The endpoint vanishing of the rescaled vorticities along the zoom sequence #
The endpoint vanishing in Steps 2 and 3 of the proof of
prop:aniso:small: once the rescaled scalar (the potential vorticity Ω_n in the finite-axis
case, the azimuthal vorticity Θ_n in the receding-axis case) converges locally uniformly up to
τ = -1, and its limit solves the limit equation (eq:aniso:zoom:finite:limit, respectively
eq:aniso:zoom:receding:limit:a) with an admissible drift, the limit inherits the decay bound
of eq:aniso:zoom:finite:bound (respectively eq:aniso:zoom:receding:bound) because
δ_n → 0, the comparison principle lem:aniso:comparison makes it vanish, and hence the
rescaled scalars tend to zero at every point of {τ = -1} (off the axis in the finite-axis
case). The zoom centres move with n, as in eq:aniso:zoom:finite:variables and
eq:aniso:zoom:receding:variables.
A fixed point of the zoomed variables with τ < 0 is eventually mapped into the unit
cylinder by the finite-axis zoom about the moving axis points (0, zc n), |zc n| ≤ ρ < 1.
δ_n² = (λ_n^{2h})² → 0 along a zoom sequence λ_n → 0⁺.
The decay bound of the finite-axis limit, inherited from eq:aniso:zoom:finite:bound
since δ_n → 0: at a point with τ < 0, a limit of Ω_n along the zoom sequence is bounded by
C |τ|^{-3/2-h}.
The decay bound of the receding-axis limit, inherited from
eq:aniso:zoom:receding:bound since δ_n → 0.
The finite-axis endpoint vanishing along the zoom sequence: if the rescaled potential
vorticities at the moving axis points converge locally uniformly on {R > 0, τ ≤ -1} to a
limit Ω whose lift solves eq:aniso:zoom:finite:limit with an admissible drift, then
Ω_n(·, -1) tends to zero at every point off the axis.
The receding-axis endpoint vanishing along the zoom sequence: if the rescaled azimuthal
vorticities at the moving centres converge locally uniformly on ℝ² × (-∞, -1] to a limit Θ
solving eq:aniso:zoom:receding:limit:a with an admissible drift, then Θ_n(·, -1) tends to
zero at every point.
F2-Q: the lifted limit of the rescaled potential vorticities is locally bounded on
ℝ⁵ × (-∞, -1), with the decay of eq:aniso:zoom:finite:bound inherited from δ_n → 0.
Uniform convergence on a set of finite measure gives convergence of the integral of the
distance, in ℝ≥0∞.
R2-L1: locally uniform convergence on Vec m × (-∞, T] gives L¹ convergence on every
compact subset of Vec m × (-∞, T).