cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.0qxlgl
title: The impact of Los Angeles basin pollution and stratospheric intrusions on the San Gabriel Mountains as seen by surface measurements, lidar, and numerical models

description: In this work, the impact of Los Angeles basin pollution transport and stratospheric intrusions on the surface ozonelevels observed in the San Gabriel Mountains is investigated based on a combination of surface and lidar measurements as wellas WRF-Chem (Weather Research and Forecasting with Chemistry) and WACCM (Whole Atmosphere Community ClimateModel) model runs. The number of days with observed surface ozone levels exceeding the National Ambient Air QualityStandards exhibit a clear seasonal pattern, with a maximum during summer, when models suggest a minimum influence of5stratospheric intrusions and the largest impact from Los Angeles basin pollution transport. Additionally, measured and modeledsurface ozone and PM10 were analyzed as a function of season, time of the day and wind direction. Measurements and modelsare in good qualitative agreement, with maximum surface ozone observed for south-west and west winds. For the prevailingsummer wind direction, slightly south of the ozone maximum and corresponding to south south-west winds, lower ozonelevels were observed. Back-trajectories suggest that this is associated with transport from the central Los Angeles basin, where10titration limits the amount of surface ozone. A quantitative comparison of the lidar profiles with WRF-Chem and WACCMmodels revealed good agreement near the surface, with models showing an increasing positive bias as function of altitude,reaching 75% at 15kmabove sea level. Finally, three selected case studies covering the different mechanisms affecting thenear-surface ozone concentration over the San Gabriel mountains, namely stratospheric intrusions and pollution transport, areanalyzed based on surface and ozone lidar measurements, as well as co-located ceilometer measurements and models.
DOI: 10.48577/jpl.4i0eps
title: Global tropospheric ozone responses to reduced NOx emissions linked to the COVID-19 world-wide lockdowns

description: Efforts to slow the transmission of COVID-19 led to rapid, global ancillary reductions in air pollutant emissions. Here, we quantify the impact of these reductions on tropospheric ozone using a multi-constituent data assimilation system. Total anthropogenic NOx emissions dropped by at least 15% globally and 18-25% regionally in April and May 2020, which led to up to a 5 ppb decrease in free tropospheric ozone, consistent with independent satellite observations. A decline in the global total tropospheric ozone burden of 6 TgO3 (2 %) in May-June 2020 was largely due to emission reductions in Asia and the Americas, the effects of which were amplified by regional ozone production efficiencies up to 4 TgO3/TgN. Our results show that COVID-19 mitigation led to a clear and global atmospheric signature that altered atmospheric oxidative 1 capacity and climate radiative forcing and can be used to inform policies that co-benefit air quality and climate.
DOI: 10.48577/jpl.jzvykp
title: The VLA Frontier Field Survey: a comparison of the radio and UV/optical size of 0.3 z 3 star-forming galaxies

description: To investigate the growth history of galaxies, we measure the rest-frame radio, ultraviolet (UV), and optical sizes of 98 radio-selected, star-forming galaxies (SFGs) distributed over 0.3 ~ z ~ 3 and median stellar mass of log(M_*/M_{Sun}) ~ 10.4. We compare the size of galaxy stellar disks, traced by rest-frame optical emission, relative to the overall extent of star formation activity that is traced by radio continuum emission. Galaxies in our sample are identified in three Hubble Frontier Fields: MACS J0416.1-2403, MACS J0717.5+3745, and MACS J1149.5+2223. Radio continuum sizes are derived from 3 GHz and 6 GHz radio images (~ 0.6 resolution, ~ 0.9 microJy beam^{-1} noise level) from the Karl G. Jansky Very Large Array. Rest-frame UV and optical sizes are derived using observations from the Hubble Space Telescope and the ACS and WFC3 instruments. Around 13% of galaxies in our sample are moderately lensed with a magnification factor magnification 2, while the rest of the galaxies have a median magnification ~ 1.1. We find no clear dependence between the 3GHz radio size and stellar mass of SFGs, which contrasts with the positive correlation between the UV/optical size and stellar mass of galaxies. Focusing on SFGs with log(M_*/M_{Sun}) 10, we find that the radio/UV/optical emission tends to be more compact in galaxies with high star-formation rates (SFR ~ 100 M_{Sun} yr^{-1}), suggesting that the production of stars in the most active SFGs preferentially occurs within a central, compact starburst. We also find that the physical radio/UV/optical size of SFGs with log(M_*/M_{Sun}) 10 increases by a factor of 1.5--2 from z ~ 3 to z ~0.3, yet the radio emission remains two-to-three times more compact than that from the UV/optical. These findings indicate that these massive SFGs at 0.3 ~ z ~ 3 tend to harbor centrally enhanced star formation activity relative to their outer-disks.
DOI: 10.48577/jpl.dk0oq9
title: Stabilized Photonic Links for Space Applications

