Multi‐payload measurement of transverse velocity shears in the topside ionosphere

Lundberg, Erik; Kintner, P. M.; Lynch, K. A.; Mella, M. R.

doi:10.1029/2011gl050018

Cited by 12 publications

(10 citation statements)

References 33 publications

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“…The 12 min 43 s flight reached an apogee of 564 km over the northern coast of Alaska at 11:11:11 UT, and left the auroral oval at 11:14:40 UT before atmospheric reentry at 11:16:42 UT. The experiment array design was chosen to address questions about (1) shears in ionospheric electric fields and their ability to drive waves [ Lundberg et al , 2012a, 2012b]; (2) proper motion of auroral structures with respect to the ambient ionosphere (this paper); and (3) quantifying parameters of dispersive Alfvén wave phenomena and their effects on auroral flux tubes.…”

Section: Methods and Instrumentation: The Cascades2 Sounding Rocket Mmentioning

confidence: 99%

Structure and dynamics of the nightside poleward boundary: Sounding rocket and ground‐based observations of auroral electron precipitation in a rayed curtain

Lynch¹,

Hampton²,

Mella³

et al. 2012

J. Geophys. Res.

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[1] The Cascades2 auroral sounding rocket provides a case study for comparing multipoint in situ ionospheric observations of a nightside auroral poleward boundary intensification with ground-based optical observations of the same event. Cascades2 was launched northward from Poker Flat Alaska on 20 March 2009 at 11:04 UT. The 13 min flight reached an apogee of 564 km over the northern coast of Alaska. The experiment included a five-payload array of in situ instrumentation, ground cameras at three different points under the trajectory, multiple ground magnetometers, the Poker Flat Incoherent Scatter Radar (PFISR) radar, and the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft in the magnetotail. The rays of the poleward boundary intensification (PBI) curtain have along-arc motions of 8.5 km/s and along-arc spacings of 16 km. Modulated maximum energy envelopes and energy fluxes of the associated electron precipitation correspond to this spatial structure of the visible rays. The electron precipitation is additionally modulated at a higher frequency, and velocity dispersion analysis of these 8 Hz signatures implies Alfvénic wave-particle acceleration of an ambient ionospheric electron source occurring a few hundred km above the observation point. These observations parameterize the curtain of Alfvénic activity above the PBI event, both in the dispersive ionosphere and in the magnetotail reconnection region. The along-arc variations in brightness correspond to variations in precipitating electron energy flux interpreted as an along-arc modulation of the maximum energy of the Alfvénic wave-particle acceleration process; this is a new interpretation of the formation of rayed structures in auroral curtains. We consider the various possible magnetospheric and ionospheric drivers for the control of the observed along-arc structuring and motions.

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Section: Methods and Instrumentation: The Cascades2 Sounding Rocket Mmentioning

confidence: 99%

Structure and dynamics of the nightside poleward boundary: Sounding rocket and ground‐based observations of auroral electron precipitation in a rayed curtain

Lynch¹,

Hampton²,

Mella³

et al. 2012

J. Geophys. Res.

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“…The subpayload carried a thermal electron retarding potential analyzer (ERPA) [ Frederick‐Frost et al , ], a Cornell University GPS Autonomous Receiver (COUGAR) [ Powell et al , ], and the Cornell Wire Boom Yo‐yo (COWBOY) electric field instrument [ Lundberg et al , , ]. As described by Lundberg et al [], the COWBOY instrument consists of a pair of crossed 12.14 m dipole antennas. Potential difference is measured between the 4.45 cm spheres at the end of each coaxial wire boom, as well as between each sphere and the payload skin.…”

Section: Observationsmentioning

confidence: 99%

Measuring the seeds of ion outflow: Auroral sounding rocket observations of low‐altitude ion heating and circulation

et al. 2016

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We present an analysis of in situ measurements from the MICA (Magnetosphere‐Ionosphere Coupling in the Alfvén Resonator) nightside auroral sounding rocket with comparisons to a multifluid ionospheric model. MICA made observations at altitudes below 325 km of the thermal ion kinetic particle distributions that are the origins of ion outflow. Late flight, in the vicinity of an auroral arc, we observe frictional processes controlling the ion temperature. Upflow of these cold ions is attributed to either the ambipolar field resulting from the heated electrons or possibly to ion‐neutral collisions. We measure trueE→×trueB→ convection away from the arc (poleward) and downflows of hundreds of m s−1 poleward of this arc, indicating small‐scale low‐altitude plasma circulation. In the early flight we observe DC electromagnetic Poynting flux and associated ELF wave activity influencing the thermal ion temperature in regions of Alfvénic aurora. We observe enhanced, anisotropic ion temperatures which we conjecture are caused by transverse heating by wave‐particle interactions (WPI) even at these low altitudes. Throughout this region we observe several hundred m s−1 upflow of the bulk thermal ions colocated with WPI; however, the mirror force is negligible at these low energies; thus, the upflow is attributed to ambipolar fields (or possibly neutral upwelling drivers). The low‐altitude MICA observations serve to inform future ionospheric modeling and simulations of (a) the need to consider the effects of heating by WPI at altitudes lower than previously considered viable and (b) the occurrence of structured and localized upflows/downflows below where higher‐altitude heating rocesses are expected.

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“…ERPA data (Frederick‐Frost et al, ) from RENU2 are shown in Figure c and illustrate a clear correlation between elevated electron temperatures and the softer particle precipitation. DC electric field measurements from the COWBOY instrument (Lundberg, Kintner, Powell et al, ; Lundberg, Kintner, Lynch et al, , and references therein), Figure d, are small but show an enhancement just equatorward of the cusp/PMAF. These measurements, when compared to the speed of this PMAF, suggest that the PMAF was not locked into the slower background convection; a somewhat unusual situation (e.g., Kozlovsky & Kangas, ).…”

Section: Data Motivating Modeling Effortsmentioning

confidence: 99%

Transient Ionospheric Upflow Driven by Poleward Moving Auroral forms Observed During the Rocket Experiment for Neutral Upwelling 2 (RENU2) Campaign

Burleigh

Zettergren

Lynch

et al. 2019

Geophysical Research Letters

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This study examines cumulative effects of a series of poleward moving auroral forms on ion upflow and downflow. These effects are investigated using an ionospheric model with inputs derived from the Rocket Experiment for Neutral Upwelling 2 (RENU2) sounding rocket campaign. Auroral precipitation inputs are constrained by all‐sky imager brightness values resulting in significant latitudinal structuring in simulated ionospheric upflows due to transient forcing. For contrast, a case with steady forcing generates almost double the O+ upflow transport through 1,000 km when compared to poleward moving auroral form‐like structures. At high altitudes, model results show a spread in upflow response time dependent on ion mass, with molecular ions responding slower than atomic ions by several minutes. While the modeled auroral precipitation is not strong enough to accelerate ions to escape velocities, source populations available for higher‐altitude energization processes are greatly impacted by variable forcing exhibited by the RENU2 event.

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Multi‐payload measurement of transverse velocity shears in the topside ionosphere

Cited by 12 publications

References 33 publications

Structure and dynamics of the nightside poleward boundary: Sounding rocket and ground‐based observations of auroral electron precipitation in a rayed curtain

Structure and dynamics of the nightside poleward boundary: Sounding rocket and ground‐based observations of auroral electron precipitation in a rayed curtain

Measuring the seeds of ion outflow: Auroral sounding rocket observations of low‐altitude ion heating and circulation

Transient Ionospheric Upflow Driven by Poleward Moving Auroral forms Observed During the Rocket Experiment for Neutral Upwelling 2 (RENU2) Campaign

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