cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.stjtr6
title: Root-derived inputs are major contributors to soil carbon in temperate forests, but vary by mycorrhizal type

description: Roots promote the formation of slow-cycling soil carbon (C), yet we have limited understanding of the magnitude and controls on this flux. We hypothesized arbuscular mycorrhizal (AM)- and ectomycorrhizal (ECM)-associated trees would exhibit differences in root-derived C accumulation in the soil, and that much of this C would be transferred into mineral-associated pools. We installed δ13C-enriched ingrowth cores across mycorrhizal gradients in six Eastern U.S. forests (n = 54 plots). Overall, root-derived C was 54% greater in AM versus ECM-dominated plots. This resulted in nearly twice as much root-derived C in putatively slow-cycling mineral-associated pools in AM compared to ECM plots. Given that our estimates of root-derived inputs were often equal to or greater than leaf litter inputs, our results suggest that variation in root-derived soil C accumulation due to tree mycorrhizal dominance may be a key control of soil C dynamics in forests.
DOI: 10.48577/jpl.57zqmz
title: Implications of surface roughness in models of water desorption on the Moon

description: The observed presence of water molecules in the dayside lunar regolith was an unexpecteddiscovery and remains poorly understood. Standard thermophysical models predict temperaturesthat are too high for adsorbed water to be stable. We propose that this problem can becaused by the assumption of locally flat surfaces that is common in such models. Here weapply a model that explicitly considers surface roughness, and accounts for solar illumination,shadows cast by topography, self–heating, thermal reradiation, and heat conduction. We couplethe thermophysical model to a model of first–order desorption of lunar surface water anddemonstrate that surface roughness substantially increases the capability of the Moon to retainwater on its sunlit hemisphere at any latitude, and within 45 of the poles, at any time of thelunar day. Hence, we show that lunar surface roughness has a strong influence on lunar wateradsorption and desorption. Therefore, it is of critical importance to take account of surfaceroughness to get an accurate picture of the amount of water on the Moon’s surface and in itsexosphere.
DOI: 10.48577/jpl.dsflgn
title: From zero to infinity: minimum to maximum diversity of the planet by spatio-parametric Rao's quadratic entropy

description: Aim: The majority of work done to gather information on Earth di- versity has been carried out by in-situ data, with known issues related to epistemology (e.g., species determination and taxonomy), spatial uncertainty, logistics (time and costs), among others. An alternative way to gather information about spatial ecosystem variability is the use of satellite remote sensing. It works as a powerful tool for attaining rapid and standardized information. Several metrics used to calculate remotely sensed diversity of ecosystems are based on Shannon's In- formation Theory, namely on the dierences in relative abundance of pixel re ectances in a certain area. Additional metrics like the Rao's quadratic entropy allow the use of spectral distance beside abundance, but they are point descriptors of diversity, namely they can account only for a part of the whole diversity continuum. The aim of this paper is thus to generalize the Rao's quadratic entropy by proposing its parameterization for the rst time. Innovation: The parametric Rao's quadratic entropy, coded in R, i) allows to represent the whole continuum of potential diversity indices in one formula, and ii) starting from the Rao's quadratic entropy, al- lows to explicitly make use of distances among pixel reflectance values, together with relative abundances. Main conclusions: The proposed unifying measure is an integration between abundance- and distance-based algorithms to map the continuum of diversity given a satellite image at any spatial scale.
DOI: 10.48577/jpl.irp4sa
title: Using Rapid Repeat SAR Interferometry to improve Hydrodynamic Models of flood propagation in Coastal Wetlands

description: The propagation of tides and riverine floodwater in coastal wetlands is controlled by subtle topographic differences and a thick vegetation canopy. High-resolution numerical models have been used in recent years to simulate fluxes across wetlands. However, these models are based on sparse field data that can lead to unreliable results. Here, we utilize high spatial-resolution, rapid repeat interferometric data from the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) to provide a synoptic measurement of sub-canopy water-level change resulting from tide propagation into wetlands. These data are used to constrain crucial model parameters and improve the performance and realism of simulations of the Wax Lake wetlands in coastal Louisiana (USA). A sensitivity analysis shows that the boundary condition of river discharge should be calibrated first, followed by iterative correction of terrain elevation specified originally by a Digital Terrain Model derived from LiDAR measurements. The calibration of bed friction becomes important only with the boundary and topography calibrated. With the model parameters calibrated, the overall Nash-Sutcliffe model efficiency for water-level change increases from 0.15 to 0.53 with the RMSE reduced by 26%. In areas with dense wetland grasses, the LiDAR signal is unable to reach the soil surface, but the L-band UAVSAR instrument detects changes in water levels that can be used to infer the true ground elevation. The high spatial resolution and repeat-acquisition frequency (minutes to hours) observations provided by UAVSAR represent a groundbreaking opportunity for a deeper understanding of the complex hydrodynamics of coastal wetlands.
DOI: 10.48577/jpl.c8aqgx
title: SmallSat Swarm Gravimetry: Revealing the Interior Structure of Asteroids and Comets

