On the nature of rainfall intermittency as revealed by different metrics and sampling approaches

Giuseppe Mascaro, R. Deidda, M. Hellies

    Research output: Contribution to journalArticle

    28 Citations (Scopus)

    Abstract

    A general consensus on the concept of rainfall intermittency has not yet been reached, and intermittency is often attributed to different aspects of rainfall variability, including the fragmentation of the rainfall support (i.e., the alternation of wet and dry intervals) and the strength of intensity fluctuations and bursts. To explore these different aspects, a systematic analysis of rainfall intermittency properties in the time domain is presented using high-resolution (1-min) data recorded by a network of 201 tipping-bucket gauges covering the entire island of Sardinia (Italy). Four techniques, including spectral and scale invariance analysis, and computation of clustering and intermittency exponents, are applied to quantify the contribution of the alternation of dry and wet intervals (i.e., the rainfall support fragmentation), and the fluctuations of intensity amplitudes, to the overall intermittency of the rainfall process. The presence of three ranges of scaling regimes between 1 min to ∼ 45 days is first demonstrated. In accordance with past studies, these regimes can be associated with a range dominated by single storms, a regime typical of frontal systems, and a transition zone. The positions of the breaking points separating these regimes change with the applied technique, suggesting that different tools explain different aspects of rainfall variability. Results indicate that the intermittency properties of rainfall support are fairly similar across the island, while metrics related to rainfall intensity fluctuations are characterized by significant spatial variability, implying that the local climate has a significant effect on the amplitude of rainfall fluctuations and minimal influence on the process of rainfall occurrence. In addition, for each analysis tool, evidence is shown of spatial patterns of the scaling exponents computed in the range of frontal systems. These patterns resemble the main pluviometric regimes observed on the island and, thus, can be associated with the corresponding synoptic circulation patterns. Last but not least, we demonstrate how the methodology adopted to sample the rainfall signal from the records of the tipping instants can significantly affect the intermittency analysis, especially at smaller scales. The multifractal scale invariance analysis is the only tool that is insensitive to the sampling approach. Results of this work may be useful to improve the calibration of stochastic algorithms used to downscale coarse rainfall predictions of climate and weather forecasting models, as well as the parameterization of intensity-duration-frequency curves, adopted for land planning and design of civil infrastructures.

    Original languageEnglish (US)
    Pages (from-to)355-369
    Number of pages15
    JournalHydrology and Earth System Sciences
    Volume17
    Issue number1
    DOIs
    StatePublished - Jan 29 2013

    Fingerprint

    rainfall
    sampling
    fragmentation
    weather forecasting
    climate
    precipitation intensity
    transition zone
    gauge
    parameterization
    infrastructure
    analysis
    calibration
    methodology
    prediction

    ASJC Scopus subject areas

    • Water Science and Technology
    • Earth and Planetary Sciences (miscellaneous)

    Cite this

    On the nature of rainfall intermittency as revealed by different metrics and sampling approaches. / Mascaro, Giuseppe; Deidda, R.; Hellies, M.

    In: Hydrology and Earth System Sciences, Vol. 17, No. 1, 29.01.2013, p. 355-369.

    Research output: Contribution to journalArticle

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