cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.k5oau4
title: Urban-focused satellite CO2 observations from the Orbiting Carbon Observatory-3: a first look at the Los Angeles Megacity

description: NASA’s Orbiting Carbon Observatory-3 (OCO-3) was designed to support the quantification and monitoring of anthropogenic CO2 emissions. Its Snapshot Area Map (SAM) and target mode measurements provide an innovative dataset for carbon studies on sub-city scales. Unlike any other current space-based instrument, OCO-3 has the ability to scan large contiguous areas of emission hot spots like cities, power plants, and volcanoes. These measurements result in dense, fine-scale spatial maps of column averaged dry-air mole fractions of carbon dioxide (XCO2). For the first time, we present and analyze XCO2 distributions over the Los Angeles (LA) megacity derived from OCO-3 SAM and target mode observations. The urban XCO2 values are elevated by 2−6 ppm relative to a clean background and show excellent agreement with nearby ground-based TCCON measurements of XCO2 . OCO-3’s dense observations reveal intra-urban variations of XCO2 over the city that have never been observed from space before. The spatial variations are mainly driven by the complex fossil fuel emission patterns and meteorological conditions in the LA Basin and are in good agreement with those from co-located TROPOMI measurements of co-emitted NO2. Differences between measured and simulated XCO2 enhancements from two models (WRF-Chem and X-STILT) are typically below 1 ppm with larger differences for some sub regions. Both models capture the observed intra-urban XCO2 gradients even when transport errors are present. Further, OCO-3’s multi-swath measurements capture about three times as much of the city emissions compared to single-swath overpasses. OCO-3’s frequent target and SAM mode observations will pave the way to constrain urban emissions at finer, sub city scales.
DOI: 10.48577/jpl.klmqru
title: Fast Outflows in Hot Dust-Obscured Galaxies Detected with Keck/NIRES

description: We present rest-frame optical spectroscopic observations of 18 Hot Dust-Obscured Galaxies (Hot DOGs) at redshifts 1.7–4.6 with KECK/NIRES. Our targets are selected based on their extreme red colors to be the highest luminosity sources from the WISE infrared survey. In 16 sources with well- detected emission we fit the key [O III], Hβ, Hα, [N II], and [S II] diagnostic lines to constrain physical conditions. Of the 13 targets with a clear detection of the [O III]λ5007 ̊A emission line, 12 display broad blueshifted and asymmetric line profiles, with widths ranging from 1000 to 8000 km s−1 and blueshifts up to 3000 km s−1 with respect to the narrow emission component. These line properties provide strong evidence for the presence of massive ionized outflows of up to 8000 M⊙ yr−1, with a median of 230 M⊙ yr−1. Three sources, and possibly as many as seven, show optical emission line ratios consistent with vigorous ongoing star formation. The resulting Balmer line star-formation rates, uncorrected for reddening, range from 30–1300 M⊙ yr−1, with a median of 80 M⊙ yr−1. Estimates of the SFR from SED fitting of the mid and far-infrared emission suggest significantly higher values. We estimate the central black hole masses to be of order 108−10 M⊙, assuming the present-day MBH −σ∗ relation. The bolometric luminosities and the estimated masses of the central black holes of these galaxies suggest that many of the AGN-dominated Hot DOGs are accreting at or above their Eddington limit. The combination of ongoing star formation, massive outflows, and high Eddington ratios suggest Hot DOGs are a transitional phase in galaxy evolution.
DOI: 10.48577/jpl.cnvxb7
title: Disseminating Scientific Results in the Age of Rapid Communication

