Space-Time Rainfall: Scaling, Extremes and Prediction

0228835 Veneziano-The项目的目标是研究降雨量在空间和时间上的比例，并开发水文应用模型，包括极端和短期预测。这是PI及其同事最近在时间降雨方面所做工作的延伸。要解决的主要问题是：标度不变性：确定是否和以何种形式的有限的多重分形标度特性的时间降雨（在小尺度和天气事件）扩展到时空。 建模：一种新型的更新模型与多重分形脉冲为基础的降雨事件已被证明是成功的时间降雨序列建模。将这些模型扩展到时空，以再现开/关统计数据、标度不变性、空间和时间依赖性、极端情况和降雨的其他关键特性。极值：根据降雨的时空特性，推导出面积-强度-持续时间-频率曲线的理论标度律。利用这些理论定律来推断观测范围之外的情况。预测：研究基于时空尺度特性的短期降雨预报方法，对水文学具有重要的理论意义和实用价值。将通过统计建模、理论比例分析、数值模拟和验证以及时空降雨记录分析（来自GATE和TOGA-COARE实验）来进行这些研究。在过去，降雨模式强调中尺度大气环流的概念脉冲结构或湍流的多重分形级联结构。我们将开发的模型联合收割机这两个方面，并使用一个简约的参数化。极值对水文设计和风险分析具有重要意义。从理论上确定它们的标度行为将使我们能够更有信心地在观测范围之外进行外推，并与气候参数联系起来。同样重要的是真实的时间预报，为此，我们打算开发灵活和实用的方法，利用时空降雨的标度特性。该项目下的发展也直接关系到通过短期降雨预测和长期洪水风险评估来减少时空降雨量和预防灾害。

0228835VenezianoThe objective of the project is to study the scaling of rainfall in space and time and develop models for hydrologic application including extremes and short-term forecasting. This is an extension of work done recently by the PI and co-workers on temporal rainfall. The main issues to be addressed are: Scaling invariance: Determine whether and in what form the limited multifractal scaling properties of temporal rainfall (at small scales and within synoptic events) extend to space-time. Modeling: A new type of renewal models with multifractal pulse-based rainfall events has proved successful in modeling temporal rainfall series. Extend these models to space-time in a way that reproduces on/off statistics, scaling invariance, spatial and temporal dependencies, extremes, and other key properties of rainfall. Extremes: Derive theoretical scaling laws for the Area-Intensity-Duration-Frequency curves based on properties of space-time rainfall. Use these theoretical laws to extrapolate beyond the observation range. Forecasting: Develop short-term forecasting methods based on the scaling properties of time-space rainfall.These issues are of great theoretical and practical importance to hydrology. They will be pursued through a combination of statistical modeling, theoretical scaling analysis, numerical simulation and validation, and analysis of space-time rainfall records (from the GATE and TOGA-COARE experiments). In the past, rainfall models have emphasized either the conceptual pulse structure of meso-scale atmospheric circulation or the multifractal cascade structure of turbulence. The models we shall develop combine both aspects and use a parsimonious parameterization. Extremes are of obvious importance for hydrologic design and risk analysis. Theoretical determination of their scaling behavior will allow more confident extrapolation beyond the observation range as well as linkage to climatic parameters. Of equal importance is real time forecasting, for which we intend to develop flexible and practical methods that take advantage of the scaling properties of space-time rainfall. The developments under this project are directly relevant also to space-time rainfall downscaling and disaster prevention through short-term rainfall prediction and long-term flood risk assessment.