Modelling the Ionosphere over Europe:Investigation of NeQuick Formulation

Benoît Bidaine1 - F.R.S.-FNRS - B.Bidaine@ulg.ac.beProf. René Warnant1,2 - R.Warnant@oma.be

1University of Liège (Unit of Geomatics), Belgium - www.geo.ulg.ac.be2Royal Meteorological Institute, Belgium - www.meteo.be

November 18th, 20085th European Space Weather Week (Brussels, Belgium)

TEC

Ionosphere

Total Electron Content CET

algorithm NeQuick 1 2

TEC has to be modelled for single frequency receivers.

• GALILEO algorithm usingNeQuick model

First step: let’s investigate NeQuick profile formulation.

• Validate and improve

1. Tools and MethodModelling and measuring the ionosphere

NeQuick 2 improvesTEC estimation over Europe.

NeQuick 2 improvesTEC estimation over Europe.

1. Tools and Method

2. Yearly StatisticsGlobal scheme

Modelling and measuring the ionosphere

NeQuick 2 improvesTEC estimation over Europe.

3. Influence of k UnificationMain modification in NeQuick 2

1. Tools and Method

2. Yearly StatisticsGlobal scheme

Modelling and measuring the ionosphere

NeQuick 2 improvesTEC estimation over Europe.

3. Influence of k UnificationMain modification in NeQuick 2

1. Tools and Method

2. Yearly StatisticsGlobal scheme

Modelling and measuring the ionosphere

4. TEC SplittingDistinguishing bottomside and topside

3. Influence of k Unification

1. Tools and Method

2. Yearly Statistics

4. TEC Splitting

NeQuick is an empirical « profiler ».

• Output = Ne

TEC with integration

• Layer peaks= anchor points

monthly median maps

• NeQuick 2 (Nava et al., 2008)

topside modification

h [km]

Ne [e- m-3]

1. Tools and Method

Bottomside

Topside

ICTP / U Graz / COST 296 and before

We investigate NeQuick formulationusing collocated data.

• Actual measurements instead of monthly median maps constrain by means of ionosonde data manually validated digisonde data

• Modelled vertical TEC vs GPS TEC collocated ionosonde and GPS receiver GIM levelling (Orus et al., 2007)

1TECu 16 cm error for L1

1. Tools and Method

We focus on mid-latitudesand high solar activity.

• Year 2002 (HSA)

• Three European locations with (nearly) collocated digisonde and IGS/EUREF station

1. Tools and Method

3. Influence of k Unification

1. Tools and Method

2. Yearly Statistics

4. TEC Splitting

TEC modelling improveson a yearly basis.

2. Yearly Statistics

0

5

10

15

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25

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35

40

El Arenosillo/San Fernando Roquetes Dourbes

TEC

[TEC

u]

Measured NeQuick 1 NeQuick 2

• TEC underestimated on average(! potential bias in GPS TEC data !)

• Bigger (around 20%) underestimation with NeQuick 2

Yearly TEC mean

TEC modelling improveson a yearly basis.

2. Yearly Statistics

Yearly relative TEC standard deviation

0%

5%

10%

15%

20%

25%

30%

El Arenosillo/San Fernando Roquetes Dourbes

TEC

[%]

NeQuick 1 NeQuick 2

• Lower (around 20%) standard deviation with NeQuick 2

3. Influence of k Unification

1. Tools and Method

2. Yearly Statistics

4. TEC Splitting

The topside shape parameter k was unified in NeQuick 2.

3. Influence of k Unification

• k involved in height-dependent scale height

• NeQuick 1: 2 formulas for k (April to September and October to March)

different statistics for each period

• NeQuick 2: 1 formula based on topside soundings

The improvement comes mainly from the topside modification.

• October to March: lower (15%) standard deviation with NeQuick 2

More homogenous with other period

3. Influence of k Unification

-30%

-25%

-20%

-15%

-10%

-5%

0%

5%

10%

El Arenosillo/San Fernando Roquetes Dourbes

Evol

ution

April to September October to March

Evolution of TEC standard deviation from NeQuick 1 to 2

3. Influence of k Unification

1. Tools and Method

2. Yearly Statistics

4. TEC Splitting

The topside plays a major role.

• Integrate bottomside Ne profile from digisonde

bottomside TEC

• Subtract to GPS TEC topside TEC

4. TEC Splitting

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5

10

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25

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El Arenosillo/San Fernando Dourbes

TEC

[TEC

u]

Bottomside Topside

• Big proportion of TEC within topside (3/4, 1/4)

The improvement comes mainly from the topside modification.

• Bias/standard deviation evolution for topside between NeQuick versions corresponding to global statistics

4. TEC Splitting

Yearly topside TEC standard deviation

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1

2

3

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9

El Arenosillo/San Fernando Dourbes

TEC

[TEC

u]

NeQuick 1 NeQuick 2

NeQuick 2 improves TEC estimation over Europe.

• Benefit from collocated data

• TEC statistics: standard deviation decrease by 20% to reach less than 20% with NeQuick 2 (mid-latitudes stations, high SA)

• Homogenisation thanks to topside modification

• Major role of topside

TEC has to be modelled for single frequency receivers.

• Comparison of different GPS TEC data sets

• Ingestion: use of effective parameters to adapt NeQuick TEC to GPS TEC

• GALILEO Single Frequency Ionospheric Correction Algorithm

Ionosphere

Modelling the Ionosphere over Europe:Investigation of NeQuick Formulation

Benoît Bidaine1 - F.R.S.-FNRS - B.Bidaine@ulg.ac.beProf. René Warnant1,2 - R.Warnant@oma.be

1University of Liège (Unit of Geomatics), Belgium - www.geo.ulg.ac.be2Royal Meteorological Institute, Belgium - www.meteo.be

November 18th, 20085th European Space Weather Week (Brussels, Belgium)

We investigate NeQuick formulationusing collocated data.

foF2 yearly difference after validation

0

0,5

1

1,5

2

2,5

El Arenosillo Roquetes Dourbes

Station

foF2

95%

leve

l [M

Hz]

a

1. Tools and Method

We investigate NeQuick formulationusing collocated data.

1. Tools and Method

sTEC differences averaged by arc (Brussels – 2002)

We investigate NeQuick formulationusing collocated data.

1. Tools and Method

Elevation filter (Brussels – March 28th, 2002)

We investigate NeQuick formulationusing collocated data.

1. Tools and Method

Impact of elevation filter thanks to NeQuick simulations (Brussels – March 28th, 2002)

The topside shape parameter k was unified in NeQuick 2.

3. Influence of k Unification

Monthly TEC mean (Roquetes - 2002)

The topside shape parameter k was unified in NeQuick 2.

3. Influence of k Unification

Monthly TEC standard deviation (Roquetes - 2002)

The improvement comes mainly from the topside modification.

3. Influence of k Unification

Daily TEC profile (El Arenosillo - February 12th, 2002)

The improvement comes mainly from the topside modification.

3. Influence of k Unification

Ne profile (El Arenosillo - February 12th, 2002 – 10 UT)

TEC has to be modelledfor single frequency receivers.

• PhD thesis at ULg – Unit of Geomatics sponsored by FNRS

• Collaborations- RMI (Brussels)- ESA/ESTEC (Noordwijk)- ICTP (Trieste, Italy)- Others to come…

After coffee break

+ posters