description: We describe basic principles of operation and report on implementation of astandalone photonic link stabilized using electronic phase conjugation technique. This methodhas been demonstrated to improve link stability by more than two orders while reducing its sizeand power consumption compared to other systems. We have demonstrated packaged robustlinks that achieve a relative frequency instability of 2 10􀀀17 (5 10􀀀17) at 10 hr averaging whilethe temperature of the fiber was varied with 2 &gt;C(15 &gt;C) magnitude.
DOI: 10.48577/jpl.hgwaop
title: Realizing Machine Learning’s Promise in Geoscience Remote Sensing

description: As machine learning and pattern recognition methods flourish in commercial applications, systematic efforts aim to introduce these technologies into Earth and planetary science practice. This is especially true in remote sensing, where scientists seek to convert massive, noisy archives into science insight. Such problems seem well suited for machine learning and pattern recognition. As the data science revolution matures, it is worth asking if it has yet made a significant impact on remote sensing. Rather than attempt a comprehensive review, we examine research in imaging spectroscopy, also known as hyperspectral imaging, as a case study of a data-centric remote sensing discipline which would be expected to benefit from machine learning. Our analysis demonstrates that articles using the term ``imaging spectroscopy'' or ``hyperspectral'' come from a handful of independent and self-citing communities. The volume of research has recently accelerated from all groups, especially from those focusing purely on the methodology of machine learning and signal processing. Nevertheless, these are seldom cited by mainstream Earth and planetary scientists. The traditional sciences (including clinical, Earth, and space science) are responsible for all but one of top-ranked journal publications, with fewer than 40% of total articles. The remaining 60% represent thousands of manuscripts and vast person-centuries of work by highly educated researchers, a reservoir of potential that geosciences could better exploit.
DOI: 10.48577/jpl.pv6bvk
title: Three new late-type stellar companions to very dusty WISE debris disks identified with VLT/SPHERE imaging

description: Debris disk stars are good targets for high contrast imaging searches for planetary systems, since debris disks have been shown to have a tentative correlation with giant planets. We selected 20 stars identified as debris disk hosts by the WISE mission, with particularly high levels of warm dust. We observed these with the VLT/SPHERE high contrast imaging instrument with the goal of finding planets and imaging the disks in scattered light. Our survey reaches a median 5σ sensitivity of 10.4 MJ at 25au and 5.9 MJ at 100au. We identified three new stellar companions (HD18378B, HD19257B and HD133778B): two are mid-M type stars and one is late-K or early-M star. Three additional stars have very widely separated stellar companions (all at &gt;2000au) identified in the Gaia catalog. The stars hosting the three SPHERE-identified companions are all older (􏰀700Myr), with one having recently left the main sequence and one a giant star. We infer that the high volumes of dust observed around these stars might have been caused by a recent collision between the planets and planetesimal belts in the system, although for the most evolved star, mass loss could also be responsible for the infrared excess. Future mid-IR spectroscopy or polarimetric imaging may allow the positions and spatial extent of these dust belts to be constrained, thereby providing evidence as to the true cause of the elevated levels of dust around these old systems. None of the disks in this survey are resolved in scattered light.
DOI: 10.48577/jpl.2rj3xc
title: Complications in the ALMA Detection of Phosphine at Venus

