Turbulence

Scale (ratio)

Intermittency

Climatology

Statistics

Chromatography

Cartography

Cascade

Precipitation

Rain gauge

Geology

Mathematics

Geography

Environmental science

Chemistry

Meteorology

Atmospheric sciences

AIP conference proceedings

In the present study, we explore the evidence of time scale dependency in cascade generator of a discrete multiplicative random cascade model (MRC) with a long-term goal in mind to see its possible application in temporal rainfall disaggregation for Peninsular Malaysia rainfall. The scale-dependent behaviour of rainfall for time scales from 1 hour to 16 hours has been explored and characterized using the bounded random cascades, a microcanonical version of MRC model. Hourly rainfall observations at 56 rain gauge stations across the peninsula for, on average, a 35-year record period are employed in this study. The stations were grouped according to four regions to investigate the effect of the local climatology and topography on the scale-dependent behaviour. The findings showed that the parameters of microcanonical model are depended on time scales, particularly parameter related to the variability of the cascade generator. The variance of the cascade generator is substantially decreased with the increased of time scales; indicates that rain within an event is smoother at finer scales than at coarser scales. Meanwhile, the probability that intermittency will occur is smaller as the time scales increased; implies that at finer scales, a wet interval is more frequently distributed into both the first and the last half of intervals. The observations of both parameters are consistent since the low variance of the cascade generator has resulted from the densely arranged and evenly distributed rainy intervals – the low probability of the rainfall intermittency at finer scales. Results on the regional differences showed rainfall field in west region displayed a strong dependency of the variability parameter on time scales, and followed by northwest, east and southwest regions. Furthermore, the distribution of rain within an event at a fine scale in the west region is found to be as smooth as rainfall events in northwest and east regions, while rainfall events in the southwest region are mostly randomly distributed.

The exploration of time scale dependency behaviour in Peninsular Malaysia rainfall data