VieVS User Workshop14 – 16 September, 2011
Vienna
External Ionospheric FilesClaudia Tierno Ros
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IntroductionVLBI S-Band + X-Band
2.3 GHz 8.4 GHzIonosphericCorrection*
Fragment from VLBI observation file (NGS file)
* Ionospheric delay depends on number of free electrons along ray path
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Introduction
Problem!!
Sometimes not possible to observe in two frequencies
Solution:
Use of external ionospheric file!!
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External Ionospheric FilesGNSS TEC maps
↓ IGS / CODE GIMs
Based on Single Layer ModelLatitude/Longitude resolution of 2.5/5°Temporal resolution 2 hoursAccuracy 2 to 8 TECU
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External Ionospheric Files
Fragment from external ionospheric file
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Example1. Start VieVSProcess the session you want as usual
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Example2. Start programC:\Vievs\ION\PROGRAM\GUI\start_createExtIonoFilesGUI.m
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Example3. Select session and GIM
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Example
We obtain this message
The GIM has been downloaded from IGS/CODE serverC:\Vievs\ION\MAPS\[IGS/CODE]\[year]
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Example4. Unzip GIMC:\Vievs\ION\MAPS\[IGS/CODE]\[year]
If the VLBI observations took place in more than one day, 2 maps will be downloaded
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Example5. Re-run programC:\Vievs\ION\PROGRAM\GUI\start_createExtIonoFilesGUI.m
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Example
We obtain this message
The ionospheric File has been created!C:\Vievs\ION\[directory chosen]
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Example6. Start VieVS7. Select session
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Example8. Select external file
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Example9. Continue as usual
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