The Experts below are selected from a list of 4140 Experts worldwide ranked by ideXlab platform
E C Pavlis - One of the best experts on this subject based on the ideXlab platform.
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High-accuracy zenith delay prediction at optical wavelengths,” Geophysical Res
2020Co-Authors: V B Mendes, E C PavlisAbstract:[1] A major limitation in accuracy in modern satellite laser ranging is the modeling of Atmospheric Refraction. Recent improvements in this area include the development of mapping functions to project the Atmospheric delay experienced in the zenith direction to a given elevation angle. In this paper, we derive zenith delay models from revised equations for the computation of the refractive index of the atmosphere, valid for a wide spectrum of optical wavelengths. The zenith total delay predicted with these models were tested against ray tracing through radiosonde data from a full year of data, for 180 stations distributed worldwide, and showed sub-millimeter accuracy for wavelengths ranging from 0.355 mm to 1.064 mm
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high accuracy zenith delay prediction at optical wavelengths
Geophysical Research Letters, 2004Co-Authors: V B Mendes, E C PavlisAbstract:[1] A major limitation in accuracy in modern satellite laser ranging is the modeling of Atmospheric Refraction. Recent improvements in this area include the development of mapping functions to project the Atmospheric delay experienced in the zenith direction to a given elevation angle. In this paper, we derive zenith delay models from revised equations for the computation of the refractive index of the atmosphere, valid for a wide spectrum of optical wavelengths. The zenith total delay predicted with these models were tested against ray tracing through radiosonde data from a full year of data, for 180 stations distributed worldwide, and showed sub-millimeter accuracy for wavelengths ranging from 0.355 μm to 1.064 μm.
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improved mapping functions for Atmospheric Refraction correction in slr
Geophysical Research Letters, 2002Co-Authors: V B Mendes, G Prates, E C Pavlis, D E Pavlis, Richard LangleyAbstract:[1] We present two new mapping functions (MFs) to model the elevation angle dependence of the Atmospheric delay for satellite laser ranging (SLR) data analysis. The new MFs were derived from ray tracing through a set of data from 180 radiosonde stations globally distributed, for the year 1999, and are valid for elevation angles above 3°. When compared against ray tracing of two independent years of radiosonde data (1997–1998) for the same set of stations, our MFs reveal submillimetre accuracy for elevation angles above 10°, representing a significant improvement over other MFs, and is confirmed in improved solutions of LAGEOS and LAGEOS 2 data analysis.
V B Mendes - One of the best experts on this subject based on the ideXlab platform.
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High-accuracy zenith delay prediction at optical wavelengths,” Geophysical Res
2020Co-Authors: V B Mendes, E C PavlisAbstract:[1] A major limitation in accuracy in modern satellite laser ranging is the modeling of Atmospheric Refraction. Recent improvements in this area include the development of mapping functions to project the Atmospheric delay experienced in the zenith direction to a given elevation angle. In this paper, we derive zenith delay models from revised equations for the computation of the refractive index of the atmosphere, valid for a wide spectrum of optical wavelengths. The zenith total delay predicted with these models were tested against ray tracing through radiosonde data from a full year of data, for 180 stations distributed worldwide, and showed sub-millimeter accuracy for wavelengths ranging from 0.355 mm to 1.064 mm
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high accuracy zenith delay prediction at optical wavelengths
Geophysical Research Letters, 2004Co-Authors: V B Mendes, E C PavlisAbstract:[1] A major limitation in accuracy in modern satellite laser ranging is the modeling of Atmospheric Refraction. Recent improvements in this area include the development of mapping functions to project the Atmospheric delay experienced in the zenith direction to a given elevation angle. In this paper, we derive zenith delay models from revised equations for the computation of the refractive index of the atmosphere, valid for a wide spectrum of optical wavelengths. The zenith total delay predicted with these models were tested against ray tracing through radiosonde data from a full year of data, for 180 stations distributed worldwide, and showed sub-millimeter accuracy for wavelengths ranging from 0.355 μm to 1.064 μm.
