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Bernese GPS Software Version 5.0 - Bernese GNSS Software

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11.4 Troposphere Modeling in the <strong>Bernese</strong> <strong>GPS</strong> <strong>Software</strong><br />

Figure 11.2: Troposphere related options in <strong>GPS</strong>EST (2).<br />

from troposphere estimation or stations for which differing absolute and/or relative sigmas<br />

should be setup. This is primarily intended to select the reference for a relative troposphere<br />

modeling in small sized networks.<br />

In addition the entry WITH TROPO for option “STATIONS TO BE EXCLUDED FROM TRO-<br />

POSPHERE ESTIMATION” allows to exclude stations from the estimation of troposphere<br />

parameters if troposphere delays are available in an input troposphere file specified in option<br />

“Troposphere estimates” (panel “<strong>GPS</strong>EST 1.1: Input Files 1”). All troposphere parameters<br />

are set up for stations with missing troposphere values in the file. It is important to know<br />

that with option WITH TROPO the a priori model and the mapping function specified in the<br />

input file is applied and the corresponding options in panels “<strong>GPS</strong>EST 3.2: General Options 2”<br />

and “<strong>GPS</strong>EST 6.3.1: Site-Specific Troposphere Parameters 1” are ignored.<br />

We refer to the corresponding help panels for further details on all options and possible<br />

applications.<br />

11.4.3 Horizontal Tropospheric Gradients<br />

The use of low elevation data (together with an elevation-dependent weighting, see Section<br />

7.4.3) is essential to improve the accuracy of <strong>GNSS</strong> analyses and to decorrelate station<br />

heights and tropospheric zenith corrections. Going down to low elevations, however, the<br />

azimuthal asymmetry of the local troposphere at an observation site gets more and more<br />

important and must be accounted for.<br />

Estimating horizontal tropospheric gradients is a common way to cope with these asymmetries.<br />

The station coordinate repeatability may be considerably improved by this measure,<br />

as shown by [Rothacher et al., 1997] and [Meindl et al., 2004].<br />

<strong>Bernese</strong> <strong>GPS</strong> <strong>Software</strong> <strong>Version</strong> <strong>5.0</strong> Page 247

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