Columnar Density Research Articles

Spatiotemporal analysis of the link between VCDtrop NO2 and population size for provinces in Sumatra Island during 2012-2020

ABSTRACT Nitrogen dioxide is one of the primary air contaminants that can cause severe ecological and human health effects. This study used the Ozone Monitoring Instrument (OMI) sensor aboard AURA satellite to analyze the spatial and temporal variations of VCDtrop (Tropospheric vertical Columnar density) NO2 concentration in Sumatra, Indonesia, during 2012–2020. Based on the seasonal characteristics, the VCDtrop NO2 amounts in the east part of Sumatra were higher in the dry season and slightly lower in the wet season. The increasing trend was recorded in some provinces; North Sumatra, Riau, South Sumatra, and Lampung with the accumulation rate around 8–9 × 1015 molecules/cm2 from 2012 to 2014. Higher VCDtrop NO2 concentrations were associated with an increase in population size. As a whole, this finding can be useful to arrange air pollution management associated with population growth in urban areas.

Spatio-temporal patterns of tropospheric NO2 over India during 2005–2019

Air pollution is the leading environmental health risk factor globally. Nitrogen dioxide (NO2) is a criteria pollutant associated with adverse health effects. In India, the focus has been mostly on ambient PM2.5; hence understanding the space-time variability of NO2 and the potential role of different NO2 sources are required. This work aimed to address these two gaps by first examining a long-term spatial heterogeneity of NO2 and linking it to the major contributing sources (e.g., power plants and industries) over the Indian region, and secondly by examining the variability in land use patterns and its changes over the years 2005–2019. We analyzed tropospheric NO2 vertical columnar densities (VCDs) from the Ozone Monitoring Instrument (OMI) onboard the Aura satellite at a resolution of 0.1° × 0.1° for the period 2005 to 2019. We calculated linear trends in tropospheric NO2 VCDs and performed a significance test to ensure real changes. We also analyzed Global Human Settlement Layer (GHSL) data to identify the land use as ‘high-density urban,’ ‘low-density urban,’ ‘rural,’ and ‘no settlement.’ The spatial analysis found higher tropospheric NO2 VCDs (>5 × 1015 molecules/cm2) in eastern (coal belt with many power plants) and northern India, along with a few locations in central India. The change in tropospheric NO2 VCDs during the last 15 years showed an increasing trend (>2 × 1013 molecules/cm2) in most parts of India. Whereas during the last decade (2010–2019), the annual average trend over the country had reduced by up to ∼76% relative to 2005–2009. Tropospheric NO2 VCDs increased by 12.5%–29.6% from 2005 to 2019 across all levels of land settlement in India. Our study suggested considering NO2 as an important pollutant in addition to PM2.5 and developing a NO2 exposure model for further health impact assessment studies.

Analyzing the role of in situ coal fire in greenhouse gases emission in a coalfield using remote sensing data and their dispersion and source apportionment study.

In situ coal fires significantly pollute the environment in many countries of the world. Monitoring these pollutants is challenging due to extensive area coverage and spatial variations. Thus, the present study demonstrates the method of deriving the spatial and temporal profiles of columnar density of three major greenhouse gases (carbon monoxide (CO), sulfur dioxide (SO2), and nitrogen dioxide (NO2)) in an in situ coal fire region (Jharia coalfield (JCF), India) using high-resolution satellite data (TROPOMI) of the European Space Agency (ESA). The study also demonstrates a new methodology for estimating greenhouse gas emissions from in situ coal burning. JCF is one of the significant polluted mining regions with multiple in situ coal fire pockets. The columnar density of the gaseous pollutants in the mining region was compared with the same in the rural, urban, and forest regions to identify the major emission inventories. The study results indicated that coal fire is the major source of CO emission in the region, as the CO was high in the fire regions compared to that of the non-fire regions. But, the major source of NO2 is the traffic, as the NO2 was high in the city area as compared to other regions. The spatial profile of SO2 does not reveal the specific emission sources. The study results indicated that TROPOMI onboard satellite sensors could be effectively used for deriving the spatial profiles of greenhouse gaseous in coal fire regions, which further assist in identifying the emission inventories. Furthermore, the satellite-based Earth observations offer information to understand and manage the greenhouse gas emissions over a large area.