description: The COVID-19 related lockdown measures spawned a host of press releases and news articles in the mainstream media on the connections between reduced human activity and improved air quality. In tandem, preprints of COVID-19 and air quality studies and articles based on the preprints began appearing in the social media (Twitter, Facebook, and LinkedIn). The COVID-19 lockdown measures offered a rare opportunity for air quality researchers to showcase their measurements and models. As the virus spread from China to other parts of the world, various countries started imposing lockdown measures one by one. This was soon followed by reports of improved air quality, as observed by satellites, that started to flood the social media outlets. Figure 1 shows the number of articles with the words “COVID-19 and PM2.5”, “COVID-19 and air quality”, “COVID-19 and NO2” found on each of the social media outlets as of August 13, 2020 when the search was made. TROPOMI is the Tropospheric Monitoring Instrument on the Copernicus Sentinel 5 Precursor (S5P) satellite launched (October 13, 2017) and operated by the European Space Agency (ESA).
DOI: 10.48577/jpl.siukqy
title: The EMIT mission information yield for mineral dust radiative forcing

description: The influence of mineral dust is one of the largest uncertainties in global radiative forcing. To address this challenge, NASA’s Earth Mineral dust source InvesTigation (EMIT) will map the mineralogy of Earth’s mineral dust forming regions, constraining the composition of mineral dust and reducing uncertainty in Earth System Models (ESMs). This mission foreshadows multiple future global spectroscopic investigations for which coupling with ESMs will play a critical role. Planning such experiments requires a methodology for assessing the impact of uncertain remote observations on ESM accuracy. In this study, we design and implement an end-to-end simulation of EMIT leveraging Bayesian statistical methods and Monte Carlo sampling to analyze uncertainties in the retrieval and processing of EMIT data products. Special focus is placed on those uncertainties caused by atmospheric water vapor and aerosol loading conditions likely to be encountered by EMIT. We apply these results to a single-column configuration of the NCAR Community Earth System Model (CESM), revealing the impact of EMIT observations on radiative forcing estimates. We find that EMIT data products stand to significantly reduce uncertainty in estimates of the dust radiative forcing due to uncertainties in surface mineralogies that are input to Earth system models, and that the information gain for radiative forcing closely tracks that for iron oxides, which dominate the radiative effects of aerosol dust.
DOI: 10.48577/jpl.di7lmv
title: TDI-1: time-delay interferometry without delays

description: The space-based gravitational-wave observatory LISA relies on a form of synthetic interferometry(time-delay interferometry, or TDI) where the otherwise overwhelming laser phase noise is canceledby linear combinations of appropriately delayed phase measurements. These observables grow inlength and complexity as the realistic features of the LISA orbits are taken into account. In thispaper we outline an implicit formulation of TDI where we write the LISA likelihood directly interms of the basic phase measurements, and we marginalize over the laser phase noises in thelimit of innite laser-noise variance. Equivalently, we rely on TDI observables that are denednumerically (rather than algebraically) from a discrete-lter representation of the laser propagationdelays. Our method generalizes to any time dependence of the armlengths; it simplies the modelingof gravitational-wave signals; and it allows a straightforward treatment of data gaps and missingmeasurements.
DOI: 10.48577/jpl.yx52gi
title: Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO2

description: Photosynthesis uses the energy in sunlight to bind CO2 to a five-carbon sugar, transferring CO2 from the atmosphere to plants (Calvin & Benson, 1948; Farquhar et al., 1980). Sugars produced by photosynthesis provide the building blocks and the primary fuel for much of life on Earth. Plant tissues, many microbes, animals, and dead organic matter are all composed of carbon-rich compounds formed from these photosynthetic sugars. In many environments, an increase in atmospheric CO2 concentration [CO2] increases photosynthesis. Thus an increase in [CO2] leads to greater plant sugar availability with the potential to increase the total amount of carbon stored in the live and dead organic matter in an ecosystem. These observations have led to the CO2-fertilisation hypothesis (Box 1): that plant responses to increasing atmospheric [CO2] drive increases in terrestrial-ecosystem carbon storage creating negative feedback on atmospheric [CO2] growth. Since the industrial revolution human activities have increased [CO2] by 48 % (1760-2019, 277-411 ppm), an increase in atmospheric CO2-carbon of 277 Pg C (Friedlingstein et al., 2019). However, global-scale carbon accounting quantifies anthropogenic emissions to the atmosphere at 645 Pg C and suggests a substantial ‘natural’ terrestrial carbon sink (a net flux of carbon from the atmosphere to intact terrestrial ecosystems) which currently removes the equivalent of 33±9 % of anthropogenic atmospheric CO2 (2009-2018 (Friedlingstein et al., 2019). Along with the ocean carbon sink, this terrestrial carbon sink is mitigating the rate of climate change. Process-based carbon-cycle models attribute increasing [CO2] (iCO2, Table 1) as the primary driver of the terrestrial carbon sink, albeit with substantial uncertainty (Huntzinger et al., 2017; Arora et al., 2019). However, iCO2 is not the only global-change factor that can influence terrestrial carbon stocks. Anthropogenic land-use and land-cover change (hereafter land-use change) and recovery (Pugh et al. 2019), nitrogen cycle changes (Fowler et al., 2013), and climate change all affect ecosystem carbon stocks (Keenan & Williams, 2018). A vast and overwhelming literature often disagrees on the size and duration of CO2- driven increases in terrestrial carbon storage and predictive understanding of this process is a longstanding and unresolved scientific goal.
DOI: 10.48577/jpl.cwfdod
title: Lower-Band “Monochromatic” Chorus Riser Subelement/Wave Packet Observations

