A comparison of wave mode identification techniques
- 1Automatic Control & Systems Engineering, The University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK
- 2Centre d’étude des Environnements Terrestre et Planétaires, 10–12 avenue de l’Europe, 78140 Vélizy, France
- 3Lab. de Physique et Chimie de l’Environment, 3A Avenue de la Recherche Scientifique, 45071 Orleans cedex 2, France
- 4also at Université de Pierre et Marie Curie, Paris, France
- 5Swedish Institute for Space Physics, Box 537, 751 21 Uppsala, Sweden
Abstract. The four point measurements available from the Cluster mission enable spatiotemporal effects in data sets to be resolved. One application of these multipoint measurements is the determination of the wave vectors and hence the identification of wave modes that exist within the plasma. Prior to multi-satellite missions, wave identification techniques were based upon the interpretation of observational data using theoretically defined relations. However, such techniques are limited by the quality of the data and the type of plasma model employed. With multipoint measurements, wave modes can be identified and their wave directions determined purely from the available observations. This paper takes two such methods, a phase differencing technique and k-filtering and compares their results. It is shown that both methods can resolve the k vector for the dominant mirror mode present in the data. The phase differencing method shows that the nature of the wave environment is constantly changing and as such both methods result in an average picture of the wave environment in the period analysed. The k-filtering method is able to identify other modes that are present.