SH33A-01
The SECCHI Experiment on the STEREO Mission
The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO) mission is a suite of remote sensing instruments consisting of an extreme ultraviolet (EUV) imager, two white light coronagraphs, and two telescopes that comprise the heliospheric imager. SECCHI will observe coronal mass ejections (CMEs) from their birth at the sun, through the corona and into the heliosphere. A complete instrument suite is being carried on each of the two STEREO spacecraft, which will provide the first sampling of a CME from two vantage points. The spacecraft, launched 25 October 2006, are orbiting the Sun, one Ahead of the Earth and the other Behind, each separating from Earth at about 22 degrees per year. The varying separation means that we will have different observational capabilities as the spacecraft separate and therefore differing science goals. The primary science objectives all are focused on understanding the physics of the CME process their initiation, 3D morphology, propagation, interaction with the interplanetary medium and space weather effects. By observing the CME from multiple viewpoints with UV and coronagraphic telescopes and by combining these observations with radio and in-situ observations from the other instruments on STEREO as well as from other satellites and ground based observatories operating at the same time, answers to some of the outstanding questions will be obtained. We will show some of the initial results.
SH33A-02 INVITED
Seeing the Heliosphere with New Eyes: First Results from the SECCHI Experiment on STEREO
The STEREO mission was launched on October, 2006 with the main objective to study Coronal Mass Ejections
(CMEs) from their initiation in the solar corona to their arrival at Earth using a suite of remote sensing and in-situ
instruments on two, almost identical, spacecraft. The mission objectives are mainly addressed by the imaging
experiment, named Sun-Earth Connection Coronal & Heliospheric Investigation (SECCHI), which comprises a
suite of five telescopes; an EUVI full disk imager, two coronagraphs covering the range from 1.5 to 15 solar radii,
and two heliospheric imagers observing along the Sun-Earth LINE from 15 solar radii to the Earth's orbit and
beyond. It is the first time that such imaging capabilities are available and they will certainly lead to important
advances in our understanding of the CME initiation, propagation, and its three-dimensional configuration. In this
talk, we will showcase the observations and initial results from the first months of operations of the SECCHI
telescopes. We will also discuss the instrument performance and synergies with existing observatories (e.g.,
SOHO). SECCHI was built by a consortium of US and European institutions under the direction of the Solar
Physics Branch at the U.S. Naval Research Laboratory.
http:secchi.nrl.navy.mil
SH33A-03 INVITED
The Value of STEREO to Space Weather Forecasting
The NASA/STEREO mission is a clear example of a scientific mission with practical utility. Not only will the science advances expected from STEREO be beneficial for future forecasts, the real-time data will be used by space weather forecasters to improve current forecast capability. The NOAA Space Environment Center has organized a global network of ground stations to ensure the data can flow continuously from both STEREO spacecraft. With this, it becomes possible to provide tools that forecasters can use to enhance situational analysis of current and future space weather conditions. Note these are tools, which are aides for improving the quality of current products, rather than new products, which require a commitment of operational observational resources into the future. We will present examples of STEREO tools in use in forecasting and planned. Included will be a discussion of why SEC specific tools are sometimes needed. However, SEC does not have the resources to accomplish all that it would like and it is not necessary for all tools to meet forecaster requirements. For these reasons, we will provide examples of tools SEC would like to have, but will have to rely on the efforts of the scientific community in the hopes such tools will be mutually beneficial. Finally, it is important to quantitatively measure the value of STEREO to forecasting. We will cover the SEC plans and motivation for measuring the value of STEREO.
SH33A-04
Solar Type III Bursts Observed Simultaneously by the STEREO/Waves And WIND/Waves Instruments
We present observations of solar type III radio bursts obtained simultaneously by the STEREO/Waves (S/WAVES) and WIND/Waves (WAVES) instruments. Using these observations, (i) we compare the absolute radio fluxes observed by the two instruments and deduce the SWAVES antenna length, capacitance and base capacitance, and (ii) we compare the direction finding capabilities of the two instruments. Finally assuming a model for the radiation pattern of type III burst at low frequencies [Bonnin, 2007] we deduce the evolution with frequency of their brightness temperatures.
SH33A-05 INVITED
STEREO measurements of shocks and in situ interplanetary type III radio bursts: early results from the S/WAVES and IMPACT experiments
We present early measurements by the STEREO/WAVES and IMPACT instruments of bow shocks, interplanetary shocks, and in situ interplanetary type III bursts. S/WAVES measures spectral density and 'burst' electric waveforms on three orthogonal antennas. IMPACT burst mode samples the thermal and suprathermal electrons and magnetic field at high cadence for several 10 minute intervals each day. The S/WAVES and IMPACT bursts systems have triggered together on several occasions at shocks and foreshock electron beams. Here we present results of these high time resolution bursts. Early in the mission, several in situ IP type III bursts were observed at 1 AU by STEREO and Wind. The similar instrumentation on the three spacecraft (with separations greater than 100 Re) allows us to limit the spatial extent of the type III radio emission region.
SH33A-06
Stereo Observations of Solar Type III Radio Bursts
The radio receivers on the STEREO spacecraft provide the first dedicated remote stereoscopic observations of solar and interplanetary radio sources. These observations, from widely separated vantage points, together with simultaneous remote radio observations from Wind/WAVES and Ulysses/URAP, are expected to provide new information and insights about the 3D locations of these radio source regions, as well as their intrinsic radiation characteristics. The STEREO observations allow several ways of doing this, e. g., by using direction-finding techniques to triangulate and directly track the source locations and by using the complementary propagation- time differences. We present here preliminary results from the analysis of timing differences observed for solar type III radio bursts that are simultaneously observed by the two STEREO spacecraft and also by WIND/WAVES and Ulysses/URAP. We will examine how these timing differences vary with observing frequency and with the separation of the various spacecraft, particularly with the separation of the STEREO spacecraft.
SH33A-07
Modeling the Solar Wind in the Inner Heliosphere
One main effort of the Center for Integrated Space Weather Modeling (CISM) is to develop space weather models for the Sun-Earth chain. Among them is the Solar Wind model that gives a 3 dimensional description of the solar wind structures in the inner heliosphere. It is driven by daily NSO/SOLIS synoptic maps. We employ the Wang- Sheeley-Arge (WSA) algorithm to compute potential field solutions of the solar corona and derive inner boundary conditions for the ideal MHD code ENLIL. It in turn propagates the solar wind structures out to Earth and beyond. With this model we can describe the ambient solar wind at the three locations of the ACE and STEREO space crafts; we are also able to predict the plasma parameters for lead times of 1 to 5 days in 6 hour cadences. We report on validation efforts and prediction performance.