description: Three lower-band (f&lt;0.5fce) chorus riser elements detected in the dayside generation region were studied in detail using the Van Allen Probe data. Two subelements/wave packets within each riser were examined for their wave “frequency” constancy within 7 consecutive wave cycles. The 7 wave cycles contained the maximum amplitudes of the subelements/packets. Maximum variance B1 zero crossings were used for the identification of wave cycle start and stop times. It is found that the frequency is constant to within ~3% (one standard deviation), with no evidence of upward frequency sweeping over the 7 cycles. Continuous wavelet power spectra for the duration of the 7 cycles confirms this conclusion. The implication is that a chorus riser element is composed of coherent ~“monochromatic” steps instead of a gradual sweep in frequency over the whole element. There was no upward frequency stepping where the wave amplitude was the largest, contrary to the sideband theory prediction. It is shown that a chorus riser involves instability of cyclotron resonant energetic electrons from ~6 keV to ~40 keV at L=5.8, i.e., essentially the whole substorm electron energy spectrum. The above findings may have important consequences for possible wave generation mechanisms. Some new ideas for mechanisms are suggested in conclusion.
DOI: 10.48577/jpl.o8ugxy
title: Transit Search for Exoplanets Around Alpha Centauri A and B with ASTERIA

description: Alpha Centauri is a triple system with two Sun-like stars, α Cen A (V=0.01) and B (V=1.33), and a third fainter star, Proxima Centauri. Current transit missions cannot produce precision photometry of α Cen A and B as they saturate for these very bright stars. The Arcsecond Space Telescope Enabling Research in Astrophysics (ASTERIA) was a technology demonstration mission with the primary objective of demonstrating key technologies necessary for precision photometry: highly stable thermal control and very precise pointing stability. The payload uses a complementary metal-oxide semiconductor (CMOS) detector that enables monitoring of the brightest stars without saturating. We obtained spatially-unresolved observations of α Cen A and B during opportunistic science campaigns as part of ASTERIA’s extended mission. The resulting photometric precision for the blended α Cen A and B data is 250 ppm (parts per million) per 9s, i.e., less than twice the photon noise limit. We establish limits for transiting exoplanets around both α Cen A and B using transit signal injection and recovery tests. We find that ASTERIA is sensitive to planets with radii as small as 3 R⊕ around α Cen A and 3.7 R⊕ around α Cen B, corresponding to signals of ∼0.5 parts-per-thousand, with periods ranging 0.5 to 6 days, illustrating the effective role of nanosatellites in achieving compelling science output.
DOI: 10.48577/jpl.64tqi4
title: Multi-view polarimetric scattering cloud tomography and retrieval of droplet size

