cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.rrhum2
title: Cloud condensation nuclei characteristics at the Southern Great Plains site: role of particle size distribution and aerosol hygroscopicity

description: activation ability of aerosols as cloud condensation nuclei (CCN) is crucial in climate and13 hydrological cycle studies, but their properties are not well known. We investigated the long-term14 measurements of atmospheric aerosol properties, CCN concentrations (NCCN) at supersaturation15 (SS = 0.1-1.0%), and hygroscopicity at the Department of Energy’s Southern Great Plains (SGP)16 site to illustrate the dependence of NCCN on aerosol properties and transport pathways. Cluster17 analysis was applied to the back trajectories of air masses to investigate their respective source18 regions. The results showed that aged biomass burning aerosols from Central America were19 characterized by higher accumulation mode particles (Naccu; median value 805 cm-3) and relatively20 high aerosol hygroscopicity (κ; median value ~0.25) values that result in the higher CCN activation21 and relatively high NCCN (median value 258-1578 cm-3 at a SS of 0.1-1.0%). Aerosols from the22 Gulf of Mexico were characterized by higher Naccu (~35%), and NCCN (230-1721 cm-3 at a SS of23 0.1-1.0%) with the lowest κ (~0.17). In contrast, relatively high nucleation mode particles (Nnucl;24 ~20%) and low NCCN (128-1553 cm-3 at a SS of 0.1-1.0%) with higher κ (~0.30) values were25 observed on the aerosols associated with a westerly wind. The results indicate particle size as the26 most critical factor influencing the ability of aerosols to activate, whereas the effect of chemical27 composition was secondary. Our CCN closure analysis suggests that chemical composition and28 mixing state information are more crucial at lower SS, whereas at higher SS, most particles become29 activated regardless of their chemical composition and size. This study affirms that soluble organic30 fraction information is required at higher SS for better NCCN prediction, but both the soluble31 organics fraction and mixing state are vital to reduce the NCCN prediction uncertainty at lower SS.
DOI: 10.48577/jpl.ad10q8
title: Evaluation of GEOS Precipitation Flagging for SMAP Soil Moisture Retrieval Accuracy

description: The precipitation flag in the Soil Moisture Active Passive (SMAP) Level 2 passive soil moisture (L2SMP) retrieval product indicates the presence or absence of heavy precipitation at the time of the SMAP overpass. The flag is based on precipitation estimates from the Goddard Earth Observing System (GEOS) Forward Processing numerical weather prediction system. An error in flagging during an active or recent precipitation event can either (1) produce an overestimation of soil moisture due to short-term surface wetting of vegetation and/or surface ponding (if soil moisture retrieval was attempted in the presence of rain), or (2) produce an unnecessary non-retrieval of soil moisture and loss of data (if retrieval is flagged due to an erroneous indication of rain). Satellite precipitation estimates from the Integrated Multi-satellite Retrievals for GPM (IMERG) Version 06 Early Run (latency of ~4 hrs) precipitationCal product are used here to evaluate the GEOS-based precipitation flag in the L2SMP product for both the 6 PM ascending and 6 AM descending SMAP overpasses over the first five years of the mission (2015-2020). Consisting of blended precipitation measurements from the GPM (Global Precipitation Mission) satellite constellation, IMERG is treated as the “truth” when comparing to the GEOS model forecasts of precipitation used by SMAP. Key results include: i) IMERG measurements generally show higher spatial variability than the GEOS forecast precipitation, ii) the IMERG product has a higher frequency of light precipitation amounts, and iii) the effect of incorporating IMERG rainfall measurements in lieu of GEOS precipitation forecasts are minimal on the L2SMP retrieval accuracy (determined vs. in situ soil moisture measurements at core validation sites). Our results indicate that L2SMP retrievals continue to meet the mission’s accuracy requirement (standard deviation of the ubRMSE less than 0.04 m3/m3).
DOI: 10.48577/jpl.oukldh
title: The Search for Binary Supermassive Black Holes amongst Quasars with Offset Broad Lines using the Very Long Baseline Array

