why the root square of rho and t?

[Super-LeoJayZhang]

Dear Gianluca,
I really like the idea of how you calculate the advective flux. However, I could not understand why you used the root square of rho and t during the calculation. I would appreciate it if you could share any literature references for the equation.

advective_fluxes/adv_flux.py

Lines 101 to 102 in aaa32ea

	q_in_x = h/ds * cps * (rho[j,k]+rho[j,k-1])**0.5 * \
	u[j,k] * (t[j,k]+t[j,k-1])**0.5