REPLY <TO COMMENT ON PAPER- PRELIMINARY RESULTS OF RADIATION MEASUREMENTS FROM THE TIROS III METEOROLOGICAL SATELLITE
Interpretation of radiation measurements from tiros iii meteorological satellite & water vapor measurements
RADIATION MEASUREMENT↗
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Theoretical interpretation of thermal arrest data from differential thermal analysis measurements
A theory was developed to interpret the thermal arrest data of HgCdTe system from differential thermal analysis measurements. A nonlinear regression program is used to model fit the data. The purpose is to obtain a set of parameters which will give the information about average radiation coefficient, latent heat of fussion, and specific heat of the HgCdTe system at various compositions. The liquidus and solidus at various compositions are also obtained. The heat radiation from the furnace, heat radiation from the system, heat capacity from both the system and the quartz tube and the heat of fusion of the system are considered, however, it neglects heat transfer through conduction and convection.
Wang, J. C.↗
Interpretation of satellite airglow observations during the March 22, 1979, magnetic storm, using the coupled ionosphere-thermosphere model developed at University College, London
The University of California, Berkeley, extreme ultraviolet spectrometer aboard the U.S. Air Force STP 78-1 satellite measured emission features in the Earth's dayglow due to neutral and ionized species in the atmosphere, in the 35 to 140-nm range. The spectrometer was operating between March 1979 and March 1980, including the period of the magnetic storm on March 22, 1979. Some of these measurements are interpreted using the predictions of the three-dimensional time-dependent coupled ionosphere-thermosphere model developed at University College, London. The observations show a reduction in the atomic oxygen 130.4-nm airglow emission at high northern latitudes following the storm. Model simulations show that this reduction in 130.4-nm emission is associated with an increase in the O2/O ratio. Analysis of model results using electron transport and radiative transport codes show that the brightness of 130.4-nm emission at high latitudes due to resonantly scattered sunlight is approximately twice that due to photoelectron impact excitation. However, the observed decrease in the brightness at high northern latitudes is mainly due to a change in the photoelectron impact source, which contributes approximately 75% of the total, as well as its multiple scattering component; for the photoelectron impact source at 70 deg latitude and 200 km altitude, the reduction in multiple scattering is 1.5 times greater than the reduction in the initial excitation. The reduction in the airglow emission is visible only in the norther n hemisphere because the south pole was not sunlit over the storm period. The comparison of model results with observations suggests that 130.4-nm emission may be useful as a tracer for global changes in the concentration of atomic energy.
Parish, H. F.↗
Correlation function metrology for warm dense matter: Recent developments and practical guidelines
X-ray Thomson scattering (XRTS) has emerged as a valuable diagnostic for matter under extreme conditions, as it captures the intricate many-body physics of the probed sample. Recent advances, such as the model-free temperature diagnostic of Dornheim et al. [Nat. Commun. 13 , 7911 (2022)], have demonstrated how much information can be extracted directly within the imaginary-time formalism. However, since the imaginary-time formalism is a concept often difficult to grasp, we provide here a systematic overview of its theoretical foundations and explicitly demonstrate its practical applications to temperature inference, including relevant subtleties. Furthermore, we present recent developments that enable the determination of the absolute normalization, Rayleigh weight, and density from XRTS measurements without reliance on uncontrolled model assumptions. Finally, we outline a unified workflow that guides the extraction of these key observables, offering a practical framework for applying the method to interpret experimental measurements.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Solar variability
The variability in the total radiant energy flux, or solar irradiance, is discussed. Direct techniques of measuring irradiance, including ground-based, balloon and rocket-borne, and spacecraft-based measurements are compared; the latter type has led to dramatic advances in accuracy since it eliminates the need for corrections for atmospheric absorption. Correlations of the measured irradiance with solar activity are described. Indirect techniques that monitor other solar parameters such as photospheric conditions or the solar diameter are reviewed, and theoretical studies which attempt to interpret the measurements are discussed. Physical mechanisms which can lead to changes in the solar luminosity are addressed, as is global time-dependent modeling of the response of the sun to structural perturbations. Finally, findings from all techniques are summarized, their weak and strong points are assessed, and suggestions for future research are made.
