Emission Signatures Research Articles

Urban land cover type determines the sensitivity of carbon dioxide fluxes to precipitation in Phoenix, Arizona.

Urbanization modifies land surface characteristics with consequent impacts on local energy, water, and carbon dioxide (CO2) fluxes. Despite the disproportionate impact of cities on CO2 emissions, few studies have directly quantified CO2 conditions for different urban land cover patches, in particular for arid and semiarid regions. Here, we present a comparison of eddy covariance measurements of CO2 fluxes (FC) and CO2 concentrations ([CO2]) in four distinct urban patches in Phoenix, Arizona: a xeric landscaping, a parking lot, a mesic landscaping, and a suburban neighborhood. Analyses of diurnal, daily, and seasonal variations of FC and [CO2] were related to vegetation activity, vehicular traffic counts, and precipitation events to quantify differences among sites in relation to their urban land cover characteristics. We found that the mesic landscaping with irrigated turf grass was primarily controlled by plant photosynthetic activity, while the parking lot in close proximity to roads mainly exhibited the signature of vehicular emissions. The other two sites that had mixtures of irrigated vegetation and urban surfaces displayed an intermediate behavior in terms of CO2 fluxes. Precipitation events only impacted FC in urban patches without outdoor water use, indicating that urban irrigation decouples CO2 fluxes from the effects of infrequent storms in an arid climate. These findings suggest that the proportion of irrigated vegetation and urban surfaces fractions within urban patches could be used to scale up CO2 fluxes to a broader city footprint.

Grinding wheel condition prediction with discrete hidden Markov model using acoustic emission signature

Tool Condition Monitoring (TCM) is a vital activity to monitor and maintain the quality of products manufactured in any machining process without any manual intervention. Hidden Markov Models (HMM) are developed in this study for predicting grinding wheel conditions in the auto-feed surface grinding process using Acoustic Emission (AE) signatures captured during the grinding operation. A correlation between AE features and tool conditions are established using Baum-Welch and Viterbi algorithms. HMMs proposed in this study are integrated with the K-means clustering algorithm. The clustered data are represented as an integer sequence and are divided into three tool states such as ‘sharp’, ‘intermediate’ and ‘worn out’. HMM, models are created for each state of the grinding wheel. The performances of the HMMs are evaluated using log-likelihood measure. It is observed that HMM models build with AE–RMS feature are predicting the grinding wheel conditions with good accuracy.

Atmospheric radiocarbon measurements to quantify CO<sub>2</sub> emissions in the UK from 2014 to 2015

Abstract. We present Δ14CO2 observations and related greenhouse gas measurements at a background site in Ireland (Mace Head, MHD) and a tall tower site in the east of the UK (Tacolneston, TAC) that is more strongly influenced by fossil fuel sources. These observations have been used to calculate the contribution of fossil fuel sources to the atmospheric CO2 mole fractions; this can be done, as emissions from fossil fuels do not contain 14CO2 and cause a depletion in the observed Δ14CO2 value. The observations are compared to simulated values. Two corrections need to be applied to radiocarbon-derived fossil fuel CO2 (ffCO2): one for pure 14CO2 emissions from nuclear industry sites and one for a disequilibrium in the isotopic signature of older biospheric emissions (heterotrophic respiration) and CO2 in the atmosphere. Measurements at both sites were found to only be marginally affected by 14CO2 emissions from nuclear sites. Over the study period of 2014–2015, the biospheric correction and the correction for nuclear 14CO2 emissions were similar at 0.34 and 0.25 ppm ffCO2 equivalent, respectively. The observed ffCO2 at the TAC tall tower site was not significantly different from simulated values based on the EDGAR 2010 bottom-up inventory. We explored the use of high-frequency CO observations as a tracer of ffCO2 by deriving a constant ratio of CO enhancements to ffCO2 ratio for the mix of UK fossil fuel sources. This ratio was found to be 5.7 ppb ppm−1, close to the value predicted using inventories and the atmospheric model of 5.1 ppb ppm−1. The TAC site, in the east of the UK, was strategically chosen to be some distance from pollution sources so as to allow for the observation of well-integrated air masses. However, this distance from pollution sources and the large measurement uncertainty in 14CO2 lead to a large overall uncertainty in the ffCO2, being around 1.8 ppm compared to typical enhancements of 2 ppm.

