Wu et al .
( 2009 ) suggested an empirical relation between the magnetic field strength along the line of sight ( LOS ) and the dispersion of Faraday rotation measure ( RM ) distribution in turbulent media with root-mean-square sonic Mach number M _ { s } \simeq 1 .
In this paper , we extend the work by incorporating the Mach number dependence .
Media with 0.5 \raise 1.29 pt \hbox { $ < $ } \kern - 7.5 pt { \lower 2.795 pt \hbox { $ \sim$ } } M _ { s } % \raise 1.29 pt \hbox { $ < $ } \kern - 7.5 pt { \lower 2.795 pt \hbox { $ \sim$ } } 2 are considered to cover the Mach number range of the warm ionized medium ( WIM ) of our Galaxy .
Three-dimensional , magnetohydrodynamic isothermal turbulence simulations with solenoidal forcing are used .
We suggest a new relation among the LOS magnetic field strength , the dispersion of RM distribution , and the Mach number , which approximately represents the relation for Alfvénic perturbations .
In addition , we suggest a relation between the Mach number and the dispersion of log-normal distribution of emission measure ( EM ) , which is basically the relation for the Mach number and the density dispersion .
The relations could be used for a quick and rough estimation of the LOS magnetic field strength in the turbulent WIM .