IHY OVERARCHING ISSUESPLUSMAGNETOSPHERES & IONOSPHERES • IHY pedigree • Progressive program innovations leading to IHY • Evolving program objectives leading to IHY • Heliospheric plasma physics: A universal science (an IHY theme) • Comparative studies of heliospheric structures and processes (an IHY program) • Examples • A proposal for an IHY initiative in comparative planetary auroras
IHY Pedigree Program Start Years After 1st International Polar Year 1882 2nd International Polar Year 1932 50 International Geophysical Year 1957 25 International Quiet Sun Year 1964 7 International M'spheric Study 1976 12 Solar-Terr. Energy Program 1990 14 International Heliospheric Year 2007 17
Karl Weyprect (1838-1881) IPY 1 1882-1883Justification • Polar expeditions should be driven by scientific research instead of exploration. • Establish network of circumpolar stations. • Synoptic studies of geomagnetism, auroras, atmospheric electricity, and meteorology. • Common data format for recording observations.
Sophus Tromholt (1851-1896) At his auroral station in Lapland, 1882 Evolution in Understanding the Auroral Oval
Concepts Advanced or Enabled by IPY 1 • Auroral oval structure and dynamics • Currents flowing in the upper atmosphere produce magnetic perturbations on the ground • Currents flow between upper atmosphere and space • i.e. Synoptic data reveal global connectedness
IPY 2 1932-1933Justification Statement of the IMO "magnetic, auroral and meteorological observations at a network of stations in the Arctic and Antarctic would materially advance present knowledge and understanding (of geomagnetic, auroral, and meteorological phenomena) not only within polar regions but in general…This increased knowledge will be of practical application to problems connected with terrestrial magnetism, marine and aerial navigation, wireless telegraphy and weather forecasting." i.e. synoptic studies
Appleton University of Saskatchewan Archives University of Saskatchewan Archives University of Saskatchewan Archives IPY 2 Instrumentation • Magnetometer network (here a station in Hudson Bay) • Kite radiosondes • Balloon radiosondes • Ionosondes (here at Tromso)
IPY 2 Results Silsbee and Vestine use IPY 2 polar magnetic data to determine average current system for magnetic bay
Also During IPY 2 Chapman and Ferraro introduce concept of neutral ionized corpuscular steam from the sun (1931-1933) and an associated current system that compresses and confines the geomagnetic field (the Chapman-Ferraro current system)
Innovations and Concepts Associated with IPY 2 • International polar observing network • New instrumentation (radiosondes and ionosondes) • Rapid run magnetometers • Simultaneous measurements at multiple stations • Global current pattern for specific magnetic disturbance (magnetic bays) • i.e. Synoptic data in the third dimension • Higher spatial and temporal resolution • More evidence of global connectedness
Sydney Chapman (1888-1970) IGY 1957-1958+Justification "The [IGY's] main aim is to learn more about the fluid envelope of our planet—the atmosphere and oceans—over all the earth and at all heights and depths. … These researches demand widespread simultaneous observations." S. Chapman i.e. expanded synoptic studies
IGY Instrumentation and Innovations • Antarctic stations • All-sky cameras • Scientific satellites • Word Data Centers
IGY Famous Result From all-sky camera data came the Akasofu model of the auroral substorm
Even More Famous Result From Explorer 1 and its followers, came the Van Allen radiation belts
New Concepts Associated with IGY • Interhemispheric network of polar stations • New instrumentation (all-sky cameras, satellites) • Major discovery (radiation belts) • New concepts (the magnetosphere, substorms) • Exploration of space • Global 3D synoptic data • Evidence of time-dependent global dynamics
IMS 1976-1979Justification 1977 IMS Report "Many new questions have emerged, mainly concerning the cause-and-effect relationship among the dynamical processes … and involving the magnetosphere as a single, integral, dynamical system." 1971 IMS Report: "The complexity and the large spatial scale of the phenomena under scrutiny demand … simultaneous measurements…both in space and on the ground." Expanded synoptic data acquisition justified by "large spatial scale" (as before) and "complexity" (new). The magnetosphere seen as an interconnected system.
