Intra‐annual rainfall variability control on interannual variability of catchment water balance: A stochastic analysis
Intra‐annual rainfall variability control on interannual variability of catchment water balance: A stochastic analysis
复制标题
年内降雨量变化对流域水平衡年际变化的控制：随机分析
DOI：
10.1029/2010wr009869
复制
发表时间：
2012
影响因子：
5.4
通讯作者：
M. Sivapalan
中科院分区：
文献类型：
--
作者：
S. Zanardo;C. Harman;P. Troch;P. Rao;M. Sivapalan
我们评估了年内降雨量变化对流域水量平衡年际变化的控制程度。为此，我们考虑了年内降水波动的随机性，忽略了所有其他变化的来源，解析地推导出了年Budyko蒸发指数B(即年实际蒸散量与年降水量之比)的概率密度函数。我们将我们的分析模型应用于位于美国毗邻地区不同气候区域的424个集水区，以执行这一评估。总体而言，我们发现该模型能够解释平均值B，但对其变异系数的预测精度较低。然而，在相当多的流域，该模型可以提供对B的概率密度函数的充分预测。在B的观测统计和预测统计之间的残差中可以区分明显的地理模式。因此，年际变化并不总是与年内的随机降雨量波动有关。在一些地区，其他控制措施，如季节性和植被适应，可能更重要。模型参数的敏感性分析有助于根据包括气候和土壤特性在内的三个无量纲比率来表征对B分布的主导控制。这项研究是对集水区水量平衡年际变化的气候控制进行诊断性、数据驱动分析的第一步。
We evaluate the extent to which within‐year rainfall variability controls interannual variability of catchment water balance. To this end, we analytically derive the probability density function of the annual Budyko evaporation index, B (i.e., the ratio of annual actual evapotranspiration to annual precipitation), by accounting for the stochastic nature of intra‐annual rainfall fluctuation and neglecting all other sources of variability. We apply our analytical model to 424 catchments located in different climatic regions across the conterminous United States to perform this assessment. In general, we found that the model is capable of explaining mean B but is less accurate in predicting its coefficient of variation. Nonetheless, in a significant number of catchments the model can provide adequate predictions of the probability density function of B. Clear geographic patterns can be distinguished in the residuals between observed and predicted statistics of B. Interannual variability is thus not always associated with random intra‐annual rainfall fluctuations. In some regions, other controls, such as seasonality and vegetation adaptations, are possibly more important. A sensitivity analysis of model parameters helped characterize the dominant controls on the distribution of B in terms of three dimensionless ratios that include climatic and soil characteristics. This study represents the first step in a diagnostic, data‐driven analysis of the climatic controls on the interannual variability of catchment water balance.