;+
; NAME:
;  vty16_dfluxdtemp_substrate
; PURPOSE: (one line)
;  Return (d flux / d T) associated with thermal inertia
; DESCRIPTION:
;  Return (d flux / d T) associated with thermal inertia
; CATEGORY:
;  Volatile Transport
; CALLING SEQUENCE:
;  phi_s = vty16_dfluxdtemp_substrate(freq, therminertia)
; INPUTS:
;  freq : frequency in s^-1
;  therminertia : thermal inertia in erg cm^-2 s^-0.5 K^-1
; OUTPUTS:
;  phi_gamma : d flux/d T in erg cm^-2 s^-1 K^-1
;    where flux is the thermal conduction
; RESTRICTIONS:
; PROCEDURE:
;  Young, L. A. 2016, Volatile transport on inhomogeneous surfaces: II. Numerical calculations (VT3D)
;   Resubmitted to Icarus.
;   Eq. 3.2-9a
; MODIFICATION HISTORY:
;  Written 2011 Apr 10, by Leslie Young, SwRI
;  2016 Mar 24 LAY. Modified for inclusion in vty16 library.
;-

function vty16_dfluxdtemp_substrate, freq, therminertia

    return, sqrt(freq) * therminertia

end