Search Publications
Characteristics of SEPs during solar cycles 21–24
Kumar, Raj; Pande, Bimal; Pande, Seema +1 more
The study of the solar energetic particle events (SEPs) and their association with solar flares and other activities are very crucial to understand the space weather. Keeping this in view, here we present the study of SEPs (intensity
Relation between solar flares and halo coronal mass ejections
Sankarasubramanian, K.; Rao, V. Koteswara; Gopal, K. Rama +2 more
Solar flares and coronal mass ejections (CMEs) are two very important active events from Sun. Inspite of several theoretical and statistical analyses, the relation between solar flares and CMEs is so far not well established, and strong opinions and arguments still continue. Statistical approaches use a lot of data available from many measurements…
Solar cycle variation of interplanetary coronal mass ejection latitudes
Li, K. J.; Gao, P. X.
With the use of interplanetary coronal mass ejections (ICMEs) compiled by Richardson and Cane from 1996 to 2007 and the associated coronal mass ejections (CMEs) observed by the Large Angle and Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO), we investigate the solar cycle variation of real ICME-associated CM…
Models of solar irradiance variations: Current status
Solanki, Sami K.; Krivova, Natalie A.
Regular monitoring of solar irradiance has been carried out since 1978 to show that solar total and spectral irradiance varies at different time scales. Whereas variations on time scales of minutes to hours are due to solar oscillations and granulation, variations on longer time scales are driven by the evolution of the solar surface magnetic fiel…
Next generation UV coronagraph instrumentation for solar cycle-24
Kohl, John L.; Cranmer, Steven R.; Raymond, John C. +4 more
Ultraviolet coronagraph observations of the extended solar corona (defined here as 1.5 to 10 solar radii from Sun-center) have become a powerful tool for obtaining detailed empirical descriptions of coronal holes, streamers, and coronal mass ejections. The empirical models resulting from ultraviolet coronagraph observations provide the constraints…
UV diagnostics for the energy budget of flares and CMEs
Raymond, J. C.
Solar flares and coronal mass ejections convert large amounts of magnetic free energy into thermal, kinetic and potential energies, and into energy of non-thermal particles. The partitioning among these forms of energy is fundamental to both the physics of the eruptive events and the space weather consequences of the eruptions. This talk describes…
Oblique Propagation and Dissipation of Alfv&én Waves in Coronal Holes
Srivastava, A. K.; Dwivedi, B. N.
We investigate the effect of viscosity and magnetic diffusivity on the oblique propagation and dissipation of Alfvén waves with respect to the normal outward direction, making use of MHD equations, density, temperature and magnetic field structure in coronal holes and underlying magnetic funnels. We find reduction in the damping length scale, grou…
The EUV Spectrum of Sunspot Plumes Observed by SUMER on SOHO
Dwivedi, B. N.; Curdt, W.; Feldman, U.
We present results from sunspot observations obtained by SUMER on SOHO. In sunspot plumes the EUV spectrum differs from the quiet Sun; continua are observed with different slopes and intensities; emission lines from molecular hydrogen and many unidentified species indicate unique plasma conditions above sunspots. Sunspot plumes are sites of system…
Electron Density and Temperature Measurements, and Abundance Anomalies in the Solar Atmosphere
Landi, Enrico; Dwivedi, Bhola N.; Mohan, Anita
Using spectra obtained from the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrograph on the spacecraft SOHO (Solar and Heliospheric Observatory), we investigate the height dependence of electron density, temperature and abundance anomalies in the solar atmosphere. In particular, we present the behaviour of the solar FIP effect …