Observational biases in the PV double-peak separation method for our reference edge-on case (i = 87°), as a functionof the DW radial extension (for α = −2, connected red dots) and emissivity index α (for r_out/r_in = 32, connected green dots): panels a and b show specific angular momentum and poloidal velocity estimated from the PV double-peak separation; c and d show launch radius and magnetic lever arm parameter inferred from the observed quantities in (a) and (b) using Anderson’s relations (Eqs. (1) and (2)). Values that would be obtained for a single ring on the outermost wind streamline are shown in dotted red curves. The true magnetic lever arm parameter λ_BP of the MHD solution and relevant values at r_in are indicated for reference in dot-dashed blue.