Mesoscale ionospheric tomography over Finland Juha-Pekka Luntama Finnish Meteorological Institute Cathryn Mitchell, Paul Spencer University of Bath 4th European Space Weather Week, 5 – 9 November, 2007

5 – 9 November, 20074th European Space Weather Week2 Outline 1) Introduction 2) MIDAS algorithm and Finnish GNSS network 3) Global and mesoscale retrievals 4) Validation of the results 5) Summary and next steps

5 – 9 November, 20074th European Space Weather Week3 Introduction Currently many services are providing global TEC maps in NRT (IGS, SWACI, JPL, …) based on observations from globally distributed GNSS stations (e.g. IGS, EUREF, …) Number of IGS and EUREF GNSS stations is low at auroral region => resolution of the global maps is limited at the area where the ionosphere is very dynamic Dense GNSS networks available in Scandinavia – already used for NWP in the EUMETNET E-GVAP framework Our objective is to retrieve high resolution TEC and electron density maps based on these observations Test data collected in December 2006 This work is done in collaboration between University of Bath and FMI

5 – 9 November, 20074th European Space Weather Week4 Multi-Instrument Data Analysis System (MIDAS) MIDAS is an advanced algorithm developed by University of Bath for imaging the Earth's ionosphere using data from various ground and space- based instrumentation. University of Bath Line integral observations of the total electron content (TEC) obtained from a network of ground-based and space-based GPS receivers may be assimilated into the algorithm along with point estimates of the local electron density. The resulting reconstructions provide a highly accurate three-dimensional image of the Earth's ionosphere and its evolution in time.

5 – 9 November, 20074th European Space Weather Week5 GPS network in Finland operated by Geotrim Ltd

5 – 9 November, 20074th European Space Weather Week6 GPS ray path intersections within the grid Level height = 300 km

5 – 9 November, 20074th European Space Weather Week7 It was a dark and stormy night… IMAGE Magnetogram on Dec 2006

5 – 9 November, 20074th European Space Weather Week8 IGS global TEC maps on Dec 2006

5 – 9 November, 20074th European Space Weather Week9 Resolution enhancement with regional observations RegionalIGS 15 December 2006, 02:00

5 – 9 November, 20074th European Space Weather Week10 3D electron density distributions

5 – 9 November, 20074th European Space Weather Week11 High resolution TEC maps 14 – 15 Dec, 2006 Question: Do these maps represent the real ionosphere?

5 – 9 November, 20074th European Space Weather Week12 Validation opportunity: Ionospheric Tomography Chain observations

5 – 9 November, 20074th European Space Weather Week13 Intercomparison on 15 Dec 2006 at 02:45 Ionospheric Tomography Chain projection plane

5 – 9 November, 20074th European Space Weather Week14 Summary These are the first results from a new ionospheric tomography testing in Finland The results indicate that mesoscale ionospheric tomography can provide electron density distributions with very high horizontal and temporal resolution Current results are based on using only ground based GPS observations => vertical resolution and accuracy of the height information is limited Real time data streaming from the GNSS network will be started before the end of the year => development of NRT user service feasible Some potential application areas: –ionospheric monitoring, storm warning, and correction service for GNSS applications –GNSS ionospheric error and scintillation forecasting research

5 – 9 November, 20074th European Space Weather Week15 Next steps Improve vertical resolution: –Use also GLONASS observations (routinely available from the Geotrim network) –Ingest spaceborne RO soundings –Combine with other types of observations => data assimilation Validation of the high resolution tomography maps is a challenge => processing of more test cases => a rigorous error analysis => analysis of the impacts on independent GNSS receivers (IGS, EUREF) => careful validation with independent observations (ionospheric tomography chain, ionosonde, EISCAT, …)