cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.dv3ssh
title: A Bayesian framework for deriving sector-based methane emissions from top-down fluxes

description: Atmospheric methane observations are used to test methane emission inventories as the sum of emissions must be balanced by the change of observed methane concentrations. Typically, concentrations are inversely projected to a net flux through an atmospheric chemistry-transport model. However attribution of flux to the underlying sector-based emissions is challenged by prior assumption about the emission distribution, spatial resolution and correlated uncertainties between fluxes, and model chemistry and transport error. Here we show a Bayesian optimal estimation method that projects these methane fluxes to sector-based emissions on an arbitrarily sized grid, while accounting for these inverse estimate characteristics. We apply this method to 2010-2015 satellite-derived fluxes over the U.S. and show how we can explicitly characterize a posterior sector-based emission budget based on fluxes. We also apply this approach to two different emissions estimates over the Permian Basin, between 2010-2015 to 2018-2019, and can robustly conclude that increased gas emissions drive the observed changes in fluxes, consistent with activity data. This approach provides robust comparisons between top-down estimates of emissions from different observing systems, critical for assessing the efficacy of policies or global agreements intended to reduce emissions using the ever increasing number of satellite observations.
DOI: 10.48577/jpl.7z4bls
title: Passive and Active Multiple Scattering of Forests Using Radiative Transfer Theory With an Iterative Approach and Cyclical Corrections

description: In this paper, a unified framework of vegetationscattering using radiative transfer theory for passive and activeremote sensing of vegetated land surfaces, especially thoseassociated with moderate to large vegetation water contents(VWCs), e.g., forest field, is presented. The framework allowsfor modeling passive and active microwave signatures of thevegetated field with the same physical parameters describingthe vegetation structure. Radiative transfer equations are solvedby a numerical iterative approach for both passive and activeconfigurations. This approach allows including higher orderscattering which represents multiple scattering. In fields likeforests with large VWCs, associated with large scattering albedoand optical thickness, multiple scattering effects are critical.In the active iterative approach, cyclical terms are identifiedand backscattering enhancement is included by doublingcontributions from cyclical terms. The method is applied to aspentrees in forest fields to compute the brightness temperatures andbackscattering coefficients for passive and active remote sensingconfigurations, respectively. In passive configuration, for forestfield with VWC of 15 kg/m2, the deviation between zeroth orderbrightness temperature, i.e., the tau-omega model results, andmultiple scattering results around 40 observation angle, can beas large as 50 K for vertical polarization and 35 K for horizontalpolarization. In active configuration, the deviation between firstorder results, which is identical to distorted Born approximation,and the multiple scattering results around 40 incidence angle, isabout 1.6 dB for V V and 0.7 dB for HH polarization. Multiplescattering is shown to be crucial for accurate forward modeling,especially over forested areas. The proposed approach is thussuitable for vegetation scattering with large VWCs. Furthermore,the proposed model is validated with the Passive and ActiveL-band Sensor (PALS) acquired in SMAPVEX12 measurementsin 2012, which demonstrates the applicability of this model.
DOI: 10.48577/jpl.ebnonm
title: The Enigmatic Brown Dwarf WISEA J153429.75−104303.3 (aka "The Accident")

description: Continued follow-up of WISEA J153429.75−104303.3, announced in Meisner et al. (2020), has proven it to have an unusual set of properties. It is one of the few faint proper motion sources known with J−ch2 &gt; 8 mag, indicating a very cold temperature consistent with the latest known Y dwarfs. Despite this, it has W1−W2 and ch1−ch2 colors ∼1.6 mag bluer than a typical Y dwarf. A new trigonometric parallax measurement from a combination of WISE, Spitzer, and HST astrometry confirms a nearby distance of 16.3+/-1.4 pc and a large transverse velocity of 207.4+/-15.9 km s known Y dwarfs, despite the highly discrepant W1−W2 and ch1−ch2 colors. We explore possible reasons for the unique traits of this object and conclude that it is most likely an old, metal-poor brown dwarf and possibly the first Y subdwarf. Given that the object has an HST F110W magnitude of 24.7 mag, broad-band spectroscopy and photometry from JWST are the best options for testing this hypothesis.
DOI: 10.48577/jpl.vk3jd4
title: Geomorphological map of the South Belet Region of Titan