description: Tomography aims to recover a three-dimensional (3D) density map of a medium or an object. In medical imaging, it is extensively used for diagnostics via X-ray computed tomography (CT). We define and derive a tomography of cloud droplet distributions via passive remote sensing. We use multi-view polarimetric images to fit a 3D polarized radiative transfer (RT) forward model. Our motivation is 3D volumetric probing of vertically-developed convectively-driven clouds that are ill-served by current methods in operational passive remote sensing. These techniques are based on strictly 1D RT modeling and applied to a single cloudy pixel, where cloud geometry defaults to that of a plane-parallel slab. Incident unpolarized sunlight, once scattered by cloud-droplets, changes its polarization state according to droplet size. Therefore, polarimetric measurements in the rainbow and glory angular regions can be used to infer the droplet size distribution. This work defines and derives a framework for a full 3D tomography of cloud droplets for both their mass concentration in space and their distribution across a range of sizes. This 3D retrieval of key microphysical properties is made tractable by our novel approach that involves a restructuring and differentiation of an open-source polarized 3D RT code to accommodate a special two-step optimization technique. Physically-realistic synthetic clouds are used to demonstrate the methodology with rigorous uncertainty quantification.
DOI: 10.48577/jpl.qpw0py
title: FDTD Modeling of Internal Electrostatic Discharge Events Coupled to High Frequency Antennas

description: Satellites that orbit planets with radiation belts are subjected to experience Internal ElectroStatic Discharge (IESD) events as they interact with charged particles. When charge accumulation exceeds the threshold of the dielectric material on the spacecraft, large discharges occur. The discharges generate electromagnetic pulses that couple to the antennas and induce high voltages. Protection from these discharges is of paramount concern for instrument fidelity of the spacecraft. Modeling the spacecraft and simulating these IESD events using a Maxwell’s equations solver can describe how IESDs couple to the antennas of the spacecraft and thus provide information on how to properly protect the instruments from these high voltages. In particular, the finite-difference time-domain (FDTD) method offers advantages for this application over other electromagnetic numerical solvers because in a straight-forward manner it can simulate wideband transient pulses and also accurately solve near-field effects. A generalized analysis method is proposed and carried out in which an FDTD model is used to obtain transfer functions for IESD’s occurring at hundreds of different locations on the spacecraft, which are then linearly combined to represent a wide variety of possible scenarios.
DOI: 10.48577/jpl.15ari4
title: A Climatology of Atmospheric Rivers and Associated Precipitation for the Seven US National Climate Assessment Regions

description: Atmospheric Rivers (ARs), long and narrow filamentary regions of enhanced vertically integrated water vapor transport (IVT), play an important role in regional hydrometeorological extremes and the global water cycle. Here an AR detection algorithm is applied to global reanalysis from Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) to characterize ARs regionally across the continental United States (CONUS). Regionally aggregated measures of AR characteristics, including area, direction, magnitude, and associated precipitation quantities, are computed across the CONUS at the grid point scale and summarized for each of the seven US National Climate Assessment (NCA) regions. Climatologically, AR frequency maxima tend to occur in the fall and winter in the West, spring in the Great Plains, and fall in the Midwest and Northeast. Basic geometry and IVT characteristics of objectively detected ARs have regional and seasonal variability. Seasonal AR IVT magnitude, direction composites reveal northeastward directed moisture fueled by the tropical Pacific in the Northwest and Southwest with multiple seasonally-varying moisture sources, from the Pacific and Atlantic, observable in the Southern Great Plains and Midwest. Linked AR precipitation characeristics suggest that a substantial proportion of 95th percentile extreme precipitation days are associated with ARs over many parts of CONUS, including the eastern US. Regional patterns of AR-driven precipitation suggest that complex dynamic, seasonally-varying, synoptically-driven transport mechanisms are important across the East compared to the West where orographically enhanced wintertime precipitation extremes are dominant.
DOI: 10.48577/jpl.oboc59
title: CYGNSS Observations and Analysis of Low-Latitude Extratropical Cyclones

