THEMIS Science Progress NASA/GSFC, Oct 26, 2007

March 23, 2007 Event “THEMIS captures the Expansion of a Substorm in space” Lead: Angelopoulos

First light: Nature’s welcome. Two substorms seen on March 23 http://sscweb.gsfc.nasa.gov/tipsod DETAILED VIEW THEMIS TH-E THE Y Y TH-A Z TH-B TH-D X TH-C SUN THA X THB THEMIS glimpsed the tail in the middle of its commissioning phase, before moving towards the dusk sector. In an orbit designed to simulate routine science operations, it captured two substorms from a good vantage point. The THEMIS probes were arrayed like pearls on a string with end-to-end separation of 10Re. The middle probes (A, B, and D) were separated by ~ 0.25Re. In addition, the POLAR spacecraft was imaging the southern auroral oval. THC Z THD SUN POLAR

THA-FGM FIT Data (3s) Available TH-FGL Overview X: Y: Z: ____ THA-FGM FIT Data (3s) Available Note: Z=SMZ Rxy rotated X= - Ewd POLAR UVI/VIS Onset 10:58UT Intensifications

From UVI At 11:18:26UT. By 11:19:40UT. By 11:23:21UT Substorm intensifies @ 23MLT By 11:19:40UT. Auroras expand to 21.5MLT By 11:23:21UT Expansion slows down

Simulation mapping OpenGGCM mapping: THEMIS just before simulation onset maps to ~22.5 MLT, i.e., right in the middle of expanding activation. Note: mapping evolves

Hfrey_mar23_GBO_movie.mpg smoke New Auroral Intensification (Main, ~11:18UT) Previous Intensification (~11:10UT)

Summary, March 23 11:18 onset First direct detection of Westward Traveling Surge motion in the magnetosphere 200km/s westward motion consistent with expectation from ground data Expansion is motion of activity westward, flows are Earthward and duskward Simultaneous inward and outward expansion of the injection Azimuthal effects are dominant in this case THEMIS tail alignments in 2008 will be able to resolve temporal relationship and relative motion of current disruption, dipolarization and particle injections, one of the primary THEMIS objectives

May 20, 2007 Event “THEMIS satellites dissect and reconstruct magnetic flux ropes at the magnetopause: ” Lead: Sibeck

E C D THA THB

ESA Electrons RDFs

ESA gmoms Ni_all Ti_all

First – ever detection of a detached FTE at the magnetopause Modeling and reconstruction of flows, fields suggests FTE is isolated from magnetopause THEMIS, with its string-of-pearls orbit offers a unique opportunity to differentiate between boundary layer waves and detached plasma structures such as this FTE A B E D C X_gse Y_gse V_sh dBxy

July 4, 2007 Event “THEMIS satellites detect extreme changes to the Earth-Sun boundary caused by interplanetary currents” Lead: Eastwood

Hot Flow Anomaly (HFA) detection HFA Geometry Hot Flow Anomaly (HFA) detection A: Blue B: Cyan C: Green D: Orange E: Red A – in solar wind B, C, D, E – in magnetosheath The discontinuity underlying the HFA had just reached the bow shock The HFA had just started

What are Hot Flow Anomalies? Questions: Plasma physics Ion heating – current sheet particle scattering or beam instabilities)? Ions: multiple populations or single population? Electrons – isotropic and ‘Maxwellian’ [Schwartz et al., 2000] – how are the electrons heated? Magnetospheric physics – what is their impact on the magnetosphere?

First observation of HFA on both sides of the bow shock Flow deflection, cavity forming, complicated series of magnetic field discontinuities First observation of HFA on both sides of the bow shock

Simulations [Omidi and Sibeck, JGR 2007] 2.5D Global Hybrid simulation, courtesy Nick Omidi

Simulations [Omidi and Sibeck, JGR 2007] 2.5D Global Hybrid simulation, courtesy Nick Omidi

Propagation of pressure pulse down flanks As the pressure pulse associated with the HFA propagates down the tail its signature moves from east to west (top to bottom) across the THEMIS magnetometer chain Petersburg Alaska

First detection of the evolution of an HFA through the magnetopause and magnetosphere. THEMIS is able to measure the evolution of particles and fields Unremarkable solar wind features can have large implications for energy input to magnetosphere

Publications: SSR Editors: J. Burch and C. T. Russell

Publications: GRL, Special Issue Editors: M. Chen and N. Ostgaard

Publications: JGR, Special Issue Editors: A. Battachargee, W. Baumjohann, Z. Pu

Science Events: Outlook AGU meeting (Dec 10-14) 40 presentations to special session on multi-spacecraft observations (Mon-Tue) Pre-AGU community engagement event under auspices of GEM THEMIS data and software tools: tutorial for the community SWT meeting (Dec 15, UCB) SWT meeting (Apr 6-9, Southern CA) First joint analysis of substorm events Intl. Substorm Conference (ICS9) meeting (May 4-8, Graz) First presentations of substorm events from THEMIS Special issue at Annales Geophysicae Joint THEMIS-Cluster Workshop, (October 2008, UNH) Results from first year of THEMIS nominal science operations