cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.wz5nnu
title: Using remote sensing to detect, validate, and quantify methane emissions from California solid waste operations

description: Solid waste management represents one of the largest anthropogenic methane emission 14 sources. However, precise quantification of landfill and composting emissions remains difficult due 15 to variety of site-specific factors that contribute to landfill gas generation and effective capture. 16 Remote sensing is an avenue to quantify process-level emissions from waste management facilities. 17 The California Methane Survey flew the Next Generation Airborne Visible/Infrared Imaging 18 Spectrometer (AVIRIS-NG) over 270 landfills and 166 organic waste facilities repeatedly during 19 2016-2018 to quantify their contribution to the statewide methane budget. We use representative 20 methane retrievals from this campaign to present three specific findings where remote sensing 21 enabled better landfill and composting methane monitoring: (1) Quantification of strong point source 22 emissions from the active face landfills that are difficult to capture by in situ monitoring or landfill 23 models, (2) emissions that result from changes in landfill infrastructure (design, construction, and 24 operations), and (3) unexpected large emissions from two organic waste management methods 25 (composting and digesting) that were originally intended to help mitigate solid waste emissions. Our 26 results show that remotely-sensed emission estimates reveal processes that are difficult to capture in 27 biogas generation models. Furthermore, we find that airborne remote sensing provides an effective 28 avenue to study the temporally changing dynamics of landfills. This capability will be further 29 improved with future spaceborne imaging spectrometers set to launch in the 2020s.
DOI: 10.48577/jpl.o6vnct
title: Completion of the AMR-C Instrument for Sentinel-6

description: The Advanced Microwave Radiometer – Climate Quality (AMR-C) is part of the European Sentinel-6A/B series, a collaboration between ESA and NASA, of two Earth-observing satellites which will be launched in 2020 and 2025. Compared to its predecessor, Jason-3, the two AMR-C radiometer instruments have an external calibration system which enables higher radiometric stability accomplished by moving the secondary mirror between well-defined targets. Sentinel-6 allows continuing the study of the ocean circulation, climate change, and sea-level rise for at least another decade. Besides the external calibration for the AMR heritage radiometer (18.7, 23.8, and 34 GHz channels) the AMR-C contains a High-Resolution Microwave Radiometer (HRMR) with radiometer channels at 90, 130, and 168 GHz. This subsystem allows for a factor of 5x higher spatial resolution at coastal transitions. This paper presents a brief description of the instrument and the measured performance of the completed AMR-C-A and AMR-C-B instruments.
DOI: 10.48577/jpl.w4va9l
title: Detection of polarization due to cloud bands in the nearby Luhman 16 brown dwarf binary

description: Brown dwarfs exhibit patchy or spatially-varying banded cloud structures, that are inferred through photometric and spectroscopic variability modeling techniques. However, these methods are insensi- tive to rotationally-invariant structures, such as the bands seen in Jupiter. Here, we present H-band VLT/NaCo linear polarization measurements of the nearby Luhman 16 L/T transition binary, that suggest that Luhman 16A exhibits constant longitudinal cloud bands. The instrument was oper- ated in pupil tracking mode, allowing us to unambiguously distinguish between a small astrophysical polarization and the ∼ 2% instrumental linear polarization. We measure the degree and angle of linear polarization of Luhman 16A and B to be pA = 0.031 ± 0.004% and ψA = −32 ± 4◦, and p = 0.010 ± 0.004% and ψ = 73+13◦, respectively. Using known physical parameters of the system, B B−11 we demonstrate that an oblate homogeneous atmosphere cannot account for the polarization measured in Luhman 16A, but could be responsible for that of the B component. Through a non-exhaustive search of banded cloud morphologies we demonstrate a two-banded scenario that can achieve a degree of linear polarization of p = 0.03%, and conclude that the measured polarization of the A component must be predominantly due to cloud banding. For Luhman 16B, either oblateness or cloud banding could be the dominant source of the measured polarization. The misaligned polarization angles of the two binary components tentatively suggests spin-orbit misalignment. These measurements provide new evidence for the prevalence of cloud banding in brown dwarfs while at the same time demonstrating a new method–complementary to photometric and spectroscopic variability methods–for characterizing the cloud morphologies of substellar objects without signs of variability.
DOI: 10.48577/jpl.yq4lyt
title: Evaluation of AIRS Cloud Phase Classification over the Arctic Ocean Against Combined CloudSat-CALIPSO Observations