Self-absorption effect in calibration-free laser-induced breakdown spectroscopy: Analysis of mineral profile in Maerua oblongifolia plant

Maerua oblongifolia is a traditional medicinal plant served for health advancing effects due to rich nutrients. The compositional analysis of this plant was carried out using the calibration-free laser-induced breakdown spectroscopy (CF-LIBS). The laser-produced plasma was generated on the pelletized samples of roots, stem, leaves, and fruits to record and analyze the corresponding emission spectra. The spectroscopic analysis revealed the presence of elements such as Na, Ca, Mg, K, Al, Fe, Li, Si, Sr, Zn, Ba, and Rb. As a prerequisite of quantitative analysis, and for the determination of reliable plasma parameters, a simplified approach was used to correct the self-absorption in the emission lines to determine the plasma temperature using Boltzmann and Saha-Boltzmann plot methods. This procedure was further used to develop the modified Saha-Boltzmann plot, which uses the columnar densities of emitting species at the ground state to determine the plasma temperature. Finally, the one-line CF-LIBS was used to quantify the concentration of all the perceived constituent elements. LIBS results were cross-validated with that obtained from ICP-MS.

A method for improving the accuracy of calibration-free laser-induced breakdown spectroscopy by exploiting self-absorption

The existence of the self-absorption effect results in a nonlinear relationship between spectral intensity and elemental concentration, which dramatically affect the quantitative accuracy of laser-induced breakdown spectroscopy (LIBS), especially calibration-free LIBS (CF-LIBS). In this work, the CF-LIBS with columnar density and standard reference line (CF-LIBS with CD-SRL) was proposed to improve the quantitative accuracy of CF-LIBS analysis by exploiting self-absorption. Our method allows using self-absorbed lines to perform the calibration-free approach directly and does not require self-absorption correction algorithms. To verify this method, the experiment was conducted both on aluminium-bronze and aluminium alloy samples. Compared with classical CF-LIBS, the average errors (AEs) of CF-LIBS with CD-SRL were decreased from 3.20%, 3.22%, 3.15% and 3.01%–0.95%, 1.00%, 1.16% and 1.78%, respectively for four aluminium-bronze alloy samples. The AEs were decreased from 0.66%, 0.70%, 0.89% and 1.30%–0.43%, 0.61%, 0.77% and 0.33%, respectively for four aluminium alloy samples. The experimental results demonstrated that CF-LIBS with CD-SRL provided higher quantitative accuracy and stronger adaptability than classical CF-LIBS, which is quite helpful for the practical application of CF-LIBS.

Analysis of the Spread of COVID-19 in the USA with a Spatio-Temporal Multivariate Time Series Model.

With the rapid spread of the pandemic due to the coronavirus disease 2019 (COVID-19), the virus has already led to considerable mortality and morbidity worldwide, as well as having a severe impact on economic development. In this article, we analyze the state-level correlation between COVID-19 risk and weather/climate factors in the USA. For this purpose, we consider a spatio-temporal multivariate time series model under a hierarchical framework, which is especially suitable for envisioning the virus transmission tendency across a geographic area over time. Briefly, our model decomposes the COVID-19 risk into: (i) an autoregressive component that describes the within-state COVID-19 risk effect; (ii) a spatiotemporal component that describes the across-state COVID-19 risk effect; (iii) an exogenous component that includes other factors (e.g., weather/climate) that could envision future epidemic development risk; and (iv) an endemic component that captures the function of time and other predictors mainly for individual states. Our results indicate that maximum temperature, minimum temperature, humidity, the percentage of cloud coverage, and the columnar density of total atmospheric ozone have a strong association with the COVID-19 pandemic in many states. In particular, the maximum temperature, minimum temperature, and the columnar density of total atmospheric ozone demonstrate statistically significant associations with the tendency of COVID-19 spreading in almost all states. Furthermore, our results from transmission tendency analysis suggest that the community-level transmission has been relatively mitigated in the USA, and the daily confirmed cases within a state are predominated by the earlier daily confirmed cases within that state compared to other factors, which implies that states such as Texas, California, and Florida with a large number of confirmed cases still need strategies like stay-at-home orders to prevent another outbreak.