description: Recently published ALMA observations suggest the presence of 20 ppb PH3 in the upper clouds of Venus. This is an unexpected result, as PH3 does not have a readily apparent source and should be rapidly photochemically destroyed according to our current understanding of Venus atmospheric chemistry. While the reported PH3 spectral line at 266.94 GHz is nearly co-located with an SO2 spectral line, the non-detection of stronger SO2 lines in the wideband ALMA data is used to rule out SO2 as the origin of the feature. We present a reassessment of wideband and narrowband datasets derived from these ALMA observations. The ALMA observations are re-reduced following both the initial and revised calibration procedures discussed by the authors of the original study. We also investigate the phenomenon of apparent spectral line dilution over varying spatial scales resulting from the ALMA antenna configuration. A 266.94 GHz spectral feature is apparent in the narrowband data using the initial calibration procedures, but this same feature can not be identified following calibration revisions. The feature is also not reproduced in the wideband data. While the SO2 spectral line is not observed at 257.54 GHz in the ALMA wideband data, our dilution simulations suggest that SO2 abundances greater than the previously suggested 10 ppb limit would also not be detected by ALMA. Additional millimeter, sub-millimeter, and infrared observations of Venus should be undertaken to further investigate the possibility of PH3 in the Venus atmosphere.
DOI: 10.48577/jpl.m8zpzj
title: ExEP: TOI-1231 b: A temperate sub-Neptune transiting the nearby M3 dwarf NLTT 24399

description: We report the discovery of a transiting, temperate, sub-Neptune exoplanet orbiting TOI-1231(NLTT 24399, L 248-27, 2MASS J10265947-5228099), a nearby M3V star (d= 27.6 pc). The planet was detected using photometric data from theTransiting Exoplanet Survey Satellite and followed up with observations from the Las Cumbres Observatory and the Antarctica Search for Transiting Ex-oPlanets program. Combining the photometric data sets, we find that the newly discovered planet has a radius of 3.68+0.20−0.19R⊕, and an orbital period of 24.246 days. Radial velocity measurements using the Planet Finder Spectrograph on the Magellan Clay telescope confirm the existence of the planet and lead to a mass measurement of 15.1+3.1−3.2M⊕. With an equilibrium temperature of just336K and a Transmission Spectroscopy Metric of 102, TOI-1231 b is one of the coolest small planets accessible for atmospheric studies thus far, and its host star’s bright NIR brightness (J=8.88, Ks=8.07)make it an exciting target for HST and JWST. Future atmospheric observations would enable the first comparative planetology efforts in the 250-350 K temperature regime via comparisons with K2-18 b.Furthermore, TOI-1231’s high systemic radial velocity (70.5 km s−1) may allow for the detection of low-velocity hydrogen atoms escaping the planet by Doppler shifting the H I Ly-alpha stellar emission away from the geocoronal and ISM absorption features.
DOI: 10.48577/jpl.t4ysxd
title: Comparison of Thermal Infrared-Derived Maps of Irrigated and Non-Irrigated Vegetation in Urban and Non-Urban Areas of Southern California

description: Understanding the distribution of irrigated and non-irrigated vegetation in rapidly expanding urban areas experiencing climate-induced changes in water availability (e.g., Los Angeles) is necessary for developing sustainable water use practices and accurately accounting for carbon exchange and water balance changes. However, pre-existing maps of irrigated vegetation are largely limited to non-urban agricultural regions and are too coarse to resolve heterogeneous and diverse urban landscapes. Previous research suggests that irrigation has a strong cooling effect on vegetation, affecting productivity and uptake of carbon, especially in semi-arid environments. The recent launch (July 2018) of the moderate-resolution (70-100 m, 3-5 day revisit) ECOsystem Spaceborne Thermal Radiometer on Space Station (ECOSTRESS) offers an opportunity to test this hypothesis using retrieved land surface temperature (LST) data in complex, heterogeneous urban environments. In this study, we demonstrate the feasibility of classifying irrigated versus non-irrigated vegetation in mixed pixel-resolution LST imagery using a vegetation-fraction weighted LST across urban and non-urban areas of southern California. We leverage 30 m sharpened afternoon summertime ECOSTRESS LST, apply very high-resolution (0.6-10 m) vegetation fraction weighting, and produce a map of irrigated versus non-irrigated vegetation in Los Angeles with 98% accuracy. We compare this classification to a range of other classifications using different combinations of sensors and offer a preliminary accuracy and uncertainty assessment. This approach verifies that ECOSTRESS LST data provides an accurate map of irrigated urban vegetation in the southern California Air Basin (SoCAB) useful for studying land use fragmentation and has the potential to reduce uncertainties in regional carbon and hydrological cycle models.
DOI: 10.48577/jpl.obdcu4
title: Multi-satellite imaging of a gas well blowout enables quantification of total methane emissions

