Values Of Atmospheric Parameters Research Articles

Modeling and simulation of dye-sensitized solar cell: Model verification for different semiconductors and dyes

In this article, the use of MATLAB/SIMULINK interface to realize a generalized photovoltaic simulation model is introduced. The model was created utilizing the photovoltaic (PV) cell fundamental circuit equations, including the effects of solar radiation and variations in temperature. This modeling approach enables the I–V and P–V curve of PV cells to be understood. It could also be used as a tool to forecast the behavior of any solar PV cell under differing environmental circumstances (e.g., temperature, irradiation conditions). These effects are simultaneously added in real-time. Due to their nonlinear features, they must be modeled to design and simulate the maximum power point of solar cells. This model applies to dye-sensitized solar cells with three different semiconductors, namely, TiO2, ZnO, and SnO2; use N3 dye. According to changes in atmospheric parameter values such as solar radiation, temperature, and operating parameter values like semiconductor type, dye concentration, and particles, the characteristic dimensions of photovoltaic systems such as power supply voltage (PV) and current–voltage (I-V) characteristics are drawn; in the MATLAB/SIMULINK interface observed. The simulation results reveal that these elements and the respective photovoltaic model affect the maximum operating performance of PV modules. The battery made of TiO2 semiconductor and N3 dye showed the greatest consistency with the model battery, followed by the battery made of ZnO, and finally, the battery made of SnO2 with the same dye N3.

Barium lines in high-quality spectra of two metal-poor giants in the Galactic halo

Context. Theoretical results showed the possibility that neutron capture elements were produced in the early Universe by two different sources: a frequent s-process source hosted by rotating massive stars, and a rare r-process source hosted most likely by neutron star mergers. The two sources produce barium with different isotopic compositions. Aims. We aim to investigate the lines of barium in two halo stars, HD 6268 and HD 4306. The spectra present an exquisite quality, both in terms of resolution (R > 100 000) and signal-to-noise (~400). Due to hyperfine splitting (hfs) effects, barium lines are expected to show slightly different profiles depending on the barium isotopic fraction. Methods. We applied a standard local thermodynamic equilibrium synthesis of the barium lines. We compared the synthetic results assuming an s-process isotopic pattern or an r-process isotopic pattern for the two barium lines for each star that exhibited hfs. We also applied a methodology, less dependent on the accuracy of the theoretical Ba hfs structure, that transforms the lines of HD 4306 into those we would observe if its atmospheric parameter values (i.e. Teff, log g, micro- and macro-turbulence, V sin i, and Ba abundance) were the same as those of HD 6268. Results. With both methods, our results show that the barium lines with hfs effects of HD 4306 are in agreement with an s-process composition and the lines in HD 6268 have a different profile, which is most likely linked to the presence of an r-process isotopic pattern. Conclusions. Two lines of barium of HD 6268 and HD 4306 seem to confirm the theoretical expectation that both r-process events and also s-process contribution by rotating massive stars have polluted the ancient halo of our Galaxy.

New atmospheric data model for constant altitude accelerated flight performance prediction calculations and flight trajectory optimization algorithms

This article presents a new method for storing and computing the atmospheric data used in time-critical flight trajectory performance prediction calculations, such as flight performance prediction calculations in flight management systems and/or flight trajectory optimization, of constant altitude cruise segments. The proposed model is constructed based on the forecast data provided by Meteorological Service Agencies, in a GRIB2 data file format, and the set of waypoints that define the lateral component of the evaluated flight profile(s). The atmospheric data model can be constructed/updated in the background or off-line, when new atmospheric prediction data are available, and subsequently used in the flight performance computations. The results obtained using the proposed model show that, on average, the atmospheric parameter values are computed six times faster than through 4D linear interpolations, while yielding identical results (value differences of the order of 10e−14). When used in flight trajectory performance calculations, the obtained results show that the proposed model conducts to significant computation time improvements. The proposed model can be extended to define the atmospheric data for a set of cruise levels (usually multiple of 1000 ft).