YBa2Cu3O7−x films with Ba2Y(Nb,Ta)O6 nanoinclusions for high-field applications

The structural and transport properties of YBa2Cu3O7−x films grown by pulsed laser deposition with mixed 2.5 mol% Ba2YTaO6 (BYTO) and 2.5 mol% Ba2YNbO6 (BYNO) double-perovskite secondary phases are investigated in an extended film growth rate, R = 0.02–1.8 nm s−1. The effect of R on the film microstructure analyzed by TEM techniques shows an evolution from sparse and straight to denser, thinner and splayed continuous columns, with mixed BYNO + BYTO (BYNTO) composition, as R increases from 0.02 nm s−1 to 1.2 nm s−1. This microstructure results in very efficient flux pinning at 77 K, leading to a remarkable improvement in the critical current density (Jc) behaviour, with the maximum pinning force density Fp(Max) = 13.5 GN m−3 and the irreversibility field in excess of 11 T. In this range, the magnetic field values at which the Fp is maximized varies from 1 T to 5 T, being related to the BYNTO columnar density. The film deposited when R = 0.3 nm s−1 exhibits the best performances over the whole temperature and magnetic field ranges, achieving Fp(Max) = 900 GN m−3 at 10 K and 12 T. At higher rates, R > 1.2 nm s−1, BYNTO columns show a meandering nature and are prone to form short nanorods. In addition, in the YBCO film matrix a more disordered structure with a high density of short stacking faults is observed. From the analysis of the Fp(H, T) curves it emerges that in films deposited at the high R limit, the vortex pinning is no longer dominated by BYNTO columnar defects, but by a new mechanism showing the typical temperature scaling law. Even though this microstructure produces a limited improvement at 77 K, it exhibits a strong Jc improvement at lower temperature with Fp = 700 GN m−3 at 10 K, 12 T and 900 GN m−3 at 4.2 K, 18 T.

Exploiting Self-Absorption for Plasma Characterization in Laser-Induced Breakdown Spectroscopy Experiments: A Comparison of Two Recent Approaches.

In this article, we compare two analytical methods that have been recently proposed: the columnar density Saha-Boltzmann plot method of Cristoforetti and Tognoni (Cristoforetti, G.; Tognoni, E. Spectrochim. Acta, Part B, 2013, 79-80, 63-71) and the C-sigma model of Aragon and Aguilera (Aragon, C.; Aguilera, J. A. J. Quant. Spectrosc. Radiat. Trans. 2014, 149, 90-102). Both methods are based on the exploitation of self-absorbed lines for the characterization of plasmas in laser-induced breakdown spectroscopy experiments. However, although the two methods can be safely applied in many cases, their usefulness is limited in many practical cases of interest because of the intrinsic constraints of the used plasma model or because of the complexity of the numerical treatment. The two methods are presented here and critically discussed. Finally, an extended C-sigma approach is proposed to merge the advantages of the two methods, overcoming their intrinsic limitations and simplifying the numerical treatment.

Determination of excitation temperature in laser-induced plasmas using columnar density Saha-Boltzmann plot

In exploiting the analytical capabilities of plasma-based spectroscopy method, the evaluation of plasma parameters, particularly the plasma temperature, is a crucial step. In this work, a modified Saha-Boltzmann plot, which uses the columnar densities of atomic and ionic ground levels, is utilized to calculate the plasma temperature in a laser-induced plasma from an aluminum alloy target. The columnar densities are here calculated by quantifying the self-absorption of resonance lines. It is demonstrated that this is a promising method for accurate determination of plasma temperature. To validate the capability of this technique, plasma emission is measured at different gate delay times. For each delay, excitation temperature is calculated both by the conventional Saha-Boltzmann plot (by using the excited states) and by exploiting the new Columnar Density Saha–Boltzmann (CD-SB) plot. The results suggest that at later times of the plasma evolution, the CD-SB plot can be more suitable for the determination of plasma temperature than conventional Saha-Boltzmann plot. These findings provide a new approach for physical characterization of plasmas and give access to a wealth of information about the state of plasma.

Estimation of molecular column density of methane (XCH4) using AVIRIS-NG data

An attempt has been made to retrieve columnar density of methane (XCH4) over a suburban area of the Shadnagar in India from the high spatial and moderate spectral resolution (5 nm ± 0.5 nm) airborne visible/infrared imaging spectrometer next generation (AVIRIS-NG) data. The data collected were part of the joint airborne campaign by National Aeronautics Space Administration/Jet Propulsion Laboratory and Indian Space Research Organisation over several Indian sites during December 2015 to January 2016. The XCH4 was retrieved following the Moderate Resolution Imaging Spectroradiometer (MODIS) water vapor retrieval algorithm and was compared with the ground-based Fourier transform infrared (FTIR) observations. FTIR measured CH4 transmittance was fitted against Fast Atmospheric Signature Code3 (FASCODE3) simulated transmittance, and found their residual lies within ±1 % , which shows a very good retrieval sensitivity of FTIR. Hence FTIR observations are used for the validation of AVIRIS-NG derived XCH4 and found in good agreement. In the present study, we utilized airborne imaging radiance data in the CH4 absorbing channel at 2.365 ± 0.006 μm and nonabsorbing channels at 2.325 ± 0.006 μm and 2.365 ± 0.006 μm to compute atmospheric transmittance spectrum. Using a line-by-line radiative transfer algorithm, the XCH4 was estimated from AVIRIS-NG transmittance data. Prior to the application of the MODIS water vapor algorithm on AVIRIS-NG transmittance, it was also compared with the FASCODE3 simulated transmittance and found comparable. Study revealed that within the Shadnagar region, retrieved XCH4 varies little to moderate with an average of 9 × 1027 molecules cm − 2 with the highest value of 12 × 1027 molecules cm − 2 near the source region of the agriculture field. The study demonstrates the capability of AVIRIS-NG to quantify the column density of atmospheric species such as CH4 over a region.

