External Ionospheric Files

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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