description: Cloud phase retrievals from the Atmospheric Infrared Sounder (AIRS) are evaluated against combined CloudSat-CALIPSO (CCL) observations using four years of data over the Arctic Ocean. AIRS cloud phase is evaluated over sea ice and open ocean separately using collocated CCL and AIRS fields of view (FOVs). Additionally, AIRS and CCL cloud phase occurrences are evaluated seasonally, zonally, and with respect to total column water vapor (TCWV) and lapse rate (Γ). Lastly, collocated MODIS cloud information is implemented in a one-month case study to assess the relationship between AIRS phase decisions, cloud cover and cloud phase throughout the AIRS FOV. Depending on the surface type, AIRS classification skill for single-layer ice and liquid-phase clouds is between 85%-95% and 22%-32%, respectively. Most unknown and liquid AIRS phase classifications correspond to mixed-phase clouds. AIRS ice- phase relative occurrence is biased low compared to CCL. However, the liquid-phase relative occurrence is similar between the two instruments. Compared to the CCL climatology, AIRS accurately represents the seasonal cycle of liquid and ice cloud phase across the Arctic as well as the relationship between cloud phase and TCWV and Γ regime in some cases. When MODIS cloud cover or cloud phase within the AIRS FOV is more heterogeneous, it tends to lead the unknown-phase classifications by the AIRS algorithm.
DOI: 10.48577/jpl.lrqpm9
title: Subsurface in-situ detection of microbes and diverse organic matter hotspots in the Greenland ice sheet

description: We used a Deep UV fluorescence mapping spectrometer, coupled to a drill system, to scan from the surface to 105 m depth into the Greenland ice sheet. The scan included firn and glacial ice and demonstrated that the instrument is able to determine small (mm) and large (cm) scale regions of organic matter concentration and discriminate spectral types of organic matter at high resolution. Both a linear point cloud scanning mode and a raster mapping mode were used to detect and localize microbial and organic matter “hotspots” embedded in the ice. Our instrument revealed diverse spectral signatures. Most hotspots were less than 20 mm in diameter, clearly isolated from other hotspots, and distributed stochastically; there was no evidence of layering in the ice at the fine scales examined (100 microns per pixel). The spectral signatures were consistent with organic matter fluorescence from microbes, lignins, fused-ring aromatic molecules, including polycyclic aromatic hydrocarbons, and biologically derived materials such as fulvic acids. In situ detection of organic matter hotspots in ice prevents loss of spatial information and signal dilution when compared to traditional bulk analysis of ice core meltwaters. Our methodology could be useful for detecting microbial and organic hotspots in terrestrial icy environments and on future missions to the Ocean Worlds of our Solar System. Key words: Deep-UV spectroscopy – Fluorescence mapping – Organic detection- Europa – Enceladus – Titan
DOI: 10.48577/jpl.ofbcqi
title: A Simplified Framework for High-Resolution Urban Vegetation Classification with Optical Imagery in the Los Angeles Megacity