Does the high density of trichomes influence the parasitism of Liriomyza sativae by Opius scabriventris on melon cultivars?

ABSTRACT: Opius scabriventris (Hymenoptera: Braconidae) is considered an important parasitoid of the leafminer Liriomyza sativae (Diptera: Agromyzidae) in the main melon (Cucumis melo L.) producing areas in Brazil. However, there is no information on the influence of trichomes on melon plant leaves on the parasitoids’ actions. Therefore, the aim of this investigation was to relate the influence of columnar trichome density on melon cultivars in the parasitism of L. sativae larvae by O. scabriventris. The study was conducted in laboratory conditions, in which melon cultivars were infested and the leafminer larvae were subjected to the parasitism. The results demonstrated that trichome density can influence the parasitism of L. sativae larvae by O. scabriventris. Among the studied materials, Piel de Sapo cultivar showed the highest density of trichomes in the leaves (534 trichomes/cm2) and the lowest parasitism (20%).

Plasma diagnostics from self-absorbed doublet lines in laser-induced breakdown spectroscopy

In this paper, a generalized approach is developed and applied for plasma characterization and quantitative purposes in laser-induced breakdown spectroscopy (LIBS) experiences by employing a selected pair of spectral lines belonging to the same multiplet. It is based on the comparison between experimental ratios of line parameters and the theoretical calculus obtained under the framework of a homogeneous plasma in local thermodynamic equilibrium. The applicability of the method was illustrated by using the atomic resonance transitions 279.55–280.27nm of Mg II, which are usually detected in laser-induced plasma (LIP) during laser ablation of many kinds of targets. The laser induced plasmas were produced using a Nd:YAG laser from a pressed pellet of powdered calcium hydroxide with a concentration of 300ppm of Mg. The experimental ratios for peak intensities, total intensities and Stark widths were obtained for different time windows and matched to the theoretical calculus. The temperature and the electron density of the plasma, as well as the Mg columnar density (the atom/ion concentration times the length of the plasma along the line-of-sight), were determined. The results were interpreted under the employed approach.

Calculation of elemental columnar density from self-absorbed lines in laser-induced breakdown spectroscopy: A resource for quantitative analysis

The presence of self-absorption of emission lines is usually an undesired effect in laser-induced breakdown spectroscopy because it introduces non linear effects in the growth of line intensity versus the concentration of the emitting species. Several methods have been proposed in recent years for identifying and quantifying self-absorption in the emission spectra. After this diagnostic stage, the lines affected by self-absorption are usually disregarded; otherwise, appropriate corrective factors are applied to their intensity before the utilization for analytical purposes. Changing the point of view, this paper remarks as self-absorption can provide useful information for analyzing the composition of laser-induced plasmas and for their characterization. Whenever the extent of self-absorption is quantified, in fact, the optical depth of the line can be rapidly calculated; then, for plasmas in local thermodynamic equilibrium conditions, the columnar density of the emitting species can be derived. Assuming the plasma homogeneity, the concentration ratio between different elements can be obtained. Moreover, in particular cases, the columnar densities can be used to calculate the plasma temperature and the absolute number densities of plasma species. Some applications of the method are reported in the paper and potentialities and limitations are discussed.

Decoupling and decommensuration in layered superconductors with columnar defects

We consider layered superconductors with a flux lattice perpendicular to the layers and random columnar defects parallel to the magnetic field B. We show that the decoupling transition temperature Td, at which the Josephson coupling vanishes, is enhanced by columnar defects by an amount ~B^2 relative to Td. Decoupling by increasing field can be followed by a reentrant recoupling transition for strong disorder. We also consider a commensurate component of the columnar density and show that its pinning potential is renormalized to zero above a critical long wavelength disorder. This decommnesuration transition may account for a recently observed kink in the melting line.