ПРИМЕНЕНИЕ РЕГРЕССИОННОГО АНАЛИЗА ДЛЯ РАСЧЕТОВ ПО ДАННЫМ ПРИБОРОВ ИКФС-2 И МТВЗА СПУТНИКА «МЕТЕОР-2»

This article examines a multiple regression method to calculate the characteristics of the at-mosphere with hyper spectral sensors data of “Meteor-2” satellite. The method was used to calculate the carbon dioxide concentration by infrared Fourier-spectrometer IKFS-2 and the integral content of water vapor of atmosphere for the microwave sensor MTVZA-GY. Analysis of the obtained results and calculation errors showed the possibility of using this method to restore the values of atmospheric parameters. The proposed method could be applied to for various sensors and it allows to expand the capabilities of other methods.

Warunki atmosferyczne a ryzyko powstania zdarzenia drogowego

In an atmospheric environment, a man is subjected to the influence of many factors of a stimulus nature, which probably affect into the behaviour of drivers in road traffic and the risk of them being exposed to certain road incidents. The aim of the paper was to answer the question whether weather conditions and what values of atmospheric parameters have an impact on the increase of the risk level regarding the occurrence of a road incident. The analyses were carried out using the road network in Elbląg as an example. There were based on detailed information regarding road incidents occurrence covering two years, and also atmospheric conditions that were made available. The work undoubtedly demonstrates that atmospheric conditions have an impact on considered risk. Moreover, the increase of this risk is highly influenced by atmospheric parameters such as humidity and air temperature.

Gaia–ESO Survey: INTRIGOSS—A New Library of High-resolution Synthetic Spectra

Abstract We present a high-resolution synthetic spectral library, INTRIGOSS, designed for studying FGK stars. The library is based on atmosphere models computed with specified individual element abundances via ATLAS12 code. Normalized SPectra (NSPs) and surface Flux SPectra (FSP) in the wavelength range 4830–5400 Å were computed with the SPECTRUM code. INTRIGOSS uses the solar composition of Grevesse et al. and four [α/Fe] abundance ratios, and consists of 15,232 spectra. The synthetic spectra are computed with astrophysical gf-values derived by comparing synthetic predictions with a solar spectrum of very high signal-to-noise ratio and the UVES-U580 spectra of five cool giants. The validity of the NSPs is assessed by using the UVES-U580 spectra of 2212 stars observed in the framework of the Gaia–ESO (European Southern Observatory) survey and characterized by homogeneous and accurate atmospheric parameter values and by detailed chemical compositions. The greater accuracy of NSPs with respect to spectra from the synthetic spectral libraries AMBRE, GES_Grid, PHOENIX, C14, and B17 is demonstrated by evaluating the consistency of the predictions of the different libraries for stars in the UVES-U580 sample. The validity of the FSPs is checked by comparing their prediction with both the observed spectral energy distribution (SED) and spectral indices. The comparison of FSPs with SEDs derived from the libraries ELODIE, INDO–U.S., and MILES indicates that the former reproduce the observed flux distributions within a few per cent and without any systematic trend. The good agreement between observational and synthetic Lick/SDSS (Sloan Digital Sky Survey) indices shows that the predicted blanketing of FSPs well reproduces the observed one, thus confirming the reliability of INTRIGOSS FSPs.

Dependence of tropical cyclone development on coriolis parameter: A theoretical model

A simple theoretical model was formulated to investigate how tropical cyclone (TC) intensification depends on the Coriolis parameter. The theoretical framework includes a two-layer free atmosphere and an Ekman boundary layer at the bottom. The linkage between the free atmosphere and the boundary layer is through the Ekman pumping vertical velocity in proportion to the vorticity at the top of the boundary layer. The closure of this linear system assumes a simple relationship between the free atmosphere diabatic heating and the boundary layer moisture convergence. Under a set of realistic atmospheric parameter values, the model suggests that the most preferred latitude for TC development is around 5° without considering other factors.The theoretical result is confirmed by high-resolution WRF model simulations in a zero-mean flow and a constant SST environment on an f −plane with different Coriolis parameters. Given an initially balanced weak vortex, the TC-like vortex intensifies most rapidly at the reference latitude of 5°. Thus, the WRF model simulations confirm the f-dependent characteristics of TC intensification rate as suggested by the theoretical model.

