Intermittency buildup across precipitation cascades: Endogenous versus exogenous factors

The temporal variability of precipitation originates from the multiplicative effects of air uplift and vapor-to-liquid conversion. The latter is commonly represented by a product of conversion efficiency and water vapor fluctuations. How exogenous effects such as those related to uplift contribute to the precipitation variance and to the build-up of intermittency within the precipitation cascade is investigated. The analysis employs a large dataset of 5-minute precipitation time series collected in a domain characterized by a combination of orographic, frontal, and convective systems, each with at least 30 years in record length. Exogenous versus endogenous factors (i.e. those related to water vapor turbulent fluctuations) responsible for intermittency build-up across the precipitation cascade were explored using the so-called propagator kernel. This analysis shows that precipitation generation maintains its signature at scales one order of magnitude smaller than the integral time. This interaction between exogenous and endogenous factors appears more significant in high-elevation precipitation records. The overall effect of such interactions is to reduce the anomalous scaling at the sub-storm time scales.