description: In several previous studies, quasars exhibiting broad emission lines with &1000 km s􀀀1 velocity 16 osets with respect to the host galaxy rest frame have been discovered. One leading hypothesis for the 17 origin of these velocity-oset broad lines is the dynamics of a binary supermassive black hole (SMBH). 18 We present high-resolution radio imaging of 34 quasars showing these velocity-oset broad lines with 19 the Very Long Baseline Array (VLBA), aimed at nding evidence for the putative binary SMBHs (such 20 as dual radio cores), and testing the competing physical models. We detect exactly half of the target 21 sample from our VLBA imaging, after implementing a 5 detection limit. While we do not resolve 22 double radio sources in any of the targets, we obtain limits on the instantaneous projected separations 23 of a radio-emitting binary for all of the detected sources under the assumption that a binary still 24 exists within our VLBA angular resolution limits. We also assess the likelihood that a radio-emitting 25 companion SMBH exists outside of our angular resolution limits, but its radio luminosity is too weak 26 to produce a detectable signal in the VLBA data. Additionally, we compare the precise sky positions 27 aorded by these data to optical positions from both the SDSS and Gaia DR2 source catalogs. We nd 28 projected radio/optical separations on the order of 10 pc for three quasars. Finally, we explore how 29 future multi-wavelength campaigns with optical, radio, and X-ray observatories can help discriminate 30 further between the competing physical models.
DOI: 10.48577/jpl.rrjhes
title: Boundary layer water vapour statistics from high spatial resolution spaceborne visible spectrometry

description: Daytime clear-sky total column water vapour (TCWV) is commonly retrieved from visible and shortwave infrared reflectance (VSWIR) measurements, and upcoming missions such as the Earth Surface Mineral Dust Source Investigation (EMIT) will offer unprecedented horizontal resolution of order 30—80 m. We provide evidence that for convective planetary boundary layers (PBLs), spatial variability in TCWV corresponds to variability in PBL water vapour. Using synthetic optimal estimation retrievals applied to Large Eddy Simulation (LES) output, we show that EMIT can retrieve horizontal variability in PBL water vapour, provided that the domain surface is uniformly composed of either vegetated surfaces or mineral surfaces. Random retrieval errors are easily quantified and removed, but biases from -7 % to +34 % remain in retrieved spatial standard deviation and are primarily related to the retrieval’s assumed atmospheric profiles. Future retrieval development could greatly mitigate these errors. Finally, we account for changing solar zenith angle (SZA) from 15—60° and show that the non-vertical solar path destroys the correspondence between footprint retrieved TCWV and the true TCWV directly above that footprint. Even at the 250 m horizontal resolution regularly obtained by current sensors, the derived maps correspond poorly to true TCWV at the pixel-scale, with r2&lt;0.6 at SZA=30°. However, the derived histograms of TCWV in an area are closely related to the true histograms of TCWV at the nominal footprint resolution. Upcoming VSWIR instruments, primarily targeting surface properties, can therefore offer new information on PBL water vapour spatial statistics to the atmospheric community.
DOI: 10.48577/jpl.43lv1h
title: A novel approach to asteroid impact monitoring and hazard assessment

description: Orbit-determination programs find the orbit solution that best fits a set of observations by minimizing the 10 RMS of the residuals of the fit. For near-Earth asteroids, the uncertainty of the orbit solution may be compatible 11 with trajectories that impact Earth. This paper shows how incorporating the impact condition as an observa12 tion in the orbit-determination process results in a robust technique for finding the regions in parameter space 13 leading to impacts. The impact pseudo-observation residuals are the b-plane coordinates at the time of close 14 approach and the uncertainty is set to a fraction of the Earth radius. The extended orbit-determination filter 15 converges naturally to an impacting solution if allowed by the observations. The uncertainty of the resulting 16 orbit provides an excellent geometric representation of the virtual impactor. As a result, the impact probability 17 can be efficiently estimated by exploring this region in parameter space using importance sampling. The pro18 posed technique can systematically handle a large number of estimated parameters, account for nongravitational 19 forces, deal with nonlinearities, and correct for non-Gaussian initial uncertainty distributions. The algorithm has 20 been implemented into a new impact monitoring system at JPL called Sentry-II, which is undergoing extensive 21 testing. The main advantages of Sentry-II over JPL’s currently operating impact monitoring system Sentry are 22 that Sentry-II can systematically process orbits perturbed by nongravitational forces and that it is generally more 23 robust when dealing with pathological cases. The runtimes and completeness of both systems are comparable, with the impact probability of Sentry-II for 99% completeness being 3 × 10−7 24 .
DOI: 10.48577/jpl.xalaup
title: Seismic Detection of the Martian Core by InSight