description: We mapped in detail Titan’s South Belet region which spans the area from longitude 60W to 120W (+W coordinates) and from latitude 60S to 0, encompassing both equatorial and southern mid-latitude regions. This mapping work is a continuation of the detailed global mapping effort introduced in Malaska et al. (2016a) and continued on in Lopes et al. (2020). We used Cassini Radar in its Synthetic Aperture Radar (SAR) mode data as our basemap but supplemented with additional datasets. We followed the mapping procedure described in Malaska et al. (2016a) for the Afekan Crater region and identified four major terrain classes in South Belet: craters, hummocky/mountainous, plains, and dunes. Each terrain class was subdivided into terrain units by characteristic morphology, including border shape, texture, general appearance, and radar backscatter. There are two terrain units that were not included in previous studies but were identified in our mapping of South Belet: “bright alluvial plains” and “pitted hummocky”. Similar to the Afekan Crater region, we find that plains dominate the surface make-up of South Belet, comprising ~ 47.0% of the mapped area. Unlike Afekan, the areal extent of the dunes closely rivals the dominance of plains, making up 43.0% of the mapped area. The next most widespread unit by area in the region following the dunes are the mountains/hummocky terrains (10.0%), and finally, crater terrains (0.01%). The introduction of two new units, “bright alluvial plains” and “pitted hummocky”, are necessary to capture the full range of morphologies seen in South Belet. However, analysis of our geomorphological mapping results suggests South Belet is consistent with the narrative of organics dominating the equatorial and mid-latitudes. This is similarly the conclusion we arrived at through our mapping and analysis of the Afekan region. Lastly, the applicability of the terrain units from our mapping of the Afekan region to our mapping of South Belet suggests latitudinal symmetry in Titan’s surface processes and their evolution.
DOI: 10.48577/jpl.hqn1dt
title: Detection of Aerosols at Microbar Pressures in an Exoplanet Atmosphere

description: Formation of hazes at microbar pressures has been explored by theoretical models of exoplanet atmo- spheres to explain Rayleigh scattering and/or featureless transmission spectra, however observational evidence of aerosols in the low pressure formation environments has proved elusive. Here, we show direct evidence of aerosols existing at ∼1 microbar pressures in the atmosphere of the warm sub- Saturn WASP-69b using observations taken with Space Telescope Imaging Spectrograph (STIS) and Wide Field Camera 3 (WFC3) instruments on the Hubble Space Telescope. The transmission spec- trum shows a wavelength-dependent slope induced by aerosol scattering that covers 11 scale heights of spectral modulation. Drawing on the extensive studies of haze in our Solar System, we model the transmission spectrum based on a scaled version of Jupiter’s haze density profile to show that WASP- 69b transmission spectrum can be produced by scattering from an approximately constant density of particles extending throughout the atmospheric column from 40 millibar to microbar pressures. These results are consistent with theoretical expectations based on microphysics of the aerosol particles that have suggested haze can exist at microbar pressures in exoplanet atmospheres.
DOI: 10.48577/jpl.yle4yr
title: The Impact of Powerful Jets on the Far Infrared Emission of an Extreme Radio Quasar at z~6

