The goal of the North American Land Data Assimilation System (NLDAS) is to construct quality-controlled, and spatially and temporally consistent, land-surface model (LSM) datasets from the best available observations and model output to support modeling activities. Data sets are available on hourly, daily, monthly and climatological time scales. NLDAS products are used in modeling, research, and applications, such as drought and flood monitoring, watershed and water quality management, and case studies of extreme events.

There are two phases referred to as NLDAS-1 and NLDAS-2. The latter spans January 1979-present. "NLDAS (Mitchell et al., 2004; Xia et al., 2012) integrates a large quantity of observation based and model reanalysis data to drive offline (not coupled to the atmosphere) land surface models (LSMs), and executes at 1/8th-degree grid spacing over central North America."