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Bernese GPS Software Version 5.0 - Bernese GNSS Software

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12. Ionosphere Modeling and Estimation<br />

TEC in TECU<br />

35<br />

30<br />

25<br />

20<br />

15<br />

10<br />

5<br />

0<br />

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2<br />

Time in days<br />

(a) 1992 Turtmann campaign<br />

TEC in TECU<br />

35<br />

30<br />

25<br />

20<br />

15<br />

10<br />

5<br />

0<br />

0.5 1 1.5 2 2.5 3 3.5 4 4.5<br />

Time in days<br />

(b) 1993 Turtmann campaign<br />

Figure 12.8: Zero-degree TEC parameter E00 extracted from local ionosphere models.<br />

12.4.2 Global, Regional, or Station-Specific Ionosphere Models<br />

The estimation of global, regional, or station-specific ionosphere models, better addressed<br />

as maps, is supported by the main parameter estimation program <strong>GPS</strong>EST (”Menu>Processing<br />

>Parameter estimation”). It is then the user’s decision to do the ionosphere analysis on either<br />

zero- or the double-difference level. We may make two recommendations to you:<br />

• If you favor the zero-difference approach, the following processing steps are presupposed:<br />

RNXSMT (”Menu>RINEX>RINEX utilities>Clean/smooth observation files”), RXOBV3 (”Menu<br />

>RINEX>Import RINEX to <strong>Bernese</strong> format>Observation files”), and CODSPP (”Menu>Processing>Codebased<br />

clock synchronization”). The use of smoothed code observations in program <strong>GPS</strong>EST<br />

is suggested.<br />

• If you follow the “traditional” double-difference approach, taking the preparing steps<br />

RXOBV3 (”Menu>RINEX>Import RINEX to <strong>Bernese</strong> format>Observation files”), CODSPP (”Menu<br />

>Processing>Code-based clock synchronization”), SNGDIF (”Menu>Processing>Baseline file creation”),<br />

MAUPRP (”Menu>Processing>Phase preprocessing”). The use of phase observations in <strong>GPS</strong>EST<br />

is strongly recommended. Ionosphere mapping on double-difference level, however, is<br />

not recommended until your ground network is of large size.<br />

The advanced user, eventually interested in doing parallel analyses on both differencing<br />

levels, might take the following processing steps: RNXSMT, RXOBV3, CODSPP, SNGDIF,<br />

MAUPRP, and finally <strong>GPS</strong>EST, selecting then either zero- or single-difference observation<br />

files.<br />

In the following, we discuss the most important options for the estimation of global or<br />

regional ionosphere model parameters on the basis of zero-difference smoothed code observations.<br />

We will highlight aspects which are relevant if double-difference phase observations<br />

are processed.<br />

In panel “<strong>GPS</strong>EST 1.1: Input Files” (see Figure 12.9), you have to select zero-difference<br />

smoothed “Code observation files” (after setting “Differencing level” to ZERO), or in the doubledifference<br />

case, single-difference “Phase observation files” (after setting “Differencing level” to<br />

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