Least-Squares Deconvolution based analysis of stellar spectra

In recent years, astronomical photometry has been revolutionised by space missions such as MOST, CoRoT and Kepler. However, despite this progress, high-quality spectroscopy is still required as well. Unfortunately, high-resolution spectra can only be obtained using ground-based telescopes, and since many interesting targets are rather faint, the spectra often have a relatively low S/N. Consequently, we have developed an algorithm based on the least-squares deconvolution profile, which allows to reconstruct an observed spectrum, but with a higher S/N. We have successfully tested the method using both synthetic and observed data, and in combination with several common spectroscopic applications, such as e.g. the determination of atmospheric parameter values, and frequency analysis and mode identification of stellar pulsations.

High-Resolution Spectroscopy of Cool Carbon-Rich and Metal-Poor Star HD 209621

Abstract Element abundances for HD 209621 obtained earlier display significant discrepancies, especially in the case of CNO and neutron-capture elements. Therefore we performed a detailed analysis of chemical composition of this star using a new high-resolution spectrum. Atmospheric parameters and abundance pattern are updated, and the mechanism of nucleosynthesis is examined. Abundances for 11 elements are calculated for the first time. The method of atmospheric models and spectral synthesis was used. The following values of atmospheric parameters are derived: Teff = 4400 K, log g = 1.0 (cgs) and ξt = 1.9 kms−1. The iron abundance of the star was found to be low, at [Fe/H] = -1.91±0.10. The carbon to oxygen ratio is high, C/O ≃ +2.0. Low carbon to nitrogen ratio, [C/N] ≃ -0.8, and low carbon isotopic ratio, 12C/13C = 17 ±5, are in agreement with the theory of nucleosynthesis of intermediate-mass AGB stars. The barium to europium ratio is high, [Ba/Eu] = +0.28, and is typical for carbon-enhanced metal-poor CEMP-r/s stars. The observed abundance pattern of neutron capture elements is reproduced well by the scaled solar system abundances.

Split-Window LST Algorithms Estimation From AVHRR/NOAA Satellites (7, 9, 11, 12, 14, 15, 16, 17, 18, 19) Using Gaussian Filter Function

A study has been carried out using MODTRAN 4.0 radiative transfer code simulations to calculate the brightness temperatures expected at the Advanced Very High Resolution Radiometer (AVHRR) on board the National Oceanic and Atmospheric Administration NOAA satellites series (7, 9, 11, 12, 14, 15, 16, 17, 18 and 19) by using Gaussian Referential Filter (GRF) and Gaussian Filter (GF) instead of filter Normalized Filter obtained from NOAA agency. The outputs of applying MODTRAN 4.0 are values of atmospheric parameters obtained by mathematical convolution using GRF and GF Filters. A detailed analysis of the total error in LST, d Total(Ts) , in function of AVHRR/NOAA satellites, shows that the algorithms are able to estimate accurate LST between a minimum of 1.256 K and a maximum of 1.415 K with amplitude of about 0.159 K. The validations show also that the algorithms are capable to produce LST with a standard deviation lower than 1.554 K and a Root Mean Square Error (RMSE) lower than 1.558 K. This result gives the opportunity to use the filter GF instead of filter Normalized Filter obtained from NOAA agency, in other studies by creation of GF filters centered in any region of the electromagnetic.

