Fig. 9

(a–b) Wave form stress contribution (R) vs wind speed (\(U_{10}\)). (c-d) wind-steepness vs \(U_{10}\). Colors represent different experiment conditions: FW (black solid), FW-F (red), TX-F (blue). Shaded area marks the confidence interval of the fit. The black line is the prediction from Donelan et al.3.