update of the esp model for solar proton risk assessment* m.a. xapsos 1, c. stauffer 2, g.b. gee 2,...
TRANSCRIPT
UPDATE OF THE ESP MODEL FOR SOLAR PROTON RISK ASSESSMENT*
M.A. Xapsos1, C. Stauffer2, G.B. Gee2, J.L. Barth1, E.G. Stassinopoulos1
and R.E. McGuire1
1NASA Goddard Space Flight Center, Greenbelt, MD 207712SGT Inc., Greenbelt, MD 20770
*Supported by the NASA SEE Program
OUTLINE
• Background on Solar Particle Models for Cumulative Fluence• Results
Construction of an Integrated Data Set of solar proton data from IMP and GOES series of satellites
Inclusion of solar minimum time period Extension of statistical model to higher energies
• Summary
SOLAR PROTON MODELS
King and
Stassinopoulos
IMP Solar Max 10 – 100 MeV
JPL IMP and OGO Solar Max 1 – 60 MeV
ESP IMP and GOES Solar Max 1 – 100 MeV
(extrap. to 300)
Model: Data*: Time Period: Energy Range:
* Data from different instruments evaluated independently
CONSTRUCTION OF ANINTEGRATED DATA SET (IDS)
• The measurements made by IMP and GOES instruments are to a large extent complementary IMP-8 GME Instrument
Data has outstanding energy resolution (30 energy bins ranging from 0.88 to 485 MeV)
Low detector noise levels Detectors saturate at high fluxes
GOES Instruments Provide 10 energy bins ranging from 0.6 to 700 MeV Relatively high noise levels, especially at high energy Performs very well at high flux rates
• Integrating these features together produces a better overall data base.
Integrated Data – October 19, 1989 Event
10/1
9/19
89
10/2
1/19
89
10/2
3/19
89
10/2
5/19
89
10/2
7/19
89
10/2
9/19
89
10/3
1/19
89
11/2
/198
9
11/4
/198
9
11/6
/198
9
11/8
/198
9
11/1
0/19
89
11/1
2/19
89
Date & Time
10-6
10-5
10-4
10-3
10-2
10-1
100
101
Dif
fere
nti
al F
lux
(cm
-2s-1
sr-1
MeV
-1)
GOES-7 SEMIMP-8 GME
121-154 MeV Protons
Fluence-Energy SpectraOctober 19, 1989 Event
100 101 102 103
Threshold Energy (MeV)
106
107
108
109
1010
Inte
gra
l Flu
enc
e (c
m-2
sr-1
)
IDS (This Work)GOES-7GOES-6
SOLAR CYCLE DEPENDENCE
• Solar activity levels vary substantially for solar max use statistical model, e.g. King, JPL, ESP
• Solar min activity level is low and reasonably constant model as low “background” activity, always present
Model Solar Minimum Flux Levels
10-1 100 101 102 103
Threshold Energy (MeV)
104
105
106
107
108
109
1010
1011
Inte
gra
l Flu
ence
Per
Yea
r (c
m-2
yr-1
)
Worst Solar Min YearWorst Solar Min PeriodAverage Solar Min YearAverage Solar Max Year
Models for Solar Maximum
10-1 100 101 102 103
Threshold Energy (MeV)
107
108
109
1010
1011
1012
Inte
gra
l Flu
ence
(cm
-2)
ESPJPL91King/StassinopoulosThis Work
2 Years Solar Max
Confidence = 90 %
Model Solar Cycle Dependence
0 1 2 3 4 5 6 7 8 9 10 11 12
Year Number
106
107
108
109
1010
Cu
mu
lati
ve F
lue
nce
(cm
-2)
Solar MinSolar Max
> 107 MeV ProtonsConfidence = 90%
SUMMARY
• An integrated data set of IMP and GOES solar proton data has been developed Used to extend the model energy range out to 327 MeV Used to model the solar minimum time period, thus giving a
complete solar cycle description
• Generally during solar minimum: Event frequencies are smaller Event magnitudes are smaller Energy spectra are softer
• Also nearly finished: Model for 1 to 100 MeV/nucleon alpha particles based on IMP and
GOES data Model for elements C thru Fe (~10 to ~100 MeV/nucleon) based on
ACE data