description: A growing interest in small body exploration has motivated research into the rapid characterization of near-Earth objects to meet economic or scientific objectives. Specifically, knowledge of the internal density structure can aid with target selection and enables an understanding of prehistoric planetary formation to be developed. To this end, multi-layer extensions to the polyhedral gravity model are suggested, and an inversion technique is implemented to present their effectiveness. On-orbit gravity gradiometry is simulated and employed in stochastic and deterministic algorithms, with results that imply robustness in both cases.
DOI: 10.48577/jpl.oalyjs
title: Reanalysis intercomparison of potential vorticity and potential-vorticity-based diagnostics

description: Global reanalyses from data assimilation systems are among the most widely used datasets in weather and climate studies, and potential vorticity (PV) from reanalyses is invaluable for many studies of dynamical and transport processes. We assess how consistently modern reanalyses represent potential vorticity (PV) among each other, focusing not only on PV but also on process-oriented dynamical diagnostics including equivalent latitude calculated from PV and PV-based tropopause and stratospheric polar vortex characterization. In particular we assess the National Centers for Environmental Prediction Climate Forecast System Reanalysis/Climate Forecast System, version 2 (CFSR/CFSv2) reanalysis, the European Centre for Medium-Range Weather Forecasts Interim (ERA-Interim) reanalysis, the Japanese Meteorological Agency’s 55-year (JRA-55) reanalysis, and the NASA Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2). Overall, PV from all reanalyses agrees well with the reanalysis ensemble mean, providing some confidence that all of these recent reanalyses are suitable for most studies using PV-based diagnostics. Specific diagnostics where some larger differences are seen include PV-based tropopause locations in regions that have strong tropopause gradients (such as around the subtropical jets) or are sparse in high-resolution data (such as over Antarctica), and the stratospheric polar vortices during fall vortex formation and (especially) spring vortex breakup; studies of sensitive situations/regions such as these should examine PV from multiple reanalyses.
DOI: 10.48577/jpl.xadx00
title: The Polar Radiant Energy in the Far InfraRed Experiment: A New Perspective on Polar Longwave Energy Exchanges

description: The Earth’s climate is strongly influenced by energy deficits at the poles that emit more thermal energy than they receive from the sun. Energy exchanges between the surface and atmosphere influence the local environment while heat transport from lower latitudes drives midlatitude atmospheric and oceanic circulations. In the Arctic, in particular, local energy imbalances induce strong seasonality in surface-atmosphere heat exchanges and an acute sensitivity to forced climate variations. Despite these important local and global influences, the largest contributions to the polar atmospheric and surface energy budgets have not been fully characterized. The spectral variation of far-infrared radiation that makes up 60% of polar thermal emission has never been systematically measured impeding progress toward consensus in predicted rates of Arctic warming, sea ice decline, and ice sheet melt. Enabled by recent advances in sensor miniaturization and CubeSat technology, the Polar Radiant Energy in the Far InfraRed Experiment (PREFIRE) mission will document, for the first time, the spectral, spatial, and temporal variations of polar far-infrared emission. Selected under NASA’s Earth Ventures Instrument (EVI) program, PREFIRE will utilize new light weight, low-power, ambient temperature detectors capable of measuring at wavelengths up to 50 micrometers to quantify Earth’s far-infrared spectrum. Estimates of spectral surface emissivity, water vapor, cloud properties, and the atmospheric greenhouse effect derived from these measurements offer the potential to advance our understanding of the factors that modulate thermal fluxes in the cold, dry conditions characteristic of the polar regions.
DOI: 10.48577/jpl.hnuhik
title: Thermal probe enhanced with pulsed plasma discharges for efficient ice penetration

description: Pulsed plasma discharges are investigated here as a means of reducing the power necessary for a thermal probe to penetrate an ice sheet. When a high-energy plasma discharge occurs in ice, the ensuing shockwave fractures the ice field and reduces its thermal conductivity. If this reduction is sufficient in both magnitude and geometric extension, it can decrease the heating power necessary to keep the thermal probe descending. This concept is investigated from a theoretical point of view by modeling in a finite element thermal analysis the effects of a cracked ice region on the thermal probe's performance. Thermal conductivity reduction and cracked region extent are introduced as the parameters which predict power savings. An experimental setup was also created to allow 80 Joule discharges through an ice sample at a voltage of 40kV. The system was used in combination with a commercial thermal properties analyzer to derive thermal conductivity reduction values to feed to the system. The cracked region was topologically divided into two regions with different cracking behavior, and the thermal conductivity of each region was measured.
DOI: 10.48577/jpl.ol7acp
title: Once upon a time, in AmeriFlux