description: The interactions between radio jets and the interstellar medium play a defining role for the co-evolution of central supermassive black holes and their host galaxies, but observational constraints on these feedback processes are still very limited at redshifts $z &gt; 2$. We investigate the radio-loud quasar PSO J352.4034--15.3373 at $z \sim 6$ at the edge of the Epoch of Reionization. This quasar is among the most powerful radio emitters and the first one with direct evidence of extended radio jets ($\sim$1.6 kpc) at these high redshifts. We analyze NOEMA and ALMA millimeter data targeting the CO\,(6--5) and C II far-infrared emission lines, respectively, and the underlying continuum. The broad $440\pm 80$~km~s$^{-1}$ and marginally resolved \cii\ emission line yields a systemic redshift of $z\!=\!5.832 \pm 0.001$. Additionally, we report a strong 215~MHz radio continuum detection, $88\pm 7$\,mJy, using the GMRT. This measurement significantly improves the constraints at the low-frequency end of the spectral energy distribution of this quasar. In contrast to what is typically observed in high-redshift radio-quiet quasars, we show that cold dust emission alone cannot reproduce the millimeter continuum measurements. This is evidence that the strong synchrotron emission from the quasar contributes substantially to the emission even at millimeter (far-infrared in the rest-frame) wavelengths. This quasar is an ideal system to probe the effects of radio jets during the formation of a massive galaxy within the first Gyr of the Universe.
DOI: 10.48577/jpl.aa9mhz
title: Modeling the Formation of Menrva Impact Crater on Titan: Implications for Habitability

description: Titan is unique in the solar system: it is an ocean world, an icy world, an organic world, and has a dense atmosphere. It is a geologically active world as well, with ongoing exogenic processes, such as rainfall, sediment transportation and deposition, erosion, and possible endogenic processes, such as tectonism and cryovolcanism. This combination of an organic and an ocean world makes Titan a prime target for astrobiological research, as biosignatures may be present in its surface, in impact melt deposits and in cryovolcanic flows, as well as in deep ice and water ocean underneath the outer ice shell. Impact craters are important sites in this context, as they may have allowed an exchange of materials between Titan’s layers, in particular between the surface, composed of organic sediments over icy bedrock, and the subsurface ocean. It is also possible that impacts may have favored the advance of prebiotic chemical reactions themselves, by providing thermal energy that would allow these reactions to proceed. To investigate possible exchange pathways between the subsurface water ocean and the organic-rich surface, we modeled the formation of the largest crater on Titan, Menrva, with a diameter of ca. 425 km. The premise is that, given a large enough impact event, the resulting crater could breach into Titan’s ice shell and reach the subsurface ocean, creating pathways connecting the surface and the ocean. Materials from the deep subsurface ocean, including salts and potential biosignatures of putative subsurface biota, could be transported to the surface. Likewise, atmospherically derived organic surface materials could be directly inserted into the ocean, where they could undergo aqueous hydrolysis to form potential astrobiological building blocks, such as amino acids. To study the formation of a Menrva-like impact crater, we staged numerical simulations using the iSALE-2D shock physics code. We varied assumed ice shell thickness from 50 to 125 km and assumed thermal structure over a range consistent with geophysical data. We analyze the implications and potential contributions of impact cratering as a process that can facilitate the exchange of surface organics with liquid water. Our findings indicate that melt and partial melt of ice took place in the central zone, reaching ca. 65 km depth and ca. 60 km away from the center of the structure. Furthermore, a volume of ca. 102 km3 of ocean water could be traced to depths as shallow as 10 km. These results highlight the potential for a significant exchange of materials from the surface (organics and ice) and the subsurface (water ocean), particularly in the crater's central area. Our studies suggest that large hypervelocity impacts are a viable and likely key mechanism to create pathways between the underground water ocean and Titan’s organic-rich surface layer and atmosphere.
DOI: 10.48577/jpl.bqqnbb
title: Fundamental Physics with a State-of-the-Art Optical Clock in Space