description: Incidents involving loss of control of oil/gas wells can result in large but variable emissions whose impact on the global methane budget is currently unknown. On November 1, 2019, a gas well blowout was reported in the Eagle Ford Shale. By combining satellite observations at different spatial and temporal scales, we quantified emissions 10 times during the 20-day event. Our multi-satellite synthesis captures both the short-term dynamics and total integrated emissions of the blowout. Such detailed event characterization was previously not possible from space, and difficult to do with surface measurements. We present 30-m methane and carbon dioxide plumes from the PRISMA satellite, which let us estimate flare combustion efficiency (87%). Integrating emissions across all satellites, we estimate 4800 ± 980 metric tons lost methane. Blowouts occur across the globe and multi-satellite observations can help to determine their pervasiveness, enable corrective action, and quantify their contribution to global methane budgets.
DOI: 10.48577/jpl.tqsjik
title: Performance of Multiple Metagenomics Pipelines in Understanding Microbial Diversity of a Low-biomass Spacecraft Assembly Facility

description: NASA planetary protection (PP) requires an assessment of the biological contamination of the potential microbial burden on spacecraft destined to explore planetary bodies that may harbor signs of life, like Mars and Europa. To help meet these goals, the performance of multiple metagenomic pipelines were compared and assessed for their ability to detect microbial diversity of a low-biomass clean room environment used to build spacecraft destined to these planetary bodies. Four vendors were chosen to implement their own metagenomic analysis pipeline on the shotgun sequences retrieved from environmental surfaces in the relevant environments at NASA’s Jet Propulsion Laboratory.All four vendors detected species of interest, including spore-forming and extremotolerant bacteria, that have the potential to hitch-hike on spacecraft and contaminate the planetary bodies explored. Some vendors demonstrated through functional analysis of the metagenomes that the molecular mechanisms for spore-formation and extremotolerance were represented in the data. However, relative abundances of these microorganisms varied drastically between vendor analyses, questioning the ability of these pipelines to quantify the number of PP-relevant microorganisms on a spacecraft surface.Metagenomics offers tantalizing access to the genetic and functional potential of a microbial community that may offer NASA a viable method for microbial burden assays for planetary protection purposes. However, future development of technologies such as streamlining the processing of shotgun metagenome sequence data, long read sequencing, and all-inclusive larger curated and annotated microbial genome databases will be required to validate and translate relative abundances into an actionable assessment of PP-related microbes of interest. Additionally, the future development of machine learning and artificial intelligence techniques could help enhance the quality of these metagenomic analyses by providing more accurate identification of the genetic and functional potential of a microbial community.
DOI: 10.48577/jpl.yuikpk
title: Did the COVID-19 pandemic response reduce Free Tropospheric Ozone across the Northern Hemisphere?

description: Throughout spring and summer 2020, ozone stations in the northern extratropics recorded unusually low ozone in the free troposphere. From April to August, and from 1 to 8 kilometers altitude, ozone was on average 7% (≈4 ppbv) below the 2000 to 2020 climatological mean. Such low ozone, over several months, and at so many stations, has not been observed in any previous year since at least 2000. Atmospheric composition re-analyses from the Copernicus Atmosphere Monitoring Service and simulations from the NASA GMI model indicate that the large 2020 springtime ozone depletion in the Arctic stratosphere has contributed less than one quarter to the observed tropospheric anomaly. The observed anomaly is consistent with recent model simulations, which assume emission reductions consistent with the COVID-19 societal impacts (Weber et al., 2020). COVID-19 related emission reductions appear to be the major cause for the observed low free tropospheric ozone in 2020.
DOI: 10.48577/jpl.bat9zu
title: Assimilation of DAWN Doppler Wind Lidar Data During the 2017 Convective Processes Experiment (CPEX): Impact on the Precipitation and Flow Structure

