Comment on “Nonlinear electron heating by resonant shear Alfvén waves in the ionosphere” by J. Y. Lu et al.

Reply to comment by J.‐P. St.‐Maurice on “Nonlinear electron heating by resonant shear Alfvén waves in the ionosphere”

“…The comment by St.‐Maurice [2005] about the energy of precipitating electrons does not undermine anything in our work. On the contrary, the low energy of precipitating electrons is one of the principal arguments which justify our nonlinear heating mechanism.…”

“…The effective potential given by Lu et al [2005] is ϕ = ε i /2 = 8 eV. This corresponds to the ionization potential ε i = 16 eV, which is even higher than the value claimed by St.‐Maurice [2005]. We acknowledge, however, that our model for ionization is only approximate.…”

“…On the contrary, the low energy of precipitating electrons is one of the principal arguments which justify our nonlinear heating mechanism. In this regard, St.‐Maurice [2005] has completely misunderstood our work. As pointed out by Lu et al [2005], precipitating electrons are effective only at high frequencies 0.1–1 Hz, and can only affect the conductivity over one half of an Alfvén wave period.…”

“… St.‐Maurice [2005] questions the validity of the resonant shear Alfvén wave electron heating mechanism proposed by Lu et al [2005]. In particular, the following arguments have been raised: (i) the electron cooling time given by Lu et al [2005] is underestimated because inelastic electron collisions are neglected; (ii) the ionization rate is incorrect; (iii) the electron and ion conductivities are wrong; (iv) the position of the energy deposition layer is incorrect; (v) the energy of precipitating electrons is not well defined, and (vi) the mechanism is simply not applicable.…”

“… St.‐Maurice [2005] has confused the ion/electron parallel electric conductivity σ with the corresponding Pedersen conductivity σ p . For example, for ions, σ i = n i e i 2 / m i ν i , does not depend on B , while σ pi = σ i does depend on the magnetic field.…”