Robin C. Colaninno

CONNECTING SPEEDS, DIRECTIONS AND ARRIVAL TIMES OF 22 CORONAL MASS EJECTIONS FROM THE SUN TO 1 AU

Forecasting the in situ properties of coronal mass ejections (CMEs) from remote images is expected to strongly enhance predictions of space weather and is of general interest for studying the interaction of CMEs with planetary environments. We study the feasibility of using a single heliospheric imager (HI) instrument, imaging the solar wind density from the Sun to 1 AU, for connecting remote images to in situ observations of CMEs. We compare the predictions of speed and arrival time for 22 CMEs (in 2008-2012) to the corresponding interplanetary coronal mass ejection (ICME) parameters at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). The list consists of front-and backsided, slow and fast CMEs (up to 2700 km s(-1)). We track the CMEs to 34.9 +/- 7.1 deg elongation from the Sun with J maps constructed using the SATPLOT tool, resulting in prediction lead times of - 26.4 +/- 15.3 hr. The geometrical models we use assume different CME front shapes (fixed-Phi, harmonic mean, self-similar expansion) and constant CME speed and direction. We find no significant superiority in the predictive capability of any of the three methods. The absolute difference between predicted and observed ICME arrival times is 8.1 +/- 6.3 hr (rms value of 10.9 hr). Speeds are consistent to within 284 +/- 288 km s(-1) . Empirical corrections to the predictions enhance their performance for the arrival times to 6.1 +/- 5.0 hr (rms value of 7.9 hr), and for the speeds to 53 +/- 50 km s(-1). These results are important for Solar Orbiter and a space weather mission positioned away from the Sun-Earth line.

FIRST DETERMINATION OF THE TRUE MASS OF CORONAL MASS EJECTIONS: A NOVEL APPROACH TO USING THE TWO STEREO VIEWPOINTS

The twin Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) COR2 coronagraphs of the Solar Terrestrial Relations Observatory (STEREO) provide images of the solar corona from two viewpoints in the solar system. Since their launch in late 2006, the STEREO Ahead (A) and Behind (B) spacecraft have been slowly separating from Earth at a rate of 225 per year. By the end of 2007, the two spacecraft were separated by more than 40° from each other. At that time, we began to see large-scale differences in the morphology and total intensity between coronal mass ejections (CMEs) observed with SECCHI-COR2 on STEREO-A and B. Due to the effects of the Thomson scattering geometry, the intensity of an observed CME is dependent on the angle it makes with the observed plane of the sky. From the intensity images, we can calculate the integrated line-of-sight electron density and mass. We demonstrate that it is possible to simultaneously derive the direction and true total mass of the CME if we make the simple assumption that the same mass should be observed in COR2-A and B.

THE FIRST OBSERVATION OF A RAPIDLY ROTATING CORONAL MASS EJECTION IN THE MIDDLE CORONA

In this Letter, we present the first direct detection of a rotating coronal mass ejection (CME) in the middle corona (5-15 R ?). The CME rotation rate is 60? day-1, which is the highest rate reported yet. The Earth-directed event was observed by the STEREO/SECCHI and SOHO/LASCO instruments. We are able to derive the three-dimensional morphology and orientation of the CME flux rope by applying a forward-fitting model to simultaneous observations from three vantage points (SECCHI-A, -B, LASCO). Surprisingly, we find that even such rapidly rotating CME does not result in significant projection effects (variable angular width) in any single coronagraph view. This finding may explain the prevalent view of constant angular width for CMEs above 5 R ? and the lack of detections of rotating CMEs in the past. Finally, the CME is a stealth CME with very weak low corona signatures as viewed from Earth. It originated from a quiet-Sun neutral line. We tentatively attribute the fast rotation to a possible disconnection of one of the CME footpoints early in the eruption. We discuss the implications of such rotations to space weather prediction.

IS SOLAR CYCLE 24 PRODUCING MORE CORONAL MASS EJECTIONS THAN CYCLE 23

Although sunspot numbers are roughly a factor of two lower in the current cycle than in cycle 23, the rate of coronal mass ejections (CMEs) appears to be at least as high in 2011-2013 as during the corresponding phase of the previous cycle, according to three catalogs that list events observed with the Large Angle and Spectrometric Coronagraph (LASCO). However, the number of CMEs detected is sensitive to such factors as the image cadence and the tendency (especially by human observers) to under-/overcount small or faint ejections during periods of high/low activity. In contrast to the total number, the total mass of CMEs is determined mainly by larger events. Using the mass measurements of 11,000 CMEs given in the manual CDAW catalog, we find that the mass loss rate remains well correlated with the sunspot number during cycle 24. In the case of the automated CACTus and SEEDS catalogs, the large increase in the number of CMEs during cycle 24 is almost certainly an artifact caused by the near-doubling of the LASCO image cadence after mid-2010. We confirm that fast CMEs undergo a much stronger solar-cycle variation than slow ones, and that the relative frequency of slow and less massive CMEs increases with decreasing sunspot number. We conclude that cycle 24 is not only producing fewer CMEs than cycle 23, but that these ejections also tend to be slower and less massive than those observed one cycle earlier.

PROPAGATION OF THE 2014 JANUARY 7 CME AND RESULTING GEOMAGNETIC NON-EVENT

On 7 January 2014 an X1.2 flare and CME with a radial speed

USING ForeCAT DEFLECTIONS AND ROTATIONS TO CONSTRAIN THE EARLY EVOLUTION OF CMEs

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ACTIVE-REGION TILT ANGLES: MAGNETIC VERSUS WHITE-LIGHT DETERMINATIONS OF JOY'S LAW

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CME Propagation: Where does Aerodynamic Drag 'Take Over'?

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Relationship of EUV Irradiance Coronal Dimming Slope and Depth to Coronal Mass Ejection Speed and Mass

was observed from near an active region close to disk center. This led many forecasters to estimate a rapid arrival at Earth (

On the 3-D reconstruction of Coronal Mass Ejections using coronagraph data

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