Integration of state-of-the-art satellite soil moisture and terrestrial water storage products with hydrological modeling in support of water security in Canada

水安全和水资源的可持续性是加拿大今天面临的最紧迫的挑战之一。为了解决这一问题，我们必须能够准确和迅速地监测和预测加拿大的水文过程在时间和空间上如何变化。卫星数据收集（地球观测）和水文建模的最新进展为更好地了解水循环行为及其如何随气候变化而变化提供了机会。然而，地球观测和水文模拟在实际应用中都存在局限性。先进的数据同化技术可用于优化地融合地球观测和水文模拟。然而，在完全集成的地下水-地表水计算模型中，缺乏卫星衍生水文产品的多尺度同化和不同变量卫星产品的联合同化。本提案旨在填补这一研究空白，特别是对加拿大流域。该项目旨在开发一个多元同化框架，将遥感土壤湿度和陆地水储存（TWS）数据与完全集成的地表-地下流动模型相结合，以促进对地球系统地表和地下水运动的物理过程的理解。土壤湿度和TWS对全球水、能量和生物地球化学循环起着根本的控制作用。美国国家航空航天局的SMAP（土壤湿度主被动）任务和欧洲航天局的SMOS（土壤湿度海洋盐度）任务代表了目前卫星土壤湿度估计的最新技术，而重力恢复和气候实验（GRACE）任务及其继任者GRACE- fo可以提供每月的TWS数据。通过开发的多元同化系统，SMAP和SMOS遥感土壤水分和GRACE/GRACE- fo的TWS观测数据将被同化成一套针对加拿大不同地区建立的地下水-地表水模型。本项目将结合开发的模拟同化系统、卫星产品和地面观测，解决一系列基础科学问题，如：卫星土壤湿度和TWS产品在多大程度上推进基于物理的地下水-地表水计算模拟？卫星观测和水文建模的结合如何提高我们监测和预测加拿大地表水和地下水资源随时间和空间变化的能力？以及控制加拿大水循环的物理过程如何随着气候变化而变化？在保护加拿大淡水资源和更好地了解全球和区域水文循环过程及其对全球变化的参与方面，拟议的项目与国家和国际优先事项非常一致。

Water security and the sustainability of water resources is one of the most urgent challenges facing Canada today. To address this concern, we must be able to accurately and rapidly monitor and predict how Canada's hydrologic processes vary over space in time. Recent advances in data collection from satellites (Earth observation) and hydrological modeling offer the opportunity to better understand the water cycle behavior and how it is changing in response to climate change. However, both Earth observation and hydrological modeling have limitations in practical applications. Advanced data assimilation technologies can be used to optimally merge Earth observation and hydrological modeling. However, there has been a lack of multiscale assimilation of satellite-derived hydrologic products and joint assimilation of different variable satellite products in fully integrated groundwater-surface water computational models. This proposal seeks to fill this research gap, particularly for Canadian drainage basins. This project aims to develop a multivariate assimilation framework for integrating remotely sensed soil moisture and terrestrial water storage (TWS) data with fully integrated surface-subsurface flow modeling to advance understanding of the physical processes that govern water movement in both the surface and subsurface domains of the Earth system. Both soil moisture and TWS exert fundamental control on global water, energy, and biogeochemical cycles. NASA's SMAP (Soil Moisture Active Passive) mission and European Space Agency's SMOS (Soil Moisture Ocean Salinity) mission represent the current state-of-the-art in satellite soil moisture estimation, while the Gravity Recovery and Climate Experiment (GRACE) mission and its successor, GRACE-FO could provide the monthly TWS data. The remotely sensed soil moisture from SMAP and SMOS and the TWS observations from GRACE/GRACE-FO will be assimilated into a suite of groundwater-surface water models established for different regions across Canada through the developed multivariate assimilation system. Through the combined use of the developed modeling and assimilation system, satellite products, and the ground observations, this project will address a series of fundamental science questions, such as: to what extent satellite soil moisture and TWS products can advance physically-based groundwater-surface water computational modeling? how an integration of satellite observations and hydrological modeling can advance our ability to monitor and predict the variations of surface water and groundwater resources over space and time in Canada? and how the physical processes that govern the water cycle in Canada is changing in response to climate change? The proposed project is very well aligned with national and international priorities in terms of protecting Canada's freshwater resources and better understanding the global and regional hydrological cycle processes and their involvement in global changes.