THE LICK/SDSS LIBRARY. II. [Ca/Fe] AND [Mg/Fe] IN F, G, AND K STARS FROM SDSS-DR7

We analyzed the spectra of 17,600 F, G, and K stars extracted from the seventh Sloan Digital Sky Survey Data Release (SDSS-DR7) database in order to derive [α/Fe], [Ca/Fe], and [Mg/Fe] ratios. Particular attention has been devoted to estimating homogeneous and self-consistent atmospheric parameter values, T eff, log g, and [Fe/H], by comparing synthetic and observational Lick/SDSS indices. We present results for the sub-sample of more than 4000 spectra whose overall quality allowed us to derive fairly accurate stellar atmospheric parameter values and, therefore, reliable abundance ratios. A Monte Carlo approach was adopted to evaluate both the errors in the observational Lick/SDSS indices and in the derived parameter estimates. The analysis of the trends of [Ca/Fe] and [Mg/Fe] versus [Fe/H] pointed out that (1) the [Ca/Fe] and [Mg/Fe] ratios increase with decreasing [Fe/H] with different slopes reaching maximum average levels of +0.25 and +0.40 dex at [Fe/H] –1.75, respectively; (2) our sample contains, at a given [Fe/H], stars characterized by significantly different amounts of α-enhancement, thus belonging to different Galactic populations; and (3) the analyzed sample shows a predominance of thick disk stars for [Fe/H] > – 0.5 and the presence of stars belonging to the high-α halo population for –2.0 < [Fe/H] <–0.5.

Análise da sensibilidade de um modelo de atenuação espectral da irradiância na atmosfera em diferentes condições atmosféricas: uma aplicação para o Sea-viewing Wide Field-of-view Sensor (SeaWiFS)

A sensibilidade de um modelo de irradiância espectral, incidente sobre a superfície do mar, variando três parâmetros atmosféricos (ozônio, visibilidade e vapor de água precipitável), é analisada, com especial ênfase para as bandas do sensor Sea-viewing Wide Field-of-view Sensor (SeaWiFS). São também analisadas as razões entre bandas de reflectância geralmente utilizadas nos algoritmos bio-óticos, para mapeamento da biomassa fitoplanctônica do espaço. Os resultados mostram que a visibilidade é o parâmetro que mais causa alteração nos valores de irradiância, embora o seu efeito nas razões entre bandas seja menor do que o efeito do ozônio. O vapor de água precipitável não causou alteração significativa nem nas irradiâncias e nem nas razões entre bandas. Os valores extremos destes parâmetros não causaram diferenças significativas para ângulos solares entre 0 e 60º. Para se obter a razão entre reflectâncias das bandas 490/510, 490/555 e 510/555 em ângulos solares menores que 60º, valores médios destes parâmetros atmosféricos testados neste trabalho são suficientes para se modelar a razão entre irradiâncias.

Galileo Photopolarimetry of Jupiter at 678.5 nm

Brightness and linear polarization measurements at 678.5 nm for four south–north strips of Jupiter are studied. These measurements were obtained in 1997 by the Galileo photopolarimeter/radiometer. The observed brightness exhibits latitudinal variations consistent with the belt/zone structure of Jupiter. The observed degree of linear polarization is small at low latitudes and increases steeply toward higher latitudes. No clear correlations were observed between the degree of linear polarization and the brightness. The observed direction of polarization changes from approximately parallel to the local scattering plane at low latitudes to perpendicular at higher latitudes. For our studies, we used atmospheric models that include a haze layer above a cloud layer. Parameterized scattering matrices were employed for the haze and cloud particles. On a pixel-wise basis, the haze optical thickness and the single-scattering albedo of the cloud particles were derived from the observed brightness and degree of linear polarization; results were accepted only if they were compatible with the observed direction of polarization. Using atmospheric parameter values obtained from Pioneer 10 and 11 photopolarimetry for the South Tropical Zone and the north component of the South Equatorial Belt, this analysis yielded acceptable results for very few pixels, particularly at small phase angles. However, for almost all pixels, acceptable results were found when the parameterized scattering matrix of the cloud particles was adjusted to produce more negative polarization for single scattering of unpolarized light, especially at large scattering angles, similar to some laboratory measurements of ammonia ice crystals. Using this adjusted model, it was found that the derived latitudinal variation of the single-scattering albedo of the cloud particles is consistent with the belt/zone structure, and that the haze optical thickness steeply increases toward higher latitudes.