Learning acoustic emission signatures from a nanoindentation-based lithography process: Towards rapid microstructure characterization

Abstract We present an approach for rapid identification of the salient microstructural phases present on a metallic workpiece surface via nanoindentation-based lithography process. We employ a machine learning approach to connect the time-frequency patterns of the corresponding acoustic emission (AE) signals with the underlying microstructural phases. Results show that the AE frequencies in the range of 0.3–1 kHz and 30–50 kHz can discriminate between the microdynamics of the lithography process arising from different microstructural compositions and thereby predict these microstructural phases with accuracies exceeding 95%. We also draw physical interpretations of our “black-box” machine learning model and demonstrate that the physical insights into the underlying AE signals allow us to identify novel patterns and possible microstructural anomalies.

Dark Matter Signatures of Supermassive Black Hole Binaries

Abstract A natural consequence of the galaxy formation paradigm is the existence of supermassive black hole (SMBH) binaries. Gravitational perturbations from a far-away SMBH companion can induce high orbital eccentricities on dark matter (DM) particles orbiting the primary SMBH via the eccentric Kozai–Lidov mechanism. This process yields an influx of DM particles into the primary SMBH ergosphere, where test particles linger for long timescales. This influx results in high self-gravitating densities, forming a DM clump that is extremely close to the SMBH. In such a situation, the gravitational-wave (GW) emission between the dark matter clump and the SMBH is potentially detectable by LISA. If dark matter self-annihilates, the high densities of the clump will result in a unique codetection of GW emission and high-energy electromagnetic signatures.

Flame structure and emission signature in distributed combustion

Colorless distributed combustion (CDC) combustion technology offers significant advantages of ultra-low pollutants emission, stable operation and improved pattern factor for high intensity stationary gas turbines applications. Detailed knowledge on distributed combustion behavior is required to further deploy this technology. This paper reports the evolution of swirl flame shape, flame expansion and pollutants emission characteristics using propane, methane, and 20% and 40% hydrogen enriched methane fuels. The entrainment of hot reactive gases was simulated by diluting the inlet air stream with inert nitrogen or carbon dioxide. OH* chemiluminescence signatures, captured at different dilution levels, manifested gradual reduction of flame luminosity when CDC was approached. Flame boundaries derived using image threshold technique helped to visualize the broadened reaction zone under CDC conditions, which had much reduced chemiluminescence signal intensity. The rms to mean OH* signal variation at different dilution levels were analyzed to detect the initiation of CDC. The higher flame lift-off observed with CO2 dilution was due to higher heat capacity of CO2, resulting in greater flame speed reduction. Flame expansion, evaluated from the area encompassed within the flame boundary at different dilution levels showed a power-law behavior with both the diluents. Expansion of 4 to 5 times of initial flame volumes was observed under CDC using CO2 and N2 dilution, respectively. Significant reduction of NO and CO emission achieved under CDC was due to reduction of overall flame temperature, hotspot mitigation, and widened reaction zone occupying large flame volume, which makes it favorable for many practical combustor applications.

Some implications of the leptonic annihilation of dark matter: possible galactic radio emission signatures and the excess radio flux of extragalactic origin

We give theoretical predictions for the radio emission of a dark matter candidate annihilating into 2-lepton and 4-lepton final states. We then compare our results with the known radio measurements of the sky temperature as a function of the frequency. In particular, we calculate the radio emission for some dark matter candidates annihilating into intermediate bosons that subsequently decay into a 4-lepton channel with a thermal annihilation cross-section. We show that within the range of frequencies from 20 MHz to 5 GHz, this channel can produce a stronger signature than direct annihilation into leptons.

In-process monitoring of porosity in additive manufacturing using optical emission spectroscopy

A key challenge in metal additive manufacturing is the prevalence of defects, such as discontinuities within the part (e.g., porosity). The objective of this work is to monitor porosity in Laser Powder Bed Fusion (L-PBF) additive manufacturing of nickel alloy 718 (popularly called Inconel 718) test parts using in-process optical emission spectroscopy. To realize this objective, cylinder-shaped test parts are built under different processing conditions on a commercial L-PBF machine instrumented with an in-situ multispectral photodetector sensor. Optical emission signatures are captured continuously during the build by the multispectral sensor. Following processing, the porosity-level within each layer of a test part is quantified using X-ray Computed Tomography (CT). The graph Fourier transform coefficients are derived layer-by-layer from signatures acquired from the multispectral photodetector sensor. These graph Fourier transform coefficients are subsequently invoked as input features within various machine learning models to predict the percentage porosity-level in each layer with CT data taken as ground truth. This approach is found to predict the porosity on a layer-by-layer basis with an accuracy of ∼90% (F-score) in a computation time less than 0.5 seconds. In comparison, statistical moments, such as mean, variation, etc., are less accurate (F-score ≈ 80%) and require a computation time exceeding 5 seconds.

