Automatic identification of Short Large-Amplitude Magnetic Structures (SLAMS) using Cluster data

Abstract: Short Large-Amplitude Magnetic Structures (SLAMS) are areas in the solar wind with increasedmagnetic field strength in comparison to the background magnetic field. In this thesis they are definedas structures with a magnetic field strength 2.5 times greater than the background magnetic field duringa short time duration. An algorithm for locating these structures in data from the ESA Cluster satellites,was developed. The structure of the algorithm was to first locate the solar wind, compute the backgroundmagnetic field and then compute the fraction of the magnetic field at each data point with the backgroundmagnetic field and sort each time period with a fraction above 2.5 as potential SLAMS. Data from Decemberto May for 2002 to 2008 were analysed since the satellites were located in the solar wind during thesetime periods.From statistical analysis of the position and properties of the identified SLAMS, it was clear that amajority of the SLAMS were found predominantly close to the bow shock, about 3 RE from the modelledbow shock. It was also clear that the majority of the SLAMS had a magnetic field strength just above2.5 times the background magnetic field, and this did not vary with the distance form the bow shock.However the few SLAMS with a greater magnetic field than 5 times the background magnetic field werepredominantly found close to the bow shock, about 3 RE from the modelled shock.