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

点击翻译按钮获取中文摘要

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.