Skewness as measure of the invariance of instantaneous renormalized drop diameter distributions – Part 1: Convective vs. stratiform precipitation

Abstract

Abstract. We investigate the variability of the shape of the renormalized drop diameter instantaneous distribution using of the third order central moment: the skewness. Disdrometer data, collected at Darwin Australia, are considered either as whole or as divided in convective and stratiform precipitation intervals. We show that in all cases the distribution of the skewness is strongly peaked around 0.64. This allows to identify a most common distribution of renormalized drop diameters and two main variations, one with larger and one with smaller skewness. The distributions shapes are independent from the stratiform vs. convective classification.

Skewness as measure of the invariance of instantaneous renormalized drop diameter distributions – Part 2: Orographic precipitation

“…Most of these are the same as those used in the companion paper (Ignaccolo and De Michele, 2012), in which case we present only a "quick" summary (the interested reader will find in the companion paper all the details), while new methods will be described in detail.…”

“…Darwin is on the coast backed by plains and it can be safely assumed the land surface "influence" on rain (intended as disturbance on rainfall rates, drop size distributions, and all the possible features of the rainfall phenomenon) is negligible. This data set is the same one used in the companion paper "Skewness as measure of the invariance of instantaneous renormalized drop diameter distributions -Part 1: Convective vs. stratiform precipitation" (Ignaccolo and De Michele, 2012). Bodega Bay is located on the coast of California, for extensive period of times (White at al., 2003;Martner et al, 2008).…”

“…In the companion paper (Ignaccolo and De Michele, 2012) we have investigated the variability at Darwin for the entire dataset and the stratiform and convective subsets. Hereby this investigation is repeated for the Bodega Bay and the Cazadero datasets in their entirety and dividing each of these in two subsets: BB (bright band echo present) and NBB (bright band echo absent).…”

“…As in the companion paper (Ignaccolo and De Michele, 2012), we divide each dataset in subsets of comparable values of skewness: skewness classes. For each skewness class subset, we compare the renormalized spectra for BB and NBB rain periods.…”

“…Here we use the skewness parameter, and the procedure developed in the companion paper (Ignaccolo and De Michele, 2012), to investigate the variability of instantaneous renormalized spectra of rain drop diameter in presence of orographic precipitation. Disdrometer data, available at Bodega Bay and Cazadero, California, are analyzed either as a whole, or as divided (using the bright band echo) in precipitation intervals weakly and strongly influenced by orography, and compared to results obtained at Darwin, Australia.…”