A case study of orographic rainfall processes incorporating multiscaling characterization techniques

Abstract

The Southern Alps field experiment was designed to identify the dominant rainfall processes in intense orographic events in the South Island of New Zealand and included the deployment of a rain gauge network and meteorological radar. Multiscaling statistics, used to characterize the rainfall from a single extreme event, revealed both orographic and temporal changes in the rainfall nature, with significantly more incessant rainfall observed in the higher‐altitude regions. Central to this work was physical interpretation of the statistical parameters, which contributes toward forming links between multiscaling analysis and meteorological processes necessary for practical applications of multiscaling statistics. A further step was taken by combining the statistical results with other meteorological data to infer details of the physical processes, hence providing an example of the utility of multiscaling characterization of rainfall for improving our understanding of physical rainfall processes. Evidence is presented of lateral broadening of precipitating elements as the alpine divide is approached and is used, in conjunction with the wind profile, to explain the quasi‐incessant rainfall observed near the divide.