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improved mapping functions for Atmospheric Refraction correction in slr
Geophysical Research Letters, 2002Co-Authors: V B Mendes, G Prates, E C Pavlis, D E Pavlis, Richard LangleyAbstract:[1] We present two new mapping functions (MFs) to model the elevation angle dependence of the Atmospheric delay for satellite laser ranging (SLR) data analysis. The new MFs were derived from ray tracing through a set of data from 180 radiosonde stations globally distributed, for the year 1999, and are valid for elevation angles above 3°. When compared against ray tracing of two independent years of radiosonde data (1997–1998) for the same set of stations, our MFs reveal submillimetre accuracy for elevation angles above 10°, representing a significant improvement over other MFs, and is confirmed in improved solutions of LAGEOS and LAGEOS 2 data analysis.
Wei Mao - One of the best experts on this subject based on the ideXlab platform.
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Atmospheric Refraction and building a local observational model
Acta Astronomica Sinica, 2009Co-Authors: Wei Mao, L Yang, Qiong-xian TieAbstract:A new application of the astronomical Atmospheric Refraction in space geodesy is introduced in this paper.To meet with high requirement of the application,it is necessary to develop an effective method for directly measuring instantaneous Atmospheric Refraction and constructing an Atmospheric Refraction model adapted to the geographical environment around the observing station.Necessary conditions for determining the Refraction values are listed in brief.Making use of structural characteristics of the Lower Latitude Meridian Circle and the error theory of this instrument,we have developed a method used to measure directly instantaneous Atmospheric Refraction,and moreover built a local observational astronomical re fraction model toward the east,south,west and north of Yunnan observatory that is classified according to the star's spectral type.
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on the discussion of astronomical Atmospheric Refraction
Acta Astronomica Sinica, 2008Co-Authors: Wei Mao, L Yang, Qiong-xian TieAbstract:The series expansion method and mapping function expansion method for astronomical Refraction are analyzed in this paper. It is shown from the comparison be- tween those two methods that the computational accuracy from the former one is not lower than that from the latter for a certain Refraction model. The series expansion method in the theoretical deriwtion is often lower in astringency because of various approximations. It is also analyzed that the actual situations on the generator function method in the as- tronomical Refraction mapping function can not indicate the characteristic of the geophysics and Atmospheric physics. It is pointed out that the previous Refraction model was built using a specific Atmospheric model in a certain place and it is not suitable for all places, in particular, it can not be used judging other Refraction model.The key to improve the correction accuracy is that the effective methods must be used while to determine directly the instantaneous Refraction values and to build the azimuth-dependent observational model of the astronomical Refraction.
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On Astronomical Atmospheric Refraction
Chinese Astronomy and Astrophysics, 2008Co-Authors: Wei Mao, Lei Yang, Qiong-xian TieAbstract:Abstract Through a comparison between the series expression and mapping function expression of the astronomical Refraction, we believe that, as far as a specific Atmospheric Refraction model is concerned, the computational accuracy is not lower in the former than in the latter, and that the convergence is poorer in the theoretically derived series expression, because of the different approximations made. From an analysis of the method of generating function of the Atmospheric Refraction mapping function it is considered that this kind of method can not embody the characteristics of geophysics and Atmospheric physics. It is pointed out from the comparison that the Atmospheric Refraction model which is constructed by adopting the specific Atmospheric distribution of a certain place does not apply to all other places and cannot be used to evaluate the other Atmospheric Refraction models. For improving the correction accuracy the key lies in the adoption of an effective method by which the instantaneous Refraction values at different positions are directly determined to construct a local, position-dependent model of Atmospheric Refraction observation.
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constructing an observational model of the neutral Atmospheric Refraction delay from measured values of the astronomical Refraction
The Astronomical Journal, 2007Co-Authors: Wei Mao, Lei Yang, Qiong-xian Tie, Hanwei ZhangAbstract:Discussing the requirements for an accurate correction of the neutral Atmospheric Refraction delay for the Global Positioning System, our paper points out that the existing theoretical correction models and the old postprocessing methods cannot attain the anticipated accuracy because the Atmospheric Refraction index has not been directly determined precisely. It is necessary to adopt Atmospheric Refraction delay models to improve the correction accuracy. The models are dependent on the observing station and the observation azimuth. By the new method we propose in this paper, the observational data of astronomical Refractions at different azimuths and different zenith distances are grouped according to azimuth and used to calculate the refractivity and mapping functions. As an example of the newmethod, we introduce the configuration of the Lower Latitude Meridian Circle and the measurement method of instantaneous astronomical Refractions, and present the observational astronomical Refraction model toward the east, south, west, and north of the Yunnan Observatory. We estimate that, without the use of any Atmospheric distribution models, the correction accuracy of the zenith delay will be within 1 mm, the correction accuracy of the Refraction delay at the lower elevation will be improved to a centimeter magnitude, and the cutoff elevation angle will be reduced to 5 degrees or less.