Aqueous Carbon Quantum Dot-Embedded PC60-PC61BM Nanospheres for Ecological Fluorescent Printing: Contrasting Fluorescence Resonance Energy-Transfer Signals between Watermelon-like and Random Morphologies.

To go beyond the PC60 surfactant structure, the double-layer micelle morphology in water motivates exploration of altered protocols to produce new morphologies. Furthermore, the low photoluminescence quantum yield of aqueous fullerene-based particles encourages high fluorescence to create a light-emitting display. With this in mind, we established new hybrid n-type nanospheres with carbon quantum dot (CQD)-embedded PC60-PC61BM particles, processed using two different protocols. The homogenizer-assisted PC60-CQD-PC61BM resulted in a watermelon-shaped spherical particle, whereas a circular morphology with randomly embedded CQDs was observed in the microwave-treated hybrids. More surprisingly, the watermelon-shaped colloid induced efficient fluorescence resonance energy transfer (FRET) between the CQD and C60 molecules of PC61BM, and the FRET-mediated emission signature diminished gradually as the stripe patterns collapsed. This phenomenon allowed different fluorescent colors in the colloidal printing film. We thereby provided the new carrier dynamics of the particle photonic activities of the developed aqueous PC60-based colloids with the possibility of ecological utilization.

Numerical simulations of wind-driven protoplanetary nebulae. II. signatures of atomic emission

Abstract We follow up on our systematic study of axisymmetric hydrodynamic simulations of protoplanetary nebula. The aim of this work is to generate the atomic analogues of the H2 near-infrared models of Paper I with the ZEUS code modified to include molecular and atomic cooling routines. We investigate stages associated with strong $\mathrm{[Fe\, {\small II}] \, 1.64\, \mathrm{\mu m} }$ and $\mathrm{ [S\, {\small II}] \, 6716}$ Å forbidden lines, the $\mathrm{[O\, {\small I}]\, 6300}$ Å airglow line, and Hα 6563 Å emission. We simulate (80 ∼ 200 km s−1) dense (∼105 cm−3) outflows expanding into a stationary ambient medium. In the case of an atomic wind interacting with an atomic medium, a decelerating advancing turbulent shell thickens with time. This contrasts with all other cases where a shell fragments into a multitude of cometary-shaped protrusions with weak oblique shocks as the main source of gas excitation. We find that the atomic wind-ambient simulation leads to considerably higher excitation, stronger peak and integrated atomic emission as the nebula expands. The weaker emission when one component is molecular is due to the shell fragmentation into fingers so that the shock surface area is increased and oblique shocks are prevalent. Position-velocity diagrams indicate that the atomic-wind model may be most easy to distinguish with more emission at higher radial velocities. With post-AGB winds and shells often highly obscured and the multitude of configurations that are observed, this study suggests and motivates selection criteria for new surveys.

In situ chemical analysis of geology samples by a rapid simultaneous ultraviolet/visible/near-infrared (UVN) + longwave-infrared laser induced breakdown spectroscopy detection system at standoff distance.

The standoff detection range of the simultaneous ultraviolet/visible/near-infrared (UVN) + longwave-Infrared (LWIR) Laser Induced Breakdown Spectroscopy (LIBS) detection system has been successfully extended from merely 10 cm to ≥ 1 meter by adopting a reflecting telescope collection scheme and UVN + LWIR LIBS emission signatures were acquired in various atmospheres from soil and mineral samples. This system simultaneously captured emission signatures from atomic, and simple and complex molecular target species existing in or near the same laser-induce plasma plume within micro-seconds. These pioneer standoff measurements of UVN + LWIR LIBS signatures have revealed an abundance of plasma-generated sample molecular emitting species in their vapor state along with atomic ones which gave intense and distinct signature emissions in both UVN (conventional LIBS) and LWIR (LWIR LIBS) spectral regions. A HITRAN simulation estimates the temperatures of those vapor molecular species to be around 2500 K. Laser-induced plasma emissions in the LWIR region provided direct information on the molecular components of the sample substances. The demonstrable capability of the LWIR LIBS on in situ characterization of carbon- and oxygen-rich materials is expected to find important applications in water discovery and organic materials signatures detection and identification. As a result laser ablation spectroscopy will be greatly augmented in both fundamental knowledge of and capability for chemical analysis.