IMS Instrumentation and Innovations Magnetometer chains ISEE 1 and ISEE 3 Satellite Situation Center Coordinated Data Analysis Workshops (CDAW 1 Dec. 1978)
IMS Famous Discovery Flux Transfer Events (FTEs) (Russell and Elphic, 1978)
Iijima & Potemra, 1976 Region 1 Region 2 Also During IMS Magnetosphere and ionosphere linked through permanent set of macroscale, field-aligned current systems The region 1 current system links the ionosphere, the magnetosphere, and the solar wind Solar wind-magnetosphere- ionosphere system seen as interactive.
STEP 1990-1997Justification The 1988 report "Framework for Action" states the "main scientific goal is to advance the quantitative understanding of the coupling mechanisms that are responsible for the transfer of energy and mass from one region of the solar-terrestrial system to another." It continues: "The program will involve coordinated observations with instruments on the ground, in the air and in space; theory and simulation studies; and data and information systems."
STEP Emphases • 3D global synoptic studies • Quantitative understanding (numerical modeling) • Coupling mechanisms (exchanges between system components) • Solar-terrestrial system • Data and information exchange and systems
S-RAMP 1998 - 2003An effort to optimize the analysis of data obtained during the STEP period, 1990-1997 Major Objectives • Facilitate understanding of coupling mechanisms between regions of the Sun-Earth system. • Facilitate data and information transfer experimenters, theoreticians, and modelers. • Demonstrate results of STEP of use and interest to funding agencies, the media, and the public.
What IPY, IGY, etc. Programs Do IPY 1 Map the phenomena IPY 2 Explore upper atmosphere IGY Explore space IQSY Complement IGY IMS Study system complexity STEP Study integrated interactive system IHY Universalize heliospheric structures and processes; Emerging nations IPY 1 Synoptic obs network of polar stations IPY 2 Add third dimension IGY Add Antarctica and space IQSY Add solar min. to IGY solar max. IMS Add SSC and CDAWs STEP Add numerical modeling IHY Add comparative heliospheric studies IHY CDF for comparative studies Web accessible data for comparative studies CDAWs for comparative studies IHY Hubble proposal for comparative planetary auroras • Organize & coordinate data gathering & analysis • Provide thematic emphases • Justify resource allocations under program themes
Justification for Suggested IHY Objectives “It cannot be emphasized too strongly that the development of a solid understanding of the magnetic activity, occurring in so many forms in so many circumstances in the astronomical universe, can be achieved only by coordinated study of the various forms of activity that are accessible to quantitative observation in the solar system.” E. Parker Cosmical Magnetic Fields
Heliospheric Plasma Physics A Universal Science I. Division of the Universe • Gravitationally organized matter: planets, stars, galaxies • Magnetically organized matter: sunspots, magnetospheres, stellar and galactic spiral fields, galactic plumes • Interactions between them: planetary ionospheres, solar and stellar winds, galactic cosmic rays
Heliospheric Plasma Physics A Universal Science Heliospheric Exemplars of Magnetic Organization of the Universe
Disequilib. Mass Tether Tether Tether Loading Release Straining R Straining B Directly Driven Blocking-Release CME Thermal Dynamo SUBSTORM Blast Drctly Drvn IMF Connec. Recon. Inst. Config. Inst. Current. Blocking-Release Inst. Mass Exchng. MIC Inst. Dis- eqlb. Triggered. Diseqlib. Figure 6.7 Pairings between similar CME and substorm scenarios
The IHY and Comparative Planetary Magnetospheres John T. Clarke and George Siscoe Boston University IHY Planning Workshop Sunspot NM April 2004
Why include Comparative Magnetospheres in IHY? • The Earth and the other planets are in the heliosphere. • Every planet with a magnetic field and a collisionally thick atmosphere also displays aurora. • The interaction of the solar wind with planetary magnetospheres is one of the most fundamental processes in the heliosphere. • Understanding the scaling laws between magnetospheres will be required to understand the more than 100 newly discovered exo-planets.