description: Excessive fossil fuel CO2 emissions and high ozone levels in Los Angeles, California make the Southern California Air Basin (SoCAB) one of the most heavily polluted regions in the United States. However, the impact of the biosphere on CO2 levels in Los Angeles is a major source of uncertainty in estimating anthropogenic emissions. Compared to other megacities, a relatively large fraction of SoCAB consists of vegetated area, and the biospheric CO2 flux in Los Angeles is non-negligible, potentially making up 15% of the excess flux at certain times of the year. To improve estimates of biospheric contributions to the urban carbon budget, high spatial resolution maps are needed to capture the heterogeneity of urban land cover while spanning the regional domain used in carbon inversion models. We present a method of data fusion using supervised classification for developing a high spatial resolution map of urban vegetation cover in SoCAB with publicly available satellite imagery. This technique uses Sentinel-2 (10-60 m x 10-60m) and NAIP (60 cm x 60 cm) imagery to classify urban and non-urban areas of impervious surface, tree, grass, shrub, non-photosynthetic vegetation, pools, and lakes. Our approach was developed for Los Angeles, a geographically complex megacity characterized by diverse Mediterranean land cover and a mix of high-rise buildings and topographic features that produce strong shadow effects. We show that a fused NAIP and Sentinel-2 classification reduces misclassified shadow pixels and resolves spatially heterogeneous vegetation gradients across urban and non-urban regions in SoCAB at 60 cm resolution with 83% accuracy. Our approach thus provides flexibility and accuracy for application in any urban region. Results from this study will enable long-term monitoring of land cover change associated with urbanization, and quantification of biospheric contributions to carbon and water cycling in cities.
DOI: 10.48577/jpl.qxvzox
title: Thermal Kinetic Inductance Detectors for Millimeter-Wave Astrophysics

description: Thermal Kinetic Inductance Detectors (TKIDs) combine the excellent noise performance of traditional bolometers with a radio frequency (RF) multiplexing architecture that enables the large detector counts needed for the next generation of millimeter wave instruments. Here we present dark prototype TKID pixels that demonstrate a noise equivalent power NEP = 2 × 10−17 W/√Hz with a 1/ f knee at 0.1 Hz, suitable for background-limited noise performance at 150 GHz from a ground-based site. We discuss the optimizations in the device design and fabrication techniques to realize optimal electrical performance and high quality factors at a bath temperature of 250 mK.
DOI: 10.48577/jpl.zhggov
title: Rapid drought-induced land subsidence and its impact on the California Aqueduct

description: The Central Valley in California is characterized by a semi-arid climate prone to droughts, a variable surface water supply, and immense agricultural areas dependent on groundwater irrigation. The complex aquifer system in the valley is composed of alternating layers of coarse sediments and fine-grained sediments acting as confining materials. Both elastic and inelastic land surface deformation are coupled with the groundwater fluctuations historically observed in the Central Valley. Surface deformation poses a hazard to the California Aqueduct, which supports Central Valley agriculture and large urban populations in Southern California. The risk of reduced aqueduct efficacy and expensive repairs compels the water resource managers to monitor land deformation. A persistent drought in the region began in 2012 and was abruptly followed by a wet period from Dec-2016 to Feb-2018. NASA’s UAVSAR L-band synthetic aperture radar acquired 31 high resolution radar images between May-2013 and Nov-2018. The interferometric phase difference between acquisitions is used to develop a time series of vertical displacement and identify and track a rapidly forming subsidence feature adjacent to the California Aqueduct. The surface area of the feature that subsided 10 cm or more by the end of the time series reaches 4452 hectares and a 10.5+ km segment of the aqueduct. This study also incorporates concurrent water elevation data, well construction reports, nearby extensometer measurements, aquifer material characterization, and environmental conditions to offer insight into subsurface properties and mechanics and estimate the permanent loss of aquifer storage volume.
DOI: 10.48577/jpl.4neyj0
title: Contributions of spore secondary metabolites to UV-C protection and virulence varies in different Aspergillus fumigatus strains