Self-consistent Predictions for LIER-like Emission Lines from Post-AGB Stars

Abstract Early-type galaxies (ETGs) frequently show emission from warm ionized gas. These low-ionization emission regions (LIERs) were originally attributed to a central, low-luminosity active galactic nucleus. However, the recent discovery of spatially extended LIER emission suggests ionization by both a central source and an extended component that follows a stellar-like radial distribution. For passively evolving galaxies with old stellar populations, hot post-asymptotic giant branch (AGB) stars are the only viable extended source of ionizing photons. In this work, we present the first prediction of LIER-like emission from post-AGB stars that is based on fully self-consistent models of stellar evolution and photoionization. We show that models where post-AGB stars are the dominant source of ionizing photons reproduce the signatures of nebular emission observed in ETGs, including LIER-like emission line ratios in standard optical diagnostic diagrams and equivalent widths of the order of 0.1–3 . We test the sensitivity of LIER-like emission to the details of post-AGB models, including the mass loss efficiency and convective mixing efficiency, and show that line strengths are relatively insensitive to variations in post-AGB timescale. Finally, we examine the UV–optical colors of the models and the stellar populations responsible for the UV excess observed in some ETGs. We find that allowing as little as 3% of the horizontal branch population to be uniformly distributed to very high temperatures (30,000 K) produces realistic UV colors for old, quiescent ETGs.

APPLICATION OF HYPERSPECTRAL THERMAL EMISSION SPECTROMETER (HYTES) DATA FOR HYSPIRI OPTIMAL BAND POSITIONING TO CHARACTERIZE SURFACE MINERALS

Abstract. This study aimed to characterize surface minerals from high dimensional HyTES (Hyperspectral Thermal Emission Spectrometer) data comprised of 256 spectral bands between 7.5 and 12 μm (i.e., TIR domain of the electromagnetic spectrum). The HyTES is across-track imager and can image 512 pixels with spatial resolution varies between 5 to 50 m depending upon aircraft flying height. HyTES is developed to support the HyspIRI (Hyperspectral Infrared Imager) mission by acquiring TIR data at much higher spectral and spatial resolutions in-order to define the optimum band positions for the TIR instrument of HyspIRI. For earth compositional mapping, the HyTES images of Cuprite and Death Valley regions were acquired in summer 2014 and spectral emissivities of fifteen minerals classes were extracted from regions of known mineral compositions and were randomly divided into training and testing sets (each mineral class com-prised of 100 spectra). These extracted emissivity signatures were then used for categorizing minerals and for finding HyspIRI's optimal band positions for earth composition mapping using Genetic Algorithm (GA) coupled with Spectral angle mapper (SAM). The GA-SAM was trained for fifteen mineral classes and the algorithms were run iteratively 40 times. High calibration (> 95 %) and validation (> 90 %) accuracies were achieved with limited numbers (seven) of spectral bands selected by GA-SAM. Knowing the important band Positions will help scientist of HyspIRI group to place spectral bands at regions were accuracies of Earth compositional mapping can be enhanced.

Non-methane hydrocarbon (C<sub>2</sub>–C<sub>8</sub>) sources and sinks around the Arabian Peninsula

