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Forbush Decrease (FD)

    A description of the Forbush Effect is given in the Wikipedia article.

    To look for a Forbush decrease one has to estimate the particle rate as percentage deviation from an average rate. The strength of a FD is then the difference between the average value before the event and the rate at the minimum. The website spaceweather shows detected FDs since 1957. The parameter of the strength Dmin is presented in the table. For a search of FDs in the data of our muon detectors and mini neutron monitors one should choose FD events with Dmin < -1. Examples of FDs measured by neutron monitors can be found on the website of the neutron monitor data base.