SAA seen by Mopitt(2000 – 2002)

Florian Nichitiu, Toronto,

Mopitt sci. meeting at IGARSS,Toronto, June-2002

We report on indirect observations of Single EventUpsets occurring in the Mopitt accelerometer device.The strong localization of these events in the SouthAtlantic Anomaly (SAA) and polar (South) regionsleads to conclusion that these SEU are caused bynuclear reactions in the piezoelectric sensing element ofthe accelerometer.

We can note that the SAA events are :- Day-Night symmetric ( in frequency and location)-The non-SAA events are highly North/Southasymmetric(with an accumulation of events in the South polarregion).

Because of a long period of observations ( 1.5 year) wewere able to showthe correlation between monthly frequency ofaccelerometer SEU and thesolar activity ( monthly average sun spot number , bigsolar flare events).

0.1 0.2 0.3 0.4 0.5 0.60

100

200

300 0.17561 0.01837

0.1 0.2 0.3 0.4 0.5 0.6 0.715960.6

15960.7

SAA event

Comp. Vib. Z

Tim

e ( 2

001/

Sept

/12)

Acc Intensity

-100 -80 -60 -40 -20 0 20 40 60 80 100

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8A

cc In

ten

sity

Lat-200 -150 -100 -50 0 50 100 150 200

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Acc In

ten

sit

y

Long

-45 -40 -35 -30 -25 -20 -15 -10 -50

20

40

-45<La <0

Latitude

-25.94759 8.10636

-80 -70 -60 -50 -40 -30 -20 -10 00

20

40

-80<Long <0

Longitude

-47.07144 13.87743

“Duck” , “Box” and “Pond” Proton flux contour at 705 Km altitude

-200 -100 0 100 2000

10

20

30

Long. for South Pole Day=59 Night=36

(Lat <-55 )18.9377 100.62552

Non-SAA events : North/South asymmetry

-200 -100 0 100 2000

2

4

6

(Lat >55 )

Long for North Pole

0 5 10 15 20 25

15

20

25

30

35

Acc Events

Sun Spot Nr

Mopitt Anomaly

Nr

of

Acc

Eve

nts

/Mo

nth

Month ( March 2000 - Oct 2001 )

0 5 10 15 20 25

80

100

120

140

160

180

80 100 120 140 160 180

15

20

25

30

35

April 2000 - Oct 2001

Sun Spot Nr/Month

Nr

of

Acc

Eve

nts

/Mo

nth

16010 16020 16030 16040 16050

-200

-150

-100

-50

0

50

100

150

200

Strong solar proton events

SAA

6 Nov 2001

Lo

ng

Time ( November 2001)

Mopitt : number of SEU in Nov = 67 .6 Nov and 24 Nov. : ACE detector saturateddue to proton event -> Strong Shock http://www.ips.gov.au/asfc/data/sol/shock.txt