Abstract. Atmospheric non-methane hydrocarbons (NMHCs) have been extensively studied around the globe due to their importance to atmospheric chemistry and their utility in emission source and chemical sink identification. This study reports on shipborne NMHC measurements made around the Arabian Peninsula during the AQABA (Air Quality and climate change in the Arabian BAsin) ship campaign. The ship traversed the Mediterranean Sea, the Suez Canal, the Red Sea, the northern Indian Ocean, and the Arabian Gulf, before returning by the same route. The Middle East is one of the largest producers of oil and gas (O&G), yet it is among the least studied. Atmospheric mixing ratios of C2–C8 hydrocarbons ranged from a few ppt in unpolluted regions (Arabian Sea) to several ppb over the Suez Canal and Arabian Gulf (also known as the Persian Gulf), where a maximum of 166.5 ppb of alkanes was detected. The ratio between i-pentane and n-pentane was found to be 0.93±0.03 ppb ppb−1 over the Arabian Gulf, which is indicative of widespread O&G activities, while it was 1.71±0.06 ppb ppb−1 in the Suez Canal, which is a characteristic signature of ship emissions. We provide evidence that international shipping contributes to ambient C3–C8 hydrocarbon concentrations but not to ethane, which was not detected in marine traffic exhausts. NMHC relationships with propane differentiated between alkane-rich associated gas and methane-rich non-associated gas through a characteristic enrichment of ethane over propane atmospheric mixing ratios. Utilizing the variability–lifetime relationship, we show that atmospheric chemistry governs the variability of the alkanes only weakly in the source-dominated areas of the Arabian Gulf (bAG=0.16) and along the northern part of the Red Sea (bRSN=0.22), but stronger dependencies are found in unpolluted regions such as the Gulf of Aden (bGA=0.58) and the Mediterranean Sea (bMS=0.48). NMHC oxidative pair analysis indicated that OH chemistry dominates the oxidation of hydrocarbons in the region, but along the Red Sea and the Arabian Gulf the NMHC ratios occasionally provided evidence of chlorine radical chemistry. These results demonstrate the utility of NMHCs as source/sink identification tracers and provide an overview of NMHCs around the Arabian Peninsula.

The ground exciton state of formamidinium lead bromide perovskite nanocrystals is a singlet dark state.

Lead halide perovskites have emerged as promising new semiconductor materials for high-efficiency photovoltaics, light-emitting applications and quantum optical technologies. Their luminescence properties are governed by the formation and radiative recombination of bound electron-hole pairs known as excitons, whose bright or dark character of the ground state remains unknown and debated. While symmetry analysis predicts a singlet non-emissive ground exciton topped with a bright exciton triplet, it has been predicted that the Rashba effect may reverse the bright and dark level ordering. Here, we provide the direct spectroscopic signature of the dark exciton emission in the low-temperature photoluminescence of single formamidinium lead bromide perovskite nanocrystals under magnetic fields. The dark singlet is located several millielectronvolts below the bright triplet, in fair agreement with an estimation of the long-range electron-hole exchange interaction. Nevertheless, these perovskites display an intense luminescence because of an extremely reduced bright-to-dark phonon-assisted relaxation.

Single photon emission in WSe2 up 160 K by quantum yield control

2D semiconductors hosting strain-induced quantum emitters offer unique abilities to achieve scalable architectures for deterministic coupling to nanocavities and waveguides that are required to enable chip-based quantum information processing technologies. A severe drawback remains that exciton emission from quantum emitters in WSe2 quenches beyond 30 K, which requires cryogenic cooling. Here we demonstrate an approach to increase the temperature survival of exciton quantum emitters in WSe2 that is based on maximizing the emitter quantum yield. Utilizing optimized material growth that leads to reduced density of nonradiative defects as well as coupling of the exciton emission to plasmonic nanocavities modes, we achieve average quantum yields up to 44%, thermal activation energies up to 92 meV, and single photon emission signatures up to temperatures of 160 K. At these values non-cryogenic cooling with thermo-electric chips becomes already feasible, while quantitative analysis shows that room temperature operation is within reach through active strain engineering.

A diversity of starburst-triggering mechanisms in interacting galaxies and their signatures in CO emission

