Direction - Conférence 1. Latest developments in MEO radiation belt Models D.Lazaro, A.Sicard-Piet, S.Bourdarie ONERA/DESP, Toulouse, France Session 2:

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Latest developments in MEO radiation

belt Models

D.Lazaro, A.Sicard-Piet, S.Bourdarie

ONERA/DESP, Toulouse, France

Session 2: Global Navigation Satellite Systems

Fifth European Space Weather Week: 17-21 November 2008, Brussels, Belgium

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Latest developments in MEO radiation belt modelsSession 2: Global Navigation Satellite Systems

• Context:• Rising number of satellites in the MEO environment• Heart of the highly dynamic electron radiation belt• Large radiation doses and significant internal charging hazards• NASA model AE8 universally used but presents deficiencies

• MEO radiation belt models efforts• New empirical & physical models• Temporal, spatial & spectral variations• Fluxes evaluation @ GNSS orbit

ONERA MEO-V2 model ESA project "Energetic Electron Environment Models for MEO"

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• ONERA MEO-V2 model:

Data set:

• From 1990 to present: • 4 GPS NavStar with BDDII:

• NS18• NS 24• NS 28• NS 33

• 1 GPS NavStar with BDDIIR:• NS 41

• 1 Russian spacecraft GLONASS-94 with DIERA2 particles detector

0

500

1000

1500

2000

2500

1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

Year

F10

.7 (W

.m-2

.Hz-1

)

250

200

150

100

50

Jan-92Jan-88 Jan-96 Jan-00 Jan-04 Jan-08

GPS-NS18/BDD2

GPS-NS24/BDD2

GPS-NS28/BDD2

GPS-NS33/BDD2

GPS-NS41/BDD2R

GLONASS-94/DIERA2

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Data analysis:• Sanitized in terms of back-ground, saturation and contamination• Compliant with COSPAR PRBEM: data analysis procedure• Cross-calibration

GOES 08

Protons80-165 MeV

GPS-NS-33

Electrons> 1.32 MeV

GOES-08Protons80-165 MeV

GPS-NS-33Electrons> 1.32 MeV

Contamination

NS24/BDD2 1992/04/29 -1996/04/18

103

105

107

3 5 7 9LEle

. >

0.2

8 M

eV (

cm-2.s

-1.s

r-1)

10-3

10-2

10-1

Saturation

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Construction of the model:

• Based on MEO-V1 model• Mean model on full solar cycle• Energy from 0.28MeV to 1.12MeV

• Improvements with:• NS41 energy up to 2.24MeV• Compliant with IGE-2006*

Global coherence between solar scale electrondynamic @ GEO and GPS orbit

*A.Sicard-Piet., S.Bourdarie, D.Boscher, R.H.W.Friedel: A model for the geostationary electron environment: POLE, from 30 keV to 5.2 MeV, IEEE Trans. Nuc. Sci. 53 (4), 1844-1850, August 2006

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1988 1992 1996 2000 2004 2008

YearE

lect

ron

s F

lux

(cm

-2.s

-1.s

r-1)

GPS > 1.12 MeV LANL > 1.1 MeV

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Calculation & validation:

1.00E+02

1.00E+03

1.00E+04

1.00E+05

1.00E+06

1.00E+07

-8 -6 -4 -2 0 2 4 6

Year of the solar cycle (min=0)

Ele

ctr

on

Flu

x (

cm

-2.s

-1.s

r-1

)

> 0.28 MeV > 0.40 MeV > 0.56 MeV > 0.80 MeV

> 1.12 MeV > 1.60 MeV > 2.24 MeV

AE8 Mean vs. MEO V2

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

0.1 1 10

Energy (M eV)

Inte

gra

ted

Flu

x (c

m-2

s-1)

Upper case

Mean case

Best case

AE8 Mean

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• ONERA MEO-V2 model conclusion:• GNSS like orbit• From 0.28MeV to 2.24MeV• Based on 17 years of GPS NavStar and GLONASS data• It is solar cycle dependent• ECSS-E-ST-10-04C standard• ONERA_DESP_LIB http://craterre.onecert.fr/home.html

• But MEO-V2 defined @ GPS altitude• Deviation from this altitude to be defined @ Galileo orbit

Main goal of the ESA project:

"Energetic Electron Environment Models for MEO"

with ONERA, QinetiQ, SSTL and CNES (Co 21403/08/NL/JD)

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• Re-analysis database used to extract the electron environment at Galileo altitude over more than a solar cycle

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• Relative importance of Galileo orbital planes• Galileo spacecrafts in different orbital planes• Orbit drift around the earth (360° per year)• Magnetic equator crossed each 6 hours

First sketch: importance of orbital plane

• 24 virtual spacecrafts• Separated in local time by 15°• Each orbit covering year 2003• 1 minute time resolution• Altitude 23174km, 56° inclinaison

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Fluxes extracted from re-analysis data base from 0.1 to 6.4 MeV

-One year average spectrum along each of the 24 GALILEO orbit (year 2003)

-Error % vs energy (the mean flux over the 24 orbital plane is the reference)-LT of maximum year average flux vs energy

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• Relative importance of Galileo orbital planes

Second sketch: importance of the phasing

• Phasing of Galileo spacecraft position• Along a given orbital plane• Worst orbital plane at 0LT• 24 spacecrafts equally separated• Each orbit covering year 2003• 1 minute time resolution• Altitude 23174km, 56° inclinaison

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Fluxes extracted from re-analysis data base from 0.1 to 6.4 MeV

-One year average spectrum along each of the 24 GALILEO orbit (year 2003)

-Error % vs energy (the mean flux over the 24 orbital plane is the reference)-Orbit index of maximum year average flux vs energy

Orb

it in

dex

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1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1990 1995 2000 2005

Year

Ele

ctro

n [M

eV-1

cm

-2 s

-1 s

r-1]

50

70

90

110

130

150

170

190

210

230

10.7

cm r

adio

flu

x [s

fu]

0.10MeV

0.20MeV

0.56MeV

1.20MeV

2.24MeV

3.20MeV

4.48MeV

F10.7

• Long term model

Year average flux along Galileo orbit

Galileo long term specification model-Solid lines is Galileo model-Dashed lines is MEO-V2 model

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• Conclusion

• Two MEO models• Solar cycle dependent• No obvious orbital plane dependence• Compliant with IGE-2006 (model @ GEO)• Available around GNSS orbit

• Perspectives

• Worst case definition• ESA project "Energetic Electron Environment Models for MEO":

• Model development• Software development• Validation

Documents

Direction - Conférence 1. Latest developments in MEO radiation belt Models D.Lazaro, A.Sicard-Piet, S.Bourdarie ONERA/DESP, Toulouse, France Session 2: