scholarly journals Abel transform of exponential functions for planetary and cometary atmospheres with application to observation of 46P/Wirtanen and to the OI 557.7 nm emission at Mars.

2021 ◽  
Author(s):  
Benoit Hubert ◽  
Guy Munhoven ◽  
Youssef Moulane ◽  
Damien Hutsemekers ◽  
Jean Manfroid ◽  
...  
Keyword(s):  
Emission Rate ◽  
Remote Sensing Data ◽  
Line Of Sight ◽  
Accuracy Control ◽  
Abel Transform ◽  
Symmetry Assumption ◽  
Volume Emission ◽  
Series Development ◽  
Rate Profile ◽  
Analytical Expressions

<p>Line-of-sight integration of emissions from planetary and cometary atmospheres is the Abel transform of the emission rate, under the spherical symmetry assumption. Indefinite integrals constructed from the Abel transform integral are useful for implementing remote sensing data analysis methods, such as the numerical inverse Abel transform giving the volume emission rate compatible with the observation. We obtain analytical expressions based on a suitable, non-alternating, series development to compute those indefinite integrals. We establish expressions allowing absolute accuracy control of the convergence of these series depending on the number of terms involved. We compare the analytical method with numerical computation techniques, which are found to be sufficiently accurate as well. Inverse Abel transform fitting is then tested in order to establish that the expected emission rate profiles can be retrieved from the observation of both planetary and cometary atmospheres. We show that the method is robust, especially when Tikhonov regularization is included, although it must be carefully tuned when the observation varies across many orders of magnitude. A first application is conducted over observation of comet 46P/Wirtanen, showing some variability possibly attributable to an evolution of the contamination by dust and icy grains. A second application is considered to deduce the 557.7 nm volume emission rate profile of the metastable oxygen atom in the upper atmosphere of planet Mars.</p>

Tomographic retrieval of the oxygen infrared atmospheric band with the OSIRIS infrared imager

2004 ◽  
Vol 82 (7) ◽  
pp. 501-515 ◽  
Author(s):  
D A Degenstein ◽  
E J Llewellyn ◽  
N D Lloyd
Keyword(s):  
Spatial Resolution ◽  
Emission Rate ◽  
Two Dimensions ◽  
Line Of Sight ◽  
Two Dimensional ◽  
Retrieval Technique ◽  
The Earth ◽  
Infrared Imager ◽  
Retrieval Scheme ◽  
Volume Emission

The infrared imager (IRI) component of the optical spectrograph and infrared imager system (OSIRIS) onboard the Odin spacecraft provides a set of line-of-sight brightness measurements of the oxygen infrared atmospheric (OIRA) band. This set of measurements is unique in the fact that they are ideal inputs to a two-dimensional retrieval scheme that accurately recovers the volume emission rate of the OIRA band. The retrieval is done simultaneously in two dimensions, the angle along the satellite track and the distance from the centre of the Earth. The latter is easily converted to altitude above the surface of the Earth. In this work, we present the measurement set, the retrieval technique, and some preliminary results. We clearly demonstrate that the OSIRIS infrared imager provides maps of the OIRA band volume emission rate with unprecedented spatial resolution. PACS Nos.: 07.05.Pj, 07.60.Dq, 94.10.Fa, 94.10.Gb, 94.10.Rk

CALCULATION OF THE DEPENDENCE OF THE DISTANCE TO THE LOCATED OBJECT FROM THE CORNER POSITION OF THE VEHICLE LINE

2018 ◽  
pp. 14-18
Author(s):  
V. V. Artyushenko ◽  
A. V. Nikulin
Keyword(s):  
Real Time ◽  
Statistical Physics ◽  
Angular Position ◽  
Three Dimensional ◽  
Line Of Sight ◽  
Two Dimensional ◽  
Radar Station ◽  
Flight Mode ◽  
Vector Algebra ◽  
Analytical Expressions

To simulate echoes from the earth’s surface in the low flight mode, it is necessary to reproduce reliably the delayed reflected sounding signal of the radar in real time. For this, it is necessary to be able to calculate accurately and quickly the dependence of the distance to the object being measured from the angular position of the line of sight of the radar station. Obviously, the simplest expressions for calculating the range can be obtained for a segment or a plane. In the text of the article, analytical expressions for the calculation of range for two-dimensional and three-dimensional cases are obtained. Methods of statistical physics, vector algebra, and the theory of the radar of extended objects were used. Since the calculation of the dependence of the range of the object to the target from the angular position of the line of sight is carried out on the analytical expressions found in the paper, the result obtained is accurate, and due to the relative simplicity of the expressions obtained, the calculation does not require much time.

scholarly journals Variations of the 630.0 nm airglow emission with meridional neutral wind and neutral temperature around midnight

2018 ◽  
Vol 36 (5) ◽  
pp. 1471-1481
Author(s):  
Chih-Yu Chiang ◽  
Sunny Wing-Yee Tam ◽  
Tzu-Fang Chang
Keyword(s):  
Emission Rate ◽  
Local Maximum ◽  
Neutral Wind ◽  
Emission Rates ◽  
Emission Layer ◽  
Neutral Winds ◽  
Neutral Temperature ◽  
Bright Spots ◽  
Different Temperatures ◽  
Volume Emission