description: We report on the detection of reflections of seismic waves from the core-mantle boundary of Mars using InSight seismic data. We constrain the radius of the liquid core to 1830±40 km, consistent with geodetic constraints. The large core precludes a bridgmanite-dominated lower mantle as in Earth with implications for the dynamical evolution of mantle and core. The inferred mean core density ranges from 5.7 g/cm3 to 6.2 g/cm3, implying a considerable fraction of light elements, including S, C, O, and H in the Fe-Ni core. To comply with cosmochemical constraints that limit sulfur to &lt;20 wt.%, the mean core density needs to exceed 6 g/cm3, encompassing the upper end of our estimate. Our results are compatible with a present-day magnetically quiescent dynamo.
DOI: 10.48577/jpl.y2dmc6
title: Wave Propagation in Vegetation Field Using a Hybrid Method

description: In this paper, we develop a hybrid method for studying wave scatterings and propagation in a vegetation field. The coherent multiple scatterings among the plants and the gaps in the vegetation field are considered through a two-step hybrid method. First, the T-matrix of a single plant is calculated using the Huygens principle and the vector cylindrical waves (VCW) expansion based on the full-wave solutions from the Ansys High Frequency Structure Simulator (HFSS). Second, the multiple scatterings between different plants are considered through the Foldy-Lax multiple scattering (FL) equations using the calculated T-matrix and the translational addition theorem. The convergence and the accuracy of the hybrid method are verified with the HFSS by comparing the solutions of scatterings from four wheat plants. The full-wave Monte Carlo simulations of a field with 169 wheat plants at L-band are subsequently performed using the hybrid method. Numerical results show that the transmission in the gap region is significantly higher than that of the inner region with the difference given quantitatively. The transmissivity of microwave through the wheat field with a large vegetation water content (VWC) can be significantly underestimated by the classical radiative transfer equation (RTE) and distorted Born approximation (DBA) model.
DOI: 10.48577/jpl.0552la
title: COVERAGE: Next generation data service infrastructure for a digitally integrated ocean observing system in support of marine science ecosystem management

description: Ocean science and decision support applications increasingly rely on the synergistic, interdisciplinary use of multivariate data from distributed agency repositories. While more available, the growing variety and volume of ocean observing data combined with the heterogeneous modalities of access continue to pose a challenge to broadscale uptake. This limits the effective utilization of costly investments in sustained ocean observation by an increasing diversity of user communities with a need for such environmental information on the oceans for the assessment of climate change and other ecosystem impacts. Leveraging an advanced cloud technology stack and ongoing multi-agency pilot effort being spearheaded by NASA, the CEOS Ocean Variables Enabling Research and Applications for GEO (COVERAGE) initiative seeks to collaboratively develop the next generation data service infrastructure for a more digitally integrated ocean observing system in support of marine science and ecosystem-based management. In particular, we envisage the implementation of a data services layer a top of existing agency repositories to provide more harmonized access to satellite, in-situ, and model data across a fragmented ocean data landscape with a set of value-added services that include integrated data search, visualization and analytics. Here we outline the motivation and importance of this effort plus efforts thus far towards the collective implementation of this ambitious vision.
DOI: 10.48577/jpl.bidxdl
title: Using Remote Sensing and In Situ Measurements for Efficient Mapping and Optimal Sampling of Coral Reefs