description: Fungi are versatile organisms, which thrive in hostile environments, including the International Space Station (ISS), an environment with increased exposure to UV radiation. Several isolates of the human pathogen Aspergillus fumigatus have been found contaminating the ISS. In other fungi, secondary metabolites (SMs) called melanins have been shown to protect spores from UV radiation. To test the hypothesis that melanin and other known spore secondary metabolites (SMs) provide UV-C protection to A. fumigatus, we subjected SM spore mutants to UV-C radiation. We found DHN melanin mutants of two clinical A. fumigatus strains (Af293 and Cea17) but not a ISS isolated strain (IF1SW-F4) were more sensitive to UV-C than their respective WTs. Three additional spore metabolites were examined in Af293 where fumiquinazoline also showed UV-C protective properties, but two other spore metabolites, monomethylsulochrin and fumigaclavine, provided no UV-C protective properties. UV-C survival was also compromised by loss of the DNA repair protein AkuA which masked protective effects of fumiquinazoline. Further, because DHN melanin has been shown to shield A. fumigatus from the host immune system, we examined all DHN mutants for virulence in the zebrafish model of invasive aspergillosis. Following recent studies highlighting pathogenic variability of different A. fumigatus isolates, we found DHN melanin to be a virulence factor in CEA17 and IF1SW-F4 but not Af293. Taken together, this work suggests differential roles of specific spore metabolites across Aspergillus isolates and type of environmental stress.Importance: Fungal spores contain secondary metabolites that can protect them from a multitude of abiotic and biotic stresses. Conidia (asexual spores) of the human pathogen Aspergillus fumigatus synthesize several metabolites including melanin which has been reported to be important for virulence in this species and protective against UV radiation in other fungi. Here we investigate the role of melanin in diverse isolates of A. fumigatus and find variability in its ability to protect spores from UV-C radiation or impact virulence in a zebrafish model of invasive aspergillosis in two clinical and one space station strain. Further, we assess the role of other spore metabolites in a clinical strain of A. fumigatus and identify fumiquinazoline as an additional UV-C protective molecule. The results show differential roles of secondary metabolites in spore protection dependent on environment and strain of A. fumigatus. As protection from elevated levels of radiation is of paramount importance for future human outer space explorations, discovery of small molecules with radiation protective potential may result in developing novel safety measures for astronauts.
DOI: 10.48577/jpl.bjscyi
title: Haze seasonal variations of Titan's upper atmosphere during the Cassini Mission

description: The 13 years of the Cassini mission provide a unique dataset monitoringthe evolution of Titan’s atmosphere during almost half of Titan's year,between the middle of the northern winter up to the northern summer solstice.In this work we present a survey of the haze vertical extinction profiles retrievedbetween 300 to 700 km altitude with an atmospheric limb multiple scattering model.We analyze 138 ISS NAC CL1-UV3 images taken between 2004 to 2017 covering theentire Cassini mission.We mainly focus on the temporal evolution of the haze contentin the upper atmosphere to track the evolution of the detached haze layer.As previously reported by West et al. 2011 (GRL vol. 38, L06204),during the northern winter the detached haze layer is presentat all latitudes below \ang{55}N and globally sunk to lower altitudemost rapidly at the vernal equinox in 2009.No permanent detached haze layer was observed in the UV3 filter between 2012 and 2015 butwe show that at the end of 2015, a new structure emerged fromthe summer hemisphere (North) and propagated to the equator. This new layerwas not as pronounced and was much more complex than the one observed at thebeginning of the mission and was likely to be the initiation of a new detached haze layer.We also investigate the short time scale variability of the detached hazelayer and no major changes is observed. Finally, we report some caseswhere the viewing geometry allows us to probe the longitudinal variabilityof the haze, highlighting some local inhomogeneities.We notice that the extinction in the detached haze layer is slightly higher in the dawnside compare to the dusk side.All these observations bring new perspectiveson the seasonal cycle of Titan's upper atmosphere, the evolution of the detachedhaze layer and its interaction with the dynamics.The main seasonal pattern predicted by the global circulation models is consistentwith our findings, but the details and the timing of the global collapseis not yet explained. Finally, comparisons with the UVIS instrument showsthat the haze extinction profiles retrieved during two stellar occultationsin 2009 are consistent with our results.
DOI: 10.48577/jpl.d6hsbl
title: Resolving the latitudinal short-scale gravity field of Jupiter using Slepian functions

