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1.
光电测距气象改正中几个大气折射率计算公式的理论分析 总被引:6,自引:0,他引:6
本文分析了目前光电测距气象改正中常用的几个大气折射率计算公式的理论精度,指出了它们之间可能存在的某种联系,为光电测距时大气折射率计算公式的合理选型提供了理论依据;提出了准确求得大气折射率的优选方案。 相似文献
2.
光电测距测线大气平均折射系数计算的实用模型 总被引:6,自引:1,他引:6
本文以多年的定位实验数据为基础,建立了光电测距测线大气平均折射系数计算的优化模型,并给出了与模型相适应的测线大气平均折射系数计算的实用公式,实验表明,本文中给出的测线大气平均折射系数计算的优化模型及实用公式比传统的测线大气平均折射系数计算模型及公式有了进一步的改善,本文得出的某些规律与特性对高精度的短距离光电测距的应用有一定的参考价值。 相似文献
3.
大气折光是测绘领域数据采集时的主要误差来源之一。本文从大气折射率与大气密度的关系入手,论述了大气折光的两种形式,详细分析了大气折光对天顶距测量和光电测距的影响,进一步论证了在温度梯度逆转时刻进行观测可以有效地削弱大气折光误差对测量结果的影响。 相似文献
4.
光电测距大气折射系数计算公式的研究进展与综合评价 总被引:4,自引:1,他引:4
阐述了光电测距中各种大气要素的采集及计算方法,给出了目前常用的几个大气折射系数计算公式的基本形式,以事实为依据,对目前常用的几个大气折射系数计算公式进行了较为客观的综合评价,推荐出了一个准确度较高的、适用性较强的大气折射系数计算公式。 相似文献
5.
削减大气折光对三角高度影响的新途径 总被引:10,自引:0,他引:10
提出一种新的光电测距三角高程导线计算方法,在折光系数变化显著地区,该法能比传统的对向观测计算法更好地消减大气折光对高程传递的影响。 相似文献
6.
提出一种新的光电测距三角高程导线计算方法,在折光系数变化显著地区,该法能比传统的对向观测计算法更好地削减大气折光对高程传递的影响。 相似文献
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双波长卫星激光测距资料处理方法的研究 总被引:1,自引:0,他引:1
为使双波长卫星激光测距的观测数据能用于大气改正的研究,本文对观测数据采用测距差分的平均和平均距离的差分两种方法来提高精度,并和Marini-Murray大气改正模型比较。在现有精度下,没有发现明显的差别。随着双波长卫星激光测距精度的提高,应用本文使用的差分方法,能提高双波长的观测资料归算精度,以用于对大气改正的研究。 相似文献
10.
介绍了光电测距中平距归算的严密公式,分析了棱镜准直误差对光电测距的影响,并就全站仪仪器自身误差对光电测距的影响进行了阐述,进而得到了系统的理论依据。最后通过实验验证了理论的正确性,同时也通过理论分析确定了实验的可靠性和有效性,通过对实验的分析得出了竖角对光电测距影响的结论。 相似文献
11.
基于大气湍流理论,严密推导出折射系数、折光角、折光曲率等折光公式。这些折光公式综合考虑了普热通量、云量、地面潮湿度等多种气象参数,更能贴切地反映大气折光的影响。最后,通过采集数据对公式进行了验证,所得结果符合湍流理论。 相似文献
12.
L. E. Sjöberg 《Journal of Geodesy》1999,73(7):362-366
The well-known International Association of Geodesy (IAG) approach to the atmospheric geoid correction in connection with
Stokes' integral formula leads to a very significant bias, of the order of 3.2 m, if Stokes' integral is truncated to a limited
region around the computation point. The derived truncation error can be used to correct old results. For future applications
a new strategy is recommended, where the total atmospheric geoid correction is estimated as the sum of the direct and indirect
effects. This strategy implies computational gains as it avoids the correction of direct effect for each gravity observation,
and it does not suffer from the truncation bias mentioned above. It can also easily be used to add the atmospheric correction
to old geoid estimates, where this correction was omitted. In contrast to the terrain correction, it is shown that the atmospheric
geoid correction is mainly of order H of terrain elevation, while the term of order H
2 is within a few millimetres.
Received: 20 May 1998 / Accepted: 19 April 1999 相似文献
13.
Lars E. Sjöberg 《Journal of Geodesy》2006,79(12):675-681
The application of Stokes’s formula to determine the geoid height requires that topographic and atmospheric masses be mathematically removed prior to Stokes integration. This corresponds to the applications of the direct topographic and atmospheric effects. For a proper geoid determination, the external masses must then be restored, yielding the indirect effects. Assuming an ellipsoidal layering of the atmosphere with 15% increase in its density towards the poles, the direct atmospheric effect on the geoid height is estimated to be −5.51 m plus a second-degree zonal harmonic term with an amplitude of 1.1 cm. The indirect effect is +5.50 m and the total geoid correction thus varies between −1.2 cm at the equator to 1.9 cm at the poles. Finally, the correction needed to the atmospheric effect if Stokes’s formula is used in a spherical approximation, rather than an ellipsoidal approximation, of the Earth varies between 0.3 cm and 4.0 cm at the equator and pole, respectively. 相似文献
14.
