Accurate reproduction of sub-hourly rainfall extremes in Poisson cluster rainfall models with a variable sinusoidal pulse

초록

Despite recent advancements in Poisson cluster rainfall models, challenges remain, particularly in estimating extremes at sub-hourly timescales. This study introduces a refined model, Randomized Bartlett-Lewis Rectangular Pulse model version 7 (RBL7), which addresses these issues by replacing rectangular rain cells with variable sinusoidal shapes. The sine function's power varies inversely with rain cell duration, better reflecting physical rainfall processes such as localized convection with high-intensity, short-duration events. Here, the power of the sine function is determined as a decreasing function of rain cell duration, controlled by three parameters-base power, base duration, and shape-allowing dynamic adjustment to capture varying rainfall intensities. The RBL7 model was calibrated solely at hourly and supra-hourly timescales using 69-year record of rainfall data from a gauge station in Bochum, Germany. Results demonstrate that RBL7 accurately reproduces rainfall extremes across sub-hourly to supra-daily timescales, outperforming existing models using rectangular shapes or sine functions with a constant power of 2. Moreover, RBL7 retains the ability to capture standard rainfall statistics, including mean, variance, covariance, skewness, and wet period proportion, across timescales from 5 min to a decade.

키워드