Surface renewal performance to independently estimate sensible and latent heat fluxes in heterogeneous crop surfaces

Summary Surface renewal (SR) analysis is an interesting alternative to eddy covariance (EC) flux measurements. We have applied two recent SR approaches, with different theoretical background, that from Castellvi (2004) , SR Cas , and that from Shapland et al. (2012a,b) , SR Shap . We have applied both models for sensible ( H ) and latent (LE) heat flux estimation over heterogeneous crop surfaces. For this, EC equipments, including a sonic anemometer CSAT3 and a krypton hygrometer KH20, were located in two zones of drip irrigated orchards of late and early maturing peaches. The measurement period was June–September 2009. The SR Cas is based on similarity concepts for independent estimation of the calibration factor ( α ), which varies with respect to the atmospheric stability. The SR Shap is based on analysis of different ramp dimensions, separating the ones that are flux-bearing from the others that are isotropic. According to the results obtained here, there was a high agreement between the 30-min turbulent fluxes independently derived by EC and SR Cas . The SR Shap agreement with EC was slightly lower. Estimation of fluxes determined by SR Cas resulted in higher values (around 11% for LE) with respect to EC, similarly to previously published works over homogeneous canopies. In terms of evapotranspiration, the root mean square error (RMSE) between EC and SR was only 0.07 mm h −1 (for SR Cas ) and 0.11 mm h −1 (for SR Shap ) for both measuring spots. According to the energy balance closure, the SR Cas method was as reliable as the EC in estimating the turbulent fluxes related to irrigated agriculture and watershed distribution management, even when applied in heterogeneous cropping systems.