Revisiting rainfall clustering and intermittency across different climatic regimes
Revisiting rainfall clustering and intermittency across different climatic regimes
复制标题
重新审视不同气候条件下的降雨聚集和间歇性
DOI：
10.1029/2008wr007352
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发表时间：
2009
影响因子：
5.4
通讯作者：
A. Porporato
中科院分区：
文献类型：
--
作者：
A. Molini;G. Katul;A. Porporato
降雨研究中的一个令人烦恼的问题是不稳定性及其非普适特征在异常标度函数中的作用。这种普遍行为的缺乏是否是由于降雨强度的突发模式或长期干旱期和高度聚集的潮湿阶段（或两者兼而有之）之间的交替，仍然是一个悬而未决的问题。为了在更窄的范围内解决这个问题，首先将降雨发生引起的不稳定性的影响与强度变率引起的降雨不稳定性分开。在这里考虑的五种气候状态中，降雨发生过程（OP）显示出（1）接近恒定的谱斜率，（2）接近恒定的聚类指数，（3）干燥阶段的概率密度函数显示出指数β = 1.5的幂律行为，与其他与锋面和风暴系统相称的时间尺度研究一致。同样对于OP，标度指数的归一化高阶结构函数揭示了广泛的单分形标度在所有五个气候制度。当考虑在一起，这些站点间的结果表明，降雨强度调制的非普遍的异常缩放的主要原因，而不是与支持的聚类特性。这些调制的性质是显着不同的比较降雨时，一个熟悉的，往往是相互关联的过程，如标量湍流。在湍流的情况下，标量耗散率的振幅变化似乎减轻了与异常标度相关的不稳定性效应，而对于降雨序列，强度波动似乎放大了它们。
One of the vexing questions in rainfall research is the role of intermittency and its nonuniversal signature in anomalous scaling functions. Whether this lack of universal behavior is due to the bursting patterns in rainfall intensity or the alternation between long dry periods and highly clustered wet phases (or both) remains an open issue. To progress on a narrower scope of this problem, the effects of intermittency originating from rainfall occurrence are first separated from rainfall intermittency induced by intensity variability. Across five climatic regimes considered here, it was shown that the rainfall occurrence process (OP) exhibits (1) a near‐constant spectral slope, (2) a near‐constant clustering exponent, and (3) a probability density function of dry phases displaying a power law behavior with an exponent β ≈ 1.5, consistent with other studies for timescales commensurate with frontal and storm systems. Also for the OP, the scaling exponents of the normalized higher order structure functions reveal an extensive monofractal scaling at all five climatic regimes. When taken together, these intersite results are suggestive that rainfall intensity modulations are the main cause of the nonuniversal anomalous scaling and not the clustering properties associated with the support. The nature of these modulations is markedly different when comparing rainfall to a familiar and often interrelated process such as scalar turbulence. In the case of turbulence, amplitude variability of scalar dissipation rates appear to mitigate the intermittency effects connected with anomalous scaling, while for rainfall series, intensity fluctuations seem to amplify them.