makes Arcadia Planitia a potentially favorable site for future missions due to the high potential for in situ resource utilization.
DOI: 10.48577/jpl.uy0lov
title: The Substructures in Disks undergoing Vertical Shear Instability: II. Observational Predictions for the Dust Continuum

description: High-angular resolution observations at sub-millimeter/millimeter wavelengths of disks surrounding young stars have shown that their morphology is made of azimuthally-symmetric or point-symmetric substructures, in some cases with spiral arms, localized spur- or crescent-shaped features. The majority of theoretical studies with the aim of interpreting the observational results have focused on disk models with planets, under the assumption that the disk substructures are due to the disk-planet interaction. However, so far only in very few cases exoplanets have been detected in these systems. Furthermore, some substructures are expected to appear before planets form, as they are necessary to drive the concentration of small solids which can lead to the formation of planetesimals. In this work we present observational predictions from high-resolution 3D radiative hydrodynamical models which follow the evolution of gas and solids in a prototoplanetary disk. We focus on substructures in the distribution of millimeter-sized and smaller solid particles produced by the vertical shear instability. We show that their characteristics are compatible with some of the shallow gaps detected in recent observations at sub-mm/mm wavelengths, and present predictions for future observations with better sensitivity and angular resolution with ALMA and a Next Generation Very Large Array.
DOI: 10.48577/jpl.2wy2wh
title: Planetary Minerals Catalyze Conversion of a Polycyclic Aromatic Hydrocarbon to a Prebiotic Quinone: Implications for Origins of Life

description: Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in astrochemical environments and are disbursed into planetary environments via meteorites and extraterrestrial infall where they may interact with mineral phases to produce quinones important for origins of life. To assess the reasonableness of this process, we assessed the potential of the phyllosilicates montmorillonite (MONT) and kaolinite (KAO) and the Enhanced Mohave Mars Simulant (MMS) to catalyze conversion of the PAH anthracene (1) to the biologically important 9,10-anthraquinone (2). All substrates catalyzed conversion over the temperature range assessed (25-500 oC). Conversion rate curves were sigmoidal for MONT and KAO, but quadratic for MMS. Conversion efficiency maxima for 2 were 3.06  0.42 %, 1.15  0.13 %, and 0.56  0.039 % for MONT, KAO, and MMS, respectively. We hypothesized that differential binding and compound loss account for the conversion kinetics observed. Loss rate curves for 1 and 2 were exponential for all substrates, suggesting a pathway for wide distribution of both compounds in warmer prebiotic environments. These findings improve upon our previously reported 2 conversion efficiency on MONT and provide support for a plausible scenario in which PAH-mineral interactions can produce biological quinones in prebiotic environments.
DOI: 10.48577/jpl.6egmhx
title: Methylobacterium ajmalii sp. nov., isolated 1 from the International Space Station

description: Gram-negative, rod-shaped, catalase positive, oxidase positive, motile bacteria, designated as IF7SW-B2T, IIF1SW-B5, and IIF4SW-B5, were isolated from different locations across two consecutive flights, from the International Space Station (ISS). The sequence similarity of all ISS strains was &lt;99.4% for 16S rRNA and &lt;97.3% for gyrB genes with the closest being Methylobacterium indicum SE2.11T. Furthermore, the multi-locus sequence analysis placed the three ISS strains in the same clade of M. indicum. The average nucleotide identity (ANI) values of three ISS strains were &lt;93% and digital DNA-DNA hybridization (dDDH) were &lt;46.4% with any validly described Methylobacterium species. Based on the ANI and dDDH analyses, the ISS strains were considered as novel species belonging to the genus Methylobacterium. The three ISS strains showed 100% ANI similarity and dDDH values with each other, indicating that these three ISS strains, isolated during various flights and locations, belong to the same species. The ISS strains were found to grow optimally at temperature between 25°C to 30°C, pH 6.0 to 8.0, and NaCl 0 to 1%. Phenotypically, the ISS strains resemble M. aquaticum and M. terrae since they assimilate similar sugars as sole carbon substrate when compared to other Methylobacterium species. Fatty acid analysis showed that the major fatty acid produced by the ISS strains are C18:1- ω7c and C18:1- ω6c. The predominant quinone was ubiquinone 10 and the major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and an unidentified lipid. Therefore, based on genomic, phylogenetic, biochemical, and fatty acid analyses, strains IF7SW-B2T, IIF1SW-B5, and IIF4SW-B5, are assigned to a novel species within the genus Methylobacterium, and the name Methylobacterium ajmalii sp. nov., is proposed. The type strain is IF7SW-B2T.
DOI: 10.48577/jpl.yitkrq
title: From COVID-19 to Future Electrification: Assessing Traffic Impacts on Air Quality by a Machine Learning Model

description: The large fluctuations in traffic during the COVID-19 pandemic provide an unparalleled opportunity to assess emission control efficacy. Here we develop a machine-learning (ML) model, based on the large volume of real-time observational data, to predict surface-level NO2, O3, and 20 fine particle concentration in Los Angeles. Our ML model exhibits high fidelity in reproducing pollutant concentrations in the Los Angeles basin and identifies major factors controlling each species. During the strictest lockdown period, the traffic reduction led to decreases in NO2 and PM2.5 by –27.8% and –17.5%, respectively, but a 6% increase in O3. Heavy-duty truck emissions contribute primarily to these variations. Future traffic emissions controls are estimated to impose 25 similar effects as observed during the COVID-19 lockdown, but with smaller magnitude. Vehicular electrification will achieve further alleviation of NO2 levels.
DOI: 10.48577/jpl.e9ihjn
title: The Need for Spectrum and the Impact on Weather Observations

description: Nearly 70 scientists and engineers from across the world with expertise in weatherobservations and forecasting came together for an in-depth discussion on their growing challenges with radio frequency interference and potential opportunities with the advent of 5G/6G and vital uses of the spectrum for science.
DOI: 10.48577/jpl.gchk0q
title: Unsaturated flow processes and the onset of seasonal deformation in slow-moving landslides

description: Predicting rainfall-induced landslide failure is challenging because shallow groundwater flow is extremely sensitive to the preexisting moisture content in the ground. Here, we use groundwater hydrology theory and numerical modeling combined with five years of field monitoring to illustrate how unsaturated groundwater flow processes modulate the seasonal pore water pressure rise and therefore the onset of motion for slow-moving landslides. The onset of landslide motion at Oak Ridge earthflow in California’s Diablo Range occurs after an abrupt water table rise to near the landslide surface 52-129 days after seasonal rainfall commences. Model results and theory suggest that this abrupt rise occurs from the advection of a nearly saturated wetting front, which marks the leading edge of the integrated downward flux of seasonal rainfall, to the water table. Prior to this abrupt rise, we observe little measured pore water pressure response within the landslide due to rainfall. However, once the wetting front reaches the water table, we observe nearly instantaneous pore water pressure transmission to the landslide base that is accompanied by landslide acceleration. We cast the timescale to reach a critical pore water pressure threshold using a simple mass balance model that considers variable moisture storage with depth and explains the onset of seasonal landslide motion with a rainfall intensity-duration threshold. Our model shows that the seasonal response time of slow-moving landslides is controlled by the dry season vadose zone depth rather than the total landslide thickness.