description: Time is an omnipresent concept in modern society and plays a central role in the foundations of physics and our understanding of the cosmos. Atomic clocks keep international time and their quantum measurements are arguably, by orders of magnitude, the most accurate measurements of any physical observable. Figure 1 shows the dramatic improvement of the accuracy of atomic clocks over the last 20 years, far faster than in the last half of the 20th century. This extremely rapid improvement of clocks at optical frequencies resulted from advancements in the manipulation of atomic quantum systems, as well as advanced techniques in laser cooling/trapping and the development of fs-laser frequency combs in 2000, which enabled the reliable counting of the ticks of the cycles of laser light at 1015 cycles per second (Ludlow et al. 2015). The most accurate versions of these optical clocks use trapped quantum absorbers (either ions or lattice-confined neutral atoms) and now have fractional frequency uncertainties approaching or exceeding 1 part in 1018, which enable transformational advances in areas ranging from navigation and ultra-precise ranging, searches for dark matter, observation of gravity waves, and stringent tests of general relativity. The accuracy of optical clocks had been advancing at the breakneck rate of the last decade. Indeed, with no foreseeable barriers to continued steady improvement as projected in Figure 1, clock accuracies would reach 1019 in 2027, 1020 by 2034, and 1021 in two decades, at which point gravity waves could be directly observed in the tick rates of clocks. While specific large advances are not possible to predict, dramatic improvements using quantum entanglement are anticipated and there is no known fundamental limitation in sight to the ultimately achievable accuracy of atomic clocks.
DOI: 10.48577/jpl.guh1l7
title: CLIMATE PATTERNS: ORIGIN and FORCING

description: This brief review described spatial-time climate patterns generated by the dy- namics and thermodynamics of the Earth’s climate system and methods of identifying these patterns. Specifically it does discuss the following major cli- mate patterns: El Nin˜o-Southern Oscillation (ENSO), Cold Ocean–Warm Land (COWL) pattern, Northern and Southern Annular Patterns (NAM and SAM), Atlantic Multidecadal Oscillation (AMO) and Atlantic Meridional Overturn- ing Crculation (AMOC), Pacific North-American Pattern (PNA) and Pacific Decadal Oscillation Pattern (PDO). In view of an extensive number of publi- cations on some climate patterns, such as the ENSO, which discussed in many hundred of publications, this review is not intended to cover all the details of individual climate patterns but intends only to give a general overview of their structure, mechanisms of their formation and response to external forcing. It is assumed that the climate patterns can be treated as attractors of dynamical systems allowing us to extract and predict some specific features of the patterns such as the origin and evolution of the climate patterns and their role in the climate change. Thus the knowledge of patterns allows the climate prediction on long time scales and understanding of how an external forcing affects the frequency of occurrence of climate patterns and their magnitude but not the spatial structure.
DOI: 10.48577/jpl.nxjtzk
title: Accreting protoplanets: Spectral signatures and magnitude of gas and dust extinction at Hα