The physical origin of enhanced star formation activity in interacting galaxies remains an open question. Knowing whether starbursts are triggered by an increase in the quantity of dense gas or an increase in the star formation efficiency therein would improve our understanding of galaxy evolution and make it possible to transfer the results obtained in the local Universe to high-redshift galaxies. In this paper, we analyze a parsec-resolution simulation of a model of interacting galaxies similar to the Antennae Galaxies. We find that the interplay of physical processes such as tides, shear, and turbulence shows complex and important variations in time and space, but that different combinations of these processes can produce similar signatures in observable quantities such as the depletion time and CO emission. Some clouds within the interacting galaxies exhibit an excess of dense gas (> 104 cm−3), while others only attain similarly high densities in the tail of their density distribution. The clouds with an excess of dense gas are found across all regions of the galaxies, but their number density varies between regions due to different cloud assembly mechanisms. This translates into variations in the scale dependence of quantities related to cloud properties and star formation. The super-linearity of the relationship between the star formation rate and gas density implies that the dense gas excess corresponds to a decrease in the depletion time, and thus leads to a deviation from the classical star formation regime that is visible up to galactic scales. We find that the αCO conversion factor between the CO luminosity and molecular gas mass exhibits stronger spatial than temporal variations in a system like the Antennae. Our results raise several caveats for the interpretation of observations of unresolved star-forming regions, but also predict that the diversity of environments for star formation will be better captured by the future generations of instruments.

Stimuli‐Responsive Copolymer and Uniform Polymeric Nanoparticles with Photochromism and Switchable Emission

AbstractAn efficient approach to make a fluorescent polymer both photoswitchable and stimuli‐responsive was successfully developed by rationally introducing a photochromic bisthienylethene derivative (BTE) and fluorescent 4‐dicyanomethylene‐2,6‐distyryl‐4H‐pyran derivative (DPC) units in the side chains via copolymerization. Benefiting from the reversible photocyclization of BTE and the intermolecular Förster Resonance Energy Transfer (FRET) effect from DPC to the closed form of BTE, the emission signatures of the polymer both in solution in organic solvents and in thin films could be tuned by the alternating irradiation of ultraviolet and visible light. Moreover, uniform polymeric nanoparticles (NPs) with reversibly photoswitchable fluorescence properties were synthesized using a facile one‐step mini‐emulsion polymerization. This polymer could act as a smart material for photoresponsive polymer illuminants and offers new platform for multifunctional molecular switching and multi‐responsive materials.

The Methods of Condition Monitoring for Circulator of HTGR

Circulator is one of the important components in an HTGR to meet the plant safety and availability. Several methods have been applied for the condition monitoring and in-service inspection especially of reactor cooling pump, which mainly for the light water reactor such as the vibration monitoring, acoustic emission and motor current signature analysis (MCSA). Despite the long experience of these condition monitoring implementation in light water nuclear power plant, however, research is still required to understand the most suitable method for a condition monitoring of the reactor cooling pump for the HTGR based on all possible monitoring methods. It is because that each method is known having its own sensitivity to detect specific faults, sensitive only on one side either the electrical motor side or the pump as well as having its own capability to meet the criteria’s to be implemented in a condition monitoring. Therefore, this paper aims to study various condition monitoring methods that are suitable for the implementation in online condition monitoring of circulator in HTGR. Because the circulator or blower has not been commonly explored for the HTGR, this paper describes the common faults in cooling pump of light water reactor, various condition monitoring, and the comparison of the applicability of each method to identify each type of faults. This paper also discusses the challenges and opportunities for further improvement in this condition monitoring research. This research highlighted that the combination of more than one online monitoring techniques with the performance may provide a better solution in identifying various faults and motor degradation.

Investigation of incoherent scatter radar spectra features with stimulated electromagnetic emissions at EISCAT

Electromagnetic (EM) and electrostatic (ES) emissions can be generated in the ionosphere by high-power high-frequency (HF) radio waves transmitted from the ground. The signatures of the EM emissions observed on the ground are known as Stimulated Electromagnetic Emissions (SEE) and can be employed for remote measurement of ionospheric parameters. The experimental data from recent HF heating experiments near the fourth electron gyro-frequency (4fce) at EISCAT are presented. This paper compares the temporal behavior of SEE within a few Hertz up to 50 kHz of the transmission frequency to the time evolution of enhanced ion line (EHIL) in the incoherent scatter radar (ISR) spectrum. The correlation of Wideband SEE (WSEE) spectral lines within 1 kHz to 100 kHz such as the downshifted maximum (DM), downshifted peak (DP), and broad upshifted maximum (BUM), with HF enhanced ion lines (EHIL) is shown. It is shown that WSEE spectral lines can be used to reproduce the EHIL characteristics including altitude range, rise and decay time, maximum and minimum amplitude. A data reduction technique is developed to derive ionospheric parameters such as the electron density profile near the interaction altitude, magnetic field strength B0 as well as the altitude profile of the EHIL using the temporal evolution of WSEE spectral lines near nfce.