1. VieVS User Workshop 14 – 16 September, 2011 Vienna External Ionospheric Files Claudia Tierno Ros

2. Introduction VieVS User Workshop 20112 VLBI S-Band + X-Band 2.3 GHz 8.4 GHz Ionospheric Correction* Fragment from VLBI observation file (NGS file) * Ionospheric delay depends on number of free electrons along ray path

3. Introduction VieVS User Workshop 20113 Problem!! Sometimes not possible to observe in two frequencies Solution: Use of external ionospheric file!!

4. VieVS User Workshop 20114 External Ionospheric Files GNSS TEC maps ↓ IGS / CODE GIMs Based on Single Layer Model Latitude/Longitude resolution of 2.5/5° Temporal resolution 2 hours Accuracy 2 to 8 TECU

5. External Ionospheric Files VieVS User Workshop 20115 Fragment from external ionospheric file

6. Example VieVS User Workshop 20116 1. Start VieVS Process the session you want as usual

7. Example 2. Start program C:\Vievs\ION\PROGRAM\GUI\start_createExtIonoFilesGUI.m VieVS User Workshop 20117

8. Example VieVS User Workshop 20118 3. Select session and GIM

9. Example VieVS User Workshop 20119 We obtain this message The GIM has been downloaded from IGS/CODE server C:\Vievs\ION\MAPS\[IGS/CODE]\[year]

10. Example VieVS User Workshop 201110 4. Unzip GIM C:\Vievs\ION\MAPS\[IGS/CODE]\[year] If the VLBI observations took place in more than one day, 2 maps will be downloaded

11. Example VieVS User Workshop 201111 5. Re-run program C:\Vievs\ION\PROGRAM\GUI\start_createExtIonoFilesGUI.m

12. Example VieVS User Workshop 201112 We obtain this message The ionospheric File has been created! C:\Vievs\ION\[directory chosen]

13. Example VieVS User Workshop 201113 6. Start VieVS 7. Select session

14. Example VieVS User Workshop 201114 8. Select external file

15. Example 9. Continue as usual VieVS User Workshop 201115

16. VieVS User Workshop 201116