University:
Boston University
Course:
CAS PY 106 | Physics 2
Academic year:

2019
Views:

158

Pages:

14
Author:

Clint W.

Different arcs move differently Tall rays: Alfvenic "E and "B (note: "E lags e- precipitation, parallel phase velocity) What would it take… To separate d/dx from d/dt To measure shears To quantify the changing aurora? Given this motion and structure! What controls it?! Magnetospheric driver?! Ionospheric control? ..some examples:! Main he, up-going energy [eV] normalized density energy flux [ergs/cm^2-sec] Main he, total c energy [e 100 10 1.00 0.10 ni, Je, #sc 0.01 1.0 0.8 0.6 0.4 0.2 0.0 1000 100 10 300 400 300 400 time [s] 500 600 500 600 700 700 MICA rocket: study of ionospheric modulation by dark aurora Model: Anatoly Streltsov, Dartmouth! H(f)AARP: modification of ionospheric conductivity Streltsov et al., JGR, 2010; GRL 2010 ! Outline •! Aurora •! Ionosphere –! –! –! –! –! •! •! •! •! Structure, composition Altitude profiles Hall and Pedersen Collisions and perpendicular J Response questions Plasma Processes Instrumentation and measurements Swarms Jan Curtis! Altitude profiles of these interactions •! Radar shows the plasma profiles •! Cameras show the input drivers •! Lidar to see the neutrals… Frederick-Frost, JGR, 2007 Ionosphere-thermosphere response to auroral drivers •! Conductance from precipitation, empirical (Reiff, 1984) •! Downward current region ionospheric electron evacuation (Marklund, 2001) •! Transport models for inversions of camera profiles (Lummerzheim, Transcar) Lynch, Zettergren, AnnGeo, 2007 Ionosphere-thermosphere response to auroral drivers •! Neutral upwelling and ion outflow •! CHAMP (Luhr 2004), RENU s studies of cusp upwelling: accelerometer signatures in cusp •! Difficult in-situ measurement: high voltages at low altitudes •! Drag studies •! Chipsats Ionosphere-thermosphere response to auroral drivers •! Empirical studies of “in” vs “out” •! Detailing the actual interactions Brambles, 2010, JGR Lanchester, 2011, JGR Ionosphere-thermosphere response to auroral drivers •! Can we quantify this? •! Rocket observations turning to study of effects rather than drivers Outline •! Aurora •! Ionosphere •! Plasma –! Characteristics of ionospheric plasma –! Sheaths and float potentials –! Thick sheaths and floating instruments •! Processes •! Instrumentation and measurements •! Swarms Jan Curtis!