Abstract. The ISUAL payload onboard the FORMOSAT-2 satellite has often observed airglow bright spots around midnight at equatorial latitudes. Such features had been suggested as the signature of the thermospheric midnight temperature maximum (MTM) effect, which was associated with temperature and meridional neutral winds. This study investigates the influence of neutral temperature and meridional neutral wind on the volume emission rates of the 630.0 nm nightglow. We utilize the SAMI2 model to simulate the charged and neutral species at the 630.0 nm nightglow emission layer under different temperatures with and without the effect of neutral wind. The results show that the neutral wind is more efficient than temperature variation in affecting the nightglow emission rates. For example, based on our estimation, it would require a temperature change of 145 K to produce a change in the integrated emission rate by 9.8 km-photons cm−3 s−1, while it only needs the neutral wind velocity to change by 1.85 m−1 s−1 to cause the same change in the integrated emission rate. However, the emission rate features a local maximum in its variation with the temperature. Two kinds of tendencies can be seen regarding the temperature that corresponds to the turning point, which is named the turning temperature (Tt) in this study: firstly, Tt decreases with the emission rate for the same altitude; secondly, for approximately the same emission rate, Tt increases with the altitude.

scholarly journals Accounting for O2 absorption in ionospheric UV volume emission rate tomography

2020 ◽  
Vol 17 (6) ◽  
pp. 153-158
Author(s):  
S.A. Kalashnikova ◽  
◽  
E.S. Andreeva ◽  
A.M. Padokhin ◽  
◽  
...  
Keyword(s):  
Emission Rate ◽  
Volume Emission

scholarly journals Quantifying the redshift space distortion of the bispectrum I: primordial non-Gaussianity

2020 ◽  
Vol 493 (1) ◽  
pp. 594-602 ◽  
Author(s):  
Somnath Bharadwaj ◽  
Arindam Mazumdar ◽  
Debanjan Sarkar
Keyword(s):  
Spherical Harmonics ◽  
Real Space ◽  
Line Of Sight ◽  
Multipole Moments ◽  
Distortion Parameter ◽  
Redshift Surveys ◽  
Space Distortion ◽  
Zero Values ◽  
Parallel Approximation ◽  
Analytical Expressions

ABSTRACT The anisotropy of the redshift space bispectrum contains a wealth of cosmological information. This anisotropy depends on the orientation of three vectors $\boldsymbol {k_1},\boldsymbol {k_2},\boldsymbol {k_3}$ with respect to the line of sight. Here, we have decomposed the redshift space bispectrum in spherical harmonics which completely quantify this anisotropy. To illustrate this, we consider linear redshift space distortion of the bispectrum arising from primordial non-Gaussianity. In the plane-parallel approximation, only the first four even ℓ multipoles have non-zero values, and we present explicit analytical expressions for all the non-zero multipoles, that is, upto ℓ = 6 and m = 4. The ratio of the different multipole moments to the real-space bispectrum depends only on β1 the linear redshift distortion parameter and the shape of the triangle. Considering triangles of all possible shapes, we have studied how this ratio depends on the shape of the triangle for β1 = 1. We have also studied the β1 dependence for some of the extreme triangle shapes. If measured in future, these multipole moments hold the potential of constraining β1. The results presented here are also important if one wishes to constrain fNL using redshift surveys.

Long-term variation of OH peak emission altitude and volume emission rate over Indian low latitudes

2016 ◽  
Vol 138-139 ◽  
pp. 161-168 ◽  
Author(s):  
M. Sivakandan ◽  
T.K. Ramkumar ◽  
A. Taori ◽  
Venkateshwara Rao ◽  
K. Niranjan
Keyword(s):  
Emission Rate ◽  
Low Latitudes ◽  
Term Variation ◽  
Volume Emission ◽  
Peak Emission

Two day wave induced variations in the oxygen green line volume emission rate: WINDII observations

1997 ◽  
Vol 24 (9) ◽  
pp. 1127-1130 ◽  
Author(s):  
W. E. Ward ◽  
B. H. Solheim ◽  
G. G. Shepherd
Keyword(s):  
Emission Rate ◽  
Green Line ◽  
Volume Emission ◽  
Wave Induced

scholarly journals Discovering Orbit and Clock Quality Based on Analysis of Wide-Lane Ambiguities Derived from PPP Models

2018 ◽  
Author(s):  
Gang Chen ◽  
Sijing Liu ◽  
Qile Zhao
Keyword(s):  
Real Time ◽  
Quality Index ◽  
Precise Point Positioning ◽  
Line Of Sight ◽  
New Approach ◽  
Actual Time ◽  
Estimation Procedures ◽  
Wide Lane ◽  
Point Positioning ◽  
Analytical Expressions

Orbit and clock products are used in real-time GNSS precise point positioning without knowing their quality. This study develops a new approach to detect orbit and clock errors through comparing geometry-free and geometry-based wide-lane ambiguities in PPP model. The reparameterization and estimation procedures of the geometry-free and geometry-based ambiguities are described in detail. The effects of orbit and clock errors on ambiguities are given in analytical expressions. The numerical similarity and differences of geometry-free and geometry-based wide-lane ambiguities are analyzed using different orbit and clock products. Furthermore, two types of typical errors in orbit and clock are simulated and their effects on wide-lane ambiguities are numerically produced and analyzed. The contribution discloses that the geometry-free and geometry-based wide-lane ambiguities are equivalent in terms of their formal errors. Although they are very close in terms of their estimates when the used orbit and clock for geometry-based ambiguities are precise enough, they are not the same, in particular, in the case that the used orbit and clock, as a combination, contain significant errors. It is discovered that the discrepancies of geometry-free and geometry-based wide-lane ambiguities are coincided with the actual time-variant errors in the used orbit and clock at the line-of-sight direction. This provides a quality index for real-time users to detect the errors in real-time orbit and clock products, which potentially improves the accuracy of positioning.

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