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
8th Cluster Workshop, Sept 30, 2004
Day 88 DMSP F-14
8th Cluster Workshop, Sept 30, 2004
Day 88 Cluster-1
8th Cluster Workshop, Sept 30, 2004
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
8th Cluster Workshop, Sept 30, 2004
Day 226 all sc
8th Cluster Workshop, Sept 30, 2004
Day 226 all Cluster
8th Cluster Workshop, Sept 30, 2004
SD frame 1
8th Cluster Workshop, Sept 30, 2004
SD frame 2
8th Cluster Workshop, Sept 30, 2004
SD frame 3
8th Cluster Workshop, Sept 30, 2004
SD frame 4
8th Cluster Workshop, Sept 30, 2004
SD frame 5
8th Cluster Workshop, Sept 30, 2004
SD frame 6
8th Cluster Workshop, Sept 30, 2004
SD frame 7
8th Cluster Workshop, Sept 30, 2004
SD frame 8
8th Cluster Workshop, Sept 30, 2004
SD frame 9
8th Cluster Workshop, Sept 30, 2004
SD frame 10
8th Cluster Workshop, Sept 30, 2004
SD frame 11
8th Cluster Workshop, Sept 30, 2004
SD frame 12
8th Cluster Workshop, Sept 30, 2004
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
Recommended
