Determining the Isotopic Composition of Surface Water Vapor Flux From High‐Frequency Observations Using Flux‐Gradient and Keeling Plot Methods

The isotopic composition of surface water vapor flux (δE) is a quantity frequently used to investigate the local and regional cycle. This study reports results comparative evaluation δE determined with Keeling plot flux-gradient methods using high-frequency data collected at cropland site lake site. Three regression models, ordinary least squares (OLS), York's solution (YS), geometric mean regression, were tested method. Results show that concentration-dependent field characterization measurement errors can improve estimation YS regression. For both sites, broad agreement was achieved among method OLS site, biased three models in reference calculated by Craig-Gordon (CG) model evaporation open water. Good aslo between CG under open-fetch conditions. A footprint analysis suggests may be less sensitive fetch than