description: In October 2020, under COVID-19 quarantine, AmeriFlux held its largest and one of its most successful annual meetings . Historically, ~100 scientists attend; this meeting had over 400 registrants and participants. Participants expressed that this was among the best virtual meetings that they had ever attended, and 100% of post-meeting survey respondents stated that they would attend again. Feedback revealed the meeting fostered a strong sense of connection to the AmeriFlux community, especially among early career and international scientists. How did a feeling of strong connection to the community arise from the seemingly cold and isolated structures of virtual meetings? The meeting emphasized Diversity, Equity, and Inclusion (DEI), which resulted in an unexpected enhancement of science communication and community connections. Additionally, the meeting experimented with an online virtual gaming-like world (Gather.town), where users controlled video/audio-enabled avatars in a conference center and poster hall environment to create spontaneous conversations and discussions. In lieu of a social-bonding field trip, participants showed videos of their field sites accompanied by informal banter, which were watched in group settings in Gather. Social mixers were structured over Zoom breakout rooms that were limited in size to promote participation with accessible games. Science talks were selected based on appeal to a demographically diverse organizing committee, which enhanced appeal to a broad meeting audience. Finally, breakout reports were given not in the format of bullet point slides, but instead as creatively improvised fairytales, which dramatically enhanced engagement. Here, we describe some of the process that went into the AmeriFlux 2020 meeting. Keeping with the theme of experimenting and fairytales, we present this narrative in the form of a fairytale; and, without further ado…
DOI: 10.48577/jpl.jpaagl
title: Examination of the Daily Cycle Wind Vector Modes of Variability from the Constellation of Microwave Scatterometers and Radiometers

description: Offshore of many coastal regions, the ocean surface wind varies in speed and direction throughout the day, owing to forcing from land/sea temperature differences and orographic effects. This near-coastal diurnal variability has been noted in microwave ocean wind scatterometer observations. Far offshore, TAO-TRITON mooring data over the Intertropical Convergence Zone (ITCZ) have revealed both diurnal and semi-diurnal wind vector variability. In this manuscript, the suite of multiple scatterometers and ocean wind radiometer data are utilized in an attempt to estimate the diurnal and semidiurnal wind components. In particular, microwave radiometer-derived winds from the Tropical Rainfall Measuring Mission (TRMM) and the Global Precipitation Measurement (GPM) are used merged with the RapidScat scatterometer data, which observe from asynchronous orbiting satellite platforms.
DOI: 10.48577/jpl.pt6ous
title: Surface temperature lowering at Bright Ephemeral Feature site on Titan’s north pole

description: We report a temperature decrease in one of the regions on Titan that has been documented as a Bright Ephemeral Feature (BEF). Spectra were recorded by the Composite Infrared Spectrometer (CIRS) on Cassini. BEFs are 5µm bright areas that appear, disappear, and shift from ﬂyby to ﬂyby at Titan’s north pole observed in Visual and Infrared Mapping Spectrometer (VIMS) data. They are inferred to be broad-specular reﬂections caused by a smooth surface on Titan or a near surface fog —both of which indicate that the atmosphere interacted with the surface. We used 24 spectra for ‘on the spot’ and 51 spectra for ‘oﬀ the spot’ (where spot is the BEF region) to determine the temperature diﬀerence during the T121 ﬂyby (July 25 2016). At the 410-560 cm−1 window where surface emissions are perceptible we see a decrease in temperature by 1±0.1 Kelvin. This lowering of temperature might indicate precipitative cooling after a fresh rainfall on Titan’s land/sea surface.
DOI: 10.48577/jpl.vip8nv
title: Unveiling wide-orbit companions to K-type stars in Sco-Cen with Gaia EDR3

