Fig. 5
The net effect for the change of the atmospheric mass by the asteroids impacting on Mars at (a) 19 [km/s] and (b) 14.5 [km/s]. ρvap is assumed to be 3000 [kg/m3] to convert the non-dimensional parameter σ to the atmospheric pressure on Mars. w denotes the volatile fraction in the vapor cloud which accumulates to the atmosphere. The net change of the atmospheric mass is given as 
, and normalized with the total impactor mass in the plot. The exponent β in the impactor flux expression is fixed to −0.47.