Earth Planets Space, Vol. 61 (No. 5), pp. 585-588, 2009LETTER
F. L. Guarnieri1, B. T. Tsurutani2, and E. Echer3
1Universidade do Vale do Paraiba (UNIVAP), Sao José dos Campos, SP, Brazil
2Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA
3Instituto Nacional de Pesquisas Espaciais, INPE, Sao Jose dos Campos, SP, Brazil
(Received February 7, 2008; Revised April 15, 2008; Accepted May 5, 2008; Online published May 29, 2009)
A new code, called the interplanetary magnetic decrease (MD) automatic detection (IMDAD) code, has been developed to enable researchers in the field to rapidly identify MD events for further analyses. The criterion used for MD selection is Bmin < X B0, where X is a variable value and B0 is the ambient magnetic field magnitude. The code can be applied to data sets from different instruments/missions located in different space plasma environments in the heliosphere. The code has been tested during slow solar wind, fast solar wind and CIR intervals at ∼5 AU (from November 28 to December 03, 1992). For this test, we used a sliding window with a width of 300~seconds applied to 1-second high-resolution magnetic field data. The events identified by the code have been confirmed by hand analyses. The routine was able to identify 57 of the 118 MDs identified by hand (∼50%). The selection criteria for IMDAD and hand-analyses MDs were not exactly the same, accounting for the different rates of occurrence. What is particularly encouraging is that IMDAD did not falsely identify any events. The discrepancies between the two methods are discussed in the text. This code will be made available to the general public.
Key words: Interplanetary magnetic decreases, solar wind, Alfvén waves.