Novel physical and numerical methods for simulating water and heat transfer in land surface models.

改进陆地水循环的陆地表面模型对于在不断变化的气候中提供更好的预测至关重要，例如洪水预测。陆地表面模型，如UKMO的联合英国陆地环境模拟器（JULES），通过理查兹一维偏微分方程（PDE）的数值形式描述土壤中的非饱和流。这样一个高度非线性方程的解决方案不可避免地会导致数值和精度问题，这会影响其水文性能。最近的注意力集中在采用新的方法来水文模型。该项目涉及两个最近的一维非饱和区流量解决方案的实施和测试（奥格登等人，2015年;李，贝恩斯和兰登，2015年）到朱尔斯。这两种方法都使用基于速度的PDE的深度方面的水含量，奥格登的方法，通过速端转换，贝恩斯的方法，通过当地的质量守恒。Ogden土壤水分速度方程（SMVE）方法已经被应用于三种土壤水分的运移，即入渗、与地表断开的湿润锋和地下水补给。Baines方法（CMF）有待发展。学生将扩展这两种方法来解释热流。该学生奖学金提供了将计算模型应用于高度重要的真实的问题的机会，并将包括访问UKMO。智力挑战将是推导出耦合土壤中水和热传输的一致方法。

Improved land surface modelling for the terrestrial water cycle is critical for providing better forecasts within a changing climate, for example in flood prediction. Land surface models, such as UKMO's Joint UK Land Environment Simulator (JULES), describe unsaturated flow in soils through a numerical form of the Richards one-dimensional partial differential equation (PDE). Such a solution to a highly non-linear equation inevitably leads to numerical and accuracy issues, which impact on their hydrological performance. Recent attention has focussed on adopting novel approaches to hydrological models.This project concerns the implementation and testing of two recent 1-D unsaturated zone flow solution methods (Ogden et al., 2015; Lee, Baines and Langdon, 2015) into JULES. Both methods use a velocity-based PDE for the depth in terms of the water content, the Ogden approach through a hodograph transformation, the Baines approach through local mass conservation. The (different) PDEs are stepped forward in time using an explicit scheme.The Ogden Soil Moisture Velocity Equation (SMVE) method has already been applied to the transport of three regimes of soil moisture, namely infiltration, wetting fronts disconnected from the surface, and groundwater recharge. The Baines approach (CMF) awaits development.The student will extend both approaches to account for heat flow.The studentship affords the opportunity to apply computational modelling to a real problem of high importance, and will include visits to the UKMO.The intellectual challenge will be to derive a consistent method for coupling water and heat transport within the soil.