description: Early gravity measurements performed by the Juno spacecraft determined Jupiter’s low16degree gravity coefficients, including the first estimate of the planet’s north-south asym17metric field. The retrieved information was used to infer that the strong zonal winds18 visible at the cloud tops must extend down a few thousand kilometers, where they are19 suppressed in the deep interior. The next frontier for the Juno gravity experiment in20cludes, among other goals, the determination of Jupiter’s small-scale gravity field with21 high accuracy, and its relation to atmospheric circulation at shorter length scales. The22 geometry of the Juno closest approaches to the planet poses a challenge to this task, as23 they span latitudes between +4 and +29 over the course of the nominal mission. Since24 Doppler measurements are the most sensitive to gravity anomalies when the spacecraft25 is close to the body, observations of Jupiter’s gravity field are mostly concentrated in the26 northern hemisphere, and traditional spherical harmonic functions are not orthonormal27 over a latitudinal subdomain. Here we define customized Slepian functions, which are28 orthogonal in a specific latitude range and are suitable to represent Jupiter’s local sur29face gravity at north latitudes. We show that with the new functions, the short-scale lat30itudinal variability of the gravity field is resolved with high accuracy between -15 and31 +45 latitude. Furthermore, preliminary results show that the estimated values for the32 Slepian coefficients from Juno data match the predictions obtained using a thermal wind33 model of Jupiter’s atmosphere for an optimized scale height.
DOI: 10.48577/jpl.knehv9
title: Underlying Fundamentals of Kalman Filtering for River Network Modeling

description: The grand challenge of producing hydrometeorological estimates every time and everywhere has motivated the fusion of sparse observations with dense numerical models, with a particular interest on discharge in river modeling. Ensemble methods are largely preferred as they enable the estimation of error properties but, at the expense of computational load and generally with underestimations. These imperfect stochastic estimates motivate the use of correction methods, i.e. error localization and inflation, although the physical justifications for their optimality are limited. The purpose of this study is to use one the simplest forms of data assimilation when applied to river modeling and reveal the underlying mechanisms impacting its performance. Our framework based on assimilating daily-averaged in situ discharge measurements to correct daily-averaged runoff was tested over a four-year case study of two rivers in Texas. Results show that under optimal conditions of inflation and localization, discharge simulations are consistently improved such that the mean values of Nash-Sutcliffe Efficiency are enhanced from -11.32 to 0.55 at observed gauges and from -12.24 to -1.10 at validation gauges. Yet, parameters controlling the inflation and the localization have a large impact on the performance. Further investigations of these sensitivities showed that optimal inflation occurs when compensating exactly for discrepancies in the magnitude of errors while optimal localization matches the distance traveled during one assimilation window. These results may be applicable to more advanced data assimilation methods as well as for larger applications motivated by upcoming river-observing satellite missions, such as NASAs Surface Water and Ocean Topography mission.
DOI: 10.48577/jpl.m4lqke
title: Mars Extant Life: What’s Next? Conference Report

description: From Nov. 5th-8th, 2019 the “Mars Extant Life: What’s Next?” conference was convened in Carlsbad, NM. The conference gathered a community of actively publishing experts in disciplines related to habitability and astrobiology. Primary conclusions are as follows: A significant subset of conference attendees concluded that there is a realistic possibility that Mars hosts indigenous microbial life. A powerful theme that permeated the conference is that the key to the search for martian extant life lies in identifying and exploring refugia (“oases”), where conditions are either permanently or episodically significantly more hospitable than average. Based on our existing knowledge of Mars, conference participants highlighted four potential martian refugium (not listed in priority order): Caves, Deep Subsurface, Ices, and Salts. The conference group did not attempt to reach a consensus prioritization of these candidate environments, and instead felt that a defensible prioritization would require a future competitive process. Within the context of these candidate environments, we identified a variety of geological search strategies that could narrow the search space. Additionally, we summarized a number of measurement techniques that could be used to detect evidence of extant life (if present). Again, it was not within the scope of the conference to prioritize these measurement techniques—that is best left for the competitive process. We specifically note that the number and sensitivity of detection methods that could be implemented if samples were returned to Earth greatly exceeds the methodologies that could be used at Mars. Finally, important lessons to guide extant life search processes can be derived both from experiments carried out in terrestrial laboratories, in analog field sites, and from theoretical modeling.