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a new method for the measurement of the Atmospheric Refraction
PNAOC, 2004Co-Authors: Wei Mao, Qiong-xian Tie, Lei YangAbstract:In this paper,we comment the theoretic basis and the compiled means of many Atmospheric Refraction versions.And we draw a conclusion that it is necessary to actually measure the values of the Atmospheric Refraction and to establish the Atmospheric Refraction model.This method must fit four strict conditions.Our instrument can just satisfy such conditions.We introduce a method to accurately measure the values of the Atmospheric Refraction in different directions.At last,a plan is brought forward to establish accuracy Atmospheric Refraction model in different directions.It is based on different locations and different circumstance conditions.
Qiong-xian Tie - One of the best experts on this subject based on the ideXlab platform.
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Atmospheric Refraction and building a local observational model
Acta Astronomica Sinica, 2009Co-Authors: Wei Mao, L Yang, Qiong-xian TieAbstract:A new application of the astronomical Atmospheric Refraction in space geodesy is introduced in this paper.To meet with high requirement of the application,it is necessary to develop an effective method for directly measuring instantaneous Atmospheric Refraction and constructing an Atmospheric Refraction model adapted to the geographical environment around the observing station.Necessary conditions for determining the Refraction values are listed in brief.Making use of structural characteristics of the Lower Latitude Meridian Circle and the error theory of this instrument,we have developed a method used to measure directly instantaneous Atmospheric Refraction,and moreover built a local observational astronomical re fraction model toward the east,south,west and north of Yunnan observatory that is classified according to the star's spectral type.
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on the discussion of astronomical Atmospheric Refraction
Acta Astronomica Sinica, 2008Co-Authors: Wei Mao, L Yang, Qiong-xian TieAbstract:The series expansion method and mapping function expansion method for astronomical Refraction are analyzed in this paper. It is shown from the comparison be- tween those two methods that the computational accuracy from the former one is not lower than that from the latter for a certain Refraction model. The series expansion method in the theoretical deriwtion is often lower in astringency because of various approximations. It is also analyzed that the actual situations on the generator function method in the as- tronomical Refraction mapping function can not indicate the characteristic of the geophysics and Atmospheric physics. It is pointed out that the previous Refraction model was built using a specific Atmospheric model in a certain place and it is not suitable for all places, in particular, it can not be used judging other Refraction model.The key to improve the correction accuracy is that the effective methods must be used while to determine directly the instantaneous Refraction values and to build the azimuth-dependent observational model of the astronomical Refraction.
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On Astronomical Atmospheric Refraction
Chinese Astronomy and Astrophysics, 2008Co-Authors: Wei Mao, Lei Yang, Qiong-xian TieAbstract:Abstract Through a comparison between the series expression and mapping function expression of the astronomical Refraction, we believe that, as far as a specific Atmospheric Refraction model is concerned, the computational accuracy is not lower in the former than in the latter, and that the convergence is poorer in the theoretically derived series expression, because of the different approximations made. From an analysis of the method of generating function of the Atmospheric Refraction mapping function it is considered that this kind of method can not embody the characteristics of geophysics and Atmospheric physics. It is pointed out from the comparison that the Atmospheric Refraction model which is constructed by adopting the specific Atmospheric distribution of a certain place does not apply to all other places and cannot be used to evaluate the other Atmospheric Refraction models. For improving the correction accuracy the key lies in the adoption of an effective method by which the instantaneous Refraction values at different positions are directly determined to construct a local, position-dependent model of Atmospheric Refraction observation.
