1. The Space Weather and Navigation Systems (SWANS) project
Solar Terrestrial Centre of Excellence
The Space Weather and Navigation Systems (SWANS) project
René Warnant , Sandrine Lejeune , Gilles Wautelet , Justine Spits , Koen Stegen ,
and
Stan Stankov
Royal Meteorological Institute (RMI)
Ringlaan 3, Avenue Circulaire
B-1180 Brussels, Belgium
Stan Stankov
for the RMI – Urania joint workshop, 14 Feb 2011, Dourbes

2. The SWANS project – intro, objectives
Outline
The SWANS project – intro, objectives
K-LOGIC – Local Operational Geomagnetic Index K Calculation
LIEDR – Local Ionospheric Electron Density Profile Reconstruction
RTK status mapping
SoDIPE - Software for Determining the Ionospheric Positioning Error
Summary and Outlook

3. SWANS - Objectives
The Space Weather and Navigation Systems (SWANS) research and development project ( is an initiative of the Royal Meteorological Institute (RMI) under the auspices of the Belgian Government via the Solar-Terrestrial Centre of Excellence (STCE).
Research on space weather and its effects on GNSS applications
Permanent monitoring of the local/regional geomagnetic and ionospheric activity
Development/operation of relevant nowcast, forecast, and alert services
Consult professional GNSS/GALILEO users in mitigating space weather effects

4. K-LOGIC - Local Operational Geomagnetic Index K Calculation
Motivation:
The enhanced geomagnetic activity and especially the geomagnetic storms often lead to substantial ionospheric plasma fluctuations/disturbances among many other space weather effects.
There is an ongoing demand for services that can provide real-time assessment of the (global and local) geomagnetic activity -- and being of importance to:
- exploration geophysics,
- radio communications and precise position/navigation practices,
- space weather research and modelling, etc.
Objective:
To develop service/s that can promptly evaluate the current level of the local geomagnetic activity and to estimate in advance the activity index K.
Stankov et al. (2010): On the local operational geomagnetic index K calculation.
Geophysical Research Abstracts, Vol.12, EGU , EGU General Assembly, 2-7 May 2010, Vienna.

5. K estimation space-based K estimation ground-based
K-LOGIC - Local Operational Geomagnetic Index K Calculation
Developments:
Nowcast. The K nowcast system is based on a fully automated computer procedure for real-time digital magnetogram data acquisition, dataset screening, establishing the regular variation of the geomagnetic field, calculating the K index, and issuing an alert if storm-level activity is indicated.
Forecast. A new hybrid model has been developed utilising space-based (solar wind) observations and local ground-based (magnetometer) measurements to predict (a proxy of) the K index.
Solar Wind
Parameters (ACE)
K estimation space-based
Ksw
K hybrid
K estimation ground-based
Magnetometer Data (1 min, Dourbes)
Kgnd
Kutiev et al. (2009): Hybrid model for nowcasting and forecasting the K index.
Journal of Atmospheric and Solar-Terrestrial Physics, 71,

6. K-LOGIC - Local Operational Geomagnetic Index K Calculation
Service Type:
Nowcast: update – every 60 min, latency less than 3 min after the hour mark
Forecast: update – every 60 min, forecast time horizon – up to 6 hours ahead
Service Output:
K index value - data files (ASCII), plots
Quality Flag (QF) – data acquisition and processing quality assessment
Alerts – web (verbose & colour code),
Registration
Nowcast
Forecast
Service Selection
K index value
Alert (web based)
Quality Flag
Date Selection

7. Ionospheric plasma density specification in real time
LIEDR – Local Ionospheric Electron Density Reconstruction
Objective:
Development of operational procedure for reconstruction of the local ionospheric electron density distribution on a real-time basis using GNSS and vertical incidence sounding measurements.
Ionospheric plasma density specification in real time
Developments – procedure and service:
Type – operational nowcast
Output – ionospheric plasma density/frequency
Altitude range – from 90 to 1100 km
Time resolution – 15 min
Latency – less then 3 min
Applications:
Research, verification of ionospheric models, ionospheric tomography, etc.
Stankov et al. (2003): A new method for reconstruction of the vertical electron density distribution in the upper ionosphere and plasmasphere.
Journal of Geophysical Research, 108(A5), 1164, doi: /2002JA

8. Ionospheric plasma density specification in real time
LIEDR – Local Ionospheric Electron Density Reconstruction
Ionospheric plasma density specification in real time
Development:
Type – operational nowcast, Output – ionospheric plasma density/frequency, Altitude range – from 90 to 1100 km, Time resolution – 15 min, Latency – less then 3 min.
enhanced
density
reduced
density
Ionosphere Plasma Frequency
ionosphere storm
Ionosphere Critical Frequencies
(F2 layer - foF2 ,
E layer - foE)
Ionosphere Total Electron Content
(TEC)
Ionosphere peak density altitude
(hmF2)
Ionosphere Peak Density
(NmF2)