Sofia, S.↗
Methanol and hydrogen sulfide in comet P/Halley
The Neutral Mass Spectrometer on the Giotto spacecraft measured the gas and ion composition in the coma of comet P/Halley. A detailed model of the ion chemistry inside the contact surface located at 4660 km is used to interpret the measured ion desnity profiles in the 32 to 35 amu/e mass range. The masses 33 and 35 amu/e are dominated by the protonated methanol and hydrogen sulfide ions CH3OH2(+) and H3S(+). Both profiles are essentially compatible with CH3OH and H2S originating from the nucleus only. The production rates relative to water are Y(CH3OH) = Q(CH3OH)/Q(H2O) = 1.7% and Y(H2S) = 0.41%. Our Y(CH3OH) agrees well with a determination from IR spectra obtained about 6 weeks after the Giotto encounter with P/Halley. In 7 other comets IR and microwave observations give Y(CH3OH) values between about 0.7 and 6%, indicating that the methanol abundance shows a strong variability from comet to comet. In three other comets Y(H2S) values between 0.2 and 0.5% have been reported. In addition to H2S(+), only ions containing minor isotopes of H, C, O and S contribute to mass 34 amu/e (e.g. (34)S(+), (13)CH3OH2(+), CH4DO(+)). These contributions can be calculated from the measured densities of the ions containing the major isotopes and the H2S(+) contribution from the measured H3S(+) density. From mass 34 amu/e we can also derive an upper limit of 1% for the abundance of deuterated methanol. This limit is at most marginally compatible with a direct interstellar origin of the CH3OH in P/Halley as the measured interstellar abundance of deuterated methanol is 1 to 6%.
Eberhardt, P.↗
Origin of the ring ellipticity in the black hole images of M87*
We investigate the origin of the elliptical ring structure observed in the images of the supermassive black hole M87*, aiming to disentangle contributions from gravitational, astrophysical, and imaging effects. Leveraging the enhanced capabilities of the Event Horizon Telescope (EHT)'s 2018 array, including improved (u,v)-coverage from the Greenland Telescope, we measured the ring's ellipticity using five independent imaging methods, obtaining a consistent average value of τ = 0.08−0.02+0.03 with a position angle of ξ = 50.1−7.6+6.2 degrees. To interpret this measurement, we compared it to general relativistic magnetohydrodynamic (GRMHD) simulations spanning a wide range of physical parameters including the thermal or nonthermal electron distribution function, spins, and ion-to-electron temperature ratios in both low- and high-density regions. We find no statistically significant correlation between spin and ellipticity in GRMHD images. Instead, we identify a correlation between ellipticity and the fraction of non-ring emission, particularly in nonthermal models and models with higher jet emission. These results indicate that the ellipticity measured from the M87* emission structure is consistent with that expected from simulations of turbulent accretion flows around black holes, where it is dominated by astrophysical effects rather than gravitational ones. Future high-resolution imaging, including space very long baseline interferometry and long-term monitoring, will be essential to isolate gravitational signatures from astrophysical effects.Key words: accretion, accretion disks / black hole physics / gravitation / galaxies: active** These authors have contributed equally to this work.*** NASA Hubble Fellowship Program, Einstein Fellow.† Deceased.
Dahale, Rohan [Granada U., Theor. Phys. Astrophys.↗
The Arctic polar stratospheric cloud aerosol - Aircraft measurements of reactive nitrogen, total water, and particles
In situ aircraft measurements in the lower stratosphere are used to investigate the reactive nitrogen, NO(y), total water, and particle components of the polar stratospheric cloud (PSC) aerosol in the Arctic. The results are compared to findings from the Antarctic derived using similar measurements and interpretive techniques. The Arctic data show that particle volume well above background values is present at temperatures above the frostpoint, confirming the result from the Antarctic that the observed PSCs are not water ice particles. NO(y) measurements inside a PSC are enhanced above ambient values consistent with anisokinetic sampling of particles containing NO(y). In the Arctic data over long segments of several flights, calculations show saturation with respect to nitric acid trihydrate without significant PSC particle growth above background.
Kawa, S. R.↗
The verification of LANDSAT data in the geographical analysis of wetlands in west Tennessee
The reliability of LANDSAT imagery as a medium for identifying, delimiting, monitoring, measuring, and mapping wetlands in west Tennessee was assessed to verify LANDSAT as an accurate, efficient cartographic tool that could be employed by a wide range of users to study wetland dynamics. The verification procedure was based on the visual interpretation and measurement of multispectral imagery. The accuracy testing procedure was predicated on surrogate ground truth data gleaned from medium altitude imagery of the wetlands. Fourteen sites or case study areas were selected from individual 9 x 9 inch photo frames on the aerial photography. These sites were then used as data control calibration parameters for assessing the cartography accuracy of the LANDSAT imagery. An analysis of results obtained from the verification tests indicated that 1:250,000 scale LANDSAT data were the most reliable scale of imagery for visually mapping and measuring wetlands using the area grid technique. The mean areal percentage of accuracy was 93.54 percent (real) and 96.93 percent (absolute). As a test of accuracy, the LANDSAT 1:250,000 scale overall wetland measurements were compared with an area cell mensuration of the swamplands from 1:130,000 scale color infrared U-2 aircraft imagery. The comparative totals substantiated the results from the LANDSAT verification procedure.