Analysis of temporal variations of the polarization of Venus observed by Pioneer Venus Orbiter

Time variations of the disk‐averaged polarization of Venus at wavelengths of 270, 365, 550, and 935 nm have been analyzed in terms of average haze optical thickness, cloud‐top pressure, and cloud absorption optical thickness at 270 nm (presumably due to gaseous SO2 absorption). The polarization data were deduced from observations made by the Pioneer Venus Orbiter between 1978 and 1990. Newton‐Raphson iteration was used to derive the atmospheric parameter values from these observations. The required multiple scattering calculations were performed using the adding/doubling method. The atmospheric model consists of a cloud layer and a haze layer. The cloud and haze particles are composed of a concentrated sulfuric acid solution and have an effective radius of 1.05 μm and 0.25 μm, respectively. It was found that the disk‐averaged haze optical thickness, cloud‐top pressure, and cloud absorption optical thickness at 270 nm varied irregularly between 1978 and 1990. No trends were identified for the cloud‐top pressure and cloud absorption optical thickness at 270 nm, but we did deduce a decrease in haze optical thickness during this 12 year period. Specific numbers are: (1) a haze optical thickness at 365 nm of about 0.25 in 1978 and less than 0.1 in 1990, (2) a cloud‐top pressure that varies between 5 and 20 mbar, and (3) a cloud absorption optical thickness that varies between 0.0 and 4.0. Finally, our analysis revealed that the disk‐averaged cloud‐top pressure and haze optical thickness behaved anomalously in 1983.

Comparison of Measured and Modeled Turbulence Spectra for a Point Rotating as on a Horizontal-Axis Wind Turbine

A theoretical model of the spectrum of rotationally sampled wind speed is tested against corresponding measured wind spectra. The ability to generate such a spectrum, independent of measurement, is important in wind turbine design and testing. The measured spectra were selected from a number of cases measured with a vertical plane array of anemometers. The array was set up to correspond to the tip circle of a nearby MOD-OA wind turbine rotor blade. For testing purposes, the turbulence and mean wind shear were treated separately. In each case the test was based on two correspondence criteria, each involving comparison of results from the theoretical model and results from real data analysis. These criteria were rotational spectra and their integration by harmonic band into energy, particularly the latter. The measured spectra were selected to represent different atmospheric stability conditions. The theory is shown to have respectable accuracy except when applied to the stable atmosphere. Recommendations were made for selection of the values of atmospheric parameters to be used for computing the theoretical result. The importance of the time length of a measured turbulence record to be used in estimating several parameters for input to the theoretical model applied to real wind conditions at a selected turbine site is discussed. The VAX 11/780 computer time required to generate a model spectrum is usually less than one minute.

Verification of theoretically computed spectra for a point rotating in a vertical plane

The ability to generate a model tubulent wind as it is seen by a rotating blade, independent of measurement, is important in wind turbine design and testing. A theoretical model of the spectrum of rotationally sampled wind speed developed at the Pacific Northwest Laboratory is tested against corresponding measured wind spectra. The measured spectra were selected from a number of cases measured with a vertical plane array of anemometers. The array was set up to correspond to the tip circle of a nearby MOD-OA wind turbine rotor blade. For purposes of testing and of illuminating the process, the turbulence and mean wind shear were treated separately. In each case the test was based on two criteria, each involving comparison of results from the theoretical model and results from real data analysis. These criteria were the rotational spectra and the integration of the spectra within each harmonic band into energy. Particularly the latter criterion was used. The measured spectra were selected to represent different atmospheric stability conditions. The theory is shown to achieve respectable accuracy readily except when applied to the stable atmosphere case. Recommendations are made for selection of the values of atmospheric parameters to be used for computing the theoretical result. The importance of the length of time of a measured turbulence record that is to be used in estimating several parameters for input to the theoretical model applied to real wind conditions at a selected turbine site is discussed. The VAX 11/780 computer time required to generate a model spectrum is usually less than one minute.

