Comment on "Distinct Thresholds for the Initiation and Cessation of Aeolian Saltation From Field Measurements" by Raleigh L. Martin and Jasper F. Kok: Alternative Interpretation of Measured Thresholds as two Distinct Cessation Thresholds

Abstract: Martin and Kok (2018a) measured two distinct aeolian saltation transport thresholds: a larger threshold below which continuous saltation transport becomes intermittent and a smaller threshold below which intermittent saltation transport ceases. In the spirit of Bagnold, they interpreted the former threshold as the \textit{fluid threshold}, associated with transport initiation, and the latter threshold as the \textit{impact threshold}, associated with transport cessation. Here I describe and support an alternative interpretation of these two thresholds as two distinct cessation thresholds associated with splash entrainment and, respectively, with compensating energy losses of rebounding particles. This interpretation was recently proposed by P\"ahtz and Dur\'an (2018a). To resolve this controversy, further field studies are needed.