Problem of selecting primary parameters has been discussed. Primaries should be defined uniquely, as well as, physically. Since no unique definition for semimajor axis exists, it should be replaced by the geoidal geopotential valueW0 or by the geopotential scale factorR0 =GM/W0, geocentric gravitational constantGM be also primary parameter. Current best estimates of some parameters are given numerically. 相似文献
This study investigates the influence of low ozone episodes on UV-B radiation in Austria during the period 1999 to 2015. To this aim observations of total column ozone (TCO) in the Greater Alpine Region (Arosa, Switzerland; Hohenpeissenberg, Germany; Hradec Kralove, Czech Republic; Sonnblick, Austria), and erythemal UV-B radiation, available from 12 sites of the Austrian UV-B monitoring network, are analyzed. As previous definitions for low ozone episodes are not particularly suited to investigate effects on UV radiation, a novel threshold approach—considering anomalies—is developed to provide a joint framework for the analysis of extremes. TCO and UV extremes are negatively correlated, although modulating effects of sunshine duration impact the robustness of the statistical relationship. Therefore, information on relative sunshine duration (SDrel), available at (or nearby) UV-B monitoring sites, is included as explanatory variable in the analysis. The joint analysis of anomalies of both UV index (UVI) and total ozone (∆UVI, ∆TCO) and SDrel across sites shows that more than 65% of observations with strongly negative ozone anomalies (∆TCO < −1) led to positive UVI anomalies. Considering only days with strongly positive UVI anomaly (∆UVI > 1), we find (across all sites) that about 90% correspond to negative ∆TCO. The remaining 10% of days occurred during fair weather conditions (SDrel ≥ 80%) explaining the appearance of ∆UVI > 1 despite positive TCO anomalies. Further, we introduce an anomaly amplification factor (AAF), which quantifies the expected change of the ∆UVI for a given change in ∆TCO.
The geopotential scale factor Ro= GM/Wo(the GM geocentric gravitational constant adopted) and/or geoidal potential Wo have been determined on the basis of the first year's (Oct 92 – Dec 93) ERS-1/TOPEX/POSEIDON altimeter data and of the POCM 4B sea surface topography model: Ro°=(6 363 672.58°±0.05) m, Wo°=(62 636 855.8°±0.05)m2s–2. The 2°–°3 cm uncertainty in the altimeter calibration limits the actual accuracy of the solution. Monitoring dWo/dt has been projected.相似文献
Summary The four primary geodetic parameters defining the geodetic reference system are discussed from the point of view of their physical meaning and current estimation of their actual accuracy. The geopotential scale factor has been treated as the primary geodetic parameter defining the Earth's dimensions.
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Stark broadening parameters for nine neutral oxygen (O I) lines have been determined within the impact approximation and the semiclassical perturbation method. The atomic data have been taken from the TOPbase and NIST atomic databases. The electron and proton Stark widths and shifts and ion broadening parameter values for these O I lines have been calculated for electron density of 10 16 cm ?3 and for 4 different electron temperatures in the range of 5000 K to 40000 K. These Stark broadening parameters are compared with our previous results (Ben Nessib, N. et al.1996, Physica Scripta, 54, 603–613), where we calculated Stark broadening parameters for only four O I spectral lines and where Stark widths and shifts were compared with experimental and theoretical data available in the literature. In the present paper, we have also compared our results with the Griem’s book (Griem, H. R. 1974, Spectral line broadening by plasmas) and VALD (Ryabchikova, T. et al.2015, Physica Scripta, 90, 054005) values. 相似文献
Summary The present theory of the determination of the position of an Earth satellite from simultaneous measurements of the topocentric
coordinates at 2 or more geodetic satellite points is not exact. The inaccuracy is caused by the fact that the measured topocentric
coordinates of the satellite are defined in a system in which the directions of the axes are not exactly parallel to the directions
of the corresponding axes of the geodetic system in which the coordinates of the satellite points are given; this difference
in direction is not respected in the solution. The paper gives an exact solution of the problem. The concepts (4) of geodetic
topocentric declination and geodetic hour angle of the satellite, i.e. the declination and hour angle in the geodetic reference
system, are introduced. With these quantities the problem of determining the position of the satellite is then solved exactly.
There always exist superabundant observations so that the method of least squares can be used. The procedure is outlined for
the case of conditioned observations (suitable for 2 satellite geodetic points) and for the case of intermediate observations
(suitable for >2 satellite geodetic points).
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