Comparative Planetary Magnetospheres Mercury Jupiter Earth Solar Wind Dominated Solar Wind Driven Rotationally Driven - Solar Wind Triggered? • Comparative Magnetospheres expands our understanding of Sun-Earth Connections through examination of common processes at other planetary systems • The scale of magnetospheres varies by a factor of ~100 from Mercury to Jupiter 3 flybys MESSENGER ~100 missions since 1957 6 flybys, 1 orbiter
HST/WFPC2 HST/STIS Jupiter Jupiter’s aurora have been imaged by HST since the early 1990’s with high sensitivity and resolution. A campaign of imaging during the Cassini flyby in Dec. 2000 / Jan. 2001 was successful but short…
Jupiter’s Three Auroral Processes • The main oval appears driven by currents resulting from the breakdown in corotation of internal plasma. • The satellite footprints are produced by their interactions with Jupiter’s magnetic field. • The polar emissions map to the outer magnetosphere, and these interactions are not yet well understood.
Key Questions about Jupiter’s Aurora: • Which processes in Jupiter’s magnetosphere are influenced by the solar wind (as at Earth), and which processes are controlled by Io? • Does plasma production depend on Io’s volcanic activity, or is it controlled by Io’s magnetospheric interaction? • How does the magnetosphere respond to internal plasma production? • What are the causes of Jupiter’s three aurora? • How are these processes similar to Earth’s and how do they differ?
Saturn • Saturn’s aurora were studied during the Voyager flybys • then more recently by HST and Cassini (Jan. 2004) • - Saturn has an aligned magnetic field and much lower • plasma than Jupiter, but greater than the Earth • - Saturn’s magnetosphere has been thought to be • intermediate between the solar-wind driven Earth and • the corotation-driven Jupiter • - The recent campaign observations show the picture to • be much more complicated than this…
16 Jan. 2004: 26 Jan. 2004: 28 Jan. 2004: 30 Jan. 2004:
Saturn Summary: • Auroral emissions vary only slowly, ~min.s to 10’s of min. - this is much slower than Jupiter’s polar regions, more similar to Jovian main oval • Some rotational modulation of auroral power is seen, based mainly on 8 Jan. images • Isolated bright emissions move at ~75 % corotation • Auroral oval always offset toward midnight by 3-4 deg. • Dawn side oval is narrow, dusk side more diffuse
Saturn Summary (cont’d): • Auroral color ratio not obviously changing with time or location, suggests incoming particles 5-10 KeV • Total auroral power 3-10 x 1010 W, 2-3 ordersof magnitude less than at Jupiter • Total auroral powers vary by at least 4-5X, correlated with both SKR emission and solar wind • Auroral oval contracts with increased solar wind pressure • Auroral oval “fills in” during storm on 26 Jan. 2004
Proposed planetary magnetosphere component for IHY: • The only existing instrument for imaging the aurora on both Jupiter and Saturn is HST. • Submit a large guest investigator proposal for HST time in Jan.-June 2007 (request ~ 100 orbits). • This program would permit imaging of each planet every other day for 3 months centered on opposition. Solar wind conditions at each planet could be scaled from 1 AU measurements. Other correlations possible?
JMEX is a mission in Phase A study which would greatly assist the IHY program, but it would not fly before 2008.
The JMEX Science Driver: Comparative Magnetospheres from Earth Orbit • JMEX will repeatedly image Jupiter’s aurora, Io’s atmosphere, and the plasma torus to establish the cause and effect relations between them • JMEX enables a comparison of key magnetospheric processes at Jupiter vs. Earth. Comparative magnetospheres is an integral part of the Sun-Earth Connections roadmap
To date, we have only snapshots of the magnetospheric emissions from the Jupiter system JMEX will provide the time coverage needed to establish understand the physics of the system, much as has been done for the Earth since the IGY IMAGE/EUV IMAGE/FUV Plasmasphere Aurora Io Torus Cassini/UVIS Jupiter Science is Now Ready for a Global, Remote Study JMEX will do for Jupiterwhat IMAGE does for Earth
What the IHY Program Can Do • Organize & coordinate data gathering & analysis • Comparative heliospheric studies • Provide thematic emphases • Universalize heliospheric structures and processes; Emerging nations • Justify resource allocations for IHY initiatives (comparative studies and emerging nations) • CDF for comparative heliospheric studies • Web accessible data for comparative studies • CDAWs for comparative heliospheric studies • IHY Hubble proposal for comparative planetary auroras