Rehder, J.↗
Modest set of simulations of local-type primordial non-Gaussianity in the DESI era
A measurement of a primordial non-Gaussianity (PNG) signal through late- or early-Universe probes has the potential to transform our understanding of the physics of the primordial Universe. While large-scale structure observables in principle contain vital information, interpreting these measurements is challenging due to poorly understood astrophysical effects. Luckily, N-body simulations, such as the abacuspng set presented in this study, consisting of 9 boxes, each of size L box = 2 Gpc/h and particle mass of 1.01 × 10 10 M ⊙ /h, provide a viable path forward. As validation, we find good agreement between the simulations and our expectations from one-loop perturbation theory (PT) and the "separate universe" method for the matter bispectrum, matter power spectrum and the halo bias parameter associated with PNG, b φ . As a science application, here we investigate the link between halo assembly bias and b φ for halo properties known to play a vital role in accurately predicting galaxy clustering: concentration, shear (environment), and accretion rate. We find a strong response for all three parameters, suggesting that the connection between b φ and the assembly history of halos needs to be taken into account by future PNG analyses. We further perform the first study of the b φ parameter from fits to early DESI data of the luminous red galaxy (LRG) and quasistellar object (QSO) samples and comment on the effect on f NL constraints for the allowed galaxy-halo models (note that σ[f NL ]∝ $\frac{σ[b_φ]}{b_φ}$). We find that the error on f NL is 15, 8, 7 for the LRGs at z = 0.5 and z = 0.8 and QSOs at z = 1.4, respectively, suggesting that a thorough understanding of galaxy assembly bias is warranted so as to perform robust high-precision analysis of local-type PNG with future surveys.
79 ASTRONOMY AND ASTROPHYSICS↗
Measurement and effective field theory interpretation of the photon-fusion production cross section of a pair of W bosons in proton-proton collisions at $\sqrt{s}=13 $ TeV
This analysis presents an observation of the photon-fusion production of W boson pairs using the CMS detector at the LHC. The total cross section of the W + W − production in photon fusion is measured using proton-proton collision data with an integrated luminosity of 138 fb −1 collected with the CMS detector in 2016–2018 at a center-of-mass energy of $\sqrt{s}=13 $ TeV. Events are selected in the final state with one isolated electron and one isolated muon, and no additional tracks associated with the electron-muon production vertex. The total and fiducial production cross sections are 643$^{+82}_{–78}$ fb and 3.96$^{+0.53}_{–0.51}$ fb, respectively, in agreement with the standard model predictions of 631 ± 126 fb and 3.87 ± 0.77 fb. This agreement enables stringent constraints on anomalous quartic gauge couplings within a dimension-8 effective field theory framework.
Hadron-Hadron Scattering↗
A model of the variability of the Venus ionopause altitude
A model for the variability of the Venus ionopause as a function of solar wind dynamic pressure and EUV flux during quiescent solar wind conditions is presented. The radio occultation measurements of the Venus ionopause from Mariner 5, 10 and Venera 9, 10 spacecraft, as well as recent in situ Pioneer Venus measurements are interpreted in terms of this model. An ionospheric model consistent with observations in the 400-1000 km region is predominantly O(+) with densities of about 10,000/cu cm and (T sub e + T sub i) approximately equal to 4500-6500 K. For ionopause measurements below 400 km the ionosphere appears severely compressed and density and temperature profiles cannot be simply described, although a strong correlation with solar wind dynamic pressure is observed. Possible effects of IMF direction switching on the dynamics and structure of the ionosphere are also considered and compared with available ionopause data.
Wolff, R. S.↗
Interpretation of CHAMP Magnetic Anomaly Data over the Pannonian Basin Region Using Lower Altitude Horizontal Gradient Data
The ESA SWARM mission will have three earth orbiting magnetometer bearing satellites one in a high orbit and two side-by-side in lower orbits. These latter satellites will record a horizontal magnetic gradient. In order to determine how we can use these gradient measurements for interpretation of large geologic units we used ten years of CHAMP data to compute a horizontal gradient map over a section of southeastern Europe with our goal to interpret these data over the Pannonian Basin of Hungary.
