Bias in closed-form gamma parameter estimates for disdrometer data

Bias in a recently introduced closed-form estimator for gamma parameters is described via simulations over a wide range of feasible parameters. The simulated data are lower truncated and grouped with a Joss-Waldvogel disdrometer bin regime. A crude model for the bias in a ratio of adjacent moments is sufficient to eliminate most of the gamma parameter bias. This provides confidence in the parameter estimates, at least for near gamma distributed data and larger sample sizes.