Multipoint observations of nightside auroral activity:

the Cascades2 sounding rocket mission

K A Lynch, Dartmouth College

2009 Fall AGU SM53D-05

Dartmouth CollegeCornell UniversityNASA Wallops Flight FacilityUniversity of New Hampshire NSROCUniversity of Alaska Fairbanks PFISRKTH-StockholmPoker Flat Research RangeSRISSL/UCB

Outline• Cascades2 mission and goals• March 2009 PFRR nightside event• Three science topics

– PBI case study (Themis, PFISR, cameras, in situ observations)– Measurement of DCE shear frequencies– Deconvolving a tall-ray event

• Summary and ongoing efforts

Science objectives and questions(1) Does dynamic aurora move with respect to the background ionosphere? How much? Does it matter? Proper motion and evolution of arc structures…

(2) What is the spatial as compared to temporal variation of auroral parameters like B and E? What does this mean for theories of energy transfer? Quantifying shears…

(3) Alfven waves carry disturbances and changes down to and through the auroral zone, giving us structured and dancing aurora. They are pretty: do they matter? Are these structures significant for magnetosphere/ionosphere coupling? Do direct observations of these motions validate theories and models? Deconvolving a tall-ray event…

Bo

PFRRPFISR Toolik Kaktovic

E and B along Bo

e- across Bo

Fast e- down Bo

Image down Bo

Ground cameras

Radar

GPS position and timing

C2 array:

Event:20 March 2009 11:11:11UT apogeeNear local magnetic midnight564 km apogeeRepeating PBI event

PBI case study• First two, unaccelerated (or minimally accelerated) Maxwellians

• Different from “typical” inverted-V arcs, but discrete

• 3rd, wave accelerated, field-aligned

Shear Frequencies

Time Max North Difference

Assuming Perp Shear

Assuming Parallel Shear

602.2-602.5 .052 V/m 3.714 Hz .186 Hz

602.5-602.8 .054 V/m 5.5 Hz .19 Hz

602.8-603.3 .148 V/m 10.57 Hz .528 Hz

Time Max East Difference

Assuming Perp Shear

Assuming Parallel Shear

602.2-602.5 .077 V/m 5.5 Hz .275 Hz

602.5-602.8 .093 V/m 6.64 Hz .332 Hz

602.8-603.3 .065 V/m 4.57 Hz .232 Hz

Tall rays

Array size: 4-6 km along B ~0.5 km across BStructure: footpoint 100-200 km altitude 2 km wide/13 km/sec = 0.15sec

Other ongoing• Magnetometer deconvolution• Ion motion up and down field line• Further development of onboard camera• Plasma density measurements• Stereo camera imaging

• Multiple-point measurements separating d/dx from d/dt….3 payloads, 4 payloads, 5 payloads, …10?

www.dartmouth.edu/~aurora