CHAMP↗
Characterization of Neutron Emission Rates of Commercial 252 Cf Sources
Accurate knowledge of 252 Cf neutron emission rates is critical for modeling and fast-neutron experiments, yet commercial sources are often supplied without traceable calibration or uncertainty estimates. This report describes a method to characterize 252 Cf sources using a pulse-shape-discrimination (PSD) scintillator. The scintillator was efficiency-calibrated against a time-tagged 252 Cf fission chamber manufactured at ORNL over 40 years ago. Isotopic evolution of the calibration source was modeled using Bateman equations to account for changes in the effective average neutrons per fission at the time of measurement. The calibrated scintillator was then used to measure absolute emission rates of several commercial 252 Cf sources, revealing deviations of up to 12% from nominal manufacturer values. This methodology provides a practical approach for establishing uncertainty-quantified 252 Cf neutron emission rates, improving fidelity in simulations and supporting the accurate interpretation of measurements.
46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AN↗
Remote sensing of Earth terrain
Remote sensing of earth terrain is examined. The layered random medium model is used to investigate the fully polarimetric scattering of electromagnetic waves from vegetation. The model is used to interpret the measured data for vegetation fields such as rice, wheat, or soybean over water or soil. Accurate calibration of polarimetric radar systems is essential for the polarimetric remote sensing of earth terrain. A polarimetric calibration algorithm using three arbitrary in-scene reflectors is developed. In the interpretation of active and passive microwave remote sensing data from the earth terrain, the random medium model was shown to be quite successful. A multivariate K-distribution is proposed to model the statistics of fully polarimetric radar returns from earth terrain. In the terrain cover classification using the synthetic aperture radar (SAR) images, the applications of the K-distribution model will provide better performance than the conventional Gaussian classifiers. The layered random medium model is used to study the polarimetric response of sea ice. Supervised and unsupervised classification procedures are also developed and applied to synthetic aperture radar polarimetric images in order to identify their various earth terrain components for more than two classes. These classification procedures were applied to San Francisco Bay and Traverse City SAR images.
Kong, Jin AU↗
Interpretation of ground-based microwave measurements of the moon using a detailed regolith properties model
A detailed model for the regolith's thermophysical and microwave properties has been used for the interpretation of ground-based measurements of the moon's microwave brightness temperature variation with lunar phase and changes during eclipses. The ground-based measurements include some crucial new lunation variation observations at 2.8, 6.0 and 13.1 cm. The many parameters in the regolith properties model were assigned values based on a careful review of Apollo in situ and lab sample measurements of thermophysical and electrical properties. The first identification of a wavelength-dependent component of scattering is reported.
Gary, B. L.↗
Air Quality Monitoring Case Study Using Mobile Low-cost Sensors Mounted on Trash-Trucks: Methods Development and Lessons Learned
Air quality monitoring (AQM) is crucial for cities to develop management plans supporting population health. However, there is a dearth of measurements due to the high cost of standard reference instruments. Mobile AQM using low-cost sensors deployed on routine fleets of vehicles can enable the continuous detection of fine-scale pollutant variations in cities at a lower cost. New methods need to be developed to interpret these measurements. This paper presents three such methods. First, we propose a technique to identify aerosol hotspots. Second, we employ techniques published previously to assess the generalizable map of fine and coarse particle number concentrations, to understand qualitatively the contribution of local and regional sources across the region sampled. By using the raw number concentration of differently sized particles from the Optical Particle Counters (OPCs) instead of the noisier mass concentrations, we obtain more robust results. Third, in order to evaluate source signatures in cities, we propose another technique, in which we cluster the entire range of aerosol size-distribution measurements acquired. The properties of each cluster provide insight into the aerosol source characteristics in the sampling environment. We test these methods using a dataset we collected by mounting OPCs on two trash-trucks in Cambridge, Massachusetts.
Drive-by sensing↗
Air Quality Monitoring Case Study Using Mobile Low-cost Sensors mounted on Trash-Trucks: Methods Development and Lessons Learned
Air quality monitoring (AQM) is crucial for cities to develop management plans supporting population health. However, there is a dearth of measurements due to the high cost of standard reference instruments. Mobile AQM using low-cost sensors deployed on routine fleets of vehicles can enable the continuous detection of fine-scale pollutant variations in cities at a lower cost. New methods need to be developed to interpret these measurements. This paper presents three such methods. First, we propose a technique to identify aerosol hotspots. Second, we employ techniques published previously to assess the generalizable map of fine and coarse particle number concentrations, to understand qualitatively the contribution of local and regional sources across the region sampled. By using the raw number concentration of differently sized particles from the Optical Particle Counters (OPCs) instead of the noisier mass concentrations, we obtain more robust results. Third, in order to evaluate source signatures in cities, we propose another technique, in which we cluster the entire range of aerosol size-distribution measurements acquired. The properties of each cluster provide insight into the aerosol source characteristics in the sampling environment. We test these methods using a dataset we collected by mounting OPCs on two trash-trucks in Cambridge, Massachusetts.
Drive-by sensing↗