9. LIEDR – Local Ionospheric Electron Density Reconstruction

10. Ionospheric slab thickness monitoring
LIEDR – Local Ionospheric Electron Density Reconstruction
Objective:
Explore the capability of this key ionosphere parameter for monitoring and estimating the level of ionosphere disturbances.
Ionospheric slab thickness monitoring
Developments (service):
Type – operational nowcast
Output - slab thickness [km]
- relative deviation [%] from monthly medians
Update rate – 15 min
Latency – less then 3 min
The ionospheric slab thickness (τ) is the depth of an idealized ionosphere which has the same electron content (TEC) as the actual ionosphere but uniform electron density equal to the maximum electron density (NmF2), τ =TEC/NmF2.
Applications:
- Research
- Modelling
Monitoring the local ionosphere disturbance,
etc.
Stankov et al. (2008): Ionospheric slab thickness – analysis and monitoring applications.
Proc. Ionospheric Effects Symposium (IES), May 13-15, 2008, Alexandria, VA, USA, pp

11. LIEDR – Local Ionospheric Electron Density Reconstruction
slab thickness relative deviation
from non-disturbed behaviour
Ionospheric
slab thickness
behaviour
during
geomagnetically
disturbed
conditions
τ rel
disturbed & depleted ionosphere τ
Ionospheric
slab thickness
Geomagnetic activity indices
Kp and Dst
Geomagnetically
disturbed
conditions
Stankov et al. (2009): Ionospheric slab thickness – analysis, modelling, and monitoring.
Advances in Space Research, 44, 1295–1303.

12. LIEDR – Local Ionospheric Electron Density Reconstruction

13. A (colour) code assigned to each station, code ranging from
RTK status mapping
Provides a quick look at the small-scale ionospheric effects on the RTK precision for several GPS stations in Belgium
Assesses the effect of small-scale ionospheric irregularities by monitoring the high-frequency rate of TEC (ROT, TECU/min) at a given station
ROT calculated using ‘geometric-free’ combination of GPS dual frequency measurements (no ambiguity resolution)
A (colour) code assigned to each station, code ranging from
“quiet” (green) to “extreme” (red) and referring to the local ionospheric conditions.
Alerts dispatched
via to subscribed users when disturbed conditions are observed.
Warnant et al. (2007): Monitoring variability in TEC which degrades the accuracy of Real Time Kinematic GPS application,
Advances in Space Research, 39(5),

14. SoDIPE – Determining the Ionospheric Positioning Error
Development of software (SoDIPE-RTK) allowing to monitor the effect of the ionosphere on high precision real time positioning (RTK targeted in particular)
13 May 2007
20 Nov 2003
SoDIPE output (positioning error) in 2 cases (quiet day, storm day)
Method:
Geometric-Free combination of double-differenced (DD) phase measurements used
Compute the ambiguity term considering the whole DD observation period
Isolate the ionospheric residual term on each carrier
Compute IPE, the positioning error (on L1) due to the ionosphere only (least-squares adjustment applied, in topocentric coordinates)
IPE mean and standard deviation computed (each baseline, 15 min time resolution)
A (colour) code assigned to each baseline, range from “nominal” (green) to “extreme” (red) error level
Wautelet et al. (2010): Monitoring the ionospheric postioning error with a GNSS dense network.
Geophysical Research Abstracts, Vol.12, EGU General Assembly, 2-7 May 2010, Vienna.

15. SoDIPE – Determining the Ionospheric Positioning Error
Positioning error is “translated” onto a map where the colors (from green to red) give the magnitude of the ionospheric error depending on the region
Yellow, Orange, Red
Iono disturbance
(small / strong / severe accuracy degradation)
Belgian
Active Geodetic Network
66 stations
160 base lines
05 Mar 2010
05 Mar 2010
Green
 No iono disturbance (no degradation)

16. SoDIPE – Determining the Ionospheric Positioning Error
Positioning error is “translated” onto a map where the colors (from green to red) give the magnitude of the ionospheric error depending on the region
Yellow, Orange, Red
Iono disturbance
(small / strong / severe accuracy degradation)
Belgian
Active Geodetic Network
66 stations
160 base lines
20 Nov 2003
20 Nov 2003
Green
 No iono disturbance (no degradation)

17. SoDIPE – Determining the Ionospheric Positioning Error
Belgian
Active Geodetic Network
66 stations
160 base lines
20 Nov 2003
20 Nov 2003
© RMI

18. Summary and Outlook
Modern GNSS-based applications demand high precision -- simultaneous real-time observation of several characteristics plus the solar/geomagnetic background is essential.
Operational applications range from ionospheric/space weather monitoring, research & modelling (further understanding the ionospheric morphology, validating existing ionospheric models) -- to improving comm/nav systems performance (incl. HF propagation and ray tracing, adverse ionospheric effects warnings/mitigation)
Further work:
Improve ionospheric storm onset determination procedure/s
Develop Dst nowcast and forecast
Develop TEC nowcast and forecast
Development of an empirical model to forecast the occurrence of ionospheric disturbances which pose a threat for GNSS positioning (TIDs, noise-like structures, …)