description: Context. Accreting planetary-mass objects have been detected at Hα, but targeted searches have mainly resulted in non-detections. Accretion tracers in the planetary-mass regime should originate from the postshock region, making them particularly susceptible to extinction by the accreting material. Also, high-resolution (R&gt;50,000) spectrographs operating at Hα will soon enable studying how the incoming material shapes the line profile.Aims. We calculate how much the gas and dust accreting onto a planet reduce the Hα flux from the shock at the planetary surface and how they affect the line shape. We also study the absorption-modified relationship between Hα luminosity and accretion rate.Methods. We compute the high-resolution radiative transfer of the Hα line using a one-dimensional model of the velocity-density-temperature structure of the inflowing matter for three representative accretion geometries: spherical symmetry, polar inflow, and magnetospheric accretion. For each, we explore the wide relevant parameter space in accretion rate and mass. We use detailed gas opacities, including resonant absorption, and critically assess what appropriate dust opacity values might be.Results. At accretion rates Mdot ≲ 3×10^-6 Mjup yr^-1, gas extinction is negligible for spherical or polar inflow and at most A_Hα ≲ 0.5 mag for magnetospheric accretion. Up to Mdot ≈ 3 × 10^−4 Mjup yr^−1, the gas contributes A_Hα ≲ 4 mag, decreasing with mass. We estimate realistic dust opacities at Hα to be κ ∼ 0.01–10 cm^2 g^−1, 10–10^4 times lower than in the interstellar medium. Extinction flattens the L_Hα–Mdot relationship, which becomes non-monotonic with a maximum luminosity L_Hα ∼ 10 L_⊙ towards Mdot ≈ 10^-4 Mjup yr^-1 for a planet mass Mp ∼ 10 Mjup. In magnetospheric accretion, the gas can introduce features in the line profile, while the velocity gradient smears them out in other geometries.Conclusions. For a wide part of parameter space, extinction by the accreting matter should be mild, simplifying the interpretation of observations, especially for planets in gaps. At high Mdot, strong absorption reduces the Hα flux, and some Hα fluxes can be interpreted as two Mdot values. Highly-resolved line profiles (R ∼ 10^5) can provide (complex) constraints on the thermal and dynamical structure of the accretion flow.
DOI: 10.48577/jpl.q9xos1
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, carbon and water cycles, and feedbacks to the climate. Temperature, light, atmospheric water demand, soil moisture, and leaf water potential 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 plant functioning and 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 fluorescence (SIF) data at different times of day. New generation operational geostationary satellites such as Himawari-8 and the GOES-R series 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 are also planned to 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 day in response to temperature and water stresses and management practices. We also envision that these emerging observations will revolutionize studies of ecosystem processes and that these observations and findings can inform agricultural and forest management and lead to improvement of Earth system models and climate projections.
DOI: 10.48577/jpl.f5pf8j
title: Nonlinearity and wideband parametric amplification in an NbTiN microstrip transmission line

description: The nonlinear response associated with the current dependence of the superconducting kineticinductance was studied in capacitively shunted NbTiN microstrip transmission lines. It was foundthat the inductance per unit length of one microstrip line could be changed by up to 20% byapplying a DC current, corresponding to a single pass time delay of 0.7 ns. To investigate nonlineardissipation, Bragg reectors were placed on either end of a section of this type of transmissionline, creating resonances over a range of frequencies. From the change in the resonance linewidthand amplitude with DC current, the ratio of the reactive to the dissipative response of the linewas found to be 788. The low dissipation makes these transmission lines suitable for a number ofapplications that are microwave and millimeter-wave band analogues of nonlinear optical processes.As an example, by applying a millimeter-wave pump tone, very wide band parametric amplicationwas observed between about 3 and 34 GHz. Use as a current variable delay line for an on-chipmillimeter-wave Fourier transform spectrometer is also considered.
DOI: 10.48577/jpl.mcs5sy
title: New sampling strategy removes imaging spectroscopy solar-smearing bias in sub-km vapour scaling statistics

description: Abstract. Upcoming spaceborne imaging spectrometers will allow retrieval of total column water vapour (TCWV) over land at horizontal resolution of 30—80 m. Here we show how to obtain, from these retrievals, exponents describing the power-law scaling of sub-km horizontal variability in clear-sky bulk planetary boundary layer (PBL) water vapour (q). Using large-eddy simulations (LES) of shallow convective PBLs we show how sunlight entering the PBL up to several km away from the footprint location degrades estimates of these exponents. We address this by calculating exponents perpendicular to the solar azimuth, that is to say flying “across” the sunlight path rather than “towards” or “away” from the Sun. Across 23 LES snapshots, at SZA=60° the mean bias in calculated exponent is 38±12 % (95 % range) along the solar azimuth, while following our strategy it is 3±9 % and no longer significant. Both bias and root-mean-square error RMSE decrease with lower SZA. We include retrieval errors from several sources including: (1) the Earth Surface Mineral Dust Source Investigation (EMIT) instrument noise model, (2) requisite assumptions about the atmospheric thermodynamic profile, and (3) spatially nonuniform aerosol distributions. This technique can be used to obtain unique information about sub-km PBL q scaling from upcoming spaceborne spectrometer missions, while mitigating errors due to challenging solar geometries.