description: Latent and sensible heat fluxes over the oceans are thought to play an important role in the genesis and evolution of marine-based extratropical cyclones (ETCs), and to affect rapid cyclogenesis. Observations of ocean surface heat fluxes are limited from existing in-situ and remote sensing platforms, which may not offer sufficient spatial and temporal resolution. Additionally, substantial precipitation frequently veils the ocean surface around ETCs, limiting the capacity of space-borne instruments to observe the surface processes within maturing ETCs. While it was designed as a tropics-focused mission, the Cyclone Global Navigation Satellite System (CYGNSS) can observe ocean surface wind speed and heat fluxes within a notable quantity of low-latitude extratropical fronts and cyclones. These observations can assist in understanding how surface processes may play a role in cyclogenesis and ETC evolution. This paper illustrates CYGNSS’s capability to observe extratropical cyclones manifesting in various ocean basins throughout the globe, and shows that the observations provide a robust sample of ETCs winds and surface fluxes, as compared with a reanalysis dataset.
DOI: 10.48577/jpl.vvg6ma
title: Controlling Microstructure of FeCrMoBC Amorphous Metal Matrix Composites via Laser Directed Energy Deposition

description: Fe-based amorphous coatings are typically known for their high hardness and wear resistance and are often applied using thermal spraying techniques. When cladding these materials, using laser directed energy deposition (DED), it becomes possible to vary the cooling rate to create unique microstructures. Herein, it is demonstrated that a common FeCrMoBC coating alloy, typically known for its high hardness, can be fabricated into a variety of microstructures using DED, including an amorphous metal matrix composite with a soft dendritic phase and intrinsic toughening mechanism. The work offers the promise of using DED to fabricate custom claddings with high toughness as well as providing a potential route for creating ductile-phase-reinforced metallic glass composites using additive manufacturing.
DOI: 10.48577/jpl.23hxch
title: Inferring (Sub)millimeter Dust Opacities and Temperature Structure in Edge-on Protostellar Disks From Resolved Multi-Wavelength Continuum Observations: The Case of the HH212 Disk

description: (Sub)millimeter dust opacities are required for converting the observable dust continuum emission to the mass, but their values have long been uncertain, especially in disks around young stellar objects. We propose a method to constrain the opacity 𝜅_𝜈 in edge-on disks from a characteristic optical depth 𝜏_0,𝜈, the density 𝜌_0 and radius 𝑅_0 at the disk outer edge through 𝜅_𝜈 = 𝜏_0,𝜈/(𝜌_0𝑅_0) where 𝜏_0,𝜈 is inferred from the shape of the observed flux along the major axis, 𝜌_0 from gravitational stability considerations, and 𝑅_0 from direct imaging. We applied the 1D semi-analytical model to the embedded, Class 0, HH 212 disk, which has high-resolution data in ALMA Band 9, 7, 6, and 3 and VLA Ka band (𝜆=0.43, 0.85, 1.3, 2.9, and 9.1 mm). The modeling of the HH 212 disk is extended to 2D through RADMC-3D radiative transfer calculations. We find a dust opacity of 𝜅_𝜈 ≈ 1.9×10^-2, 1.3×10^-2, and 4.9×10^-3 cm^2 per gram of gas and dust for ALMA Bands 7, 6, and 3, respectively, with uncertainties dependent on the adopted stellar mass. The inferred opacities lend support to the widely used prescription 𝜅_𝜆 = 2.3 × 10^-2 (1.3mm/𝜆) cm^2 g^-1 advocated by Beckwith et al. (1990). We inferred a temperature of ∼45 K at the disk outer edge which increases radially inward. It is well above the sublimation temperatures of ices such as CO and N_2, which supports the notion that the disk chemistry cannot be completely inherited from the protostellar envelope.
DOI: 10.48577/jpl.ldbejh
title: Application of a self-injection locked cyan laser for Barium ion cooling and spectroscopy

description: Compact, high power lasers with narrow linewidth are important tools for the manipulation of quantum systems. We demonstrate a compact, self-injection locked, Fabry-Perot semiconductor laser diode with high output power at 493 nm. A high quality factor magnesium fluoride whispering gallery mode resonator enables both high passive stability and 1 kHz instantaneous linewidth. We use this laser for laser-cooling, in-situ isotope purifcation, and probing barium atomic ions confined in a radio-frequency ion trap. The results here demonstrate the suitability of these lasers in trapped ion quantum information processing and for probing weak coherent optical transitions.