8th Cluster Workshop, Sept 30, 2004

Cluster/DMSP Conjunctions in the Cusp

Wayne KeithNASA Goddard Space Flight Center

With grateful acknowledgements to M. Goldstein, T. Stubbs, D. Winningham, A. Fazakerley, and H. Rème

8th Cluster Workshop, Sept 30, 2004

To what degree are cusp structures comparable from mid to low altitudes?

8th Cluster Workshop, Sept 30, 2004

Finding Magnetic Conjunctions

• Appropriate common (mapped) coordinates• Identify cusp crossings for Cluster• Search Cluster crossings for DMSP

satellites within 5° (~550 km) of Cluster footprint

• Rank quality of DMSP data• Compare relative timing of particle

signatures

8th Cluster Workshop, Sept 30, 2004

Automated Search Procedure• Mapped Cluster center-of-mass coordinates

calculated via T01 and ingested into system• Conjunction software run for all Cluster cusp

crossing times• For times when a DMSP satellite is within a “cusp

box”, check their proximity using:

• If < 5°, write start/stop times to a file• Automatically generate DMSP plot for closest

approach ±2 min€

=cos−1( ˆ R C • ˆ R D )

8th Cluster Workshop, Sept 30, 2004

The score so far:

• January through August 2001 searched• 73 Cluster cusp crossings• 172 DMSP magnetic close-approaches• 53 of which contained “good” particle signatures• 35 Cluster passes contained at least one good DMSP

crossing• 14 good coincidence between closest approach and cusp

signature• 2 conjunctions under study (one in each major Cluster

“cusp season”)

8th Cluster Workshop, Sept 30, 2004

29 March, 2001Cluster ~ 8 Re

8th Cluster Workshop, Sept 30, 2004

Day 88 footprint map

8th Cluster Workshop, Sept 30, 2004

Day 88 DMSP F-12

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Day 88 DMSP F-14

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Day 88 Cluster-1

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Day 88 all sc

8th Cluster Workshop, Sept 30, 2004

Day 88 all Cluster

8th Cluster Workshop, Sept 30, 2004

14 August, 2001

Cluster ~ 5 Re

8th Cluster Workshop, Sept 30, 2004

Day 226 footprint map

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Day 226 all sc

8th Cluster Workshop, Sept 30, 2004

Day 226 all Cluster

8th Cluster Workshop, Sept 30, 2004

SD frame 1

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SD frame 2

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SD frame 3

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SD frame 4

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SD frame 5

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SD frame 6

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SD frame 7

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SD frame 8

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SD frame 9

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SD frame 10

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SD frame 11

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SD frame 12

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SD frame 13

8th Cluster Workshop, Sept 30, 2004

Conclusions

• Cluster/DMSP conjunctions identified using combination of automated and manual search techniques

• Mapped Cluster cusp location usually poleward of DMSP cusp location

• Cusp appears narrow in Invariant Latitude and extended in Magnetic Local time

• Cusp structures appear similar in general, but Cluster data requires more study