description: Coral reefs are of undeniable importance to the environment, yet little is known of them on a global scale. Assessments rely on laborious, local in-water surveys. In recent years remote sensing has been useful on larger scales for certain aspects of reef science such as benthic functional type discrimination. However, remote sensing only gives indirect information about reef condition. Only through combination of remote sensing and in situ data can we achieve coverage to understand reef condition and monitor worldwide condition. This work presents an approach to global mapping of coral reef condition that intelligently selects local, in situ measurements that refine the accuracy and resolution of global remote sensing. To this end, we apply new techniques in remote sensing analysis, probabilistic modeling for coral reef mapping, and decision theory for sample selection. Our strategy represents a fundamental change in how we study coral reefs and assess their condition on a global scale. We demonstrate feasibility and performance of our approach in a case study using remote sensing together with high-quality airborne data from NASA’s CORAL mission. Results indicate that our method is capable of extrapolating in situ samples and refining information from remote sensing with great accuracy. Furthermore, the results confirm that decision theory is a powerful tool for sample selection.
DOI: 10.48577/jpl.gsnrc7
title: Rapid and Accurate Methods for Computing Whiskered Tori and their Manifolds in Periodically Perturbed Planar Circular Restricted 3-Body Problems

description: When the planar circular restricted 3-body problem (RTBP) is peri- odically perturbed, families of unstable resonant periodic orbits break up into whiskered tori, with most tori persisting into the perturbed system. In this study, we 1) develop a quasi-Newton method which simultaneously solves for the tori and their center, stable, and unstable directions; 2) implement continuation by both perturbation as well as rotation numbers; 3) compute Fourier-Taylor param- eterizations of the stable and unstable manifolds; 4) regularize the equations of motion; and 5) globalize these manifolds. Our methodology improves on efficiency and accuracy compared to prior studies, and applies to a variety of periodic per- turbations. We demonstrate the tools on the planar elliptic RTBP.
DOI: 10.48577/jpl.g8u1um
title: Pluto in Glory: Discovery of its Huge Opposition Surge

description: Near-infrared observations of the Pluto Charon system were captured with the Palomar High Angular Resolution Observer (PHARO) adaptive optics system on the 200-inch Hale telescope during the historically small solar phase angles in 2018-2019. Both objects exhibit large opposition surges of ~30-35% in the last half degree of solar phase angle, which is among the largest observed for icy moons and other Kuiper Belt Objects. In addition, Pluto’s surge is exceptionally steep. Pluto’s unusual phase curve may be due to an unusual surface texture caused by seasonal volatile transport and active geologic processes. These observations enable accurate determination of Pluto’s geometric albedo in the JHK filter system, which we find to be 0.86±0.04, 0.59±0.05, and 0.39±0.04 for Pluto, respectively, and 0.68±0.06 for Charon in the J-filter.
DOI: 10.48577/jpl.gu6rso
title: ALMA Observations of the Asymmetric Dust Disk around DM Tau

description: We report an analysis of the dust disk around DM Tau, newly observed with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.3 mm. The ALMA observations with high sensitivity (8.4 Jy/beam) and high angular resolution (35 mas, 5.1 au) detect two asymmetries on the ring at r 20 au. They could be two vortices in early evolution, the destruction of a large scale vortex, or double continuum emission peaks with dierent dust sizes. We also found millimeter emissions with 50 Jy (a lower limit dust mass of 0.3 MMoon) inside the 3-au ring. To characterize these emissions, we modeled the spectral energy distribution (SED) of DM Tau using a Monte Carlo radiative transfer code. We found that an additional ring at r = 1 au could explain both the DM Tau SED and the central point source. The disk midplane temperature at the 1-au ring calculated in our modeling is less than the typical water sublimation temperature of 150 K, prompting the possibility of forming small icy planets there.
DOI: 10.48577/jpl.ufywvs
title: Success Stories of Satellite Altimeter Applications