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constructing an observational model of the neutral Atmospheric Refraction delay from measured values of the astronomical Refraction
The Astronomical Journal, 2007Co-Authors: Wei Mao, Lei Yang, Qiong-xian Tie, Hanwei ZhangAbstract:Discussing the requirements for an accurate correction of the neutral Atmospheric Refraction delay for the Global Positioning System, our paper points out that the existing theoretical correction models and the old postprocessing methods cannot attain the anticipated accuracy because the Atmospheric Refraction index has not been directly determined precisely. It is necessary to adopt Atmospheric Refraction delay models to improve the correction accuracy. The models are dependent on the observing station and the observation azimuth. By the new method we propose in this paper, the observational data of astronomical Refractions at different azimuths and different zenith distances are grouped according to azimuth and used to calculate the refractivity and mapping functions. As an example of the newmethod, we introduce the configuration of the Lower Latitude Meridian Circle and the measurement method of instantaneous astronomical Refractions, and present the observational astronomical Refraction model toward the east, south, west, and north of the Yunnan Observatory. We estimate that, without the use of any Atmospheric distribution models, the correction accuracy of the zenith delay will be within 1 mm, the correction accuracy of the Refraction delay at the lower elevation will be improved to a centimeter magnitude, and the cutoff elevation angle will be reduced to 5 degrees or less.
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a new method for the measurement of the Atmospheric Refraction
PNAOC, 2004Co-Authors: Wei Mao, Qiong-xian Tie, Lei YangAbstract:In this paper,we comment the theoretic basis and the compiled means of many Atmospheric Refraction versions.And we draw a conclusion that it is necessary to actually measure the values of the Atmospheric Refraction and to establish the Atmospheric Refraction model.This method must fit four strict conditions.Our instrument can just satisfy such conditions.We introduce a method to accurately measure the values of the Atmospheric Refraction in different directions.At last,a plan is brought forward to establish accuracy Atmospheric Refraction model in different directions.It is based on different locations and different circumstance conditions.
Hanwei Zhang - One of the best experts on this subject based on the ideXlab platform.
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constructing an observational model of the neutral Atmospheric Refraction delay from measured values of the astronomical Refraction
The Astronomical Journal, 2007Co-Authors: Wei Mao, Lei Yang, Qiong-xian Tie, Hanwei ZhangAbstract:Discussing the requirements for an accurate correction of the neutral Atmospheric Refraction delay for the Global Positioning System, our paper points out that the existing theoretical correction models and the old postprocessing methods cannot attain the anticipated accuracy because the Atmospheric Refraction index has not been directly determined precisely. It is necessary to adopt Atmospheric Refraction delay models to improve the correction accuracy. The models are dependent on the observing station and the observation azimuth. By the new method we propose in this paper, the observational data of astronomical Refractions at different azimuths and different zenith distances are grouped according to azimuth and used to calculate the refractivity and mapping functions. As an example of the newmethod, we introduce the configuration of the Lower Latitude Meridian Circle and the measurement method of instantaneous astronomical Refractions, and present the observational astronomical Refraction model toward the east, south, west, and north of the Yunnan Observatory. We estimate that, without the use of any Atmospheric distribution models, the correction accuracy of the zenith delay will be within 1 mm, the correction accuracy of the Refraction delay at the lower elevation will be improved to a centimeter magnitude, and the cutoff elevation angle will be reduced to 5 degrees or less.
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a possible means of improving the accuracy of Refraction delay correction of neutral atmosphere
Chinese Astronomy and Astrophysics, 2007Co-Authors: Hanwei Zhang, Binhua Li, Lei YangAbstract:Abstract The space geodetic technology requires an accurate model of correction of Refraction delay by the neutral atmosphere that varies from one observing station to another, and from one azimuth to the next. It is pointed out that under the present condition the astronomical Refraction can not yet be directly determined, any correction model because of its high dependence on the assumed Atmospheric distribution, is incapable of achieving the required accuracy or of improving the cut-off altitude. In this paper, based on the special properties of the lower latitude meridian circle at Yunnan Observatory and our experience of determining Atmospheric Refraction therewith, a new method is proposed for improving the accuracy of Refraction delay correction. Namely, the measured data of astronomical Refraction of an observing station from near zenith to low altitudes in different azimuths are used to evaluate the refractivities and the parameters of the mapping functions, thereby establishing a model of Atmospheric Refraction delay correction that varies with the observing station and the azimuth. Since it is unnecessary for the new method to adopt any Atmospheric distribution model, application of this new method will improve correction accuracy of Refraction delay to better than 1mm at zenith and to centimeters at low altitudes, and improve the cut-off altitude to below 5 degrees.