Magnetic Properties of Metric Noise Storms Associated with Coronal Mass Ejections

Using Nancay Radioheliograph （NRH） imaging observations, combined with SOHO/Michelson Doppler Imager （MDI） magnetogram observations and coronal magnetic field extrapolation, we studied the magnetic nature of metric noise storms that are associated with coronal mass ejections （CMEs）. Four events arc selected： the events of 2000 July 14, 2001 April 26, 2002 August 16 and 2001 March 28. The identified noise storm sources cover or partially cover the active regions （ARs）, but the centers of storm sources are offset from the ARs. Using extrapolated magnetic field lines, we find that the noise storm sources trace the boundary between the open and closed field lines. We demonstrate that the disappearance of noise storm source is followed by the appearance of the burst source. The burst sources spread on the solar disk and their distributions correspond to the extent of the CME in LASCO C2 field of view. All the SOHO/Extreme Ultraviolet Imaging Telescope （EIT） dimmings associated with noise storm sources are located at the periphery of noise storms where the magnetic lines of force were previously closed and low-lying. When the closed field becomes partially or fully open, the basic configurations of noise storm sources are changed, then the noise storm sources are no longer observed. These observations provide the information that the variations of noise storms manifest the restructuring or reconfiguring of the coronal magnetic field.

Transequatorial Filament Eruption and Its Link to a Coronal Mass Ejection

We revisit the Bastille Day flare/CME Event of 2000 July 14, and demonstrate that this flare/CME event is not related to only one single active region （AR）. Activation and eruption of a huge transequatorial filament are seen to precede the simultaneous filament eruption and flare in the source active region, NOAA AR 9077, and the full halo-CME in the high corona. Evidence of reconfiguration of large-scale magnetic structures related to the event is illustrated by SOHO EIT and Yohkoh SXT observations, as well as, the reconstructed 3D magnetic lines of force based on the force-free assumption. We suggest that the AR filament in AR 9077 was connected to the transequatorial filament. The large-scale magnetic composition related to the transequatorial filament and its sheared magnetic arcade appears to be an essential part of the CME parent magnetic structure. Estimations show that the filament- arcade system has enough magnetic helicity to account for the helicity carried by the related CMEs. In addition, rather global magnetic connectivity, covering almost all the visible range in longitude and a huge span in latitude on the Sun, is implied by the Nan^ay Radioheliograph （NRH） observations. The analysis of the Bastille Day event suggests that although the triggering of a global CME might take place in an AR, a much larger scale magnetic composition seems to be the source of the ejected magnetic flux, helicity and plasma. The Bastille Day event is the first described ex- ample in the literature, in which a transequatorial filament activity appears to play a key role in a global CME. Many tens of halo-CME are found to be associated with transequatorial filaments and their magnetic environment.

Kinematics and amplitude evolution of global coronal extreme ultraviolet waves

With the observations of the Solar-Terrestrial Relations Observatory （STEREO） and the Solar Dynamics Observatory （SDO）, we analyze in detail the kine- matics of global coronal waves together with their intensity amplitudes （so-called ＂perturbation profiles＂）. We use a semi-automatic method to investigate the pertur- bation profiles of coronal waves. The location and amplitude of the coronal waves are calculated over a 30~ sector on the sphere, where the wave signal is strongest. The position with the strongest perturbation at each time is considered as the location of the wave front. In all four events, the wave velocities vary with time for most of their lifetime, up to 15 rain, while in the event observed by the Atmospheric Imaging Assembly there is at, additional early phase with a much higher velocity. The velocity varies greatly between different waves from 216 to 440 km s-1. The velocity of the two waves initially increases, subsequently decreases, and then increases again. Two other waves show a deceleration followed by an acceleration. Three categories of am- plitude evolution of global coronal waves are found for the four events. The first is that the amplitude only shows a decrease. The second is that the amplitude initially increases and then decreases, and the third is that the amplitude shows an orderly in- crease, a decrease, an increase again and then a decrease. All the extreme ultraviolet waves show a decrease in amplitude while propagating farther away, probably because the driver of the global coronal wave （coronal mass ejection） is moving farther away from the solar surface.

Probing the solar transition region： current status and future perspectives

The solar transition region （TR） is the temperature regime from roughly 0.02 MK to 0.8 MK in the solar atmosphere. It is the transition layer from the collisional and partially ionized chromosphere to the collisionless and fully ionized corona. The TR plays an important role in the mass and energy transport in both the quiet solar atmosphere and solar eruptions. Most of the TR emission lines fall into the spectral range of far ultraviolet and extreme ultraviolet （~400/^-1600/~）. Imaging and spec- troscopic observations in this spectral range are the most important ways to obtain information about the physics of the TR. Static solar atmosphere models predict a very thin TR. However, recent high- resolution observations indicate that the TR is highly dynamic and inhomogeneous. I will summarize some major findings about the TR made through imaging and spectroscopic observations in the past 20 years. These existing observations have demonstrated that the TR may be the key to understanding coronal heating and origin of the solar wind. Future exploration of the solar TR may need to focus on the upper TR, since the plasma in this temperature regime （0.1 MK-0.8 MK） has not been routinely imaged before. High-resolution imaging and spectroscopic observations of the upper TR will not only allow us to track the mass and energy from the lower atmosphere to the corona, but also help us to understand the initiation and heating mechanisms of coronal mass ejections and solar flares.

Twist in a polar blowout jet

It is well known that some coronal jets exhibit helical structures and un- twisting. We attempt to inspect the origin of twist in a blowout jet. By means of multiwavelength and multi-angle observations from Solar Dynamics Observatory （SDO） and Solar Terrestrial Relations Observatory-Ahead （STEREO-A）, we firstly report a polar untwisting jet that is a blowout jet which leads to a jet-like coronal mass ejection. From the viewpoint of SDO, the jet shows clear untwisting behavior and two jet-spires. However, from the viewpoint of STEREO-A the jet actually comes from the whiplike prominence eruption and is followed by a white-light jet. Our observations indicate that twist in blowout jets may result from the erupting mini-prominences/mini- filaments in the jet base.

Relationship between CME dynamics and solar flare plasma

The relationship between the velocity of CMEs and the plasma temperature of the associated X-ray solar flares is investigated. The velocity of CMEs increases with plasma temperature （R = 0.82） and photon index below the break energy （R = 0.60） of X-ray flares. The heating of the coronal plasma appears to be significant with respect to the kinetics of a CME from the reconnection region where the flare also occurs. We propose that the initiation and velocity of CMEs perhaps depend upon the dominant process of conversion of the magnetic field energy of the active region to heating/accelerating the coronal plasma in the reconnected loops. Results show that a flare and the associated CME are two components of one energy release system, perhaps, magnetic field free energy.