Deriving Mutually-Consistent Carbon-Water Fluxes at the Regional Scale from Observations by Using a Coupled Biosphere-Atmosphere Model

尽管观测能力显著增强，但由于缺乏一个单一、一致的框架来模拟碳循环和水循环，以利用新的观测结果，反映出水文学和碳科学之间的学科分离，因此碳和水的地表通量仍然存在很大的不确定性。研究人员将开发一个分析系统，通过将众多飞机活动，卫星传感器和地面平台的观测与最先进的大气和陆地表面模型相结合，同时量化区域尺度的碳和水通量。其目标是量化和显著减少过去和未来地表碳和水通量估计的不确定性，并从同时使用多个数据流中提取关于碳-水循环的信息，综合的正向和反向建模框架将与碳和水文观测相结合。首先，研究人员将在北美区域实施一个正演模拟系统SiBRAMS，该系统以WLEF涡度协方差测量塔为中心，其中有许多支持卫星塔，以便于收集观测信息，用于模型评估和改进。其次，他们将通过以下方式建立碳-水联合反演系统：（a）将水及其大气源/汇加入基于STILT的反演系统，（B）检查碳-水反演中线性近似产生的误差，（c）对联合碳-水通量进行初始反演分析，（d）将反演结果与IHOP和COBRA实验的井约束观测结果进行比较。该项目的主要成果包括开发一个分析框架，该框架包括正向和反向模型，并利用碳和水文相关观测，以及以WLEF塔为中心的北美区域相互一致的碳和水通量估计。该项目的广泛影响是教育性的，并有可能弥合水文-碳社区和促进新的研究方向。

Despite significant enhancements in observational capability, substantial uncertainties remain in surface fluxes of carbon and water due to the lack of a single, consistent framework that models both the carbon and water cycles to make use of new observations, reflecting the disciplinary separation between the hydrological and carbon sciences. The investigators will develop an analysis system that simultaneously quantifies regional-scale carbon and water fluxes by combining observations from numerous aircraft campaigns, satellite sensors, and ground-based platforms with state-of-the-art models of the atmosphere and land surface. The objectives are to quantify and significantly reduce uncertainties in past and future estimates of surface carbon and water fluxes and extract information on the carbon-water cycles from simultaneous use of multiple data streams.The integrated forward and inverse modeling framework will be anchored to both carbon- and hydrologic observations. First, the investigators will implement a forward modeling system SiBRAMS over a North American domain, which is centered over the WLEF eddy covariance measurement tower where a number of support satellite towers are available, to facilitate the gathering of observational information for model evaluation and improvement. Second, they will build the joint carbon-water inversion system by (a) adding water and its atmospheric sources/sinks to STILT-based inversion system, (b) examining errors resulting from linear approximation in carbon-water inversion, (c) conducting initial inversion analysis of joint carbon-water fluxes, and (d) comparing inversion results with well-constraint observations from IHOP and COBRA experiments. Main deliverables from this project include the development of an analysis framework, which includes both forward and inverse models and makes use of both carbon- and hydrologically related observations, and estimates of mutually-consistent carbon and water fluxes over a North American domain centered around WLEF tower. Broad impacts of this project are educational and in the potential to bridge the hydrology-carbon communities and foster new research directions.