The Jack Rabbit chlorine release experiments: Implications of dense gas removal from a depression and downwind concentrations

► The 2010 Jack Rabbit chlorine dispersion field experiment is described. ► A 1 or 2 ton chlorine cloud was released in 30 s into a shallow depression. ► The Briggs et al. (JHM, 1990) theory captures the hold-up time of the dense cloud. ► The time duration td for detrainment depends strongly on the wind speed u. ► Observed downwind concentrations compare well with SLAB model predictions.