Space Science Group
Pattern recognition and statistical analysis of solar activity
Head of Research Group Prof Valentina Zharkova
Prof Zharkova currently holds a PPARC grant due to commence in October 2007 ‘Protons Versus Electrons Kinetics in Flaring Atmospheres’ £167,805.
The Bradford Space Science team has developed the searchable database of solar features http://solar.inf.brad.ac.uk automatically extracted from solar images. This database contains the locations, sizes and intensities of active region, sunspots and filaments extracted from white light, H-alpha and Ca KIII full disk solar images obtained from the space (SOHO) and ground (Meudon) observatories in the past solar cycle 23 (1996-2006).
Based on the statistical analysis of long time variations of sunspot and active region sizes, areas, cumulitative areas and flare occurrences for the whole disk and for the Northern and Southern hemispheres of the Sun, we detected strong North-South asymmetries in the sunspot and AR areas and their excess magnetic fields as well as short term (2.5 years) and long-term (~10 years) periodicities associated with the solar dynamo cycle. The new database allowed us to investigate further statistical properties of the detected features as a function of their longitudes and latitudes and their links with the changes of the global solar magnetic field. This statistical analysis opens new perspectives in modelling the solar activity cycle with solar dynamo and its forecast using the Artificial Intelligence and Bayesian techniques.
Particle kinetics and dynamics in flaring atmospheres
Another development of Bradford Space Science group includes the investigation in kinetic approach of electron and proton acceleration and precipitation in flaring atmospheres with density gradients, see: http://kinetics.inf.brad.ac.uk. A simple model of 3D reconnecting current sheet is considered to describe the primary energy release in solar flares and geomagnetic tail. This model helped to discover spatial separation and temporal delay in the appearances of hard X-ray and gamma-ray sources on the Sun and to predict the ejection of particle beams with power law energy spectra. Also this model allows us to connect the spectral indices of hard X-ray and gamma-ray energy spectra with the magnetic field topologies occurring in flaring atmospheres and to link them with the global solar activity. Further precipitation of these proton and electrons beams to the bottom of a flaring atmosphere and their resulting double power hard X-ray photon spectra are also investigated. This allowed to explain often observed double power law hard X-ray photon spectra and soft-hard-soft (SHS)spectral evolution from the same flare with the additional electron energy losses in the self-induced electric field (see the website for the RHESSI satellite, the nuggets from 24/04/06 and 05/06/06 (http://sprg.ssl.berkeley.edu/~tohban/nuggets/ ).
These two developments will help us to understand the nature of the solar activity in solar activity centres during its different phases and to test the model predictions for the solar cycle 23.
European Grid of Solar Observations (EGSO)
EGSO was an EU funded Grid project involving 10 groups from 5 countries. The main contribution of the Bradford Cybernetics team to the larger project was the development of feature recognition algorithms in application to the solar image database system, e.g. the occurrence and location of active region, flares, filament and other features derived from the data stored within the grid itself. see the group's website for more information.
EGSO is funded under the IST (Information Society Technologies) thematic programme of European Commission's Fifth Framework Programme (FP5). The project started in March 2002 and will last for 3 years. The EGSO consortium comprises 10 institutes from Europe and the US, and is led by the Mullard Space Science Laboratory (MSSL) of University College London (UCL).