SUMMA 2.0.0

SUMMA (Clark et al., 2015a;b;c) is a hydrologic modeling framework that can be used for the systematic analysis of alternative model conceptualizations with respect to flux parameterizations, spatial configurations, and numerical solution techniques. It can be used to configure a wide range of hydrological model alternatives and we anticipate that systematic model analysis will help researchers and practitioners understand reasons for inter-model differences in model behavior. When applied across a large sample of catchments, SUMMA may provide insights in the dominance of different physical processes and regional variability in the suitability of different modeling approaches. An important application of SUMMA is selecting specific physics options to reproduce the behavior of existing models – these applications of \"model mimicry\" can be used to define reference (benchmark) cases in structured model comparison experiments, and can help diagnose weaknesses of individual models in different hydroclimatic regimes.

SUMMA is built on a common set of conservation equations and a common numerical solver, which together constitute the “structural core” of the model. Different modeling approaches can then be implemented within the structural core, enabling a controlled and systematic analysis of alternative modeling options, and providing insight for future model development.

The important modeling features are:

The formulation of the conservation model equations is cleanly separated from their numerical solution;

Different model representations of physical processes (in particular, different flux parameterizations) can be used within a common set of conservation equations; and

The physical processes can be organized in different spatial configurations, including model elements of different shape and connectivity (e.g., nested multi-scale grids and HRUs).

SUMMA（Clark等人，2015a、b、c）是一款水文建模框架，可针对通量参数化、空间配置与数值求解技术，系统开展不同模型概念化方案的对比分析。该框架支持配置多样化的水文模型变体，我们预期通过系统化的模型分析，能够帮助研究者与实践者理解不同模型在行为表现上产生差异的根源。当在大量流域样本中应用时，SUMMA可助力洞察不同物理过程的主导地位，以及不同建模方法适用性的区域异质性。SUMMA的一项重要应用是选取特定的物理选项以复现现有模型的运行特征——这类“模型复刻（model mimicry）”应用可用于在结构化模型对比实验中定义参考（基准）案例，同时有助于诊断不同水文气候区下单个水文模型的缺陷。

SUMMA基于一套通用的守恒方程与通用数值求解器构建，二者共同构成该模型的“结构核心”。随后，各类不同的建模方法可在该结构核心内实现部署，从而实现对不同建模选项的受控且系统化的对比分析，并为未来的模型开发提供参考依据。

该框架的核心建模特性如下：
1. 守恒模型方程的构建过程与数值求解过程实现了清晰解耦；
2. 在通用守恒方程体系下，可采用不同的物理过程模型表征方式（尤其是不同的通量参数化方案）；
3. 物理过程可通过多种不同的空间配置进行组织，包括不同形状与连通性的模型单元（例如嵌套多尺度网格与水文响应单元（Hydrologic Response Units, HRUs））。