Presentation on theme: "The Solar Wind and Heliosphere (with a space weather emphasis!) V J Pizzo (NOAA/SEC)"— Presentation transcript:
The Solar Wind and Heliosphere (with a space weather emphasis!) V J Pizzo (NOAA/SEC)
Key role of solar wind of the solar wind in Space Weather Sun is source of disturbances launched at Earth, but … structure at Sun is poorly observed structure evolves during propagation to Earth effect on geospace depends upon prior state of magnetosphere State of science: terrestrial weather prediction analog observationally, like 1890 (telegraph alert) numerically (models) like 2000?
Another key point: Over 4π sphere (or even 1 sterad spread of major IP disturbance), TINY element actually strikes Earth Solar wind fronts can be structured on these scales
Main components of solar input to SW global ambient solar wind erupted magnetic flux distribution outward pressure due to hot corona extended heating for fast wind rotational interactions transients solar energetic particles and cosmic rays energetic photon emission
Basics of solar wind expansion Parker model (hydrodynamic, spherically sym, thermally driven) Two insights: behave as fluid pressure gradient out to stellar background Confirmed by Mariner 2 s/c in 1962
How measured in situ: detectors (0.3 to >80 AU) protons, electrons, ions (neutrals, neutrons, dust) remote: coronagraph XUV IPS – radio wave surface field extrapolation
What you should know about Observations In situ calibration and intercalibration problems at point within enormous 4π volume part that intercepts Earth Remote sensing line of sight integration fog 3D overlap forward modeling
What you should know about Observations [LOS Fig]
Global ambient Why study: recurrent activity most of SW path for CMEs path for SEPs and CRs “killer” electrons
Non-uniform outflow distribution Fast from holes (fig -- xray phenomenon) uniform, hot, low density Slow from over streamer belt ragged, cold, high density Varies over solar cycle (min/max corona plot) IMF formed by drawing rooted open field into IP space (Parker spiral) Helios, Ulysses confirmation Rotational interaction (streams)
Transients Fundamentally a magnetic phenomenon General interaction – gopal Specific interaction – O & P shock much bigger interaction strongly a function of bkgd Cme/cme interaction Particles (SEPs) flare vs coronal shock origin controversy
Transients Associations game – relating events at Sun with subsequent events at Earth cant see what you really need to what are they? – coronal field, 3D mass distr too often judged on only what you can see flare/cme myth Signatures (incl helioseismology)
3-D IPS TOMOGRAPHY Assume static structures in frame corotating with Sun, use rotation to provide multiple views Several different realizations (e.g., Jackson and Hick, Kojima et al.) incorporate density and velocity info
Cosmic Rays and Space Weather SEPs are hazard to astronauts outside LEO, but… High-Z Gev particle flux main CR concern Source is galaxy (also some from termination shock) Spectrum, spatial and temporal variation well established by Voyager, Pioneer Biological effects? Historical experience Shielding?
Philosophy of Modeling Purpose operational prediction (forecast tool) basic research (understanding – gedanken experiment) Internet downside availability (Zeus) Most profitable approach: Use model to address specific questions
Concentrate on physical understanding rather than modeling technique or methodology (unless that is your specific goal!) the criterion for “good modeling” – you should learn something about underlying physical system! but be careful – it is the visuals or the essence?
12 May 19971 May 1998 21 April 2002 24 August 2002