description: Context. Detection of low-mass companions to stellar hosts is important to test formation scenarios of these systems. Companions at wide separations are particularly intriguing objects as they are easily accessible for variability studies towards rotational dynamics and cloud coverage of these brown dwarfs or planetary-mass objects.Aims. We aim to identify new low-mass companions to young pre-main sequence stars using the astrometric measurements provided by the Gaia space mission and high-contrast imaging data collected with VLT/SPHERE.Methods. We present an algorithm that enables detection of co-moving companions to arbitrary samples of stars using the second data release of the Gaia mission. Based on the provided positions, proper motions, and magnitudes, we identify all objects within a pre- defined radius, whose differential proper motions are consistent with a gravitationally bound system. If the system age is known, the masses of the companions can be determined by comparison to evolutionary tracks. For a brown dwarf companion of the debris disk host TYC 8252-533-1 we use additional data collected with VLT/SPHERE and VLT/NACO to assess the accuracy of the properties of the companion based on Gaia photometry alone.Results. Applying this algorithm to a sample of K-type, pre-main sequence stars in the Scorpius Centaurus association, we identify62 co-moving companions that have a dynamical companionship likelihood of more than 95%. Further color-magnitude analysisconfirms strong compliance with Sco-Cen membership. With Gaia DR2 5860803696599969280, Gaia DR2 6073106193460538240,Gaia DR2 6083750638540951552 (TYC 8252-533-1 B), Gaia DR2 5984404849554176256, and Gaia DR2 6245781131640479360we identify five especially intriguing companions that have masses in the brown dwarf regime down to 40 MJup. Our high-contrastimaging data confirm that TYC 8252-533-1 B is indeed a co-moving companion to its solar-type host star as suggested by Gaia alone.It is likely to be located outside the debris disk around its primary star and SED modeling of Gaia, SPHERE, and NACO photometryprovides a companion mass of 44+9 MJup. This measurement does not only corroborate the brown dwarf nature of the companion but −6also confirms the mass estimate derived from individual Gaia photometry.Conclusions. We show that the Gaia database is well suited for identifying low-mass companions at wide separations from their host stars. For K-type Sco-Cen members Gaia can detect sub-stellar objects at projected separations larger than 300 au and is sensitivity limited beyond 1,000 au with a lower mass limit down to 20 MJup . As the presented algorithm can be easily applied to members in other star-forming regions, it can be used to significantly enlarge the sample size of such objects and test formation and evolution theories of planetary systems. Future data releases of the Gaia mission will enable the identification of additional fainter and lower mass companions and facilitate dynamical analyses of these systems.
DOI: 10.48577/jpl.7b9eiz
title: Demonstration of a trapped-ion atomic clock in space

description: Atomic clocks, which lock the frequency of an oscillator to the extremely stable quantized energy levels of atoms, are essential for navigation applications such as deep space exploration1 and global navigation satellite systems2 , and are useful tools with which to address questions in fundamental physics3–6 . Such satellite systems use precise measurement of signal propagation times determined by atomic clocks, together with propagation speed, to calculate position. Although space atomic clocks with low instability are an enabling technology for global navigation, they have not yet been applied to deep space navigation and have seen only limited application to space-based fundamental physics, owing to performance constraints imposed by the rigours of space operation7 . Methods of electromagnetically trapping and cooling ions have revolutionized atomic clock performance8–13. Terrestrial trapped-ion clocks operating in the optical domain have achieved orders-ofmagnitude improvements in performance over their predecessors and have become a key component in national metrology laboratory research programmes13, but transporting this new technology into space has remained challenging. Here we show the results from a trapped-ion atomic clock operating in space. On the ground, NASA’s Deep Space Atomic Clock demonstrated a short-term fractional frequency stability of 1.5 × 10−13/τ1/2 (where τ is the averaging time)14. Launched in 2019, the clock has operated for more than 12 months in space and demonstrated there a long-term stability of 3 × 10−15 at 23 days (no drift removal), and an estimated drift of 3.0(0.7) × 10−16 per day. Each of these exceeds current space clock performance by up to an order of magnitude15–17. The Deep Space Atomic Clock is particularly amenable to the space environment because of its low sensitivity to variations in radiation, temperature and magnetic felds. This level of space clock performance will enable one-way navigation in which signal delay times are measured in situ, making near-real-time navigation of deep space probes possible.
DOI: 10.48577/jpl.idcnkm
title: Quantifying Global Power Plant Carbon Dioxide Emissions With Imaging Spectroscopy

description: Anthropogenic carbon dioxide (CO2) emissions dominate uncertainties in the global carbon budget. Reporting programs, such as the IPCC National Greenhouse Gas Inventories, have latencies of 12-24 months and may not keep pace with rapidly changing infrastructure, particularly in the developing world. Our work reveals that airborne and satellite imaging spectrometers provide 3 – 30 m spatial resolution and accurate quantification of CO2 emissions at the facility scale. Examples from 17 power plants across the United States demonstrate robust correlation and 21% agreement on average between our remotely sensed estimates and simultaneous in situ measured emissions. We highlight four examples in India, Poland, and South Korea, where we quantify significant carbon dioxide emissions from power plants where limited public emissions data exist. Leveraging previous work on methane (CH4) plume detection, we present a strategy to exploit joint CO2 and CH4 plume imaging to quantify carbon emissions across entire supply chains. We show an example of a coal operation, where we attribute 25% of greenhouse gas emissions to coal extraction (CH4) and the remaining 75% to energy generation (CO2). Satellites allow for quantification of emissions from the highest producing global power plants contributing at least 60% of global coal carbon dioxide emissions. Multiple revisits and coordinated targeting of these high emitting facilities by multiple spaceborne instruments will be key to reducing uncertainties in global anthropogenic CO2 emissions and supporting emissions mitigation strategies.