共查询到17条相似文献,搜索用时 125 毫秒
1.
近地层大气折光系数变化特征分析 总被引:6,自引:0,他引:6
本文从大气垂直折光基本定义出发,分析了导致近地层折光系数变化的根本原因和直接原因,指出折光系数的变化具有5个特征,即时间、气候、高度、土壤及均值特征,并据此提出了应用中的一些看法。 相似文献
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大气垂直折光是影响珠峰高程测量成果和精度的重要因素之一。本文根据2005年珠峰高程测量实际数据详细分析研究了大气温度垂直梯度与大气垂直折光系数的计算原则、方法及其变化特征与变化趋势,结合同以往(1975、1992年)珠峰高程测量中大气温度垂直梯度与大气垂直折光系数变化趋势的比较,得出气温垂直梯度与大气垂直折光系数均存在周日变化并给出了它们的变化趋势,提高了珠峰高程的计算精度。 相似文献
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测区垂直大气折光系数的变化及因地选择大气折光系数的意义 总被引:5,自引:0,他引:5
根据几年的测量数据统计出岔路河测区夏季垂直大气折光系数的变化,并得到其平均值、同期变化幅度、年变化幅度、同一地区不同测线的变化幅度,从而为该地区的测量工作和气象地质等研究提供了参考数据.由此,也得出垂直大气折光系数差值对正反高差较差的影响,随边长的增大而增大,边长较长时必须选用接近实际的垂直大气折光系数. 相似文献
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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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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
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精密EDM三角高程测量中的折光改正实用方法 总被引:3,自引:0,他引:3
大气折光是影响精密EDM三角高程测量精度的主要因素,其对观测结果的影响必须通过利用折光系数进行折光改正的方式予以削减。本文介绍一种求折光系数的实用方法—综合反演法,可以直接利用对向EDM三角高程测量结果计算往测和返测的折光系数。 相似文献
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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
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F. K. Brunner 《Journal of Geodesy》1977,51(4):257-264
New formulae are developed for the evaluation of the refraction coefficient of microwaves, which is the key factor for the
curvature correction of microwave EDM. These new formulae are based on two distinct humidity distributions which often characterize
the atmosphere during daytime. The first case assumes that the relative humidity is constant with height. For this distribution
the new formulae are based on a revised form of the Robitzsch formula which enables also the evaluation of the microwave refraction
coefficient from a known refraction coefficient of light. The second case assumes that the specific humidity is constant with
height. 相似文献
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J. Saastamoinen 《Journal of Geodesy》1964,38(3):265-269
The usual methods for curvature correction, which consist of a geometric and a velocity component, are based on standard atmospheric
conditions and thus take no account of variable refraction. A formula has been developed expressing the correction as a function
of atmospheric refraction: K=(1-k_2 S2/(24 R2) whereS is the measured distance, R is the radius of the earth, and k is the coefficient of refraction. This formula leads to a practical
procedure employing trigonometric levelling in the determination of curvature correction for long-range geodimeter measurements. 相似文献
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Ole Remmer 《Journal of Geodesy》1994,69(1):21-25
Despite the noisy character of the data in the new North American levelling net (Zilkoski et al. 1989) it is quite easy to see the refraction corrections mirrored in the polygon closing errors if one takes only those polygons with sufficiently high refraction corrections. The following table illustrates this point. In the table the first column denotes the limit of the accumulated refraction corrections (found from temperature measurements) along a polygon, that is only polygons where the refraction correction exceeds this limit participate in the analysis. The second column is the estimate of the correlation coefficient between refraction corrections and the closing errors of the polygons while the third column is the significance level in the conventional student-test of whetherr is different from zero. 相似文献
14.
J. Saastamoinen 《Journal of Geodesy》1965,39(4):317-338
To facilitate the calculation of atmospheric refraction from radiometeorological sounding observations, the coefficients of
refraction for light and microwaves have been expressed in the general form k=A.p+B.U+(C·p+D·U) dt/dz+E·dU/dz where p is total
pressure, U is relative humidity and A, B, C, D and E are tabulated functions of temperature t. Three-place tables are given
in metric units for the temperature range −10°C to +30°C.
The paper includes a general discussion of the variation of refraction with weather, and outlines computation procedures for
electromagnetic measurement of long lines on the basis of radiosonde data. 相似文献
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W. S. B. Paterson 《Journal of Geodesy》1955,29(4):42-54
Values of the refraction coefficient, calculated from simultaneous reciprocal vertical angles measured on a traverse across
North Greenland, and meteorological observations made at the same time are analysed statistically. A relation is established
between diurnal changes in refraction and changes in air temperature. Values of the refraction coefficient are also correlated
with wind speed, amount of cloud, and presence of drifting snow near the surface. No correlation is found between refraction
and atmospheric pressure over the range of pressures encountered. A regression equation is given for estimating refraction
from observed meteorological conditions. Direct measurements of temperature gradient in the air layers near the surface are
compared with gradients deduced from the refraction observations.
Zusammenfassung Der Inhalt der vorliegenden Arbeit ist eine statistische Analyse der Schwankungen des Refraktionskoeffizienten in Gr?nland und seiner Korrelationen mit den meteorologischen Beobachtungen, also mit der Temperatur, der Windgeschwindigkeit, der Dunstbildung und des Flugschnees. Ferner werden Vergleiche der Temperaturgradienten angestellt, die sich einerseits aus direkten Messungen, andererseits aus den Refraktions-messungen ergeben.
Resumen El articulo presenta un análisis estadístico de las variaciones del coeficiente de refracción en Groenlandia y de sus correlaciones con las observaciones meteorológicas—temperatura, velocidad del viento, nubosidad, viento de nieve. Se comparan igualmente los gradientes de la temperatura, tales como resultan de medidas directas y de las medidas de la refracción.
Résumé L’article présente une analyse statistique des variations du coefficient de réfraction au Groenland et de ses correlations avec les observations météorologiques—température, vitesse du vent, nébulosité, vent de neige. On compare également les gradients de la température, tels qu’ils résultent de mesures directes et des mesures de la réfraction.
Riassunto L’articolo presenta un analisi statistica delle variazioni del coefficiente di rifrazione in Groenlandia e delle correlazioni con le osservazioni meteorologiche: temperatura, velocità del vento, nebulosità, vento di neve. Vi compaiono anche i gradienti della temperatura come essi risultano da misure dirette e da misure della rifrazione.相似文献
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《测量评论》2013,45(23):16-20
AbstractThis paper is written primarily with the object of ascertaining how other Colonies and Dominions deal. with the adjustment of their trigonometricallevels; further, since the greater part of Nigeria is now covered by a framework of levels of primary accuracy it is of interest to examine the results. Moreover, the evaluation of the coefficient of refraction, and from it the temperature lapse-rate, is of some importance in view of the recent publication of the War Office Aneroid Tables. These tables are based on a standard lapse-rate of temperature. 相似文献
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中性大气对非差伪距定位的影响及其模型改正分析 总被引:2,自引:1,他引:1
中性大气包括对流层和平流层,它们对GPS信号造成的延迟影响是GPS定位的一个主要误差源。与电离层的影响相比,消除中性大气的延迟影响更复杂,只能用经验模型进行改正。本文就中性大气对GPS定位的影响进行详细地分析和说明,对中性大气改正模型及其相关问题进行明确地论述。最后以中国IGS跟踪站一年中不同季节的观测数据为基础,通过对相同的数据采用不同的中性大气改正模型分别进行相同的定位解算,并对不同模型的定位结果进行分析,得出有关中性大气模型改正与GPS定位之间及改正模型间的定性和定量的关系。 相似文献