Cosmic Sense – Hydrological Modeling:Coupled distributed modeling of soil moisture, snow and atmosphere interaction – tuned by cosmic-ray neutron sensing

在Cosmic Sense研究单元的第一阶段，我们开发了一个一致的框架，用于将场尺度固定CRNS观测同化到Noah-MP陆面模式中，该模式与天气研究与预报模式WRF及其水文增强衍生模式WRF- hydro相结合。固定CRNS观测的空间支持是有限的，因为局地降水和潜热通量型对距离的依赖性减弱。为了实现更大的覆盖范围，同化框架现在应该扩展，以便在状态和参数估计过程中同化移动CRNS观测。此外，由于模型中的温度偏差，模拟的雪水储存的季节过程往往与实际情况有很大差异，导致模型在雪季初始化较差。在这里，从CRNS中扩展雪水当量（SWE）估计的同化框架可能是解决这个问题的一种方法。为了在第二阶段实现这些目标，在与Cosmic Sense的合作伙伴密切合作的第一步中，将扩展和评估在模拟水层和中子计数之间进行转换的Cosmic正演算子，以便将中子观测与移动传感器和CRNS测量结合起来。同时，将研究固定和移动CRNS土壤湿度观测数据相结合的最佳同化方法。在此基础上，利用移动平台空间分布的CRNS观测数据在二维空间估计Noah-MP陆面模型的敏感参数，并利用同化框架的状态增强方法估算土壤湿度和SWE。此外，建模领域将扩展到Rott和Ammer流域之外，还将包括计划位于北莱茵威斯特伐利亚州和哈尔茨/德国中部低地地区的第二阶段新的实地活动地点。关于SWE的研究将集中在Ammer和Isar河流域的高寒地区，这两个地区已经包括在第一阶段的模型设置中。我们将进一步完善关于海拔依赖和亚网格异质性效应的方法。更新后的参数化将用于分布式区域模式模拟，在DART-WRF-Hydro模式框架内研究对陆地-大气耦合相互作用的影响。这些完全耦合的模拟将特别使我们能够详细研究同化的CRNS观测对边界层大气变量的影响。

In the first phase of the Cosmic Sense research unit, we developed a consistent framework for the assimilation of field-scale stationary CRNS observations into the Noah-MP land surface model coupled with the Weather Research and Forecasting model WRF and its hydrologically enhanced derivative WRF-Hydro. Stationary CRNS observations are limited with respect to their spatial support as local precipitation and latent heat flux patterns exhibit weakening dependence with larger distances. To achieve larger scale coverage the assimilation framework shall now be extended to allow for the assimilation of mobile CRNS observations in the state- and parameter estimation process. Furthermore, because of temperature biases in the models, the seasonal course of the simulated snow water storage often differs significantly from reality and leads to poor model initializations during the snowy season. Here, extending the assimilation framework for snow water equivalent (SWE) estimates from CRNS could be a remedy for the problem. To address these objectives in phase II, in a first step, and in close cooperation with the partners from Cosmic Sense, the COSMIC forward operator that translates between simulated water layers and neutron counts, will be extended and evaluated for the incorporation of neutron observations with mobile sensors and CRNS measurements over snow. In parallel efforts, an optimal way to combine stationary and mobile CRNS soil moisture observations for data assimilation will be investigated. Based on this setup, spatially distributed CRNS observations from mobile platforms will be used to estimate sensitive parameters of the Noah-MP land surface model in 2D space for soil moisture and SWE estimations with the state augmentation method of the assimilation framework. Furthermore, the modeling domain will be extended beyond the Rott and Ammer catchment, also to include the new field campaign sites of phase II which are planned to be located in North Rhine Westphalia and in the region of the Harz/Central German Lowland. The investigations with respect to SWE will focus on the Alpine region of the Ammer and Isar river catchments, both of which were already included in the model setup of phase I. We will further refine the methods with respect to elevation dependence and sub-grid heterogeneity effects. The updated parametrization will then be used for distributed regional model simulations to study the effect on coupled land atmospheric interactions within the DART-WRF-Hydro modeling framework. These fully coupled simulations will particularly allow us to investigate in detail the impact of assimilated CRNS observations on atmospheric variables in the boundary layer.