The generation of baroclinic rossby waves by meridional oscillations of a zonal wind stress

Abstract This paper investigates the generation of linear baroclinic Rossby waves by meridional oscillations of a climatological zonal wind stress in a reduced gravity ocean bounded by an eastern coastline. Using a power series technique an analytical solution is derived for the interfacial displacement. It is found that for a given period of oscillation of the zonal winds, a finite number of propagating Rossby waves will be generated with frequencies equal to a harmonic of the forcing frequency. The number of propagating modes increases with increasing period of the wind stress. In addition to the propagating waves the complete solution for the interfacial displacement consists of a rapidly convergent infinite sum of evanescent terms. The displacement field is calculated for atmospheric forcing parameters typical of those found at mid-latitudes. Further, it is shown that a near resonant response can be generated using atmospheric parameter values typical of those found over the North Pacific.

The determination and analysis of the orbit of NIMBUS 1 ROCKET, 1964-52B: Part 2: Variations in orbital eccentricity

The influence of aerodynamic drag and the geopotential on the motion of the satellite 1964-52B is considered. A model of the atmosphere is adopted that allows for oblateness, and in which the density behaviour approximates to the observed diurnal variation. A differential equation governing the variation of the eccentricity, e, combining the effects of air drag with those of the Earth's gravitational field is given. This is solved numerically using as initial conditions 310 computed orbits of 1964-52B. The observed values of eccentricity are modified by the removal of perturbations due to luni-solar attraction, solid Earth and ocean tides, solar radiation pressure and low-order long-periodic tesseral harmonic perturbations. The method of removal of these effects is given in some detail. The behaviour of the orbital eccentricity predicted by the numerical solution is compared with the modified observed eccentricity to obtain values of atmospheric parameters at heights between 310 and 430 km. The daytime maximum of air density is found to be at 14.5 hours local time. Analysis of the eccentricity near 15th order resonance with the geopotential yielded values of four lumped geopotential harmonics of order 15, namely: 10 9 C 1,0 15 = −78.8 ± 7.0 , 10 9 S 1,0 15 = −69.4 ± 5.3 , 10 9 C −1,2 15 = −41.6 ± 3.5 10 9 S −1,2 15 = −26.1 ± 8.9 , at inclination 98.68°.

Near-circular satellite orbits in an oblate, diurnally varying atmosphere

The influence of air drag and the geopotential on near-circular satellite orbits, eccentricity e &lt; 0.01, is considered. A model of the atmosphere is adopted that allows for oblateness, and in which the density behaviour approximates to the observed diurnal variation. Differential equations governing the variation in e and the argument of perigee ω are derived by combining the effects of air drag with those of the Earth’s gravitational field. These are solved numerically using initial conditions obtained from a series of computed orbits of the satellite 1963-27 A. The behaviour of the orbital elements predicted by the numerical solution is compared with the observed elements to test the developed theory, and to obtain values of atmospheric parameters at heights near 400 km.

Inversion of radiometric measurements1

Inversion of satellite radiometer measurements to yield values of atmospheric parameters is expected to be an important source of data within the next few years. A review of inversion methods, based in part on a recent workshop, is presented to outline their present status. General considerations indicate that fine structure will not be resolved, and that the number of parameters determined may be less than the number of measurements. Using infrared data, temperature profiles appear to be inferable with an accuracy of about ±3K, and water vapor distributions may be obtained, over clear skies or broken cloud. Microwave measurements appear to allow temperature determinations with similar accuracy which are less affected by underlying cloud. Water vapor and cloud liquid water content can also be determined, although there are engineering problems. Inversion of visible and ultraviolet data is not as far advanced, but may yield ozone distributions, cloud top heights and information on aerosols. A few of the present problem areas are mentioned.