description: An improved representation of the 3-D air motion and precipitation structure through forecast models and assimilation of observations is vital for improvements in weather forecasting capabilities. However, there is little independent validation data to properly validate a model forecast of precipitation structure when the underlying dynamics are evolving on short convective times scales. Using data from the JPL Ku/Ka-band Airborne Precipitation Radar (APR-2) and the 2-um Doppler Aerosol Wind (DAWN) lidar collected during the 2017 Convective Processes Experiment (CPEX), the NASA Unified Weather Research and Forecasting (WRF) Ensemble Data Assimilation System (EDAS) modeling system was used to quantify the impact of the high resolution, sparsely-sampled DAWN measurements on the analyzed variables and on the forecast when the DAWN winds were assimilated. Overall, the assimilation of the DAWN wind profiles had a discernible impact to the wind field and the evolution and timing of the 3-D precipitation structure. Comparing the assimilation results to the control run, the wind patterns were organized differently at low and high altitudes, and the 2-m air temperature anomaly (cold pool signature) had a more clearly defined feature and boundary. The precipitation was increased and organized differently in the flight area, more closely positioned to where and when it was observed by APR-2 and nearby overpasses from the Global Precipitation Measurement (GPM) satellite. Onset of the vertical evolution of the precipitation showed similar radar-derived cloud top heights, but delayed in time. While this investigation was limited to a single CPEX flight date, the investigation design is appropriate for further investigation of the impact of airborne Doppler wind lidar observations upon short-term convective precipitation forecasts.
DOI: 10.48577/jpl.qlrmhk
title: Arctic ozone depletion in 2019/20: Roles of chemistry, dynamics and the Montreal Protocol

description: We use a three-dimensional chemical transport model and satellite observations to investigate Arctic ozone depletion in winter/spring 2019/20 and compare with earlier years. Persistently, low temperatures caused extensive chlorine activation through to March. March-mean polar-cap-mean modeled chemical column ozone loss reached 78 DU (local maximum loss of ∼108 DU in the vortex), similar to that in 2011. However, weak dynamical replenishment of only 59 DU from December to March was key to producing very low (&lt;220 DU) column ozone values. The only other winter to exhibit such weak transport in the past 20 years was 2010/11, so this process is fundamental to causing such low ozone values. A model simulation with peak observed stratospheric total chlorine and bromine loading (from the mid-1990s) shows that gradual recovery of the ozone layer over the past 2 decades ameliorated the polar cap ozone depletion in March 2020 by ∼20 DU.
DOI: 10.48577/jpl.w3sqpw
title: Air quality impact of the Northern California Camp Fire of November 2018

description: The Northern California Camp Fire that took place in November 2018 was one of the most damaging environmental events in California history. Here, we analyze ground-based station observations of airborne particulate matter that has a diameter &lt; 2.5 micrometers (PM2.5) across northern California and conduct numerical simulations of the Camp Fire using the Weather Research and Forecasting model online coupled with Chemistry (WRF-Chem). Simulations are evaluated against ground-based observations of PM2.5, black carbon, and meteorology, as well as satellite measurements, such as Tropospheric Monitoring Instrument (TROPOMI) aerosol layer height and aerosol index. The Camp Fire led to an increase in Bay Area PM2.5 to over 70 µg m-3 for nearly two weeks, with localized peaks exceeding 300 µg m-3. Using the Visible Infrared Imaging Radiometer Suite (VIIRS) high resolution fire detection products, the simulations reproduce the magnitude and evolution of surface PM2.5 concentrations, especially downwind of the wildfire. The overall spatial patterns of simulated aerosol plumes and their heights are comparable with the latest satellite products from TROPOMI. WRF-Chem sensitivity simulations are carried out to analyze uncertainties that arise from fire emissions, meteorological conditions, feedback of aerosol radiative effects on meteorology, and various physical parameterizations, including the planetary boundary layer model and the plume rise model. Downwind PM2.5 concentrations are sensitive to both flaming and smoldering emissions over the fire, so the uncertainty in the satellite derived fire emission products can directly affect the air pollution simulations downwind. Our analysis also shows the importance of land surface and boundary layer parameterization in the fire simulation, which can result in large variations in magnitude and trend of surface PM2.5. Inclusion of aerosol radiative feedback moderately improves PM2.5 simulations, especially over the most polluted days. Results of this study can assist in the development of data assimilation systems as well as air quality forecasting of health exposures and economic impact studies.