2H-NMR Detection of the Pressure Effect on Packing Modulations in a Columnar Liquid Crystal

The effect of high pressure on the columnar density modulation of the hexaoctylether of rufigallol, resulting from the incommensurability of the aromatic and aliphatic packing, is studied by 1D and 2D 2 H-NMR spectroscopy. The mobility of the side chains can be used to probe the local packing density along the columns. We show that the numbers of molecules in regions of high and low packing density are strongly dependent both on temperature and on pressure. 2D-exchange NMR spectra show that the rate of exchange between these regions decreases considerably at increasing pressure, which is attributed to an increase of the length scale of the pinched regions. Our findings are consistent with the model proposed by de Gennes to resolve the incommensurability problem. A large decrease in the rate of molecular reorientation about the column axis is observed at the II-III phase transition.

Significance of nitrogen dioxide absorption in estimating aerosol optical depth and size distributions

Abstract Concurrent measurements of spectral direct beam solar radiation and columnar nitrogen dioxide (NO2) content at a suburban site, McMaster University, in Hamilton, Ontario, were used to determine the effect of NO2 absorption upon aerosol optical depths, derived size distributions, and the columnar particle number density and mass. Aerosol optical depths were reduced by 22–47, 12–25, 3–6% and 1% at wavelengths of 400, 500, 610 and 670 nm, respectively, when the gaseous absorption was included. The smaller reductions refer to average NO2 amounts (3 × 10−3 atm‐cm) and the larger to high amounts (>6 × 10−3 atm‐cm). Columnar number density was reduced by 51–95% and mass by 13–26%. At high NO2 amounts the inclusion of NO2 absorption narrowed the size distribution derived from median optical depths and changed it from bimodal to unimodal.

Formation of a solar coronal transient with forerunner

view Abstract Citations (1) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Formation of a Solar Coronal Transient with Forerunner Gliner, Erast B. ; Osherovich, Vladimir A. Abstract A model of a solar coronal transient in the course of its formation is constructed. The main idea is that the formation of a coronal transient occurs at a quasi-stationary state of the solar atmosphere as a result of the interaction of weak coronal currents with a slowly growing magnetic field originating below the future transient area. The explanation of forerunner formation which takes place much before the appearance of the transient itself is one of the verifications of the model. The application of the model to the transient event of Jan. 10, 1974, demonstrates the reasonable values of model parameters for reproducing the observed columnar density distribution. Publication: The Astrophysical Journal Pub Date: January 1987 DOI: 10.1086/164886 Bibcode: 1987ApJ...312..412G Keywords: Coronal Loops; Magnetohydrodynamic Flow; Solar Atmosphere; Solar Corona; Density Distribution; Skylab Program; Solar Magnetic Field; Stellar Models; Solar Physics; HYDROMAGNETICS; SUN: CORONA full text sources ADS |

On the X-ray and ultraviolet spectrum of the high-redshift quasar 3C 446

Existing IUE and Einstein observations of the high-redshift (z = 1.414) quasar 3C 446 have been analyzed. In the UV the continuum is characterized by a steep slope. The lack of signal shortward of 2300 Å is probably due to the Lyman continuum absorption at the source. The X-ray spectrum shows the "universal" slope of active galactic nuclei coupled with a hydrogen columnar density in excess of the Galactic value, suggesting that the absorption occurs in or around the source.

Variations in stratospheric aerosol optical depth during northern warmings

In this paper the properties of the stratospheric aerosol optical depth (above 50 mbar) have been studied by using aerosol extinction profiles (at 1 μm) derived from the Stratospheric Aerosol Measurement (SAM II) and Stratospheric Aerosol and Gas Experiment (SAGE) during warming periods in the northern hemisphere. It is shown that, during the disturbed periods in winter, low values of aerosol optical depth (<0.2×10−3) are found within the low‐pressure system(s) (at the 30‐mbar pressure surface), while high values are found outside. Similar characteristics are found to exist for the simultaneously observed SAGE O3 and NO2 columnar density distributions. Strong longitudinal gradients are shown with the low values within and wherever the vortex exists. This characteristic is maintained during and after the circumpolar vortex is disturbed, even after breakdown, indicating an isolation of the material within the vortex.

Forbidden O II studies of galactic planetary nebulae and extragalactic H II complexes

The 3727-A doublet ratio of forbidden O II was observed in five planetary nebulae and nine extragalactic groupings of H II regions (H II Complexes). The theoretical relation between this doublet ratio and nebular density was rederived using the most up-to-date atomic parameters, permitting columnar densities to be determined for all objects. The structure of extragalactic H II Complexes is discussed, and a preferred model advanced. A new method of distance determination for extragalactic systems is proposed and evaluated in the context of the presently available data.