Steps toward a high precision solar rotation profile: Results from SDO/AIA coronal bright point data

Coronal bright points (CBP) are ubiquitous small brightenings in the solar corona associated with small magnetic bipoles. We derive the solar differential rotation profile by tracing the motions of CBPs detected by the Atmospheric Imaging Assembly (AIA) instrument aboard the Solar Dynamics Observatory (SDO). We also investigate problems related to detection of coronal bright points resulting from instrument and detection algorithm limitations. To determine the positions and identification of coronal bright points we used a segmentation algorithm. A linear fit of their central meridian distance and latitude versus time was utilised to derive velocities. We obtained 906 velocity measurements in a time interval of only 2 days. The differential rotation profile can be expressed as $\omega_{rot} = (14.47\pm 0.10 + (0.6\pm 1.0)\sin^{2}(b) + (-4.7\pm 1.7)\sin^{4}(b))$\degr day$^{-1}$. Our result is in agreement with other work and it comes with reasonable errors in spite of the very short time interval used. This was made possible by the higher sensitivity and resolution of the AIA instrument compared to similar equipment as well as high cadence. The segmentation algorithm also played a crucial role by detecting so many CBPs, which reduced the errors to a reasonable level. Data and methods presented in this paper show a great potential to obtain very accurate velocity profiles, both for rotation and meridional motion and, consequently, Reynolds stresses. The amount of coronal bright point data that could be obtained from this instrument should also provide a great opportunity to study changes of velocity patterns with a temporal resolution of only a few months. Other possibilities are studies of evolution of CBPs and proper motions of magnetic elements on the Sun

Geoeffectiveness of Coronal Mass Ejections in the SOHO era

The main objective of the study is to determine the probability distributions of the geomagnetic Dst index as a function of the coronal mass ejection (CME) and solar flare parameters for the purpose of establishing a probabilistic forecast tool for the geomagnetic storm intensity. Several CME and flare parameters as well as the effect of successive-CME occurrence in changing the probability for a certain range of Dst index values, were examined. The results confirm some of already known relationships between remotely-observed properties of solar eruptive events and geomagnetic storms, namely the importance of initial CME speed, apparent width, source position, and the associated solar flare class. In this paper we quantify these relationships in a form to be used for space weather forecasting in future. The results of the statistical study are employed to construct an empirical statistical model for predicting the probability of the geomagnetic storm intensity based on remote solar observations of CMEs and flares

Preliminary results on the solar rotation determined tracing SDO/AIA coronal bright points

In this paper we present preliminary results on the solar differential rotation measured tracing coronal bright points in SDO/AIA images. An automatic recognition method was applied to the series of images taken in the test period, 1-2 January 2011. Coronal bright points are suitable tracers for the determination of the solar differential rotation, because they are localized objects which are very well distributed over solar disc. Results presented in this paper show that the SDO/AIA data are very useful for that aim, due to the high spatial and temporal resolution of the images