description: For nearly three decades, satellite nadir altimeters have provided essential information to understand, primarily ocean, and also, inland water dynamics. A variety of parameters can be inferred via altimeter measurements, including sea surface height, sea surface wind speeds, significant wave heights, and topography of land and ice sheets. Taking advantage of these parameters with the long record of altimeter data spanning multiple decades has allowed a diverse range of societal applications. As the constellation of altimeter satellites grows, the proven value of the missions to a diverse audience can now be demonstrated by highlighting a selection of verifiable success stories. In this paper, we review twenty altimeter success stories which incorporate altimetry data, alone or in conjunction with numerical models or other earth observations, to solve a key societal problem. First, we define the problem or the key challenge of each use case, and then we articulate the uptake of the successful altimeter-based solution. Our study revealed steady progress by scientific and stakeholder communities in bridging the gap between data availability and their actual uptake to address a variety of applications. Highlighting these altimeter-based success stories can serve to further promote the widespread adoption of the planned Surface Water and Ocean Topography (SWOT) mission scheduled for launch in 2022. SWOT has a wide-swath altimetry instrument based on interferometry with an on-board nadir altimeter. Knowledge of the breadth of utility of altimeter observations can support the scientific and applied science communities in tracking information about the applications they enable. This can help to maximize the societal value of current and planned suite of altimeters, as well as of future missions with expanded capabilities, such as SWOT.
DOI: 10.48577/jpl.znn9lq
title: Satellite Monitoring for Air Quality and Health

description: Data from satellite instruments provide estimates of gas and particle levels relevant to human health, even pollutants invisible to the human eye. However, the successful interpretation of satellite data requires an understanding of how satellites relate to other data sources, as well as factors affecting their application to health challenges. Drawing from the expertise and experience of the 2016–2020 NASA HAQAST (Health and Air Quality Applied Sciences Team), in this review we discuss satellite data for air quality and health applications. We include a discussion of satellite data for epidemiological studies and health impact assessments, as well as the use of satellite data to evaluate air quality trends, support air quality regulation, characterize smoke from wildfires, and quantify emission sources. The primary advantage of satellite data compared to observations collected at air quality monitoring stations is their spatial and temporal coverage. Satellite data can reveal where pollution levels are highest around the world, how levels have changed over daily to decadal periods, and where pollutants are transported from urban to global scales. To date, air quality and health applications have primarily utilized satellite observations and satellite-derived products relevant to near-surface particulate matter &lt;2.5 μm in diameter (PM2.5) and nitrogen dioxide (NO2). Health and air quality communities have grown increasingly engaged in the use of satellite data, and this trend is expected to continue. From health researchers to air quality managers and from global applications to community impacts, satellite data are transforming the way air pollution exposure is evaluated.
DOI: 10.48577/jpl.6vi6ln
title: Discovery of a Possible Splashback Feature in the Intracluster Light of MACS J1149.5+2223

description: We present an analysis of the intracluster light in the Frontier Field Cluster MACSJ1149.5+2223 (z=0.544), which combines new and archival Hubble WFC3/IR imagingto provide continuous radial coverage out to 2.8 Mpc from the brightest cluster galaxy. Employingcareful treatment of potential systematic biases and using data at the largest radii todetermine the background sky level, we reconstruct the surface brightness profile out to a radiusof 2 Mpc. This radius is the largest to which the intracluster light (ICL) has been measuredfor an individual cluster. Within this radius, we measure a total luminosity of 1.5E13 L_Sunfor the brightest cluster galaxy plus ICL light. From the profile and its logarithmic slope, weidentify the transition from the brightest cluster galaxy to ICL at r~70 kpc. Remarkably, wealso detect an inflection in the profile centered in the 1.2-1.7 Mpc (0.37-0.52 r200m) radialbin, a signature of an infall caustic in the stellar distribution. Based upon the shape and strengthof the feature, we interpret it as potentially being at the splashback radius, although the radiusis smaller than theoretical predictions. If this is the splashback radius, then it is the first suchdetection in the ICL and the first detection of the splashback radius for an individual cluster.Similar analyses should be possible with the other Frontier Field clusters, and eventually withclusters from the Euclid and Roman missions.