中国科学院长春净月潭遥感试验场是对国内外开放的进行遥感实验研究的场地。为了高质量地进行对地定量遥感,必须了解该场上空大气气溶胶的光学特性,以便进行有效的大气订正。另一方面大气气溶胶本身也是遥感的对象。为提供这一背景性信息,本工作利用试验场所装备的太阳直接辐照光谱仪在1990年(无火山活动期)与1991年(强火山爆发期)两年进行的观测,经分析整理和反演推导,获得该站上空气溶胶引起的光学厚度(消光)谱和由此反演得到的气溶胶粒子谱分布。由于两年分别代表火山平静和活动期的情况,所得结果将为该地区遥感大气订正提供依据,同时可供其它北半球中纬地区参考。 相似文献
15.
A 29-year time-series of four-times-daily atmospheric effective angular momentum (EAM) estimates is used to study the atmospheric
influence on nutation. The most important atmospheric contributions are found for the prograde annual (77 μas), retrograde
annual (53 as), prograde semiannual (45 as), and for the constant offset of the pole (δψsinɛ0=−86 as, δɛ=77 as). Among them only the prograde semiannual component is driven mostly by the wind term of the EAM function,
while in all other cases the pressure term is dominant. These are nonnegligible quantities which should be taken into account
in the new theory of nutation. Comparison with the VLBI corrections to the IAU 1980 nutation model taking into account the
ocean tide contribution yields good agreement for the prograde annual and semiannual nutations. We also investigated time
variability of the atmospheric contribution to the nutation amplitudes by performing the sliding-window least-squares analysis
of both the atmospheric excitation and VLBI nutation data. Almost all detected variations of atmospheric origin can be attributed
to the pressure term, the biggest being the in-phase annual prograde component (about 30 as) and the retrograde one (as much
as 100200 as). These variations, if physical, limit the precision of classical modeling of nutation to the level of 0.1 mas.
Comparison with the VLBI data shows significant correlation for the retrograde annual nutation after 1989, while for the prograde
annual term there is a high correlation in shape but the size of the atmospherically driven variations is about three times
less than deduced from the VLBI data. This discrepancy in size can be attributed either to inaccuracy of the theoretical transfer
function or the frequency-dependent ocean response to the pressure variations. Our comparison also yields a considerably better
agreement with the VLBI nutation data when using the EAM function without the IB correction for ocean response, which indicates
that this correction is not adequate for nearly diurnal variations.
Received: 10 September 1997 / Accepted: 5 March 1998 相似文献
16.
Atmospheric turbulence theory applied to GPS carrier-phase data 总被引:3,自引:3,他引:0
Turbulent irregularities in the lower atmosphere cause physical correlations between Global Positioning System (GPS) carrier-phase
measurements. Based on turbulence theory, a variance–covariance model is developed in this paper that reflects these correlations.
The main result shows that the obtained fully-populated variance–covariance matrices depend not only on the satellite-station
geometry, but also on the prevailing atmospheric conditions, which are parameterised by, e.g., the von Karman spectrum of
refractivity fluctuations and the wind velocity vector. It is shown that the amount of the correlation between two GPS carrier-phase
observations is inversely related to the separation distance of the corresponding ray paths through the turbulent atmosphere.
Furthermore, the wind velocity and direction play a key role in the correlation. 相似文献
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利用模拟数据,评价Autonomous Atmospheric Compensation(AAC)算法的抗噪性,认为AAC算法的抗噪性较弱。基于TASI实测数据,利用AAC算法开展反演计算时,计算结果呈现出多样性问题。结合In-scene Atmospheric Compensation(ISAC)算法中黑体像元的标定方法,提出了一种复合改进算法。首先,利用ISAC算法反演的大气透过率和路径辐射,重新计算AAC算法中大气透过率之比(Tr)和相邻两强弱吸收通道的路径辐射之差(Pd),再次,运用经验公式获得稳定的大气反演结果(大气透过率和路径辐射),有效解决了计算结果多样性的问题。利用复合改进算法,开展的温度与发射率分离实验,证明反演得到的发射率波谱更接近野外实测波谱。 相似文献
19.
F. K. Brunner 《Journal of Geodesy》1982,56(4):341-355
Telescopic observations to terrestrial and extraterrestrial objects are affected by atmospheric turbulence. The structure
of atmospheric turbulence is reviewed in tems of the refractive index structure parameter. The mean and fluctuating refraction
effects of the turbulent atmosphere on the propagation of electromagnetic waves are addressed. The known formulae for the
variance and the spectrum of the angle-of-arrival fluctuations are presented and experimental results are summarised. The
angular resolution is compared with the pointing precision of a telescope for visual observations through a turbulent atmosphere.
The ultimate precision of direction measurements is shown to be a function of instrumental design parameters, the strength
of atmospheric turbulence, and the length of the averaging period. 相似文献