3D Reconstruction of Density Enhancements Behind Interplanetary Shocks from Solar Mass Ejection Imager White-Light Observations

Abstract

The Solar Mass Ejection Imager (SMEI) observes the increased brightness from the density enhancements behind interplanetary shocks that are also observed in situ near the Earth. We use the University of California, San Diego (UCSD) time?dependent three?dimensional (3D) reconstruction technique to map the extents of these density enhancements. Here, we examine shock?density enhancements associated with several well?known interplanetary coronal mass ejections (ICMEs) including those on 30 May 2003 and on 21 January 2005. We compare these densities with reconstructed velocities from the Solar?Terrestrial Environment Laboratory (STELab) interplanetary scintillation (IPS) observations for the 30 May 2003 ICME, and show the shock is present at the front edge of the reconstructed high speed solar wind. The SMEI analyses certify that the brightness enhancements observed behind shocks identified and measured in situ near Earth are a direct response to the plasma density enhancements that follow the shocked plasma

Three-dimensional reconstruction of heliospheric structure using iterative tomography: A review

“…et al, 2007a), and at the Ulysses Spacecraft (e.g., Fujiki et al, 2003;Hayashi et al, 2003b;Kojima et al, 2007;Bisi et al, 2007bBisi et al, , 2008bBisi et al, , 2010a, and finally using a variety of data sets from radio arrays in Cambridge (UK), STELab, the Ootacamund (Ooty) Radio Telescope (ORT), in India, and the European Incoherent SCATter (EISCAT) radar telescopes in northern Scandinavia. For Thomson-scattering data sets, comparisons of 3-D reconstructions from Helios photometer data have been made with in-situ data from the Helios spacecraft (Jackson et al, 2001;Jackson and Hick, 2005), and reconstructions from SMEI compared with many different nearEarth monitors and STEREO in-situ measurements (e.g., Jackson et al, 2008aJackson et al, , 2010aBisi et al, 2008a). These comparisons become more successful as the numbers of lines of sight available from the remote-sensing data sets increase, and thus enhance the 3-D reconstruction resolution.…”

Solar Mass Ejection Imager (SMEI) 3-D reconstruction of density enhancements behind interplanetary shocks: In-situ comparison near Earth and at STEREO

“…This work has inspired certification and comparisons of these analyses using the measurements of in-situ proton ''columnar excess'' surrounding fast interplanetary shocks that are also observed as enhancements in remotely-sensed Solar Mass Ejection Imager (SMEI) Thomson-scattering observations and IPS velocity. In previous articles this same quantity was referred to as flux per event, but we here re-define this, the total number of excess protons in a square cm column that passes the spacecraft, as columnar excess (e.g., Jackson et al, 2010a). The proton columnar excess from a shock as determined from in-situ measurements is CE¼N p  V  T derived from hourly averages of density above the surrounding base density during the event.…”

A Heliospheric Imager for Deep Space: Lessons Learned from Helios, SMEI, and STEREO

“…That all these criteria can be met has been amply shown by SMEI whose observations have been used to successfully reconstruct in-situ densities, observed near Earth, and at the STEREO spacecraft, both for the "quiet" background solar wind as well as for transient heliospheric structures (CMEs, corotating structures, and the density enhancements behind interplanetary Shocks; Bisi et al, 2008a;Jackson et al, 2008aJackson et al, , 2010, and references therein; see, e.g., Figure 7). The current 3D reconstructions of heliospheric structures available from the SMEI data use only about 1/50th of the information available on SMEI skymaps.…”

“…IPS observations taken using the Cambridge IPS array in the UK (Houminer, 1971), show structures that can be classified as either corotating or detached from the Sun (Gapper et al, 1982;Hewish and Bravo, 1986;Behannon, Burlaga, and Hewish, 1991). More recently, IPS data used in conjunction with tomographic threedimensional (3D) reconstruction techniques have shown the global shapes of heliospheric density and velocity structures including corotating regions and coronal mass ejections (CMEs) or their interplanetary counterparts (ICMEs) in the solar wind (see, e.g., Jackson et al, 1998;Kojima et al, 1998;Asai et al, 1998;Jackson, Hick, and Buffington, 2002;Jackson et al, 2003;Jackson and Hick, 2005;Tokumaru et al, 2007;Tokumaru, Kojima, and Fujiki, 2010;Bisi et al, 2007Bisi et al, , 2008aBisi et al, , 2008bBisi et al, , 2009aBisi et al, , 2009bJackson et al, 2008aJackson et al, , 2008bJackson et al, , 2009Jackson et al, , 2010. These tomographic analyses match in-situ spacecraft measurements from near-Earth spacecraft fairly well.…”