1. A method of selecting an operating parameter value for supplying energy to an ablation electrode, comprising: (a) receiving a first signal representing a value of a fluid flow rate; (b) receiving a second signal representing a value of an impedance; (c) receiving a third signal representing a value of a distance from an ablation electrode surface to a target tissue surface; and (d) selecting a value for an operating parameter for supplying energy to the ablation electrode as a function of the first, second and third signals.