Search Publications
Spatio-Temporal Analysis of Photospheric Turbulent Velocity Fields Using the Proper Orthogonal Decomposition
Vecchio, A.; Carbone, V.; Veltri, P. +4 more
The spatio-temporal dynamics of the solar photosphere are studied by performing a proper orthogonal decomposition (POD) of line-of-sight velocity fields computed from high-resolution data coming from the SOHO/MDI instrument. Using this technique, we are able to identify and characterize the different dynamical regimes acting in the system. All of …
EIS/ Hinode Observations of Doppler Flow Seen through the 40-Arcsec Wide-Slit
Madjarska, M. S.; Innes, D. E.; Hara, H. +1 more
The Extreme ultraviolet Imaging Spectrometer (EIS) onboard Hinode is the first solar telescope to obtain wide-slit spectral images that can be used for detecting Doppler flows in transition region and coronal lines on the Sun and to relate them to their surrounding small-scale dynamics. We select EIS lines covering the temperature range 6×104…
Similarities and Dissimilarities between the Variations of CME and Other Solar Parameters at Different Heliographic Latitudes and Time Scales
Kane, R. P.
From the LASCO CME (Coronal Mass Ejection) catalog, the occurrence frequencies of all CMEs (all strong and weak CMEs, irrespective of their widths) were calculated for 3-month intervals and their 12-month running means determined for cycle 23 (1996 - 2007) and were compared with those of other solar parameters. The annual values of all-CME frequen…
Latitude Dependence of the Variations of Sunspot Group Numbers (SGN) and Coronal Mass Ejections (CMEs) in Cycle 23
Kane, R. P.
The 12-month running means of the conventional sunspot number Rz, the sunspot group numbers (SGN) and the frequency of occurrence of Coronal Mass Ejections (CMEs) were examined for cycle 23 (1996 - 2006). For the whole disc, the SGN and Rz plots were almost identical. Hence, SGN could be used as a proxy for Rz, for which latitude data are not avai…
Determination of the True Shape of Coronal Loops
Gontikakis, C.; Alissandrakis, C. E.; Dara, H. C.
Using line of sight velocity measurements from the SUMER and CDS instruments aboard SOHO, in conjunction with a simple geometrical model, we reconstructed the true, 3D shape and the velocity of plasma flow along coronal loops. The projection of the loop on the sky and the position of the footpoints define a family of curves. Assuming that the loop…
Widespread Occurrence of Trenching Patterns in the Granulation Field: Evidence for Roll Convection?
Getling, A. V.; Buchnev, A. A.
Time-averaged series of granulation images are analysed using COLIBRI, a purpose-adapted version of a code originally developed to detect straight or curvilinear features in aerospace images. The image-processing algorithm utilises a nonparametric statistical criterion that identifies a straight-line segment as a linear feature (lineament) if the …
Cross-Calibration of TIMED SEE and SOHO EIT Irradiances
Eparvier, F. G.; Hock, R. A.
Absolutely calibrated solar images are necessary for a variety of solar physics problems, such as the identification of solar variability sources and the derivation of differential emission measure (DEM) maps. SOHO EIT is absolutely calibrated by using TIMED SEE spectra to provide a method of determining physical values of irradiance for EIT image…
Analysis of Two Coronal Loops with Combined TRACE and SOHO/CDS Data
Martens, P. C. H.; Cirtain, J. W.; Scott, J. T.
We use an innovative research technique to analyze combined images from the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO) and the Transition Region and Coronal Explorer (TRACE). We produce a high spatial and temporal resolution simulated CDS raster or "composite" map from TRACE data and use this composite m…
Coronal Mass Ejections, Magnetic Fields, and the Green Corona in Cycle 23
Rušin, V.; Minarovjech, M.; Saniga, M.
We study a time - latitudinal distribution of CMEs observed by the SOHO spacecraft, their projected speeds and associated magnetic fields, as well as the north - south (N - S) asymmetry of solar surface magnetic fields, and the coronal green line intensities. We have found that (a) there exists an intricate relation between the average projected v…
Very Large Array, SOHO, and RHESSI Observations of Magnetic Interactions and Particle Propagation across Large-Scale Coronal Loops
Groff, Tyler D.; Willson, Robert F.
Very Large Array (VLA) observations at wavelengths of 20 and 91 cm have been combined with data from the SOHO and RHESSI solar missions to study the evolution of transequatorial loops connecting active regions on the solar surface. The radio observations provide information about the acceleration and propagation of energetic electrons in these lar…